# data[].attributes.body
MSBTE MODEL ANSWER & Q PAPER

# data[].attributes.body
Steam Properties

# data[].attributes.attachment_link.readable_text
Associate Professor at The NorthCap University & Consultant

1. 1. Thermodynamic Properties & Measurement Dr. Rohit Singh Lather

2. 2. Important fundamental base SI units * Mass: Kilogram (kg), Pound (lbm) - Kilogram (kg): is a mass equal to the mass of the international prototype of the kilogram (a platinum-iridium bar stored in Paris), roughly equal to the mass of one liter of water at standard temperature and pressure * Length: Meter (m), Foot (ft) - Meter (m): the length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second * Time: seconds (s) - Second: (s), the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom * Temperature: an equilibrium property which roughly measures how hot or cold an object is - Note our senses are poor judges of temperature - Our bodies actually have more sensitivity to heat fluxes instead of temperature; heat leaves our body more rapidly when in contact with high density objects like snow relative to that of low density objects like air Introduction Source: Joseph M. Powers, "Lecture notes on thermodynamics", University of Notre Dame, Notre Dame, Indiana, USA

3. 3. - Kelvin: (K) the fraction 1/273.16 of the thermodynamic temperature of the triple point of water - Rankine: (◦R) * Energy: roughly speaking, the ability to do work, found from the product of force and distance - Joule: (J), 1 J = 1 (N m) - Foot-pound force: (ft lbf) * Specific Volume: the volume per unit mass, known as v = V/m - !" #$ , %&" '(! * Density: the mass per unit volume, the inverse of specific volume ρ = m/V Source: Joseph M. Powers, "Lecture notes on thermodynamics", University of Notre Dame, Notre Dame, Indiana, USA

4. 4. Pressure 1 Pa = 1 N/m2 1 bar = 1 x 105 Pa = 0.1 MPa 1 atm = 101325 Pa 1 torr = 133.3 Pa Static and Dynamic Pressure The unit of pressure are Pa, psi, atm., bar, torr force in newton or lb area in m2 or in2 Dynamic Pressure Pressure exerted by a fluid or gas when it impacts on a surface or an object due to its motion or flow Static Pressure Pressure of fluid or gases that are stationary or not in motion * Pressure as the normal component of force per unit area (exerts on solids, gas and liquid) P = ) * Note that stress is not a true pressure since it is not scalar Pressure is related to momentum, while temperature is related to kinetic energy

5. 5. * In most thermodynamic investigations we are concerned with absolute pressure * In thermodynamics, we are almost always concerned with the absolute pressure as opposed to the gauge pressure * Most pressure and vacuum gauges read the difference between the absolute pressure and the atmospheric pressure existing at the gauge. This is referred to as gauge pressure The gauge and absolute pressures are related via the formula Pgauge = Pabsolute − Patm. We nearly always interpret P as an absolute pressure, so we could also say Pgauge = P − Patm. - Pascal: (Pa), 1 Pa = 1 N/m2; 1 bar = 105 Pa, 1 atm = 1.01325 × 105 Pa = 101.325 kPa = 0.101325 MPa - (psia): 1 psia = 1 lbf/in.2 1 atm = 14.696 psia. The a denotes the "absolute" pressure as opposed to the "gauge" pressure. The units psig refer to a gauge pressure

6. 6. * Pressure is a property of fluids, which, by definition cannot support a shear * Stress comes in three forms: * Tensile/compressive stresses are related to forces normal to a surface * Shear stresses are in the plane of the surface * The bulk modulus is related to hydrostatic forces (pressure) * Except for the fact that the bulk modulus is measured by applying hydrostatic pressure, stress relates to properties of solids

7. 7. Absolute zero reference Pressure Absolute Pressure Gauge Pressure Local atmospheric Pressure reference Gauge Pressure Suction/Vacuum Gauge Pressure is relative pressureAbsolute Pressure is Real Pressure (pg > 0 or pg < 0; while pabs > 0 always) ∴ pabs = pg + patm > 0 Gauge Pressure Pressure measured w.r.t atmospheric pressure (unit = psig) Absolute Pressure Pressure measured w.r.t a vacuum (unit = psia) Atmospheric Pressure Pressure on the earth's surface due to the weight of gases in the earth's atmosphere

8. 8. Pressure Measuring Instrument * The techniques for pressure measurement is depending on pressure level. (moderate, very high, very low) Very high pressure level is higher than 1000 bar Very low pressure level is below than 0.001 bar Low Pressure Measurement - McLeod gauge - Pirani gauge - Ionization gauge High Pressure Measurement - Electrical Resistance pressure gauge Moderate Pressure Measurement - Manometer - Elastic elements (diaphragm, bellows, capsules, bourdon tubes, spiral, helix)

9. 9. Manometer * Manometer: a pressure measuring instrument, usually limited to measuring pressures near to atmospheric * Pressures below atmospheric and slightly above atmospheric, and pressure differences (for example, across an orifice in a pipe), are frequently measured with a manometer, which contains water, mercury, alcohol, oil, or other fluids. * The term manometer is often used to refer specifically to liquid column hydrostatic instruments * Manometer is the simplest device for measuring static pressure ΔP = m.g.Δh Pressure line connected Fluid water/ mercury or any other suitable fluid in the manometer tube Column forced down Fluid rises Measure the difference in height of the fluid in the two columns Pressure of the inlet can be expressed in inches of fluid

10. 10. Fluid at P, mg PatmA PA PATM A g y Newton's Second Law of motion m +, - +&, = P.A − Patm .A − m.g For static cases, the acceleration +, - +&, = 0 Thus, we require a force balance, i.e. mechanical equilibrium, which is achieved when 0 = P.A − Patm.A − m.g P.A = Patm.A + m.g So, Thus, P.A = PatmA + ρ.A.H.g P = Patm + ρ.g.H ∆P = P − Patm = Pgauge = ρ.g.H m.g = ρ.V.g V is the volume of the fluid V = A.H H m.g = ρ.A.H.g Source: Joseph M. Powers, "Lecture notes on thermodynamics", University of Notre Dame, Notre Dame, Indiana, USA ρ

11. 11. Types of Manometer U-tube Manometer Well-type Manometer Incline-tube Manometer Photo Source: www.cnx.org

12. 12. * Absolute pressure is zero referenced against a "perfect vacuum" (it-the value-is equal to gauge pressure plus atmospheric pressure) * Gauge pressure is zero referenced against ambient air pressure; it-the value-is equal to absolute pressure minus atmospheric pressure. Negative signs are usually omitted; often expressed as "inches of vacuum" or some such * Differential pressure is the difference in pressure between two points

13. 13. Mercury Barometer Photo Source: www.cnx.org Mercury Barometer measures atmospheric pressure Pressure due to weight of mercury equals atmospheric pressure The atmosphere is able to force mercury in the tube of a height because the pressure above the mercury is zero

14. 14. Hydrostatic Pressure * Hydrostatic pressure is the pressure in a liquid * The pressure increases as the depth in a liquid increases, due to its weight * In term of equation, P = ρgh ρ = density in kg/m3 g = acceleration due to gravity (9.8m/s2) h = depth in liquid in m P = pressure in Pa Hydrostatic gauges (such as the mercury column manometer) compare pressure to the hydrostatic force per unit area at the base of a column of fluid Hydrostatic gauge measurements are independent of the type of gas being measured, and can be designed to have a very linear calibration. They have poor dynamic response

15. 15. Piston Types Gauge * Piston-type gauges counterbalance the pressure of a fluid with a solid weight or a spring * For example dead-weight testers used for calibration and Tire-pressure gauges

16. 16. Mechanical Gauges - Bourdon type, Bellows type * Key concept: pressure difference across different areas of inner and outer surfaces causes crescent to flex Photo Source: www.cnx.org

17. 17. Heat * For quantitative purposes we utilize the change of volume which takes place in all bodies when heated under constant pressure, for this admits of exact measurement * Heating produces in most substances an increase of volume, and thus we can tell whether a body gets hotter or colder, not merely by the sense of touch, but also by a purely mechanical observation affording a much greater degree of accuracy * The conception of heat arises from that particular sensation of warmth or coldness which is immediately experienced on touching a body Direct sensation, however, - gives no quantitative scientific measure of a body's state with regard to heat - It yields only qualitative results, which vary according to external circumstances Source: Treatise on Thermodynamics , DR. Max Plank, The University of Berlin, Translated by Alexander Ogg University of Capetown, S.A. 3rd Edition * Temperature is a measure of the 'intensity of heat' * Temperature: - is a measure of the average kinetic energy of the constituent entities (say molecules) - is the parameter which determines the distribution of species (say molecules) across various energy states available.

18. 18. * If two bodies, one of which feels warmer than the other, be brought together (for example, a piece of heated metal and cold water), it is invariably found that the hotter body is cooled, and the colder one is heated up to a certain point, and then all change ceases. The two bodies are then said to be in thermal equilibrium * Experience shows that such a state of equilibrium finally sets in, not only when two, but also when any number of differently heated bodies are brought into mutual contact A B C A B C If a body, A, be in thermal equilibrium with two other bodies, B and C, then B and C are in thermal equilibrium with one another A B C Thermal Equilibrium Source: Treatise on Thermodynamics , DR. Max Plank, The University of Berlin, Translated by Alexander Ogg University of Capetown, S.A. 3rd Edition

19. 19. Zeroth law of thermodynamics - Axiom * The so-called zeroth law of thermodynamics is the axiom which is probably most fundamental * Formalized after the so-called first and second laws, and so it is called the zeroth law Zeroth law of thermodynamics: When two bodies have equality of temperature with a third body, then they have equality of temperature The equivalent statement in mathematical logic is that if x = y and x = z, then y = z; this is in fact equivalent to the first of Euclid's common notions: things that are equal to the same thing are also equal to each other * Definition of the zeroth law enables the use of a thermometer as a measurement device * A scale however needs to be defined. * The old metric temperature scale, Celsius (C), was defined so that 0C is the freezing point of water, and 100 C is the boiling point of water Source: Joseph M. Powers, "Lecture notes on thermodynamics", University of Notre Dame, Notre Dame, Indiana, USA

20. 20. * Enable us to compare the degree of heat of two bodies, B and C, without bringing them into contact with one another * Namely, by bringing each body into contact with an arbitrarily selected standard body, A (for example, a mass of mercury enclosed in a vessel terminating in a fine capillary tube) * By observing the volume of A in each case, it is possible to tell whether B and C are in thermal equilibrium or not * If they are not in thermal equilibrium, we can tell which of the two is the hotter * A an arbitrarily selected normal volume, namely, the volume of A when in thermal equilibrium with melting ice under atmospheric pressure A SteamAIce * This volumetric difference, which, by an appropriate choice of unit, is made to read 100 when A is in contact with steam under atmospheric pressure is called the temperature in degrees Centigrade with regard to A as thermometric substance Two bodies of equal temperature are, therefore, in thermal equilibrium, and vice versa The temperature readings of no two thermometric substances agree, in general, except at 0nand 100 The definition of temperature is therefore somewhat arbitrary Source: Treatise on Thermodynamics , DR. Max Plank, The University of Berlin, Translated by Alexander Ogg University of Capetown, S.A. 3rd Edition

21. 21. * Permanent gases, in particular which are hard to condense, such as hydrogen, oxygen, nitrogen, and carbon monoxide, and are taken as thermometric substances * They agree almost completely within a considerable range of temperature, and their readings are sufficiently in accordance for most purposes * Besides, the coefficient of expansion of these different gases is the same, as equal volumes of them expand under constant pressure by the same amount about . ,/" of their volume when heated from 0∘C to 1∘C * Since, also, the influence of the external pressure on the volume of these gases can be represented by a very simple law, we are led to the conclusion that - these regularities are based on a remarkable simplicity in their constitution - therefore, it is reasonable to define the common temperature given by them simply as temperature. - Consequently reduce the readings of other thermometers to those of the gas thermometer Source: Treatise on Thermodynamics , DR. Max Plank, The University of Berlin, Translated by Alexander Ogg University of Capetown, S.A. 3rd Edition

22. 22. Thermodynamic Temperature Scale * A temperature scale that is independent of the properties of any substance or substances is called a thermodynamic temperature scale * All temperature scales are based on some easily reproducible states such as the freezing and boiling points of water, which are also called the ice point and the steam point, respectively A Triple Point Cell Solid Ice, Liquid Water and Water Vapor Co-exist in thermal Equilibrium By international Agreement the temperature of this mixture has been defined to be 273.16K Steam Point: A mixture of liquid water and water vapor (with no air) in equilibrium at 1 atm pressure Ice Point: A mixture of ice and water that is in equilibrium with air saturated with vapor at 1 atm pressure

23. 23. * The temperature scales used in the SI and in the English system Celsius scale (Swedish astronomer A. Celsius, 1702-1744) On the Celsius scale, is defined so that 0∘C is the freezing point of water, and 100∘C is the boiling point of water Degree Celsius is commonly used in meteorological observation Fahrenheit scale (German instrument maker G. Fahrenheit, 1686-1736) The corresponding values on the Fahrenheit scale are 32 and 212°F. These are often referred to as two-point scales since temperature values are assigned at two different points T(F) = 1.8T (C) + 32

24. 24. The Celsius and Fahrenheit Scales TC = T − 273.15

25. 25. * Volume varies with pressure however, so different values would be obtained on top of a mountain versus down in the valley, and so this is not a good standard * The modern Celsius scale is defined to be nearly the same, but has - 0.01 C as the so-called triple point of water − 273.15 ◦C as absolute zero in K * The triple point of water is defined at the state where three phase of water (solid, liquid, and gas) are observed to co-exist * The transformation between the absolute Kelvin scale and the Celsius scale is given by K = C + 273.15. Celsius Scale

26. 26. Kelvin Scale * The thermodynamic temperature scale in the SI is the Kelvin scale, named after Lord Kelvin * The temperature unit on this scale is the kelvin, which is designated by K * The lowest temperature on the Kelvin scale is absolute zero, or 0 K * A temperature scale that turns out to be nearly identical to the Kelvin scale is the ideal-gas temperature scale The Kelvin scale is related to the Celsius scale by T(K) = T(C) + 273.15 T(R) = 1.8T(K) * The reference temperature chosen in the original Kelvin scale was 273.15 K (or 0°C), which is the temperature at which water freezes (or ice melts) and water exists as a solid-liquid mixture in equilibrium under standard atmospheric pressure (the ice point) * The reference point was changed to a much more precisely reproducible point, the triple point of water, which is assigned the value 273.16 K

27. 27. Rankine scale * The thermodynamic temperature scale in the English system is the Rankine scale, named after William Rankine * The temperature unit on this scale is the Rankine, which is designated by R * The temperatures on this scale are measured using a constant-volume gas thermometer, which is basically a rigid vessel filled with a gas, usually hydrogen or helium, at low pressure. * This thermometer is based on the principle that "at low pressures, the temperature of a gas is proportional to its pressure at constant volume". - The temperature of a gas of fixed volume varies linearly with pressure at sufficiently low pressures - Then the relationship between the temperature and the pressure of the gas in the vessel can be expressed as T = a + bP constants a and b for a gas thermometer are determined experimentally Once a and b are known, the temperature of a medium can be calculated from this relation by immersing the rigid vessel of the gas thermometer into the medium and measuring the gas pressure when thermal equilibrium is established between the medium and the gas in the vessel whose volume is held constant. The Rankine scale is related to the Fahrenheit scale by T(R) = T(F) + 459.67

28. 28. * An ideal-gas temperature scale can be developed by measuring the pressures of the gas in the vessel at two reproducible points (such as the ice and the steam points) and assigning suitable values to temperatures at those two points * Considering that only one straight line passes through two fixed points on a plane, these two measurements are sufficient to determine the constants a and b * Then the unknown temperature T of a medium corresponding to a pressure reading P can be determined from that equation by a simple calculation * The values of the constants will be different for each thermometer, depending on the type and the amount of the gas in the vessel, and the temperature values assigned at the two reference points * If the ice and steam points are assigned the values 0°C and 100°C, respectively, then the gas temperature scale will be identical to the Celsius scale Ideal Gas Temperature Scale

29. 29. The Constant Volume Gas Thermometer T = CpThe temperature of a body can be defined as , where p is the pressure in the bulb Assuming at the triple point, we also have with the same constant C. Therefore, But only when the gas is of a very small amount, this measurement gives consistent results among different materials used This is called the 'ideal gas temperature'. Temperature T to be measured

30. 30. * In this case the value of the constant a (which corresponds to an absolute pressure of zero) is determined to be -273.15°C regardless of the type and the amount of the gas in the vessel of the gas thermometer * This is the lowest temperature that can be obtained by a gas thermometer * Thus we can obtain an absolute gas temperature scale by assigning a value of zero to the constant a. * In that case, T = bP, and thus we need to specify the temperature at only one point to define an absolute gas temperature scale - Absolute gas temperature scale is not a thermodynamic temperature scale, since it cannot be used at very low temperatures (due to condensation) and at very high temperatures (due to dissociation and ionization) - Absolute gas temperature is identical to the thermodynamic temperature in the temperature range in which the gas thermometer can be used * Thus, we can view the thermodynamic temperature scale at this point as an absolute gas temperature scale that utilizes an "ideal" or "imaginary" gas that always acts as a low- pressure gas regardless of the temperature. * If such a gas thermometer existed, it would read zero kelvin at absolute zero pressure, which corresponds to -273.15°C on the Celsius scale

# data[].attributes.attachment_link.description
Associate Professor at The NorthCap University & Consultant 1. Thermodynamic Properties & Measurement Dr. Rohit Singh Lather 2.

# data[].attributes.body
Energy

# data[].attributes.attachment_link.readable_text
Undergraduate Chemical Engineering course given at the Higher Colleges of Technology (Abu Dhabi, UAE)

1. 1. Listen...Learn....Think...Enjoy Yourself WELCOME TO THERMODYNAMICS CHEM 222 Zin-Eddine Dadach 2014-2015

2. 2. Listen...Learn....Think...Enjoy Yourself What is thermodynamics?  A branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics

3. 3. Listen...Learn....Think...Enjoy Yourself DEFINITION OF THERMODYNAMICS  Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power)  During our course, we will study the effects of heat and work transfer on a specified system.

4. 4. Listen...Learn....Think...Enjoy Yourself

5. 5. Listen...Learn....Think...Enjoy Yourself LAWS OF THERMODYNAMICS The thermodynamics is the lawyer of nature and has different laws to be applied.

6. 6. Listen...Learn....Think...Enjoy Yourself THE IMPORTANCE OF THE LAWS  The starting point for most thermodynamic considerations are the laws of thermodynamics, which postulate that energy can be exchanged between physical systems as heat or work.  They also postulate the existence of a quantity named entropy, which can be defined for any system.

7. 7. Listen...Learn....Think...Enjoy Yourself THE SYSTEM The most important point in thermodynamics: DEFINING THE SYSTEM

8. 8. Listen...Learn....Think...Enjoy Yourself SYSTEM VS SURROUNDINGS  In thermodynamics, interactions between large ensembles of objects are studied and categorized.  Central to this are the concepts of system and surroundings.

9. 9. Listen...Learn....Think...Enjoy Yourself WHAT IS A SYSTEM?  A system is composed of particles, whose average motions define its properties, which in turn are related to one another through equations of state.  In chemical engineering, a system could be a gas or a liquid flowing in a pipe or in a tank or reactor

10. 10. Listen...Learn....Think...Enjoy Yourself PROPERTIES OF A SYSTEM  Any system can be defined by its pressure, temperature, composition, or other more complicated properties like SPECIFIC entropy , SPECIFIC enthalpy....

11. 11. Listen...Learn....Think...Enjoy Yourself SYSTEM & THERMODYNAMICS  Thermodynamics describes how systems respond to changes in their surroundings.  This can be applied to a wide variety of topics in science and engineering, such as engines, phase transitions, chemical reactions, transport phenomena, and even black holes.  The results of thermodynamics are essential for other fields of physics and for chemistry, chemical engineering, cell biology, biomedical engineering, and materials science to name a few

12. 12. Listen...Learn....Think...Enjoy Yourself DEFINING A SYSTEM

13. 13. Listen...Learn....Think...Enjoy Yourself WHAT IS A SYSTEM?  A Thermodynamic System is that part of the universe that is under consideration or study.  A real or imaginary boundary separates the system from the rest of the universe, which is referred to as the environment or surroundings (sometimes called a reservoir.)

14. 14. Listen...Learn....Think...Enjoy Yourself

15. 15. Listen...Learn....Think...Enjoy Yourself Exchange between Systems & Surroundings  A useful classification of thermodynamic systems is based on the nature of the boundary and the flows quantities through it as matter, energy, work, heat, and entropy.  A system can be anything, for example a piston, a fluid in a test tube, a living organism, or a planet

16. 16. Listen...Learn....Think...Enjoy Yourself DIFFERENT KINDS OF SYSTEMS

17. 17. Listen...Learn....Think...Enjoy Yourself WHAT IS AN ISOLATED SYSTEM?  Isolated systems are completely isolated in every way from their environment.  They do not exchange heat, work or matter with their environment.  An example of an isolated system would be an insulated rigid container, such as an insulated gas cylinder.

18. 18. Listen...Learn....Think...Enjoy Yourself WHAT IS A CLOSED SYSTEM?  Closed systems are able to exchange energy (heat and work) but not matter with their environment.  A greenhouse is an example of a closed system exchanging heat but not work with its environment.  Whether a system exchanges heat, work or both is usually thought of as a property of its boundary.  Figure 1.16 page 10

19. 19. Listen...Learn....Think...Enjoy Yourself WHAT IS AN OPEN SYSTEM?  open systems: exchanging both energy (heat and work) and matter with their environment.  A boundary allowing matter exchange is called permeable.  The ocean would be an example of an open system.  Figure 1.19 page 11

20. 20. Listen...Learn....Think...Enjoy Yourself PROPERTIES OF A SYSTEM

21. 21. Listen...Learn....Think...Enjoy Yourself WHAT IS A PROPERTY OF A SYSTEM ?  Any characteristic of a system is called a property.  Some familiar properties are pressure P, temperature T, volume V and mass m.  We can include viscosity, thermal conductivity, modulus of elasticity, thermal expansion, ....  Not all properties are independent however, some are defined in terms of others.  Example : ρ = m/V

22. 22. Listen...Learn....Think...Enjoy Yourself WHAT IS AN INTENSIVE PROPERTY?  Thermodynamic properties can be divided into two gen eral classes, intensive and extensive properties.  An intensive property is independent of the amount of mass.  Examples of intensive properties include:  temperature  viscosity  density  electrical resistivity  melting point  boiling point  color (in solution)  flammability .  Figure 1.20 page 12

23. 23. Listen...Learn....Think...Enjoy Yourself WHAT IS AN EXTENSIVE PROPERTY?  An extensive property is a property that changes when the size of the sample changes.  Examples of extensive properties include:  mass  volume  entropy  energy  electrical resistance  texture  Figure 1-20 page 12

24. 24. Listen...Learn....Think...Enjoy Yourself STATE OF A SYSTEM DEFINING COMPLETELY THE SYSTEM

25. 25. Listen...Learn....Think...Enjoy Yourself STATE OF A SYSTEM  A system not undergoing any change  All the properties can be measured or calculated throughout the entire system  This set of properties describe the state of the system

26. 26. Listen...Learn....Think...Enjoy Yourself THERMODYNAMICS & EQUILIBRIUM  Thermodynamics deal ONLY with equilibrium states, that means there is no driving forces within the system  The word Equilibrium implies a state of balance  Outside the equilibrium, systems can exchange heat and work and matter with the surroundings

27. 27. Listen...Learn....Think...Enjoy Yourself ZEROTH LAW OF THERMODYNAMICS  It is observed that a higher temperature object which is in contact with a lower temperature object will transfer heat to the lower temperature object.  The two objects will approach the same temperature, and in the absence of loss to other objects, they will then maintain a constant temperature.  They are then in thermal equilibrium.  Thermal equilibrium is the subject of the Zeroth Law of Thermodynamics.  Also Figure 1.24 page 14

28. 28. Listen...Learn....Think...Enjoy Yourself WHAT IS A THERMODYNAMIC EQUILIBRIUM?  If you put a hot cup of coffee or tea in a cold room, heat will flow from the cup and its contents into the room. But if you leave it there for two hours and come back, the cup of coffee or tea will be at the same temperature as the room.  The coffee and the room will have achieved a state of thermodynamic equilibrium Thermodynamic Equilibrium or Thermal equilibrium.  Thermodynamic equilibrium is when heat ceases to flow between two systems.  There is no heat transfer when thermodynamic equilibrium is reached.

29. 29. Listen...Learn....Think...Enjoy Yourself Class Work  Study examples 1-1 and 1-2 page 8

30. 30. Listen...Learn....Think...Enjoy Yourself The different phases of the system Remember in our course the system will be a fluid or solid SOLID-LIQUID-GAS

31. 31. Listen...Learn....Think...Enjoy Yourself DIFFERENT PHASES OF THE MATTER (THE SYSTEM)  Matter can exist in four phases (or states), solid, liquid, gas, and plasma plus a few other extreme phases, like critical fluids and degenerate gases

32. 32. Listen...Learn....Think...Enjoy Yourself SOLID PHASE  A solid is matter in which the molecules are very close together and cannot move around.  Examples of solids include rocks, wood, and ice (frozen water).

33. 33. Listen...Learn....Think...Enjoy Yourself LIQUID PHASE  A liquid is matter in which the molecules are close together and move around slowly. Examples of liquids include drinking water, alcohol, oil, mercury at room temperature, and lava (molten rock).

34. 34. Listen...Learn....Think...Enjoy Yourself GAS PHASE  A gas is matter in which the molecules are widely separated, move around freely, and move at high speeds. Examples of gases include the gases we breathe (nitrogen, oxygen, and others), the helium in balloons, and steam (water vapor).

35. 35. Listen...Learn....Think...Enjoy Yourself This P-T phase diagram of water shows its phases at various temperatures and pressures

36. 36. Listen...Learn....Think...Enjoy Yourself LET'S ANALYZE THE DIAGRAM  FROM THE SOLID STATE:  When a solid is heated (or as pressure decreases), it will change to a liquid form,  and when the liquid is heated it will eventually become a gas.  FOR THE DIAGRAM:  ice (frozen water) melts into liquid water when it is heated or pressure decreases. As the water is heated , the water evaporates and becomes water vapor.

37. 37. Listen...Learn....Think...Enjoy Yourself WHAT IS A SUBCOOLED LIQUID?  Liquid refrigerant which is cooled below its saturation temperature.  NO READY TO VAPORISE  EXAMPLE:  Consider a piston cylinder ( Figure 3-6, page 114) device containing liquid water at 200C and 1 atm. Under these conditions, water exist in liquid phase and is called compressed liquid or subcooled liquid

38. 38. Listen...Learn....Think...Enjoy Yourself WHAT IS A SATURATED LIQUID?  A Liquid that is about to vaporize Example:  If we heat the water liquid at 400C , the liquid will expand and its specific volume increases  If we continue to heat the water liquid up to 1000C ( Figure 3.7 page 114)  At this point the water is still liquid BUT any additional heat will cause some liquid to vaporize ( Phase change process from liquid to gas)  WE HAVE A SATURATED LIQUID

39. 39. Listen...Learn....Think...Enjoy Yourself WHAT IS A SATURATED VAPOR?  A Vapor that is about to condense  A vapor + one drop of liquid  Once boiling starts, the temperature of the liquid stops rising and the vapor starts to be produced   we have change of phase from vapor to liquid  Figure 3.9 page 115

40. 40. Listen...Learn....Think...Enjoy Yourself WHAT IS A SUPERHEATED VAPOR?  Once the phase change is completed, we are in a single phase state which is vapor only  When a vapor is far from condensing , it's called Superheated vapor  Figure 3-10 page 115

41. 41. Listen...Learn....Think...Enjoy Yourself WHAT IS WET STEAM?  Mixture of liquid and steam of the same substance in which both are at saturation temperature.  If additional heat is added to the wet steam at constant pressure, the temperature remains constant until all liquid is evaporated (saturated steam);  it is only at this point that the temperature increases above the saturation temperature (superheated steam )

42. 42. Listen...Learn....Think...Enjoy Yourself WHAT IS SATURATION TEMPERATURE?  The term saturation defines a condition in which a mixture of vapor and liquid can exist together at a given temperature and pressure.  The temperature at which vaporization ( Boiling) starts to occur for a given pressure is called the saturation temperature or boiling point

43. 43. Listen...Learn....Think...Enjoy Yourself WHAT IS A SATURATION PRESSURE?  The pressure at which the vaporization ( boiling) starts to occur for a given temperature is called the saturation pressure  For water at 2120F, the saturation pressure is 14.7 psia  For water at 14.7 psia, the saturation temperature is 2120F.  The graphical representation of this relationship between temperature and pressure at saturated conditions is the VAPOR PRESSURE CURVE

44. 44. Listen...Learn....Think...Enjoy Yourself DRAW A VAPOR PRESSURE CURVE (Psat vs Tsat) OF WATER  T ( 0C) : -10, -5, 0, 5,10,15,20,25,30,40,50,100, 150,  Saturation Pressure ( kPa) 0.26,0.40,0.61,0.87,1.23,1.71,2.34,3.17, 4.25,7.38,12.35, 101.3, 475.8,

45. 45. Listen...Learn....Think...Enjoy Yourself GROUP- WORK  Draw a T-V diagram for the temperature change from 100 to 3000C.

46. 46. Listen...Learn....Think...Enjoy Yourself CHANGES OF PHASE

47. 47. Listen...Learn....Think...Enjoy Yourself Latent heat and sensitive heat  when your system is heated up or cooled down without changing phase  the temperature changes and we have sensitive heat  When the system is changing phase, the heat is used by the system for the change of phase by breaking down the bridges between molecules.  if we have a pure component, the temperature stays constant  if we have a mixture, the temperature will change during the change of phase

48. 48. Listen...Learn....Think...Enjoy Yourself WHAT IS LATENT HEAT?  The amount of energy needed or is released during a phase- change process is called the latent heat  For a pure substance, the change of phase happens in constatnt temperature

49. 49. Listen...Learn....Think...Enjoy Yourself Latent heat of fusion  The amount of heat absorbed during melting

50. 50. Listen...Learn....Think...Enjoy Yourself Latent heat of vaporization  A change of state from saturated liquid to saturated vapor at constant temperature also requires the input of energy, called the latent heat of vaporization.

51. 51. Listen...Learn....Think...Enjoy Yourself Magnitudes of latent heat  The magnitudes of the latent heats of condensation and vaporization depend on the temperature or pressure at which phase change occurs.  At 1atm , the latent heat of fusion of water is 333.7 kJ/kg and the latent heat of vaporization of water is 2257.1 kJ/kg around 99.80 0C

52. 52. Listen...Learn....Think...Enjoy Yourself Wet steam region  Figure 3.34 page 129: relative amount of liquid and vapor  Figure 3.35: Average volume

53. 53. Listen...Learn....Think...Enjoy Yourself Specific volume of Sat. Liquid and Sat. vapor  In the wet steam region, we have a mixture of saturated liquid and saturated vapor  Let's study saturated steam tables A-4 & A-5 pages 916-917: At 450C => PS= 9.5953 kPa ( A-4) At 20kPa =>TS= 60.060C ( A-5) At 1000C => Specific Volume of Sat.Liq= 0.001043 m3/kg => Specific Volume of Sat.Vap= 1.6720 m3/kg

54. 54. Listen...Learn....Think...Enjoy Yourself Quality of wet steam  The quality x of a wet steam is defined as the ratio of the mass of vapor over the Total mass  x= Massvapor/Masstotal And:  Masstotal= Mass vapor + Massliquid

55. 55. Listen...Learn....Think...Enjoy Yourself Example of the use of Quality  For the volume: Vtotal= Vliquid + Vvapor In table A-4 ( page 916) for 1000C Vf ( liquid)= 0.001043 m3/kg Vg(vapor) = 1.6720 m3/kg  V= (mf .vf) + (mg.vg) V= ({mt-mg} .vf) + (mg.vg)

56. 56. Listen...Learn....Think...Enjoy Yourself Average value of a property of a mixture  V=m.Vaverage  Diving both sides by mt  Vaverage= (1-x).Vf + x.Vg  Vaverage= Vf-x.Vf+x.Vg  = Vf + x. ( Vg-Vf)  = Vf +x. Vfg  Can be applied to other properties in the tables.

57. 57. Listen...Learn....Think...Enjoy Yourself CLASS WORK  Work problems 3-1c to 3-9c page 154  WORK EXAMPLES 3-1 TO 3-9 PAGES 128-135

58. 58. Listen...Learn....Think...Enjoy Yourself Class work  Complete the tables 3.23 to 3.28 page 155  Solve : 3-29 to 3-36 pages 155-156

59. 59. Listen...Learn....Think...Enjoy Yourself EXCHANGE OF HEAT AND WORK SYSTEM AND SURRONDINGS

60. 60. Listen...Learn....Think...Enjoy Yourself SYSTEM & SURRONDINGS  DURING ANY PROCESS, A CLOSED SYSTEM AND SURRONDINGS EXCHANGE HEAT AND WORK.  THE LEVEL OF ENERGY OF THE SYSTEM WILL BE CHANGED DURING THE CHANGE OF STATE. 1) Across a pump, the pressure of liquid will increase ( Energy increases) 2) Across a heat exchanger, the temperature of the system will change ( energy changes).

61. 61. Listen...Learn....Think...Enjoy Yourself WHAT IS ENERGY?  Energy is defined as: "the ability to do work."  Our bodies transform the energy stored in the food into energy to do physical work  Work means moving something, lifting something, warming something, lighting something. All these are a few of the various types of work.  But where does energy come from?

62. 62. Listen...Learn....Think...Enjoy Yourself SOURCES OF ENERGY?  The forms of energy in nature we will look at include: Electricity Biomass Energy - energy from plants Geothermal Energy Fossil Fuels - Coal, Oil and Natural Gas Hydro Power and Ocean Energy Nuclear Energy Solar Energy Wind Energy

63. 63. Listen...Learn....Think...Enjoy Yourself Total and specific energy  Energy can exist in different forms such as thermal, mechanical, kinetic, potential, electric, magnetic, chemical and nuclear  The total energy E is an extensive property  The specific energy is an intensive property defined as the total energy of a system by unit mass: e=E/m

64. 64. Listen...Learn....Think...Enjoy Yourself Energy in thermodynamics  Thermodynamics deals only with the change of the total energy and give no information about the absolute value of the total energy ( we need a reference).  The macroscopic forms of energy are those a system posses as a whole such as kinetic energy and potential energy.  The microscopic energy are related to the molecular structure and the sum of all the microscopic energies is called internal energy (U)

65. 65. Listen...Learn....Think...Enjoy Yourself WHAT IS KINETIC ENERGY?  Kinetic energy is energy of motion. The kinetic energy of an object is the energy it possesses because of its motion.  The kinetic energy* of a point mass m is given by : ( Figure 2.3 page 53) 

66. 66. Listen...Learn....Think...Enjoy Yourself WHAT IS POTENTIAL ENERGY?  Gravitational potential energy is energy an object possesses because of its position in a gravitational field. Figure 2.37 page 70

67. 67. Listen...Learn....Think...Enjoy Yourself WHAT IS INTERNAL ENERGY?  Internal energy is defined as the energy associated with the random, disordered motion of molecules. Figures 2.5 and 2.6 page 55  it refers to the invisible microscopic energy on the atomic and molecular scale

68. 68. Listen...Learn....Think...Enjoy Yourself WHAT IS WORK?  Systems possess energy BUT they can not posses work or heat  Energy can be transferred to or from a closed system in two distinct forms : work or heat ( Figure 2-11 page 60)  Work is an energy interaction between a system and its surroundings ( Figures 2.24- 2.30 pages 65-67)  Work is an energy transfer associated with a force acting through a distance

69. 69. Listen...Learn....Think...Enjoy Yourself WHAT IS HEAT?  Form of energy that is transferred between a system and its surroundings by virtue of a temperature difference ( Figures 2.12 to 2-14 page 60)  Energy is recognized as heat transfer only as it crosses the system boundaries ( Figure 2.13 page 61)

70. 70. Listen...Learn....Think...Enjoy Yourself WHAT IS POWER?  Power is defined as work (or energy transfer) per unit time: P = dW / dt The SI unit of power is watt (w).  1 w= 1 J/s

71. 71. Listen...Learn....Think...Enjoy Yourself CLASS WORK  Do problems 2-7 to 2-11 page 98.  Do problems 2-18 to 2-20 page 98.

72. 72. Listen...Learn....Think...Enjoy Yourself THERMODYNAMIC STATES

73. 73. Listen...Learn....Think...Enjoy Yourself WHAT IS A THERMODYNAMIC STATE?  A thermodynamic state (from Latin status = to stand) is the state of a thermodynamic system as defined by its properties  A minimum number of parameters are necessary to specify the state of the system.

74. 74. Listen...Learn....Think...Enjoy Yourself STATE OF A SYSTEM  The state of a system can be thought of as an optimal ensemble of thermodynamic parameters, namely temperature, pressure, density, composition, etc., which characterize the system, but neither by its surroundings nor by its history.

75. 75. Listen...Learn....Think...Enjoy Yourself WHAT IS A STATE FUNCTION?  In thermodynamics, a state function, is any property of a system that depends only on the current state of the system, not on the way in which the system got to that state  Some familiar state functions are volume, V, pressure, P, and temperature, T. 

76. 76. Listen...Learn....Think...Enjoy Yourself STATE FUNCTION  For example, if we take a state from 00C to 1000C, the change in the temperature is +100oC whether we go straight up the temperature scale or we first cool the sytem for a few degrees then take the system to the final temperature.  The change in temperature is independent of the route taken so temperature is a state function ( FIGURE 1-26 page 15 & figure 1.28 page 16)  Conversely, if the change in a function is dependent on the route taken, then the function is known as a path function

77. 77. PATH FUNCTION  A function that depends on the path  Heat and Work depend on the way the exchange is performed between system and surroundings.  Efficiency depends on the way  Work and Heat are path functions Listen...Learn....Think...Enjoy Yourself

78. 78. Listen...Learn....Think...Enjoy Yourself Internal energy U & Enthalpy H

79. 79. Listen...Learn....Think...Enjoy Yourself WHAT IS INTERNAL ENERGY? . Internal energy, represented by U , is essentially the thermal energy contained in a system (or particles making up the system) . A change in internal energy ΔU is due to the transfer of energy into or out of a system, but the volume stays constant. For example, energy transferred into the system, usually heat (q) and work (w), represents an increase of internal energy, ΔU, of the system. Thus,  ΔU = q + w

80. 80. Listen...Learn....Think...Enjoy Yourself Internal Energy  Internal Energy U of a system does not tell how energy was transferred.  It is purely an accounting of energy content of the system.  The internal energy, U, is called a state function.

81. 81. Listen...Learn....Think...Enjoy Yourself WHAT IS ENTHALPY?  Enthalpy (symbolized H, also called heat content)  Is the sum of the internal energy of matter and the product of its volume multiplied by the pressure  Enthalpy is defined by the following equation:  Enthalpy is a quantifiable state function, and the total enthalpy of a system cannot be measured directly; the enthalpy change of a system is measured instead.  We need a reference. Example : Enthalpy at 00C.

82. 82. Listen...Learn....Think...Enjoy Yourself Enthalpy  The enthalpy of a system includes the internal energy and work ( external energy).  Work is performed only if there is a volume change (Figures 4-1 & 4-2 page 166) W= P.ΔV

83. 83. Listen...Learn....Think...Enjoy Yourself P-V Diagram  In a P-V diagram, Work is the area under the process from point 1 to point 2 ( Figure 4-3 & 4-4 page 167)

84. 84. Listen...Learn....Think...Enjoy Yourself Class work  Work examples 4-1, 4-2, 4-3 and 4- 6 pages 168-176)  Work problem 4.9 page 202

85. 85. Listen...Learn....Think...Enjoy Yourself Sensitive Heat & Specific heat Intensive property in heat transfer

86. 86. Latent & Sensitive heat  Latent heat or hidden is the heat for the change of phase. Heat needed to destroy the intra-molecular forces.  Sensitive heat is visible heat due to the rise of temperature during the heating of a single phase ( solid, liquid or gas). Listen...Learn....Think...Enjoy Yourself

87. 87. Listen...Learn....Think...Enjoy Yourself WHAT IS SPECIFIC HEAT?  The specific heat is an intensive property.  The amount of sensitive heat per unit mass required to raise the temperature by one degree Celsius.  The relationship between sensitive heat and temperature change is usually expressed in the form shown below where c is the specific heat.  unlike the extensive variable heat capacity, which depends on the quantity of material, specific heat is an intensive variable and has units of energy per mass per degree (or energy per number of moles per degree).

88. 88. Listen...Learn....Think...Enjoy Yourself Specific heat a constant pressure  A heat capacity by a capital C with a subscript denoting which variable is held constant during the temperature change. Figures 4-17 & 4-18 page 178  For example, the heat capacity at constant pressure is defined by: CP= ( ΔQ/ΔT)p = (ΔH/ΔT) P  where (ΔQ/ ΔT) is the change in heat with temperature. Here we can have work  Enthalpy is used

89. 89. Listen...Learn....Think...Enjoy Yourself Specific heat at constant volume At constant volume : no work CV= ( ΔQ/ΔT)V = (ΔU/ΔT)v where (ΔQ/ ΔT) is the change in heat with temperature.

90. 90. Listen...Learn....Think...Enjoy Yourself Class Work  Work examples 4-7, 4-8 and 4-10 pages 183 -185

91. 91. Listen...Learn....Think...Enjoy Yourself PROCESSES

92. 92. Listen...Learn....Think...Enjoy Yourself WHAT IS REVERSIBLE PROCESS?  A reversible process for a system is defined as a process that, once having taken place, can be reversed, and in so doing leaves no change in either the system or surroundings  In other words, the system and the surroundings are returned to their original condition

93. 93. Listen...Learn....Think...Enjoy Yourself REVERSIBLE PROCESS  In reality, there are no truly reversible process , therefore the reversible process is a starting point for thermodynamics calculations.  One way to make a real process close to a reversible process is to carry out the process in a series of infinitesimal steps

94. 94. Listen...Learn....Think...Enjoy Yourself WHAT IS AN IRREVERSIBLE PROCESS?  An irreversible process is a process that can not return both the system and the surroundings to their original conditions  It means if the system is reversed, the system and the surroundings will not return to their original conditions.

95. 95. Listen...Learn....Think...Enjoy Yourself EXAMPLE  For example, an automobile engine does not give back fuel it took to drive up a hill as it coasts back down the hill.  Main causes of Irreversibility: Friction, unrestrained expansion, heat transfer through finite temperature difference and mixing two different substances

96. 96. Listen...Learn....Think...Enjoy Yourself WHAT IS A CYCLIC PROCESS?  When a system in a given initial state goes through a number of different states ( go through various processes) and finally returns to its initial values , the system has undergone a cyclic process or cycle.  Therefore, all the properties have the same value they had at the beginning.

97. 97. Listen...Learn....Think...Enjoy Yourself EXAMPLE  Steam that circulates through a closed cooling loop undergoes a cycle.

98. 98. Listen...Learn....Think...Enjoy Yourself WHAT IS AN ISOTHERMAL PROCESS?  An isothermal process is a thermodynamic process in which the temperature of the system stays constant: ΔT = 0.  This typically occurs when a system is in contact with an outside thermal reservoir (heat bath), and processes occur slowly enough to allow the system to continually adjust to the temperature of the reservoir through heat exchange

99. 99. Listen...Learn....Think...Enjoy Yourself  In an isothermal process, therefore, all of the heat absorbed by the system is converted into work.

100. 100. Listen...Learn....Think...Enjoy Yourself WHAT IS AN ISOBARIC PROCESS?  An isobaric process is a thermodynamic process in which the pressure stays constant; ΔP = 0.  The heat transferred to the system does work but also changes the internal energy of the system.

101. 101. Listen...Learn....Think...Enjoy Yourself WHAT IS AN ISOCHORIC PROCESS?  An isochoric process, also called an isometric process, is a thermodynamic process in which the volume stays constant; ΔV = 0.  This implies that the process does no pressure-volume work, since such work is defined by  ΔW = PΔV,

102. 102. Listen...Learn....Think...Enjoy Yourself WHAT IS AN ADIABATIC PROCESS?  In thermodynamics, an adiabatic process is a process in which no heat is gained or lost in the working fluid.  For example, there are no chemical processes taking place in the fluid and there is no heat transfer from the environment.  The term "adiabatic" describes things that are impermeable to heat transfer; for example, an adiabatic boundary is a boundary that is impermeable to heat transfer and the system is said to be adiabatically (or thermally) insulated.  An adiabatic process which is also reversible is called an isentropic process.

103. 103. Listen...Learn....Think...Enjoy Yourself CLASS WORK # 1  DO EXAMPLES 2-1 to 2-9 in pages 57-69 of the book

104. 104. Listen...Learn....Think...Enjoy Yourself THERMODYNAMIC DIAGRAMS

105. 105. Listen...Learn....Think...Enjoy Yourself THE P-V-T SURFACE  The equilibrium states of a simple, compressible substance can be specified in terms of its pressure, volume and temperature.  If any two of these state variables is specified, the third is determined.  This implies that the states of the substance can be represented as a surface in a three dimensional P-V-T space

106. 106. Listen...Learn....Think...Enjoy Yourself PVT SURFACE ( FIGURE 2.26)

107. 107. Listen...Learn....Think...Enjoy Yourself WHAT ARE THE REGIONS IN A PVT SURFACE?  The solid, liquid and gas (vapor) phases can be represented by regions on the surface.  Note that there are regions on the surface which represent a single phase, and regions which are combinations of two phases.  A point lying on a line between a single-phase and a two-phase region represents a "saturation state".

108. 108. Listen...Learn....Think...Enjoy Yourself Saturation Lines  The line between the liquid and the liquid-vapor regions is called the liquid-saturation line and any point on that line represents a saturated-liquid state.  A point on the boundary between the vapor and the liquid-vapor regions is called a saturated-vapor state.

109. 109. Listen...Learn....Think...Enjoy Yourself P-V-T SURFACE FOR LIQUID-VAPOR REGION

110. 110. Listen...Learn....Think...Enjoy Yourself

111. 111. Listen...Learn....Think...Enjoy Yourself

112. 112. Listen...Learn....Think...Enjoy Yourself P-V Diagram  A process performed at constant pressure is called an isobaric process. It's a horizontal line  A process performed at constant volume is called an isochoric process. It's a vertical line  A process performed at constant temperature is called an isothermal process.  On a p-V diagram, lines of constant temperature curve from the upper left to the lower right.  During an adiabatic process no heat is transferred to the gas, but the temperature, pressure, and volume of the gas change as shown by the dashed line.

113. 113. Listen...Learn....Think...Enjoy Yourself T-V Diagram

114. 114. Listen...Learn....Think...Enjoy Yourself  In this figure :  The isotherms are ...........  The isochores are ..........  The isobars are ..............  

115. 115. Listen...Learn....Think...Enjoy Yourself WHAT IS THE CRITICAL POINT?  The two phase region is bounded by the saturated liquid curve on one side and the saturated vapor curve on the other.  Notice that these two curves meet at a point that corresponds to where one (and only one) of the isobars becomes horizontal at a single point.  This point is called the critical point and  it corresponds to the highest temperature and highest pressure for which a vapor and liquid can coexist.  The temperature at this point is called the critical temperature Tc.

116. 116. Listen...Learn....Think...Enjoy Yourself  The isobar that passes through this point (the only isobar that is horizontal at a single point) is called the critical pressure Pc.  The specific volume at this point is called the critical volume Vc.

117. 117. Listen...Learn....Think...Enjoy Yourself WHERE IS THE SUBCOOLED LIQUID REGION?  The single phase liquid region, also known as the subcooled liquid region is to the left of the two phase region.  It is sometimes considered to end at the critical temperature as shown

118. 118. Listen...Learn....Think...Enjoy Yourself WHERE IS THE SUPERHEATED VAPOR REGION?  The single phase vapor region, also known as the superheated vapor region, is to the right of the two phase region.  This region often is (arbitrarily) considered to end at the critical isobar.

119. 119. Listen...Learn....Think...Enjoy Yourself WHAT IS THE SUPERCRITICAL FLUID REGION?  You may have noticed that there is a region on the diagram that we have not yet discussed.  The supercritical fluid region is so called because states in this region are above both the critical temperature and critical pressure. 

120. 120. Listen...Learn....Think...Enjoy Yourself Supercritical Fluid  Material in this region has properties somewhat intermediate between what most people would call a gas and what most would call a liquid.  Sometimes this is called the dense gas region and other times the expanded liquid region.  The word fluid covers both gases and liquids so perhaps supercritical fluid is the best way to describe this region.

121. 121. Listen...Learn....Think...Enjoy Yourself WHAT IS THE CRITICAL STATE?  Note the critical state where the saturated-liquid and saturated-vapor lines meet.  The state variables of this unique point are denoted by Pc, vc and Tc.  If a substance is above the critical temperature Tc, it cannot condense into a liquid, no matter how high the pressure.

122. 122. Listen...Learn....Think...Enjoy Yourself Supercritical State  This merging of the liquid and vapor states above the critical temperature is a characteristic of all known substances.  While a pure vapor state can exist at a pressure lower than Pc, at pressures above Pc it is constrained to be a vapor.  States with pressures above Pc are described as "supercritical states".

123. 123. Listen...Learn....Think...Enjoy Yourself WHERE IS THE SUPERCRITICAL FLUID REGION?

124. 124. Listen...Learn....Think...Enjoy Yourself THE P-T DIAGRAM

125. 125. Listen...Learn....Think...Enjoy Yourself  The vapor pressure curve which is shown in red.  The vapor pressure curve terminates at the critical point. Remember that this point marks the highest temperature (T = Tc) and highest pressure (P = Pc) for which vapor and liquid can coexist.  The other end of the vapor pressure curve is marked by the triple point 

126. 126. Listen...Learn....Think...Enjoy Yourself CLASS WORK  DO EXAMPLES 3-1 TO 3-9 PAGE 128 BY STUDYING THE DIFFERENT THERMODYNAMIC CURVES CORRESPONDING TO THE PROBLEMS.

127. 127. Listen...Learn....Think...Enjoy Yourself THE GAS PHASE

128. 128. Listen...Learn....Think...Enjoy Yourself WHAT IS A GAS?  In a gas phase, the atoms or molecules constituting the matter basically move independently, with no forces keeping them together or pushing them apart.  Their only interactions are rare and random collisions.

129. 129. Listen...Learn....Think...Enjoy Yourself THE GAS ATOMS

130. 130. Listen...Learn....Think...Enjoy Yourself VAPOR VS GAS ( FIGURE 3.26 page 125)  Although vapor and gas are frequently (incorrectly) used interchangeably,  vapor refers to a gas phase in a state of equilibrium with identical matter in a liquid or solid state below its boiling point, or at least capable of forming solid or liquid at the temperature of the vapor.  The term gas refers to a compressible fluid phase, as in common usage  GAS EXIST AT TEMPERATURES HIGHER THAN TC  VAPOR EXIST AT TEMPERATURES LOWER THAN TC

131. 131. Listen...Learn....Think...Enjoy Yourself THE GAS PHASE  The thermodynamic state of a gas is characterized by:  its volume, its temperature, which is determined by the average velocity or kinetic energy of the molecules,  and its pressure, which measures the average force exerted by the molecules colliding against a surface.  These variables are related by the fundamental gas laws, which state that the pressure in an ideal gas is proportional to its temperature and number of molecules, but inversely proportional to its volume.

132. 132. Listen...Learn....Think...Enjoy Yourself IDEAL GAS VS REAL GAS  An ideal gas or perfect gas is a hypothetical gas consisting of identical particles of zero volume, with no intermolecular forces.  Real gases do not exhibit these exact properties, although the approximation is often good enough to describe real gases.  The approximation breaks down at high pressures and low temperatures, where the intermolecular forces play a greater role in determining the properties of the gas

133. 133. Listen...Learn....Think...Enjoy Yourself IDEAL GAS

134. 134. Listen...Learn....Think...Enjoy Yourself IDEAL-GAS LAW  Any equation that relates the pressure, temperature and specific volume of a substance is called equation of state.  In 1662, Robert Boyle observed, during his experiments with a vacuum chamber that the pressure of gases is inversely proportional to their volume  In 1802, Guy Lussac, experimentally determined that a low pressures the specific volume of a gas is proportional to its temperature That is Pv = RT -1- With R being the gas constant, this equation is called And v is the specific volume by unit mass IDEAL-GAS EQUATION OF STATE

135. 135. Listen...Learn....Think...Enjoy Yourself UNIVERSAL GAS CONSTANT  In equation -1-, R is different for each gas ( Figure 3.45 page 137)  ON THE OTHER HAND, The universal gas constant RU is THE SAME FOR ALL GASES AND defined as : RU= R.M -2- Where M is the molar mass or molecular weight of the gas. Values of RU in different units are given in page 1`38 . For example in SI units RU= 8.314 kJ/kmol.K

136. 136. Listen...Learn....Think...Enjoy Yourself IDEAL GAS  Pv = Ru.T with v is the specific volume by unit mole OR PV=NRU T  Pv=RT with v is the specific volume by unit mass OR PV=mRT

137. 137. Listen...Learn....Think...Enjoy Yourself EXAMPLES OF IDEAL GASES?  At low pressures and high temperatures, the density of gases decreases and the gas behaves like a ideal gas ( FIGURE 3.49 page 140)  Gases like Air, O2, N2, H2 and also heavy gases like CO2 CAN be treated as ideal gases at low densities  However, dense gases such as water vapor in steam power plant and refrigerant vapors in refrigerators can not be treated as ideal gases.

138. 138. Listen...Learn....Think...Enjoy Yourself REAL GASES

139. 139. Listen...Learn....Think...Enjoy Yourself WHAT IS A REAL GAS?  If a gas behaves exactly as the ideal gas laws would predict it to behave in terms of volume, pressure, moles, and temperature, then the gas is said to be an ideal gas.  If, on the other hand, the gas deviates from Ideal Gas behavior, then the gas is said to be acting like a "real gas".

140. 140. Listen...Learn....Think...Enjoy Yourself What causes deviation from ideal gas behavior?  Intermolecular forces called Van Der Waals forces . There are three such types of Van Der Waals forces:  London Dispersion Forces which are forces that exist between molecules as a result of positive nuclei of one molecule attracting the electrons of another molecule..  Dipole-Dipole interactions which are forces that exist between polar molecules where the positive end of one molecule attracts the negative end of another molecule.  Hydrogen bonding interactions are forces that exist between molecules that have a hydrogen atom bonded to a highly electronegative atom such as Oxygen, Nitrogen, or Flourine.

141. 141. Listen...Learn....Think...Enjoy Yourself What is the compressibility factor?  The term "compressibility" is used in thermodynamics to describe the deviance in the thermodynamic properties of a real gas from those expected from an ideal gas.  The compressibility factor is defined as *  In the case of an ideal gas, the compressibility factor Z is equal to unity, and the familiar ideal gas law is recovered: *  Z can, in general, be either greater or less than unity for a real gas.

142. 142. Listen...Learn....Think...Enjoy Yourself REAL PHASE REGION  The deviation from ideal gas behavior tends to become particularly significant (or, equivalently, the compressibility factor stays far from unity) : near the critical point,  in the case of high pressures  low temperatures. In these cases, an alternative equation of state better suited to the problem must be utilized to produce accurate results.

143. 143. Listen...Learn....Think...Enjoy Yourself COMPRESSIBILITY FACTOR  The compressibility factor can be estimated from figure 3-51 page 141 if we know the reduced temperature and the reduced pressure of the gas:  PR= P/PC and TR= T/TC The compressibility factor Z is almost the same for all the gases at the same reduced pressure and reduced temperature . This is called the principle of corresponding states

144. 144. Listen...Learn....Think...Enjoy Yourself CLASS WORK Work examples 3-10 to 3-12 page 139 143 Work problems 3.73, 3.74 and 3.77 page 158 Work problems : 3-82; 3-85;3-88 and 3.91 page 159

145. 145. REAL GASES EQUATIONS OF STATE Listen...Learn....Think...Enjoy Yourself

146. 146. Listen...Learn....Think...Enjoy Yourself EQUATIONS OF STATE FOR REAL GASES  The ideal-gas equation is very simple, but its range and applicability are limited.  Several equations of state have been proposed in the literature to describe the behavior of real gases  We will discuss : Van der Waals equation  Beattie- Bridgeman equation

147. 147. Listen...Learn....Think...Enjoy Yourself Van der Waals equation of state  Proposed in 1873  It has two constants  a/v2 is a correction of the ideal gas equation related to the intermolecular forces  b is a correction of the ideal gas equation related to the volume occupied by the gas molecules RT)bv)( v a P( 2 

148. 148. Listen...Learn....Think...Enjoy Yourself Determination of a and b cr cr P TR a 64 27 22  cr cr P RT b 8 

149. 149. Listen...Learn....Think...Enjoy Yourself Beattie- bridgeman equation of state  Proposed in 1928  It has five experimental constants  Values are given in table 3.4 page 146 232 u v A )Bv)( vT c 1( v TR P  )1(....).......1( 00 v b BBand v a AA 

150. 150. Listen...Learn....Think...Enjoy Yourself ENERGY OF GASES

151. 151. Listen...Learn....Think...Enjoy Yourself SPECIFIC HEATS vv T u C )(    pp T h C )(   

152. 152. Listen...Learn....Think...Enjoy Yourself INTERNAL ENERGY OF IDEAL GAS  The internal energy of an ideal gas is a function of the temperature only, that is  u=u (T) Figure 2.66 shows the experiment done by Joule. du= Cv(T) dT dTTCu v )( 2 1 

153. 153. Listen...Learn....Think...Enjoy Yourself Enthalpy of ideal gas  Definition: h=u+pv and for ideal gas ( Pv=RT), we have the relation h=u+RT  Therefore h depends also only on temperature for an ideal gas  dh = Cp(T)dT  And  2 1 )( dTTCh p

154. 154. Listen...Learn....Think...Enjoy Yourself Specific heat relations of ideal gases  h=u+RT  dh= du +RdT  Replacing dh by CpdT and du by CvdT  WE OBTAIN Cp= Cv +R  When the specific heats are given on a molar basis, R is replaced by Ru

155. 155. Listen...Learn....Think...Enjoy Yourself CLASS WORK  Work examples 3-13 and 3-14 pages 147 and 152  Work problems 3.85; 3.88, 3.91 3.98, page 159-160

156. 156. Listen...Learn....Think...Enjoy Yourself ENERGY TRANSFER DURING PROCESSES

157. 157. Listen...Learn....Think...Enjoy Yourself ENERGY TRANSFER BY HEAT, WORK AND MASS ( Chapter 3)  HEAT TRANSFER:  Energy can cross a boundary of a system as heat or work  Heat is defined as the form of energy that is transferred by virtue of temperature difference  A process with no heat transfer is called adiabatic

158. 158. Listen...Learn....Think...Enjoy Yourself Heat Transfer  Heat can be transferred by conduction, convection or radiation  Heat is easy to recognize , its driving force between the system and the surroundings being the temperature difference ( Figure 2.12 Page 60)

159. 159. Listen...Learn....Think...Enjoy Yourself ENERGY TRANSFER BY WORK  If the energy crossing a boundary is not heat  It must be WORK  The work done per unit time is called POWER  Work can be electrical , mechanical work ( moving boudary, shaft work, spring work,....)

160. 160. Listen...Learn....Think...Enjoy Yourself CONVENTION SIGNS  Heat and work are directional quantities  A complete description of work and heat need a magnitude and a direction  The generally accepted formal sign convention for heat and work is as follow:  Heat amd work In :POSITIVE  Heat and work OUT : NEGATIVE

161. 161. Listen...Learn....Think...Enjoy Yourself Moving Boundary work ( Figure 4.1, page 166)  It is associated to an expansion or compression of a gas in a piston-cylinder device.  It is also called PdV work  In Figure 4.3, the work can be defined as PdVPAdsFdsWb 

162. 162. Listen...Learn....Think...Enjoy Yourself Boundary Work  The total boundary work done during the entire process is defined by:  The area under the process is defined by ( Figure 4.3 page 167):  2 1 .dVPWb  2 1 PdVAAREA

163. 163. Listen...Learn....Think...Enjoy Yourself A GAS CAN FOLLOW DIFFERENT PATHS ( FIGURE 4.4)  A gas can follow different paths and since work is a path function  the area under each path is different ( Figure 4.4 )

164. 164. Listen...Learn....Think...Enjoy Yourself Class work  1) Work examples 4.1 to 4.3 pages 168-171)  2) Work problems 4.11, 4.12, 4.14 page 202

165. 165. Listen...Learn....Think...Enjoy Yourself FIRST LAW OF THERMODYNAMICS CONSERVATION OF ENERGY

166. 166. Listen...Learn....Think...Enjoy Yourself FIRST LAW OF THERMODYNAMICS?  Also known as the conservation of energy principle, the first law states that:  energy can never be created not destroyed, it can only changes form  Example: ( Figure 2.37 page 70) The rock at some elevation possesses some potential energy. As the rock falls, part of its potential energy is converted into kinetic energy.

167. 167. Listen...Learn....Think...Enjoy Yourself WHAT IS ENERGY?  Energy can exist in different forms:  Internal ( sensible, latent, chemical and nuclear)  Kinetic  Potential  Electrical  Magnetic  Surface tension effects

168. 168. Listen...Learn....Think...Enjoy Yourself FOR A SIMPLE COMPRESSIBLE SYSTEM  The change of total energy is : PEKEUE  )( )( 2 1 )( 12 2 1 2 2 12 zzmgPE vvmKE uumU   

169. 169. Listen...Learn....Think...Enjoy Yourself FOR A STATIONARY ( CLOSED) SYSTEM 0 PEKE UE 

170. 170. Listen...Learn....Think...Enjoy Yourself MECHANISMS OF ENERGY TRANSFER  Energy can be transferred to or from a system in three forms: Heat transfer: Q  Work : W  Mass Flow : m

171. 171. Listen...Learn....Think...Enjoy Yourself HEAT TRANSFER?  Caused by a difference of TEMPERATURE  TO A SYSTEM : Increases the ENERGY of molecules and thus the INTERNAL ENERGY  FROM A SYSTEM : Decreases the INTERNAL ENERGY of the system because the heat comes from the energy of molecules

172. 172. Listen...Learn....Think...Enjoy Yourself WORK TRANSFER?  ENERGY interactions not caused by a temperature difference  Examples :  Rising Piston  Rotating Shaft  Electrical wire  Work transfer to a system  Esystem ↑  Work transfer from a system  Esystem↓

173. 173. Listen...Learn....Think...Enjoy Yourself MASS FLOW ? Because mass carries energy with it  Mass enters the system  Esystem↑  Mass leaving the system Esystem↓

174. 174. Listen...Learn....Think...Enjoy Yourself NET ENERGY TRANSFER?  Energies transferred by heat, work and mass can de added ( FIGURE 2.45 page 74): Ein-Eout=( Qin-Qout)+( Win-Wout)+(Emass,in-Emass out)  IN RATE FORM ( KW): ΔË = Ëin-Ëout outinsystem EEE 

175. 175. Listen...Learn....Think...Enjoy Yourself ENERGY BALANCE FOR CLOSED SYSTEM  QNET IN= QIN-QOUT  WNET OUT= WOUT-WIN outnetinnet WQE ,,  outnetinnet WQU ,, 

176. 176. Listen...Learn....Think...Enjoy Yourself CLASS WORK  WORK EXAMPLES 4.5, 4.8,4.9 and 4.10 pages 174-187

177. 177. Listen...Learn....Think...Enjoy Yourself CLASS WORK#1  Work examples 5.1 page 226; 5.3 page 231; 5.6 page 238 and 5.7 page 239.

178. 178. Listen...Learn....Think...Enjoy Yourself HOMEWORK #2  Do problems : 4.5 , 4.6E , 4.18, 4.24, 4.26E, 4.33, 4.36 pages 201- 204.

179. 179. Listen...Learn....Think...Enjoy Yourself THE USES OF THE FIRST LAW OF THERMODYNAMICS 1) ENERGY BALANCES 2) DESIGN OF THE EQUIPMENTS ( FIND THEIR DUTY)

180. 180. Listen...Learn....Think...Enjoy Yourself WHAT IS ENERGY ( ENTHALPY OR INTERNAL ENERGY)?  THE LINK BETWEEN THE SYSTEM AND THE SURRONDINDS  CAN BE DEFINED BY THE PROPERTIES OF THE SYSTEM FROM TABLES  CAN BE CALCULATED BY THE ENERGY BALANCE out,netin,net WQE 

181. 181. Listen...Learn....Think...Enjoy Yourself SOLVING PROBLEM CASE I ( ENERGY BALANCE) WE WANT TO DETERMINE ONE OF THE STATES OF THE SYSTEM KNOWING THE DUTIES QNET IN AND WNET OUT

182. 182. Listen...Learn....Think...Enjoy Yourself STATIONARY RIGID TANK SYSTEM  ΔKE=ΔPE =0  NO MASS EXCHANGE WITH THE SURRONDINDS  NO BOUNDARY WORK  ΔE=ΔU outnet,innet, WQΔU 

183. 183. Listen...Learn....Think...Enjoy Yourself STATIONARY AND CLOSED PISTON CYLINDER  ΔKE=ΔPE =0  NO MASS EXCHANGE WITH THE SURRONDINDS  THERE IS BOUNDARY WORK  WNET OUT SHOULD NOT INCLUDE BOUNDAY WORK outnet,innet, WQΔH 

184. 184. Listen...Learn....Think...Enjoy Yourself STEADY FLOW SYSTEM  WE WILL STUDY NEXT )gz 2 v h(m)gz 2 v h(mWQ i 2 i iie 2 e ee  

185. 185. Listen...Learn....Think...Enjoy Yourself IN CASE I 1) WE SHOULD KNOW THE SPECIFIC ENERGY OF ONE STATE ( ENTHALPY OR INTERNAL ENERGY) 2) CALCULATE THE TOTAL ENERGY KNOWING THE MASS OR MASSFLOW 3) CALCULATE THE ENERGY OF THE SECOND STATE USING ENERGY BALANCE ( KNOWN DUTIES OF THE EQUIPMENTS)

186. 186. Listen...Learn....Think...Enjoy Yourself  CALCULATE THE SPECIFIC ENERGY OF THE SECOND STATE BY DIVIDING BY THE MASS ORMASS FLOW  USING THE CALCULATED SPECIFIC ENERGY TO DEFINE THE SECOND STATE AND CALCULATE ALL ITS PROPERTIES

187. 187. Listen...Learn....Think...Enjoy Yourself HOW TO FIND u OR h FOR DIFFERENT SYSTEMS  SUBCOOLED OR COMPRESSED LIQUID  WE NEED TWO VARIABLES FROM P,T,v  APPROXIMATION FOR COMPRESSED LIQUIDS:  v(P,T)= vsat (T)  u(P,T)=usat (T)  h(P,T)= hsat (T)+ vsat(T) { P-Psat(T)}

188. 188. Listen...Learn....Think...Enjoy Yourself  SATURATED LIQUID: WE NEED ONE VARIABLE P OR T OR v  WET STEAM: WE NEED TWO VARIABLES ( P OR T) AND OTHER VARIABLE ( EX: QUALITY OR SPECIFIC VOLUME)

189. 189. Listen...Learn....Think...Enjoy Yourself  SATURATED VAPOR: WE NEED ONE VARIABLE P OR T OR v  SUPERHEATED VAPOR: WE NEED TWO VARIABLES BETWEEN P,T AND v  IDEAL GAS: WE NEED ONLY TEMPERATURE BECAUSE U AND H DEPENS ONLY ON TEMPERATURE

190. 190. Listen...Learn....Think...Enjoy Yourself CASE 2 ( DESIGN PROBLEM ) WE WILL HAVE THE ENERGIES OF BOTH STATES AND WILL CALCULATE THE MISSING DUTY OF THE EQUIPMENT (WORK OR HEAT ) EXCHANGE WITH THE SURRONDINGS

191. 191. Listen...Learn....Think...Enjoy Yourself  WE SHOULD DEFINE THE TWO STATES  FIND THE SPECIFIC ENERGIES AT BOTH STATES  CONVERT TO TOTAL ENERGIES  APPLY THE ENERGY BALANCE  FIND THE DUTY OF THE EQUIPMENT USED TO EXCHANGE WORK ( TURBINE, COMPRESSORE, PUMP) OR HEAT ( HEAT EXCHANGER , COOLER. HEATER, FURNACE)

192. 192. Listen...Learn....Think...Enjoy Yourself STEADY FLOW SYSTEMS ? ( FIGURE 5.7 page 225)  During a steady flow process, no intensive or extensive property within the control volume change with time  V, m and E of the control volume remains constant  mcv=CST AND ECV=CST A large number of engineering devices ( turbines, compressors, nozzles) are classified as steady flow devices

193. 193. Listen...Learn....Think...Enjoy Yourself MASS BALANCE FOR STEADY FLOW SYSTEMS  mcv=CST  min=mout  With multiple inlets and exits: FIGURES 4.23 and 4.24 page 181   ei mm

194. 194. Listen...Learn....Think...Enjoy Yourself ENERGY BALANCE FOR STEADY FLOW SYSTEMS ECV=CST  ΔECV=0  Rate of net energy transfer by heat, work and mass IN is equal to the rate of net energy transfer by heat, work and mass OUT ).(0 FLOWSTEADYEEE systemoutin  outin EE 

195. 195. Listen...Learn....Think...Enjoy Yourself ENERGY BALANCE FOR A GENERAL STEADY FLOW SYSTEM ) 2 () 2 ( 22 i i iie e ee gz v hmgz v hmWQ  

196. 196. Listen...Learn....Think...Enjoy Yourself SECOND LAW OF THERMODYNAMICS DIRECTION OF A PROCESS AND ENTROPY

197. 197. Listen...Learn....Think...Enjoy Yourself THE SECOND LAW OF THERMODYNAMICS  In the last chapter, we have studied the first law of thermodynamics or the conservation of energy principle.  Any process can take place only if the first law is respected  Is This enough?  The answer belongs to the second law of thermodynamics or law of entropy

198. 198. Listen...Learn....Think...Enjoy Yourself EXAMPLE #1  If we put a hot coffee in a cold room  the coffee will lose heat to the room ( Fig 6.1 page 284)  If we consider the opposite process: Can the coffee get hotter getting heat from the cold room?  The answer is NO but the inverse process still respect the first law of thermodynamics which is conservation of energy  SO WHAT IS WRONG IN THE REVERSE PROCESS?

199. 199. Listen...Learn....Think...Enjoy Yourself RESTRICTION OF THE SECOND LAW  It is clear, from this example, that the first law of thermodynamics places no restriction on the direction of the process. The reverse process violates the second law of thermodynamics

200. 200. Listen...Learn....Think...Enjoy Yourself EXAMPLE #2  CONSIDERING A REFRIGERATOR: THE INLET IS GETTING COLDER AND THE OUTSIDE AIR IS GETTING HOTER  DOES IT VIOLATE THE SECOND LAW OF THERMODYNAMICS?

201. 201. Listen...Learn....Think...Enjoy Yourself EXAMPLE #3  From Figure 6.8 page 286, we can observe that the mechanical energy done by the shaft is first converted into INTERNAL ENERGY of water  This energy may leave the water as heat  However, can we rotate the shaft by heating the water?  ANSWEER: LATER

202. 202. Listen...Learn....Think...Enjoy Yourself CAN WE TRANSFORM HEAT INTO WORK?  To explain this , is often convenient to have a hypothetical body with a relatively large thermal energy capacity that can supply or absorb finite amount of energy without undergoing any change in temperature  Such a body is called THERMAL ENERGY RESERVOIR ( FIGURE 6.6 page 285)

203. 203. Listen...Learn....Think...Enjoy Yourself WHAT IS A THERMAL ENERGY RESERVOIR?  A thermal energy reservoir that supplies energy in the form of heat is a SOURCE ( FIGURE 6.7)  A thermal energy reservoir that absorbs energy in the form of heat is a SINK (FIGURE 6.7)  Thermal energy reservoirs are known as HEAT RESERVOIRS.

204. 204. Listen...Learn....Think...Enjoy Yourself THE SECOND LAW ( FIGURE 6.9)  In figure 6.9 PAGE 286, we can see that only a part of heat received by a heat engine is converted into work while the rest is rejected to a sink CONCLUSION: WE CAN NEVER TRANSFORM HEAT COMPLETELY INTO WORK

205. 205. Listen...Learn....Think...Enjoy Yourself FINAL ANSWEER  WORK CAN BE CONVERTED TO HEAT DIRECTLY AND COMPLETELY  HOWEVER, TO TRANSFORM HEAT INTO WORK REQUIRES THE USE OF SOME DEVICES CALLED: HEAT ENGINES

206. 206. Listen...Learn....Think...Enjoy Yourself HEAT ENGINES

207. 207. Listen...Learn....Think...Enjoy Yourself HEAT ENGINES?  Heat engines differ considerably from one another but all can be characterized by the following STEPS:  They receive heat from a high temperature source ( solar, furnace, nuclear reactor  They convert part of this heat into work ( usually in the form of rotating shaft: turbine)  They reject the remaining waste heat to a low temperature sink ( air, rivers, sea,...)  They operate on a cycle

208. 208. Listen...Learn....Think...Enjoy Yourself EXAMPLE: STEAM POWER PLANT ( figure 6.10) page 287  Qin= amount of heat supplied to steam in boiler from a high temperature source ( furnace)  Qout = amount of heat rejected from steam in condenser to a low temperature sink ( atmosphere)  Wout= amount of work delivered by steam as it expands in turbine  Win = amount of work required to compress water to boiler pressure

209. 209. Listen...Learn....Think...Enjoy Yourself NET WORK OUT?  WE PRODUCE Wnet.out Wnet, out= Wout- Win ( kJ)  Since is a cycle  ΔU=0  Wnet,out= Qin-Qout

210. 210. Listen...Learn....Think...Enjoy Yourself WHAT IS THERMAL EFFICIENCY?  In general, we define efficiency as the amount of energy you give divided by the amount of energy you spent for:  The fraction of the heat input that is converted into net work is a measure of the performance of the heat engine and is called thermal efficiency

211. 211. Listen...Learn....Think...Enjoy Yourself CLASS WORK #1  From figure 6.10 page 287 show that in out in out,net th Q Q 1 Q W 

212. 212. Listen...Learn....Think...Enjoy Yourself Class work #2  Work examples 6.1 and 6.2 page 290  Work problems 6.20-6.23 page 321  Work problems 6.18 ,6.19,6.24,6.28

213. 213. Listen...Learn....Think...Enjoy Yourself REFRIGERATORS & HEAT PUMPS

214. 214. Listen...Learn....Think...Enjoy Yourself REFRIGERATORS ( FIG 6.19 PAGE 292)  In order to transfer heat from a cold space ( inside refrigerator) to hot space ( kitchen) refrigerator must receive work.  As shown in figure 6.20 page 292 , the performance of a refrigerator ( COPR) is the ratio between the desired output over the required input COPR= QL/Wnet,in

215. 215. Listen...Learn....Think...Enjoy Yourself HEAT PUMPS ( FIGURE 6.21 PAGE 293)  Work like the refrigerator but the objective is different  Now we want to heat up an apartment during cold weather  Therefore : form figure 6.21 page 293, we have COPHP = QH/Wnet in

216. 216. Listen...Learn....Think...Enjoy Yourself Class work #4  Work examples 6.3 and 6.4 page 295  Work problems 6.39, 6.42, 6-50 AND 6.52 pages 322-323

217. 217. Listen...Learn....Think...Enjoy Yourself CARNOT HEAT ENGINE THE CARNOT CYCLE

218. 218. Listen...Learn....Think...Enjoy Yourself REVERSIBLE PROCESS Reversible versus Irreversible process?  Reversible process is defined as a process that can be reversed without leaving any trace on the surroundings.  Both the system and the surroundings are returned to their initial states at the end of the reverse process  This is possible only if the net heat and net work exchange is zero for the combined ( original and reverse process)

219. 219. Listen...Learn....Think...Enjoy Yourself IRREVERSIBLE PROCESS  All real processes are Irreversible and the Reversible process is a theoretical process used as a limit for the corresponding irreversible process  Irreversibility is caused by FRICTION

220. 220. Listen...Learn....Think...Enjoy Yourself THE CARNOT CYCLE  WE HAVE ALREADY MENTIONNED THAT HEAT ENGINES ARE CYCLIC DEVICES  REVERSIBLE CYCLES CAN NOT EXIST BECAUSE OF THE FRICTION.  THE CARNOT CYCLE IS A THEORITICAL REVERSIBLE CYCLE PROPOSED IN 1824 BY SADI CARNOT ( A FRENCH ENGINEER)

221. 221. Listen...Learn....Think...Enjoy Yourself THE CARNOT CYCLE : FIGURE 6.37 page 304  THE CARNOT CYCLE IS COMPOSED OF:  Reversible Isothermal Expansion  Reversible Adiabatic Expansion  Reversible Isothermal Compression  Reversible Adiabatic Compression

222. 222. Listen...Learn....Think...Enjoy Yourself CARNOT CYCLE

223. 223. Listen...Learn....Think...Enjoy Yourself CARNOT CYCLE  FIGURE 6.38 ( PAGE 305) SHOWS THE CARNOT CYCLE  PROCESS 1->2 EXPANSION AT CONSTANT TH: The gas is in contact with a source at TH.  As the gas expands , TH tends↓ by dT  However, the heat input QH from the source TH, will increase again T to TH in a reversible way  AT THE END OF THE PROCESS , THE GAS HAS ABSORBED QH

224. 224. Listen...Learn....Think...Enjoy Yourself CARNOT CYCLE  PROCESS 2->3:ADIABATIC EXPANSION WHERE TEMPERATURE DROPS FROM TH TO TL:  At State 2, the reservoir is removed and replaced by an insulation  The gas continues to expand slowly doing work on the surroundings until T TL

225. 225. Listen...Learn....Think...Enjoy Yourself CARNOT CYCLE  PROCESS 3->4: ISOTHERMAL COMPRESSION AT TL  At state 3, the insulation is removed and the gas is in contact with a sink at temperature TL.  The piston is pushed inward by an external force doing work on the gas  As the gas compresses , T ↑by dT but the sink will absorb this elevation of temperature  At the end of the process 3->4, the gas has rejected QL

226. 226. Listen...Learn....Think...Enjoy Yourself CARNOT CYCLE  PROCESS 4->1: ADIABATIC COMPRESSION WHERE TEMPERATURE RISES FROM TL TO TH:  The sink is removed and the insulation is put back and the gas is compressed in a reversible manner  The gas returns to its initial state which completes the cycle

227. 227. Listen...Learn....Think...Enjoy Yourself EFFICIENCY OF CARNOT HEAT ENGINE  The second law of thermodynamics states that no heat engine can have efficiency of 100%  The maximum efficiency is for reversible cycle as Carnot heat engine. CARNOT EFFICIENCY IS EQUAL TO:  Temperature in Kelvin. H L H L REVTHCARNOT T T Q Q  11,

228. 228. Listen...Learn....Think...Enjoy Yourself CLASS WORK  WORK EXAMPLE 6.5 PAGE 310  Work problems 6.80 and 6.81 page 325

229. 229. Listen...Learn....Think...Enjoy Yourself THE CARNOT REFRIGERATOR  Operates on the reverse Carnot cycle  The Coefficient of performance of any refrigerator ( reversible or irreversible): 1 1   L H R Q Q COP

230. 230. Listen...Learn....Think...Enjoy Yourself THE CARNOT HEAT PUMP  Operates as a reverse Carnot cycle  The Coefficient of performance of any heat pump ( reversible or irreversible): H L HP Q Q COP   1 1

231. 231. Listen...Learn....Think...Enjoy Yourself COP FOR REVERSIBLE PROCESS  REVERSIBLE REFRIGERATOR:  REVERSIBLE HEAT PUMP 1 1 ,   L H REVR T T COP H L REVHP T T COP   1 1 ,

232. 232. Listen...Learn....Think...Enjoy Yourself CLASS WORK  WORK EXAMPLES : 6.6 AND 6.7 page 314  WORK PROBLEMS: 6.94-6.97pages 326-327

233. 233. Listen...Learn....Think...Enjoy Yourself ENTROPY?

234. 234. Listen...Learn....Think...Enjoy Yourself WHAT IS ENTROPY?  MEASURES DESORDER  AS A SYSTEM BECOMES MORE DESORDERED  THE POSITION OF MOLECULES BECOME LESS PREDICTABLE  THE ENTROPY INCREASES  USEFUL PROPERTY FOR SECOND LAW  EXTENSIVE PROPERTY

235. 235. Listen...Learn....Think...Enjoy Yourself CHANGE OF ENTROPY?  The entropy is a state function  The entropy change of a process from state 1 to state 2 can be determined by the relation: rev T Q SSS int, 2 1 12 )(  

236. 236. Listen...Learn....Think...Enjoy Yourself SPECIAL CASE  For an internally reversible isothermal heat transfer process, the change of entropy reduces to :  WORK EXAMPLE 6-1 page 305 0T Q S 

237. 237. Listen...Learn....Think...Enjoy Yourself PROPERTY DIAGRAMS INVOLVING ENTROPY  In the second law, is very useful to use the T-S diagram or H-S diagrams  From the previous equations , we can write   2 1 int, .dSTQ rev

238. 238. Listen...Learn....Think...Enjoy Yourself T-S DIAGRAM  In figure 6-16 page 314, we can calculate Qint,rev as the area of the curve under the states 1 and 2  Isentropic process is a vertical line ( Figure 6-17 page 315)  T-S diagram of water is in appendix in figure A-9

239. 239. Listen...Learn....Think...Enjoy Yourself T-S DIAGRAM OF A CARNOT CYCLE?  WORK EXAMPLE 6-6 PAGE 315

240. 240. Listen...Learn....Think...Enjoy Yourself CARNOT VAPOR CYCLE Chapter 10 page 565

241. 241. Listen...Learn....Think...Enjoy Yourself CARNOT VAPOR CYCLE  CARNOT CYCLE is the most efficient cycle operating between two temperatures  IS CARNOT CYCLE EFFICIENT FOR VAPOR POWER PLANT?

242. 242. Listen...Learn....Think...Enjoy Yourself CARNOT VAPOR CYCLE  FIGURES 10.1 a and b PAGE 566 show two Carnot vapor cycles: Figure 10.1 a:  Process 1-2 : The fluid is heated reversibly and isothermally in a boiler  Process 2-3: The fluid is expanded isentropically in a turbine  Process 3-4 : The fluid is condensed reversibly and isothermally in a condenser  Process 4-1:The fluid is compressed to the initial state

243. 243. Listen...Learn....Think...Enjoy Yourself IMPRACTICALITIES OF THE CARNOT VAPOR CYCLE  A) In Figure 10.1 A , Processes 1-2 and 3-4 ( Boiler and condenser) use two phases- region for the water , This can be easily done in practice by maintaining a constant pressure in the boiler and condenser , however the maximum temperature of the source should remain below the critical temperature of water ( 3740C)  This will limit the thermal efficiency  B) To increase the maximum temperature of water above the critical temperature, we need to heat the steam water at constant temperature  not easy in practice

244. 244. Listen...Learn....Think...Enjoy Yourself PROCESS 23  B) The turbine will have to handle steam with poor quality ( steam with high moisture)  The droplets of water will cause erosion in the turbine

245. 245. Listen...Learn....Think...Enjoy Yourself PROCESS 4 1  C) In the isentropic compression, the pump will handle 2 phases fluid ???  cavitation of the pump

246. 246. Listen...Learn....Think...Enjoy Yourself Figure 10.1 b page 566  This Carnot process involves isentropic compression at very high pressures and isothermal heat transfer at variable pressures  Not possible in practice

247. 247. Listen...Learn....Think...Enjoy Yourself RANKINE VAPOR CYCLE IDEAL CYCLE FOR STEAM POWER PLANT

248. 248. Listen...Learn....Think...Enjoy Yourself RANKINE VAPOR CYCLE  The difficulties encountered in the CARNOT vapor cycle can be eliminated using the RANKINE vapor cycle  This can be done by; SUPERHEATING the steam in boiler CONDENSE all the steam in condenser  FIGURE 10.2 PAGE 567

249. 249. Listen...Learn....Think...Enjoy Yourself RANKINE VAPOR CYCLE  IS THE IDEAL CYCLE FOR VAPOR POWER CYCLES: DIAGRAM IN PAGE 567  PROCESSES OF THE CYCLE:  3-4:Isentropic EXPANSION (turbine)  4-1:Isobaric heat rejection ( condenser)  1-2:Isentropic COMPRESSION (pump)  2-3:Isobaric heat addition ( boiler)

250. 250. Listen...Learn....Think...Enjoy Yourself

251. 251. Listen...Learn....Think...Enjoy Yourself

252. 252. Listen...Learn....Think...Enjoy Yourself WORKS INVOLVED IN RANKINE CYCLE Work output of the cycle (Steam turbine) W1 Work input to the cycle (Pump) W2 are respectively:  W1 = m (h1-h2)  W2 = m (h4-h3) where m is the mass flow of the cycle.

253. 253. Listen...Learn....Think...Enjoy Yourself HEATS INVOLVED IN RANKINE CYCLE  Heat supplied to the cycle (boiler), Q1  Heat rejected from the cycle (condenser), Q2 are respectively:  Q1 = m (h1-h4)  Q2 = m (h2-h3)

254. 254. Listen...Learn....Think...Enjoy Yourself NET WORK OUTPUT  The net work output of the cycle is: W = W1 - W2

255. 255. Listen...Learn....Think...Enjoy Yourself THERMAL EFFICIENCY  The thermal efficiency of a Rankine cycle is: IN OUT IN NET RANKINE Q Q Q W  1

256. 256. Class Work  Work Example 10-1 page 569 Listen...Learn....Think...Enjoy Yourself

257. 257. Listen...Learn....Think...Enjoy Yourself SOLUTION OF EXAMPLE 10-1  A) Draw the process  B) Draw the T-S Diagram of the process  C) Put the data on the process

258. 258. Listen...Learn....Think...Enjoy Yourself  STATE 1: P1= 75 kPa and saturated liquid  Table A-5: h1=hf= 384.39 kJ/kg v1=vf= 0.001037 m3/kg

259. 259. Listen...Learn....Think...Enjoy Yourself  STATE 2: P2= 3MPa and s2=s1 wpump = v1 ( P2-P1) = 0.001037 ( 3000- 75) = 3.03 kJ/kg h2= h1+wpump= 384.39+3.03= 387.42 kJ/kg

260. 260. Listen...Learn....Think...Enjoy Yourself  STATE 3: ( superheated vapor) P3= 3Mpa and T3= 3500C  Table A-6 : h3= 3115.3 kJ/kg s3= 6.7428 kJ/kg.K

261. 261. Listen...Learn....Think...Enjoy Yourself  STATE 4: ( MIXTURE) P4= 75 kPa and s4=s3 WHAT IS THE PERCENTAGE OF VAPOR? x4= ( 6.7428- 1.213)/ 6.2434 = 0.8857 fg f s ss x   4 4

262. 262. Listen...Learn....Think...Enjoy Yourself  h4? h4= hf + x4.hfg = 384.39 + 0.8857x 2278.6 = 2402.6 kJ/kg

263. 263. Listen...Learn....Think...Enjoy Yourself Heats in and out ?  Qin= h3 - h2= 3115.3- 387.42= 2727.9 kJ/kg  Qout= h4-h1= 2402.6-384.39= 2018.2 kJ/kg

264. 264. Listen...Learn....Think...Enjoy Yourself THERMAL EFFICIENCY %26 9.2727 2.2018 11  in out Q Q 

265. 265. Listen...Learn....Think...Enjoy Yourself Class work  Solve problems 10.15 , 10.18, 10.19 page 605

266. 266. Listen...Learn....Think...Enjoy Yourself RANKINE VAPOR CYCLE  THE IDEAL CYCLE FOR VAPOR POWER CYCLES  PROCESSES OF THE CYCLE:  1-2:Isentropic EXPANSION (turbine)  2-3:Isobaric heat rejection ( condenser)  3-4:Isentropic COMPRESSION (pump)  4-1:Isobaric heat addition ( boiler)

267. 267. Listen...Learn....Think...Enjoy Yourself

268. 268. Listen...Learn....Think...Enjoy Yourself

269. 269. Listen...Learn....Think...Enjoy Yourself DEVIATION FROM RANKINE CYCLE  FIRST Cause of deviation: A) Fluid friction causes pressure drop in the boiler, condenser and the piping:  RESULTS: 1)The steam leaves the boiler at some LOWER pressure 2) The pressure at the inlet of turbine is somewhat LOWER 3) The pressure drop in the condenser is usually very small SEE FIGURE 10-4 A PAGE 572 AND COMPARE ACTUAL CYCLE TO IDEAL RANKINE CYCLE

270. 270. Listen...Learn....Think...Enjoy Yourself Solution for pressure drop in the system TO COMPENSATE the problem of pressure drop in the system: THE PUMP SHOULD WORK AT HIGHER PRESSURE THAN THE IDEAL CYCLE.

271. 271. Listen...Learn....Think...Enjoy Yourself Second cause of deviation from Rankine cycle B) The other cause of irreversibility is the heat loss from the steam to the surroundings  As a result : MORE HEAT NEEDS TO BE TRANSFERRED TO THE STEAM

272. 272. Listen...Learn....Think...Enjoy Yourself IRREVERSIBILITY OCCURING IN THE PUMP AND THE TURBINE  AS A RESULT OF IRREVERSIBILITY ON THE IDEAL RANKINE CYCLE: Figure 10-4b page 572  A pump requires a greater work input and the turbine produces a smaller work output

273. 273. Listen...Learn....Think...Enjoy Yourself ISENTROPIC EFFICIENCIES  FROM FIGURE 10-4b page 573  A) ISENTROPIC EFFICIENCY OF THE PUMP :  B) ISENTROPIC EFFICIENCY OF THE TURBINE 12 12 hh hh w w a s a s PUMP    s a s a TURBINE hh hh w w 43 43   

274. 274. Listen...Learn....Think...Enjoy Yourself CLASS WORK  WORK EXAMPLE 10-2 PAGE 573  WORK PROBLEM 10.19 PAGE 605

275. 275. Listen...Learn....Think...Enjoy Yourself HOW CAN WE INCREASE THE EFFICIENCY OF RANKINE CYCLE  Steam power plant are responsible for the production of most electric power in the world  Even small increase in thermal efficiency can mean large savings in fuel consumption

276. 276. Listen...Learn....Think...Enjoy Yourself The basic concept  The basic concept is to: η= 1-(TL/TH)  Increase the average temperature at which heat is transferred to the working fluid in the boiler  Decrease the average temperature at which heat is rejected from the working fluid to the condenser  BUT DO NOT FORGET: ONLY FOR CARNOT CYCLE , WE HAVE η= 1-(TL/TH)

277. 277. Listen...Learn....Think...Enjoy Yourself The actions  A) Lowering the condenser pressure  this will lower the TLOW,av  Figure 10.6 page 574  B) Superheating the steam to higher temperatures  Increases Thigh, av  Figure 10.7 page 575  C) Increasing the boiler pressure  Increases Thigh,av  Figure 10.8 page 575  Increase efficiency but increases the moisture at the turbine

278. 278. Listen...Learn....Think...Enjoy Yourself IDEAL REHEAT RANKINE CYCLE  How we can take advantage of increasing the efficiencies at higher boiler pressures without facing the problem of excessive moisture at the final stage of the turbine?  TWO POSSIBILITIES

279. 279. Listen...Learn....Think...Enjoy Yourself POSSIBILITY #1  SUPERHEAT THE STEAM TO VERY HIGH TEMPERATURES BEFORE IT ENTERS THE TURBINE  COULD BE UNSAFE FOR THE METAL OF THE TURBINE

280. 280. Listen...Learn....Think...Enjoy Yourself POSSIBILITY #2  EXPAND THE STEAM IN THE TURBINE IN TWO STAGES AND REHEAT IT BETWEEN THE TWO STAGES REHEAT IS THE PRACTICAL SOLUTION FOR THE HIGH MOISTURE IN THE TURBINE T  FIGURE 10-11 PAGE 579

281. 281. CLASS WORK  Work example 10.4 page 580  Work problems 10.35, 10.39 pages 607-608 Listen...Learn....Think...Enjoy Yourself

282. 282. Listen...Learn....Think...Enjoy Yourself HOMEWORK  TO PREPARE YOUR FINAL EXAM, TRY TO SOLVE THE PROBLEMS 4.28, 4.31, 4.38, 4.44, 5.50, 5.52, 5.58, 6.17, 6.18,6.42, 6.44, 6.52, 6.82, 6.83, 6.95,6.96, 6.99, 9.17, 9.18 , 10.15, 10.20,10.22,10.35  GOOD LUCK

# data[].attributes.attachment_link.description
Undergraduate Chemical Engineering course given at the Higher Colleges of Technology (Abu Dhabi, UAE) 1. Listen...Learn....Think...Enjoy Yourself WELCOME TO THERMODYNAMICS CHEM 222 Zin-Eddine Dadach 2014-2015 2. Listen...Learn....Think...Enjoy Yourself What is thermodynamics?  A branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics 3.

# data[].attributes.body
Steam Formation

# data[].attributes.attachment_link.readable_text
Successfully reported this slideshow.

Steam and it's properties.

1. 1. Formation and Properties Of Steam Submitted to - Prashant sir Submitted by - Anuharsh Gaur

2. 2. Introduction: What is Steam? * Steam is vapour of water and is invisible when pure and dry * It is used as the working substance in the operation of steam engines and steam turbines * Steam does not obey laws of perfect gases until it is perfect dry

3. 3. Formation of steam at a constant pressure from water

4. 4. Theoretical description of above figure * Consider 1 kg of water at 0 degree Celsius contained in piston cylinder arrangement as shown in above figure(i) the piston and weights maintains a constant pressure in cylinder *if we heat water contained in cylinder it will converted to steam as follows

5. 5. Contd..... * The volume of water will increase slightly as increase in temperature hence it will cause the piston to move upwards and work is obtained . * On further heating temperature reaches boiling point , the boiling point of water is 100 degree Celsius at 1.103 bar but increases with increase in pressure . When boiling point is reached, temperature remains constant and water evaporates thus pushing the piston up at constant pressure . The specific volume of steam increases as shown in (iii). At this stage steam will have some particles of water in suspension and is termed as wet steam . Process will continue till whole water is converted to steam

6. 6. Cont.. * On further heating the suspended water particles will get converted into steam. The entire steam in such a state is called dry steam (iv). It acts as a perfect gas * On further heating the temperature of steam starts rising and is termed as superheated steam(v)

7. 7. Temperature vs Total Heat Graph during Steam Formation

8. 8. Theoretical explanation of above graph * The process of steam formation above can also be explained in graphical form. * The point A represents the initial condition of water at 0 degree Celsius and pressure 'p'. * The graph is depicted in following three stages

9. 9. Cont.. 1. The heating of water up to boiling temperature or saturation temperature 'Ts'is shown by AB the heat absorbed by water is AF known as sensible heat 2. The change of state from liquid to steam is shown by BC heat absorbed during this stage is FG known as latent heat of vaporization 3. The superheating process is shown by CD heat absorbed during stage is GH , known as heat of superheat

10. 10. Cont.. * If the pressure is increased the boiling temperature also increase. The point B1 represent the boiling temperature or saturation temperature at pressure p1 and point F is point of dry saturated steam * Line C1D1 shows the constant pressure process in which steam is super heated

11. 11. Cont.. * Line passing through points A,B,B1,B2 are known as saturated liquid line * Line passing through A1,C,C1,C2 are known as dry saturated steam line .

12. 12. Important terms for steam

13. 13. Basic definitions * Wet steam - when the steam contains the moisture or particles of water in suspension . it is said to be wet steam ,evaporation of water is not complete and whole of latent heat is not absorbed * Dry saturated steam when the wet steam is further heated and it does not contain any suspended water particles it is called dry steam

14. 14. Cont.. * Superheated steam- when dry steam is further heated at constant pressure thus raising its temperature i.e. it is said to be super heated steam * Sensible heat - it is the amount of heat absorbed by 1 kg of water to raise the temperature from 0 degree to temperature of saturation point

15. 15. cont * Latent heat of vaporization- it is the amount of heat required to evaporate 1 kg of water at its boiling point without changing its temperature * Specific volume - it is defined as volume occupied per unit mass at a given temperature and pressure.

16. 16. Advantages of Superheated Steam * We already know that when dry steam is further heated then the steam is superheated steam . The process of superheating follows Charles law 1 . It contain more heat content and has more power to do a specific work 2. Increased thermal efficiency

17. 17. Internal energy of the system * It is the actual heat energy stored in the system above the freezing point of water * It is calculated by subtracting external work done during evaporation from enthalpy or total heat of steam .

18. 18. Dryness Fraction * It is defined as ratio of mass of actual dry steam to the mass of same quantity of wet steam * Generally denoted by 'x' * Formulae - Mg/Mg+Mf = Mg/M Mg = mass of dry steam Mf = mass of suspended water particles M = Mg+Mf

19. 19. References * Slideshare.net * Google.com * Wikipedia.org

20. 20. Thank you

Recommended

# data[].attributes.attachment_link.description
Successfully reported this slideshow. Steam and it's properties. 1. Formation and Properties Of Steam Submitted to - Prashant sir Submitted by - Anuharsh Gaur 2. Introduction: What is Steam?

# data[].attributes.attachment_link.readable_text
mechanical engineer at study

1. 1. STEAM BOILERS

2. 2. INTRODUCTIONINTRODUCTION STEAM GENERATOR OR BOILER A steam generator or boiler is usually a closed vessel made of steel. Its function is to transfer the heat produced by the combustion of fuel to water and ultimately to generate steam.

3. 3. The steam generated may be supplied : 1.To an external combustion engine, i.e., steam engine and steam turbines 2.At low pressures for industrial process work in cotton mills, sugar factories , breweries etc., and 3.For producing hot water, which can be used for heating installations at much lower pressures

4. 4. Purpose of boilers * For generating power in steam engines or steam turbines * In textile industries for sizing and bleaching * For heating the buildings in cold weather and for producing hot water for hot water supply

5. 5. Primary requirements of a boiler * The water must be contained safely * The steam must be safely delivered in desired condition (as regard its pressure, temperature, quality and required rate)

6. 6. IMPORTANT TERMS:IMPORTANT TERMS: * Boiler shell * Combustion chamber * Grate * Furnace * Heating surface * Mountings * Accessories

7. 7. Shell: Consists of one or more steel plates bent into a cylindrical form and riveted or welded together. The shell ends are closed with end plates

8. 8. Furnace: it is the chamber formed by the space above the grate and below the boiler shell, in which combustion takes place.

9. 9. Grate: it is a platform in the furnace upon which fuel is burnt

10. 10. BURNER - A device for the introduction of fuel and air into a furnace at the desired velocity.The burner is the principal device for the firing of oil and/or gas.

11. 11. Ash Pit The ash pit is the space where ashes accumulate under the fire. The ashes fall through the fire grate into a (often) removable box.

12. 12. Mud Ring or Mud Drum A typically cylindrical shaped space at the bottom of the water space. Sediment, mud, and other impurities gather there. SAFETY VALVE - A spring loaded valve that automatically opens when pressure attains the valve setting. Used to prevent excessive pressure from building up in a boiler.

13. 13. * Pressure Gauge. This indicates the pressure of the steam in the boiler. * Fusible Plug . A fusible plug operates as a safety valve when dangerous temperatures, rather than dangerous pressures, are reached in a closed vessel.

14. 14. * Feed Check Valve. The high pressure feed water is supplied to the boiler through this valve. This valve opens towards the boiler only and feeds the water to the boiler. * Steam Stop Valve. * It regulates the flow of steam supply outside.

15. 15. Classification of boilers * Horizontal, vertical or inclined * Fire tube and water tube * Externally fired and internally fired * Forced circulation and natural circulation * High pressure and low pressure * Stationary and portable * Single tube and multi tube

16. 16. Horizontal, vertical or inclined * If the axis of the boiler is horizontal, vertical or inclined then it is called horizontal, vertical or inclined boiler respectively

17. 17. Fire tube and water tube * If hot gases are inside the tube and water is outside the tube, it is called fire-tube boiler. * Examples: Cochran, Lancashire and locomotive boilers * If water is inside the tube and hot gases are outside the tube, it is called fire-tube boiler. * Examples: Babcock and Wilcox, Stirling, Yarrow boiler etc

18. 18. Externally fired and internally fired * The boiler is known as externally fired if the fire is outside the shell. * Examples: Babcock and Wilcox, Stirling * The boiler is known as internally fired if the furnace is located inside the boiler shell. * Examples: Cochran, Lancashire

19. 19. Forced circulation and natural circulation * In forced circulation type of boilers, the circulation of water is done by a forced pump * Examples: Velox, Lamont, Benson boiler * In natural circulation type of boilers, circulation of water in the boiler takes place due to natural convection currents produced by the application of heat * Examples: Lancashire, Babcock and Wilcox

20. 20. High pressure and low pressure * The boilers which produce steam at pressures of 80 bar and above are called high pressure boilers * Examples: Babcock and Wilcox, Velox, Lamont, Benson boilers * The boilers which produce steam at pressure below 80 bar are called low pressure boilers * Examples: Cochran, Cornish, Lancashire and locomotive boilers

21. 21. Stationary and portable * Stationary boilers are used for power plant- steam, for central station utility power plants, for plant process steam etc * Mobile or portable boilers include locomotive type, and other small unit for temporary use at sites

22. 22. Single tube and multi tube * The fire tube boilers are classified as single tube or multi-tube boilers, depending upon whether the fire tube is one or more than one * Examples of single tube boilers are Cornish and simple vertical boiler

23. 23. WATER TUBE STEAM BOILER:WATER TUBE STEAM BOILER: The water is contained inside the tubes(called water tubes)which are surrounded by flames and hot gases from outside. Ex: Babcock and Wilcox boiler, stirling boiler, la - Mont boiler, yarrow boiler and loeffler boiler

24. 24. FIRE TUBE BOILER In fire tube steam boilers, the flames and hot gases produced by the combustion of fuel pass through the tubes(called multi tubes) which are surrounded by water. The heat is conducted through the walls of the tube from the hot gases through the surrounding water. Ex: Cochran boiler, Lancashire boiler, Cornish boiler,

25. 25. Comparison of fire tube and water tube boilers ParticularsParticulars Fire-tube boilersFire-tube boilers Water-tube boilersWater-tube boilers Position of water and hotPosition of water and hot gasesgases Hot gases inside the tubesHot gases inside the tubes and water outside theand water outside the tubestubes Water inside the tubesWater inside the tubes and hot gases outside theand hot gases outside the tubestubes Mode of firingMode of firing Generally internally firedGenerally internally fired Externally firedExternally fired Operation pressureOperation pressure Limited to 16 barLimited to 16 bar Can go up to 100 barCan go up to 100 bar Rate of steam productionRate of steam production LowerLower HigherHigher SuitabilitySuitability Not suitable for largeNot suitable for large power plantspower plants Suitable for large powerSuitable for large power plantsplants Risk on burstingRisk on bursting Involves lesser risk ofInvolves lesser risk of explosion due to lowerexplosion due to lower pressurepressure More risk on burstingMore risk on bursting due to high pressuredue to high pressure Floor areaFloor area For a given power itFor a given power it occupies more floor areaoccupies more floor area For a given power itFor a given power it occupies less floor areaoccupies less floor area ConstructionConstruction DifficultDifficult SimpleSimple

26. 26. Cont... ParticularsParticulars Fire-tube boilersFire-tube boilers Water-tube boilersWater-tube boilers TransportationTransportation DifficultDifficult SimpleSimple Shell diameterShell diameter Large for same powerLarge for same power Small for same powerSmall for same power Chances of explosionChances of explosion LessLess MoreMore Treatment of waterTreatment of water Not so necessaryNot so necessary More necessaryMore necessary Accessibility of variousAccessibility of various partsparts Various parts not so easilyVarious parts not so easily accessible for cleaning,accessible for cleaning, repair and inspectionrepair and inspection More accessibleMore accessible Requirement of skillRequirement of skill Require less skill forRequire less skill for efficient and economicefficient and economic workingworking Require more skill andRequire more skill and careful attentioncareful attention

27. 27. COCHRAN BOILERCOCHRAN BOILER

28. 28. Cochran boiler * Shell diameter: 2.75 mm * Height: 5.79 m * Working pressure: 6.5 bar * Steam capacity: 3500 kg/hr * Heating surface: 120 m3 * Efficiency : 75%

29. 29. WORKING OF AN COCHRANWORKING OF AN COCHRAN BOILERBOILER Considered to be one of the most efficient type multi tubular boilers. Consists of external cylindrical shell and fire box. The shell and fire box both are hemispherical. The fire box and combustion chamber is connected through a short pipe. The flue gases from the combustion chamber flow to the smoke box through a

30. 30. WORKING OF AN COCHRANWORKING OF AN COCHRAN BOILERBOILER number of smoke tubes. The gases from the smoke box pass to the atmosphere through a chimney The external diameter of pipe is 62.5mm and are 165in number. Manhole is provided for cleaning.

31. 31. LANCASHIRE BOILERLANCASHIRE BOILER *

32. 32. Specifications * Dia . Of shell: 2-3m * Length of shell: 7-9 m * Max. working pressure: 16 bar * Steam capacity: 9000 kg/hr * Efficiency: 50-70%

33. 33.  The boiler consists of a long cylindrical external shell (1) built of steel plates in sections riveted together.  It has two large internal flue tubes (2).  A fire grate (3) is also called furnace is provided at one end of the flue tubes on which solid fuel is burnt.  At the end of the fire grate there is a brick arch (5) to deflect the flue gases upwards.  The hot flue gases leaving internal flue tubes passes through the bottom tube(6). WORKING OF LANCASHIRE BOILER

34. 34.  These flue gases move to the front of the boiler where they divide and flow into side tube (7).  The flue gases then enter the main flue (9) which leads them to chimney.  The damper (8) is fitted at one side flues to control the draught and thus regulate the rate of generation of steam.  A spring loaded safety valve (10) and stop valve (11) are mounted.

35. 35. CORNISH BOILERCORNISH BOILER The capacity and working pressure of a Cornish boiler is low as compared to Lancashire boiler.

36. 36. Specifications of cornish boiler * No.of flue tubes: 1 * Diameter of shell: 1.25-1.75m * Length of the shell: 4-7m * Pressure of steam: 10.5 bar * Steam capacity:6500 kg/hr

37. 37. CORNISH BOILERCORNISH BOILER It is a similar type of Lancashire boiler in all respects, except there is only one flue tube in Cornish boiler instead of two in Lancashire boiler. The diameter of Cornish boiler is generally 1m to 2m and its length various from 5m to 7.5m. The diameter of flue tube may be 0.6 times that of shell.

38. 38. Locomotive boiler

39. 39. Specifications of locomotive boiler * Barrel diameter: 2.095m * Length of barrel: 5.206m * No of ordinary tubes:116 * no of superheated tubes: 38 * Working pressure: 14 bar * Efficiency: 70%

40. 40. * Consists of cylindrical barrel with rectangular fire box at one end and smoke box at another end * Hot gases generated due to burning of coal are deflected by an arch of fire bricks, so that walls of the fire box may be heated properly * The heat of the hot gases is transmitted into water through the heating surfaces of fire tubes

41. 41. Babcock and Wilcox boiler

42. 42. Specifications of babcock boiler * Diameter of drum:1.22-1.83m * Length :6.096-9.144m * Size of water tubes:7.62-10.16cm * Working pressure:40 bar * Steam capacity:40000 kg/hr * Efficiency:60-80%

43. 43. Cont... * It consists of a drum connected to a series of front end and rear end header by short riser tubes * To these headers are connected a series of inclined (150 or more) water tubes * A hand hole is provided in the header in front of each tube for cleaning and inspection of tubes

44. 44. * Stirling boiler * The Stirling boiler is an early form of water-tube boiler, used to generate steam in large land- based stationary plants. * Stirling boilers are one of the larger arrangements for a water-tube boiler. They consist of a large brick-built chamber with a sinuous gas path through it, passing over near-vertical water-tubes that zigzag between multiple steam drums and mud drums.

45. 45. Specification of stirling boiler * Steam capacity:50000 kg/hr * Steam pressure:60 bar

# data[].attributes.attachment_link.description
mechanical engineer at study 1. STEAM BOILERS 2. INTRODUCTIONINTRODUCTION STEAM GENERATOR OR BOILER A steam generator or boiler is usually a closed vessel made of steel. Its function is to transfer the heat produced by the combustion of fuel to water and ultimately to generate steam. 3.

# data[].attributes.attachment_link.readable_text
BOILER MOUNTINGS AND ACCESSORIES

G N PATEL COLLEGE OF DAIRY TECNOLOLOGY

SDAU

1. 1. APRESENTATIONON BOILER MOUNTING AND ACCESSORIES BY ANKIT BIHOLA ROLL NO. : 1(ONE) REGESTRATION NO. : 14-01-2017 SUBMITTED TO, MR. R D KATHAROTIYA SIR

2. 2. BOILER MOUNTING AND ACCESSORIES

3. 3. BOILER MOUNTINGS * Mainly seven (7) mountings are required and essential to a Boiler : 1. Water level indicator. (Water gauge) 2. Main steam stop valve. 3. Pressure gauge. 4. Feed check valve. 5. Fusible plug. 6. Blow down valve. (Blow off cock) 7. Safety valve.

4. 4. Blow-Off Cock Function: The function of blow-off cock is to discharge mud and other sediments deposited in the bottom most part of the water space in the boiler, while boiler is in operation. It can also be used to drain-off boiler water. Hence it is mounted at the lowest part of the boiler. When it is open, water under the pressure rushes out, thus carrying sediments and mud.

5. 5. Working * When rectangular hole of plug is brought in line with casing hole by rotating spindle, the water flow out. When the solid portion of the plug is in front of casing hole (this position shown in the fig.) the water cannot flow out of boiler.

6. 6. Fusible plug * Function : It is use to protect the boil against damage due to overheating caused by low water level in the boiler.

7. 7. Working * In normal working condition, the upper surface of fusible plug is covered with water which keeps the temperature of the plug below its melting point while other end of plug is exposed to fire or hot gases. The low melting point (tin or lead) does not melt till the upper surface of plug is submerged in water. But in case of water level in boiler falls below the danger levels, the fusible plug uncovered by the water and get exposed to steam. This overheats the plug and the fusible metal having low melting point which melts quickly. Thus the third plug drops down and second hollow gun became open, the steam rushes into the furnace and puts out the fire (stop).

8. 8. Feed check valve * Function: It controls the supply of water from the boiler when the feed pump pressure is less than boiler pressure or pump is stopped.

9. 9. WORKING Inlet and outlet pipe of valve expose different pressure .at inlet of valve the feed pump pressure acts and outlet pipe of the valve the boiler pressure act . When feed pump is in operation, The pressure on the feed pump side(inlet) is more than pressure on the boiler side(outlet).This pressure difference lifts the non return valve, And allows water flow into boiler.

10. 10. WATER LEVEL INDICATOR Function:- It indicate the water level inside the boiler vessel. It shows the level in the boiler drum.

11. 11. WORKING * When steam cock and water cock opened, steam rushes from upper passage and water rushed from lower from passage to the glass tube. This will indicate the level of water in the boiler. Two ball are places at the junction of metal tube. Under normal operating condition the ball are kept. full line circle in case the glass tube is broken, steam will rushes from upper passage and water from lower passage due to pressure difference between boiler pressure at atmospheric pressure. the ball are carrier along the passage to and of glass tube and then closed passages. This position of ball sown in fig by dotted circle. Thus flow of water and steam out of boiler is prevented.

12. 12. Steam Stop Valve * Function:-It regulate the flow of steam from boiler to the steam pipe or from one steam pipe to the other.

13. 13. WORKING * The spindle it rotated by help of hand wheel due to rotation of spindle the valve move up and down. When the valve sits over the valve seat, the passage of steam is completely closed. The steam passage may be partially or fully opened by moving the valve up, help of rotating the hand wheel the clearance (passage) between valve and valve seat regulates the flow of steam out of boilers. in locomotive boilers, the supply of the steam is regulated by means of a regulator which is placed inside boiler cell and operated by a handle from driver's cabin.

14. 14. Pressure Gauge * Function : It indicates the pressure of steam in boiler.

15. 15. Working * When pressure is applied to inside of oval bourdon tube. It cross section tends to becomes circular, and free end of bourdon tube try to becomes straight, so turning the spindle by the links and gearing. This causes the needle to move and indicate pressure on graduated dial.

16. 16. Safety valves * Function : Safety valves are located on the top of the boiler. They guard the boiler against the excessive high pressure of steam inside the drum. If the pressure of steam in the boiler drum exceeds the working pressure then the safety valve allows blow-off the excess quantity of steam to atmosphere. Thus the pressure of steam in the drum falls. The escape of steam makes a audio noise to warm the boiler attendant.

17. 17. Safety valves :There are four types of safety valve: 1. Dead weight safety valve. 2. Spring loaded safety valve 3. Lever loaded safety valve 4. High steam and low water safety valve

18. 18. Dead weight safety valve

19. 19. Lever safety valve * The main disadvantages of dead weight safety valve as heavy weights required for high pressure boiler is eliminated in a lever safety valve by use of a lever.

20. 20. Spring loaded safety valve * There are various types of spring loaded safety valve use on different boilers.

21. 21. High steam & low water safety valve

22. 22. Function 1) The steam automatically escapes out when the level of water falls below a normal level. 2) It automatically discharges the excess steam when the pressure of steam rises above a normal pressure.  This valve is generally used in Cornish or Lancashire boiler.

23. 23. Boiler :Accessories:

24. 24. :Boilers Accessories: :are as under: (1) Feed pump (2) Injector (3) Economizer (4) Air preheater (5) Superheater (6) Steam separator (7) Steam trap

25. 25. Feed Pump * Function: * The feed pump is a pump which is used to deliver feed water to the boiler. * Double feed pump is commonly employed for medium size boilers.

26. 26. Types of Feed pumps There are Three types of feed Pumps mainly: Reciprocating pumps-simplex,duplex,Triplex Rotary pumps Centrifugal pumps

27. 27. Reciprocating Duplex Pump Duplex pump is very common steam driven reciprocating pump. It consist of two steam cylinder placed side by side. There are two steam ports for each of the cylinders.

28. 28. Injector Fucntion : Injector is used to feed water in the boiler . It is commonly employees for vertical boiler and does not find its application in large capacity high pressure boilers . it also uses more space is not available for the installation for feed pump.

29. 29. Economizer Function: Economizer increases the temperature of feed water using waste of heat to flue gases leaving the boiler through chimney.

30. 30. Construction and working: Economizer consist of a large vertical cast iron or steel water pipes,one end of vertical pipes is connected with vertivcal pipes A and other end with B. Hot flue gases from boiler pass over the vertical tubes .The heat transfer take place from flue gases to cold water rising in vertical tubes

31. 31. Super heater *The function of super heater is to increase the temperature of the steam above its saturation point.

32. 32. Working *Tosuperheat the steam generated by boiler. *Super heaters are heat exchangers in which heat is transferred to the saturated steam to increase its temperature. * Superheated steam has the following advantages : i)Steam consumption of the engine or turbine is reduced. ii) Losses due to condensation in the cylinders and the steam pipes are reduced. iii)Erosion of turbine blade is eliminated. iv) Efficiency of steam plant is increased

33. 33. Steam Separator A Steam separator, sometimes referred to as a moisture separator, is a device for separating water droplets from steam. The simplest type of steam separator is the steam dome on a steam locomotive. Stationary boilers and nuclear reactors may have more complex devices which impart a "spin" to the steam so that water droplets are thrown outwards by centrifugal force and collected.

34. 34. Steam Trap: :: A steam trap is a device used to discharge condensate and non condensable gases with a negligible consumption or loss of live steam. Most steam traps are nothing more than automatic valves. They open, close or modulate automatically. Others, like venture traps, are based on turbulent 2-phase flows to obstruct the steam flow.::

35. 35. Air Preheater * An air preheater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a recuperative heat system or to replace a steam coil.

# data[].attributes.attachment_link.description
BOILER MOUNTINGS AND ACCESSORIES G N PATEL COLLEGE OF DAIRY TECNOLOLOGY SDAU 1. APRESENTATIONON BOILER MOUNTING AND ACCESSORIES BY ANKIT BIHOLA ROLL NO. : 1(ONE) REGESTRATION NO. : 14-01-2017 SUBMITTED TO, MR. R D KATHAROTIYA SIR 2. BOILER MOUNTING AND ACCESSORIES 3. BOILER MOUNTINGS * Mainly seven (7) mountings are required and essential to a Boiler : 1.

# data[].attributes.attachment_link.readable_text
A presentation on Steam Nozzles.

1. 1. LECTURE NOTES - POWER PLANT ENGINEERING STEAM NOZZLES VANITA THAKKAR ASSOCIATE PROFESSOR MECHANICAL ENGINEERING DEPARTMENT, BABARIA INSTITUTE OF TECHNOLOGY, VARNAMA, VADODARA

2. 2. VANITA THAKKAR - BIT 2 INTRODUCTION  A Power Plant / Power Station is an industrial facility for generation of Electric Power.  It is a set-up consisting of systems and sub-systems, equipments and auxiliaries required for the generation of Electricity, which involves conversion of energy forms like chemical energy, heat energy or gravitational potential energy into Electrical Energy.

3. 3. 3 VANITA THAKKAR - BIT ENERGY CONVERSION PROCESS The energy content in a primary source of energy, like  Chemical Energy of a Fossil Fuel,  Potential Energy of water stored at a height,  Renewable / Non-conventional sources, like Solar Thermal Energy, Wind energy, Geothermal Energy, Tidal Energy, Wave Energy, etc. is converted stage-wise to Mechanical Energy (Rotational Energy) to obtain Electricity by creating relative motion between a magnetic field and a conductor.

4. 4. VANITA THAKKAR - BIT 4 THERMAL POWER PLANTS  In Thermal Power Plants, mechanical power is produced by a Heat Engine that transforms Thermal Energy, often from Combustion of a Fuel, into Rotational Energy.  Most Thermal Power Stations produce steam, and these are sometimes called Steam Power Plants / Stations.  Not all thermal energy can be transformed into mechanical power, according to the Second Law of Thermodynamics. Therefore, there is always heat lost to the environment.  If this loss is employed as useful heat, for industrial processes or distinct heating, the power plant is referred to as a Cogeneration Power plant or CHP (combined heat-and- power) plant.

5. 5. VANITA THAKKAR - BIT 5 RANKINE CYCLE  A Thermal Power Plant is a power plant in which the prime mover is steam driven.  Water is heated, turns into steam in Boiler and spins a Steam Turbine which either drives an Electrical Generator or does some other work, like Ship Propulsion.  After it passes through the turbine, the steam is condensed in a Condenser and recycled to where it was heated.  This is known as a Rankine cycle - as shown in the figure.

6. 6. VANITA THAKKAR - BIT 6 MORE ABOUT RANKINE CYCLE  The Rankine cycle is a thermodynamic cycle which converts heat into work.  The heat is supplied externally to a closed loop, which usually uses water as the working fluid.  This cycle generates about 80% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants.  It is named after William John Macquorn Rankine, a Scottish polymath.

7. 7. VANITA THAKKAR - BIT 7 WILLIAM RANKINE  The Rankine Cycle is named after William Rankine. Trained as a civil engineer, William Rankine was appointed to the chair of civil engineering and mechanics at Glasgow in 1855. He developed methods to solve the force distribution in frame structures.  He worked on heat, and attempted to derive Sadi Carnot's law from his own hypothesis. His work was extended by Maxwell.  Rankine also wrote on fatigue in the metal of railway axles, on Earth pressures in soil mechanics and the stability of walls. He was elected a Fellow of the Royal Society in 1853.  Among his most important works are Manual of Applied Mechanics (1858), Manual of the Steam Engine and Other Prime Movers (1859) and On the Thermodynamic Theory of Waves of Finite Longitudinal Disturbance.

8. 8. VANITA THAKKAR - BIT 8 PROCESSES IN RANKINE CYCLE  There are Four processes in the Rankine cycle, each changing the state of the working fluid.  Process 1-2: Working fluid is PUMPED from low to high pressure, as the fluid is a liquid at this stage the pump requires little input energy.  Process 2-3: The high pressure liquid enters a BOILER where it is heated at constant pressure by an external heat source to become a dry saturated vapour (or wet vapour).  Process 3-4: The dry saturated vapour expands through a TURBINE, generating power. Due to decrease in temperature and pressure of the vapour, and some condensation may occur.  Process 4-1: The wet vapour then enters a CONDENSER where it is condensed at a constant pressure and temperature to become a saturated liquid. The pressure and temperature of the condenser is fixed by the temperature of the cooling coils as the fluid is undergoing a phase- change.

9. 9. VANITA THAKKAR - BIT 9 RANKINE CYCLE : PRACTICAL CARNOT CYCLE  The Rankine cycle is sometimes referred to as a Practical Carnot cycle as, when an efficient turbine is used, the TS diagram will begin to resemble the Carnot cycle.  The main difference is that a pump is used to pressurize liquid instead of gas. This requires about 1/100th (1%) as much energy than that in compressing a gas in a compressor (as in the Carnot cycle).

10. 10. VANITA THAKKAR - BIT 10 Thus, BASIC COMPONENTS OF THERMAL POWER PLANT  BOILER  STEAM TURBINE : The Prime Mover  CONDENSER  FEED PUMP Supported by various sub-systems / accessories / equipments required for their proper, efficient working and to ensure their proper working in co-ordination with each other.

11. 11. VANITA THAKKAR - BIT 11 SCHEMATIC OF A STEAM POWER PLANT

12. 12. VANITA THAKKAR - BIT 12 STEAM TURBINES  A steam turbine is a mechanical device - a PRIME MOVER - that extracts thermal energy from high pressure, high temperature steam, and converts it into rotary motion.  PRIME MOVER : A machine that transforms energy from thermal or pressure form to mechanical form; typically  ENGINE : A mechanical device used to produce rotation to move vehicle or otherwise provide the force needed to generate kinetic energy OR  TURBINE : Any of various rotary machines that use the kinetic energy of a continuous stream of fluid - a liquid or a gas - to turn a shaft.

13. 13. VANITA THAKKAR - BIT 13 HISTORICAL BACKGROUND OF STEAM TURBINES  The AEOLIPILE is considered to be the first recorded steam engine or reaction steam turbine. The name - derived from the Greek words "aeolos" and "pila" - translates to "the ball of Aeolus" (Aeolus : Greek god of the wind).  It is a rocket style jet engine described in the first century BC by Vitruvius in his treatise De architectura. Later, in the first century AD, Hero of Alexandria also described the instrument, and many sources mistakenly give him the credit for its invention.  It used steam power directed through two jet nozzles so as to cause a sphere to spin rapidly on its axis.  It was a stand-alone device, and was presumably intended as a temple 'wonder', like many of the other devices described in Hero's Pneumatica.

14. 14. VANITA THAKKAR - BIT 14 HISTORICAL BACKGROUND OF STEAM TURBINES (contd.)  More than a thousand years later, the first impact steam turbine with practical applications was invented in 1551 by Taqi al-Din in Ottoman, Egypt, who described it as a prime mover for rotating a SPIT (a cooking aid - a long solid rod used to hold food while it is being cooked over a fire in a fireplace or over a campfire, or roasted in an oven ).  Similar smoke jacks were later described by John Wilkins in 1648 and Samuel Pepys in 1660.  Another steam turbine device was created by Italian Giovanni Branca in 1629. Spitted fowl are rotated by a hand-crank and basted with a long-handled spoon in this illustration from the Romance of Alexander, Bruges, 1338-44 (Bodleian Library).

15. 15. VANITA THAKKAR - BIT 15 HISTORICAL BACKGROUND OF STEAM TURBINES (contd.)  The modern steam turbine was invented in 1884 by the Englishman Sir Charles Parson, whose first model was connected to a dynamo that generated 7.5 kW of electricity.  The invention of Parson's steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare.  His patent was licensed and the turbine scaled-up shortly after by an American, George Westinghouse. A number of other variations of turbines have been developed.  The de Laval turbine (invented by Gustaf de Laval - Swedish Engineer) accelerated the steam to full speed before running it against a turbine blade (IMPULSE TURBINE). This was good, as the turbine is simpler, less expensive and does not need to be pressure-proof. It can operate with any pressure of steam. It is, however, considerably less efficient. The Parson's turbine also turned out to be relatively easy to scale- up. His invention adopted for all major world power stations. The size of his generators had increased from his first 7.5 kW set up to units of 50,000 kW capacity. Within Parson's lifetime the generating capacity of a unit was scaled-up by about 10,000 times.

16. 16. VANITA THAKKAR - BIT 16 ENERGY CONVERSION IN STEAM TURBINE Energy Conversion in Steam Turbine takes place in TWO STEPS :  High Pressure, High Temperature Steam expands in Nozzles and comes out at a high velocity.  High velocity steam jets from Nozzles impinge on the blades mounted on a wheel - Rotor - get deflected by an angle and suffer a loss of momentum which is absorbed by the Rotor in producing Torque. Thus, STEAM TURBINE = Assemblage of Nozzles and Blades (mounted on Rotor).

17. 17. VANITA THAKKAR - BIT 17 NOZZLES  A NOZZLE is a device, a DUCT of smoothly varying c/s area, that increases the velocity of a fluid at the expense of pressure.  The chief use of nozzle is to produce a jet of steam (or gas) of high velocity to produce thrust for the propulsion of rocket motors and jet engines and to drive steam or gas turbines.  A DIFFUSER is a device that increases the pressure of a fluid by slowing it down.  Diffusers are used in compressors, combustion chambers etc.

18. 18. VANITA THAKKAR - BIT 18 TYPES OF NOZZLES TWO types of nozzles :  Convergent : The cross section of the nozzle tapers to a smaller section to allow for changes which occur due to changes in velocity, specific volume, dryness fraction - as the fluid expands. It has lower Expansion Ratio and hence lower outlet velocities.  THE SMALLEST SECTION OF THE NOZZLE IS CALLED THROAT.  Convergent - Divergent (c-d nozzle) : The nozzle which converges to throat and diverges afterwards. It has higher Expansion Ratio - as addition of divergent portion produces steam at higher velocities. CONVERGENT NOZZLE CONVERGENT-DIVERGENT NOZZLE

19. 19. VANITA THAKKAR - BIT 19 FLOW THRO' NOZZLES : VELOCITY AND HEAT DROP ASSUMPTIONS :  Steady state  Adiabatic boundaries (Fluid Velocity is very high, so there is no time available for heat exchange with surroundings.)  Equilibrium states at inlet and outlet  Mass average velocities adequate for calculations  No shaft work  Change in potential energy is negligible. 1 2 Consider fluid flow through a nozzle, initially at : pressure = p1; Enthalpy = h1, inlet velocity = V1 Outlet conditions are respectively p2, h2 and V2 (denoted by subscript 2). According to Steady Flow Energy Equation (SFEE) : (h1 + V1 2/2) = (h2 + V2 2/2) => (h1 - h2 ) = (V2 2/2 - V1 2/2 )

20. 20. VANITA THAKKAR - BIT 20 FLOW THRO' NOZZLES : VELOCITY AND HEAT DROP (contd.) => V2 = √{V1 2 + 2 (h1 - h2)} Since, V1 << V2, V2 = √{2 (h1 - h2)} OR V2 = √{2 ∆h} Since, enthalpy is usually expressed in kJ/kg, and velocity in m/s, V2 = √1000{2 ∆h} => V2 = [44.72√∆h] m/s ..... (1) When the expanding fluid is a vapour, ∆h is called Rankine Heat Drop, which can be found from Mollier Chart or Steam Tables for steam. For Gases : pvγ = Constant ∆h = Cp.∆T

21. 21. VANITA THAKKAR - BIT 21 CROSS SECTION AREA AT OUTLET FOR GIVEN INLET AREA From Continuity Equation : (A1V1/v1) = (A2V2/v2) = m = (AV/v) (in general); Where, A = Area (m2); v = specific volume (m3/kg); m = mass flow rate (kg/s) Area per unit mass flow, (A/m) = (v/V) i.e., (A/m) = (v/ 44.72√∆h) [From (1)] Thus, it can be seen that : for calculating variations in area of the nozzle, it is essential to know how expansion takes place, i.e. how specific volume and enthalpy vary in the duct.

22. 22. VANITA THAKKAR - BIT 22 2. GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow)  To Study : the effect of Area variation on the velocity and pressure.  Here, we determine the effect of change in area, A, on the velocity V, and the pressure p. From Steady Flow Energy Equation (SFEE) between two planes at an infinitesimal distance apart : dQ = dh + d(V2/2) +dW For adiabatic flow in a Nozzle / Diffuser : dQ = 0 and dW = 0 Hence, dh + d(V2/2) = 0 ................ (1) From Second Law of Thermodynamics, for reversible flow between planes at infinitesimal distance : dQ = T.ds From First Law of Thermodynamics : (dQ)rev = du + p.dv Thus, Tds = du + p.dv = [dh - d(pv)] + p.dv = dh - v.dp For an isentropic process, dQ = T.ds = 0, hence, dh = v.dp .............. (2) From (1) and (2) : v.dp + d(V2/2) = 0 i.e., dp/ρ + d(V2/2) = 0 .................. (3) [as v = 1/ρ]

23. 23. VANITA THAKKAR - BIT 23 GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow) - contd. Dividing by ρ/V2, .............. (4) Logarithmic Differentiation of Continuity Equation, (AV/v) = constant : [ln A+ lnV - lnv = contant]; Differentiating : (dA/A) + (dV/V) - (dv/v) = 0 i.e. ............. (5) From (4) and (5) : OR

24. 24. VANITA THAKKAR - BIT 24 GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow) - contd. For Isentropic Process : [a2 = dp/dρ] Hence : ........... (5) Thus, we see that For Ma<1 an area change causes a pressure change of the same sign, i.e. positive dA means positive dp for Ma<1. For Ma>1, an area change causes a pressure change of opposite sign, i.e. positive dA means negative dp for Ma>1.

25. 25. VANITA THAKKAR - BIT 25 GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow) - contd. From (4) and (5) : ....(6) Thus, we see that For Ma<1, an area change causes a velocity change of opposite sign, i.e. positive dA means negative dV for Ma<1. For Ma>1, an area change causes a velocity change of same sign, i.e. i.e. positive dA means positive dV for Ma>1

26. 26. VANITA THAKKAR - BIT 26 GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow) - contd.  If a nozzle is used to obtain a supersonic stream staring from low speeds at the inlet, then the Mach number should increase from Ma=0 near the inlet to Ma>1 at the exit.  It is clear that the nozzle must converge in the subsonic portion and diverge in the supersonic portion.  Such a nozzle is called a convergent- divergent nozzle (De Laval Nozzle).  It is also clear that the Mach number must be unity at the throat, where the area is neither increasing nor decreasing. This is consistent with Equation (6), which shows that dV can be non-zero at the throat only if Ma=1. It also follows that the sonic velocity can be achieved only at the throat of a nozzle or a diffuser.

27. 27. VANITA THAKKAR - BIT 27 More about Flow through c-d nozzle Ma may not necessarily be unity at the throat. According to Eq. (6), such situations are possible when Ma≠1 at the throat and if dV=0.  The flow in a convergent-divergent duct may be subsonic everywhere with Ma increasing in the convergent portion and decreasing in the divergent portion with Ma≠1 at the throat (see upper Fig.). The first part of the duct is acting as a nozzle, whereas the second part is acting as a diffuser.  Alternatively, in a convergent-divergent duct in which the flow is supersonic everywhere with Ma decreasing in the convergent part and increasing in the divergent part and again at the throat Ma≠1 (see lower Fig.). Here, First part : Diffuser; Second Part : Nozzle.

28. 28. VANITA THAKKAR - BIT 28 4. CONDITION FOR MAXIMUM FLOW THROUGH A NOZZLE Consider fluid flow through a nozzle, initially at : pressure = p1; Enthalpy = h1, inlet velocity = V1 Outlet conditions are respectively p2, h2 and V2 (denoted by subscript 2). According to Steady Flow Energy Equation (SFEE) : (h1 + V1 2/2) = (h2 + V2 2/2) => (h1 - h2 ) = (V2 2/2 - V1 2/2 ) => V2 = √{V1 2 + 2 (h1 - h2)} Since, V1 << V2, V2 = √{2 (h1 - h2)} OR V2 = √{2 ∆h} From Second Law of Thermodynamics, for reversible flow between planes at infinitesimal distance : dQ = T.ds From First Law of Thermodynamics: (dQ)rev = du + p.dv Thus, Tds = du + p.dv = [dh - d(pv)] + p.dv = dh - v.dp For an isentropic process, dQ = T.ds = 0, hence, dh = v.dp .............. (1)

29. 29. VANITA THAKKAR - BIT 29 CONDITION FOR MAXIMUM FLOW THROUGH A NOZZLE (contd.) => Assuming that the pressure and volume of steam during expansion obey the law pvn = constant, where n is the isentropic index, ( ) 1 1 1 2 2 2 1 1 n n n n n n p v p p n − −   −   = −   −    

30. 30. VANITA THAKKAR - BIT 30 CONDITION FOR MAXIMUM FLOW THROUGH A NOZZLE (contd.) i.e., ∆h Now, mass flow rate : => Therefore, the mass flow rate at the exit of the nozzle : ..... (2) OR .......(2) (As V = √{2 ∆h}) ( ) 1 1 2 2 1 1 1 1 n n n n p v p v p n −  − −  −  

31. 31. VANITA THAKKAR - BIT 31 CONDITION FOR MAXIMUM FLOW THROUGH A NOZZLE (contd.) The exit pressure, p2 determines the for a given inlet condition. There will be only one value of pressure ratio called critical pressure ratio which gives maximum discharge (mass flow rate). The mass flow rate is maximum when, i.e. For maximum , ......(3) i.e., the discharge through the nozzle will be the maximum at the critical pressure ratio (p*/p1), shown above.

32. 32. VANITA THAKKAR - BIT 32 CONDITION FOR MAXIMUM FLOW THROUGH A NOZZLE (contd.) Comparing this with the results of sonic properties - Refer : GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow) - the critical pressure occurs at the throat for Ma = 1. The critical pressure ratio is defined as the ratio of pressure at the throat to the inlet pressure, for choked flow (MAX. MASS FLOW CONDITION), i.e. when Ma = 1 at throat. n For P2/p1 or p*/ p1 1.4 for diatomic gases 0.528 1.3 for super saturated steam 0.546 1.135 for dry saturated steam 0.58 1.035 + 0.1x wet steam with dryness fraction x (Dr. Zenner's Equation)

33. 33. VANITA THAKKAR - BIT 33 MAXIMUM DISCHARGE THROUGH THE NOZZLE ( ) ( ) ( ) ( ) 2 1 1 12 2 1 1max 1 1 1 . 2 1 n n n n n n n n n A n m p v v n + − −                     + +             =   −  ( ) ( ) ( ) 2 1 1 12 2 1 1max 1 1 1 . 2 1 n n n n n A n m p v v n + − −       −     + +       =   −  ( ) ( ) ( ) 2 1 1 11 2 2 max 1 1 1 . 2 1 n n n n n pn m A n v + − −       −     + +       =   − 

34. 34. VANITA THAKKAR - BIT 34 MAXIMUM DISCHARGE THROUGH THE NOZZLE (contd.) ( ) ( ) ( ) 2 1 1 1 1 1 1 2 1max 1 1 . 2 2 1 1 n n n n n n pn m A n v n   +  −    − −   +  −    −   +         =     − +   ( ) ( ) ( ) ( ) 1 1 1 1 1 2 1max 1 1 . 2 2 1 1 n n n n n pn m A n v n − − +  −    −   +         =     − +   ( ) ( ) 1 1 1 1 2 1max 1 1 . 2 2 1 1 n n n pn m A n v n − + −    −   +       =     − +   ( ) 1 1 1 max 1 . 2 1 2 1 1 2 n npn n m A n v n + −  −    =       − +     1 1 1 max 1 . 2 . ., 1 n np i e m A n v n + −   =    +  

35. 35. VANITA THAKKAR - BIT 35 CONCLUSIONS REGARDING MAXIMUM DISCHARGE CONDITIONS From the equation it is clear that Maximum mass flow or CHOKED FLOW :  depends only on the initial condition of the steam (p1, v1) and the throat area.  does not depend on the final pressure of the steam, i.e. at the exit of the nozzle. The addition of divergent part of the nozzle after the throat does not affect the discharge of steam passing through the nozzle, but it only accelerates the steam leaving the nozzle. 1 1 1 max 1 . 2 1 n np m A n v n + −    =     +  

36. 36. VANITA THAKKAR - BIT 36 CONCLUSIONS REGARDING MAXIMUM DISCHARGE CONDITIONS (contd.) Discharge through nozzle increases as the pressure at the throat of nozzle (p2) decreases, when the supply pressure p1 is constant. Keeping the inlet pressure p1 constant, when the nozzle outlet pressure, p2 reaches the critical value given by : the discharge becomes maximum and after that the throat pressure and mass flow rate remain constant irrespective of the pressure at the exit.

37. 37. VANITA THAKKAR - BIT 37 VELOCITY AT THROAT IS SONIC UNDER MAXIMUM DISCHARGE CONDITIONS Under maximum discharge conditions, when the pressure ratio at the throat of the nozzle has critical pressure value, the velocity at throat - critical velocity = sonic velocity. Refer : GENERAL RELATIONSHIP BETWEEN AREA, VELOCITY AND PRESSURE (Effect of Area on Flow Properties in Isentropic Flow)

38. 38. VANITA THAKKAR - BIT 38 MAXIMUM VELOCITY OF STEAM (CRITICAL VELOCITY) From Continuity Equation : => From equations (2) and (3), i.e. & Thus, the velocity is also dependent on the initial conditions of the steam. ( )max 1 1 1 2 1 1 n n V p v n n   −  =     − +   ( )max 1 12 1 n V p v n   =   +  ( ) 1 1 max 1 1 2 2 1 1 1 n n n nn V p v n n − −          −      − +        

39. 39. VANITA THAKKAR - BIT 39 CHOKED FLOW THROUGH A CONVERGENT NOZZLE .... WHEN A NOZZLE OPERATES UNDER MAXIMUM FLOW CONDITIONS, IT IS SAID TO BE CHOKED. Consider a convergent nozzle with constant inlet pressure p1, whose back pressure pb can be varied by a valve. When pb= p1, there is no fluid flow through the nozzle. As pb decreases, mass flow through the nozzle increases, as enthalpy decreases and velocity increases. When pb = p*, i.e. CRITICAL PRESSURE, further reduction in pb cannot affect the mass flow. Also, when pb = p*, velocity at the exit is sonic and mass flow rate through the nozzle is maximum.

40. 40. VANITA THAKKAR - BIT 40 CHOKED FLOW THROUGH A CONVERGENT NOZZLE (contd.) If pb is reduced below p*, mass flow remains maximum, exit pressure p2 remains at p* and fluid expands violently outside the nozzle down to pb. Thus maximum flow through a convergent nozzle is obtained when the pressure ratio across the nozzle is critical pressure ratio.

41. 41. VANITA THAKKAR - BIT 41 CHOKED FLOW THROUGH A C-D NOZZLE For a C-D Nozzle with sonic velocity at the throat, the cross-section area of the throat fixes the mass flow through the nozzle for fixed inlet conditions. A correctly designed C-D Nozzle is always choked.

42. 42. VANITA THAKKAR - BIT 42 EFFECT OF FRICTION AND NOZZLE EFFECIENCY For steam flowing through a nozzle, its final velocity for a given pressure drop is reduced due to :  Friction between nozzle surface and steam.  Internal friction of steam itself.  Shock losses. Most of the frictional losses occur between the throat and exit in c-d nozzle, producing following effects :  Expansion is no more isentropic.  Enthalpy drop is reduced.  Final dryness fraction of steam increases (kinetic energy  heat, due to friction and gets absorbed.)  Specific Volume of steam increases. (steam becomes more dry due to frictional reheating.)

43. 43. VANITA THAKKAR - BIT 43 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) Point 1 : nozzle entrance, DRY SATURATED STEAM. Line 1-2 : steam expansion from entrance to throat (friction neglected) Line 2-3 : steam expansion from throat to exit (friction neglected). Friction occurs mainly between throat and exit, hence, considering friction, heat drop is represented by Line 2-3'.

44. 44. VANITA THAKKAR - BIT 44 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) The horizontal line from point 3' cuts the pressure line on which point 3 lies on 2', which represents the final condition of the steam (nozzle exit). Hence actual process of expansion is given by : Line 1-2-2'. Dryness Fraction of steam is more at 2' than at 3. Hence, the effect of friction is to improve the quality of steam.

45. 45. VANITA THAKKAR - BIT 45 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) Point 4 : nozzle entrance, SUPERHEATED STEAM. Line 4-5 : steam expansion from entrance to throat (friction neglected) Line 5-6 : steam expansion from throat to exit (friction neglected) Friction occurs mainly between throat and exit, hence, considering friction, heat drop is represented by Line 4-6'.

46. 46. VANITA THAKKAR - BIT 46 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) The horizontal line from point 6' cuts the pressure line on which point 6 lies on 5', which represents the final condition of the steam (nozzle exit). Hence actual process of expansion is given by : Line 4-5- 5'. Dryness Fraction of steam is more at 5' than at 6. Hence, the effect of friction is to superheat the steam.

47. 47. VANITA THAKKAR - BIT 47 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) NOZZLE EFFICIENCY : The ratio of ACTUAL ENTHALPY DROP to ISENTROPIC ENTHALPY DROP between the same pressure. Nozzle efficiency : (FOR DRY, SATURATED STEAM) (FOR SUPERHEATED STEAM) 1 3' zzle 1 3 h h h h Νο − η = − 4 6' zzle 4 6 h h h h Νο − η = −

48. 48. VANITA THAKKAR - BIT 48 Why friction is considered only between throat and exit in c-d nozzle ? Reasons why friction is assumed between throat and exit only for c-d nozzle : 1.Small inlet velocity in the convergent portion, hence friction losses are also small. 2.No losses due to turbulence in convergent part. 3.Divergent part of the nozzle is longer to avoid flow separation. 4.Velocity is high in divergent portion. 5.Angle of divergence is less than 20o. 6.There are losses in the divergent portion due to turbulence.

49. 49. VANITA THAKKAR - BIT 49 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) Exit velocity under isentropic conditions = V3 Let, Actual exit velocity = V2' By steady flow energy equation (SFEE) : or (ISENTROPIC CONDITIONS) or (ACTUAL CONDITIONS) 2 2 1 2' 1 2' 2 2 V V h h+ = + 2 2 2' 1 1 2' 2 V V h h − − = 22 31 1 3 2 2 VV h h+ = + 2 2 2' 1 Nozzle 2 2 3 1 Nozzle Efficiency, V V V V − η = − 2 2 3 1 1 3 2 V V h h − − =

50. 50. VANITA THAKKAR - BIT 50 EFFECT OF FRICTION AND NOZZLE EFFECIENCY (contd.) As V1 <<< V2', V3 Value of Nozzle Efficiency depends on : 1.Nozzle material. 2.Workmanship in manufacture of nozzle. 3.Shape and size of nozzle. 4.Angle of divergence. 5.Nature of fluid flowing and its state. 6.Fluid velocity. 7.Friction 8.Turbulence in nozzle flow passages. 2 2' Nozzle 2 3 Nozzle Efficiency, V V η =

51. 51. VANITA THAKKAR - BIT 51 FACTORS AFFECTING NOZZLE EFFECIENCY Nozzle Type Velocity Coefficient Roughly cast nozzles 0.93 to 0.94 Machined nozzles 0.95 to 0.96 Smoothly milled nozzles 0.96 to 0.97 VELOCITY COEFFICIENT : Ratio of ACTUAL EXIT VELOCITY to the EXIT VELOCITY WHEN THE FLOW IS ISENTROPIC between the same pressure. Thus, Velocity Coefficient is the square root of Nozzle Efficiency when the inlet velocity is assumed to be negligible. 2 ' Nozzle 3 Velocity Coefficient V V = = η

52. 52. VANITA THAKKAR - BIT 52 SUPERSATURATED FLOW When steam flows / expands through a nozzle, it would be normally expected that the discharge of steam through the nozzle would be slightly less than the theoretical value. But, experiments on flow of wet steam show that Discharge is slightly greater than that calculated by the formulae. This can be explained as follows :  The converging part of the nozzle is so short and the steam velocity is so high that the molecules of steam have insufficient time to collect and form droplets.  So, normal condensation does not take place.

53. 53. VANITA THAKKAR - BIT 53 SUPERSATURATED FLOW (contd.)  There is a phase of rapid expansion, which is said to be metastable and it produces supersaturated state.  In supersaturated state, steam is undercooled to a temperature less than that corresponding to its pressure.  So, density of the steam increases and hence the weight of discharge.

54. 54. VANITA THAKKAR - BIT 54 SUPERSATURATED FLOW - WILSON'S LINE Prof. Wilson showed it experimentally that : "When dry saturated steam is suddenly expanded in absence of dust, it does not condense until its density is about EIGHT TIMES that of the saturated vapour at the same pressure." The limiting condition of under-cooling at which condensation commences and is assumed to restore conditions of normal thermal equilibrium is called WILSON LINE.

55. 55. VANITA THAKKAR - BIT 55 SUPERSATURATED FLOW (contd.) Consider the h-s diagram shown in the figure. The process 1-2 is the isentropic expansion. The change of phase should begin to occur at point 2. BUT, Vapour continues to expand in a dry state.

56. 56. VANITA THAKKAR - BIT 56 SUPERSATURATED FLOW(contd.) Steam remains in an unnatural superheated state until its density is about eight times that of the saturated vapour density at the same pressure (As per Prof. Wilson's Experiment). When this limit is reached, the steam will suddenly condense.

57. 57. VANITA THAKKAR - BIT 57 SUPERSATURATED FLOW(contd.) Point 3 is achieved by extension of the curvature of constant pressure line p3 from the superheated region which strikes the vertical expansion line at 3 and through which Wilson line also passes. The point 3 corresponds to a metastable equilibrium state of the vapour. The process 2-3 shows expansion under super-saturation condition which is not in thermal equilibrium. It is also called under cooling.

58. 58. VANITA THAKKAR - BIT 58 SUPERSATURATED FLOW(contd.) At any pressure between p2 and p3 i.e., within the superheated zone, the temperature of the vapours is lower than the saturation temperature corresponding to that pressure. Since at 3, the limit of supersaturation is reached, the steam now condenses instantaneously to its normal state at the constant pressure and constant enthalpy which is shown by the horizontal line 3-3' where 3' is on normal wet area pressure line of the same pressure p3.

59. 59. VANITA THAKKAR - BIT 59 SUPERSATURATED FLOW(contd.) 3'-4' is again isentropic expansion in thermal equilibrium. To be noted that 4 and 4' are on the same pressure line. Effect of supersaturation : *Increase in entropy and specific volume of the steam. *Slight reduction in the enthalpy drop during expansion and corresponding reduction in final velocity.

60. 60. VANITA THAKKAR - BIT 60 SUPERSATURATED FLOW(contd.) Effect of supersaturation (contd.) : *Final dryness fraction increases. *Density of supersaturated steam is more than that for equilibrium conditions [As no condensation during supersaturated expansion => supersaturation temperature < saturation temperature corresponding to the pressure]. *Thus, Measured discharge (=> mass) is greater than that theoretically calculated.

61. 61. VANITA THAKKAR - BIT 61 SUPERSATURATED FLOW(contd.) Degree of super heat = p3 = Limiting saturation pressure p3s = Saturation pressure at temperature T3 shown on T-s diagram Degree of undercooling = T3s - T3 T3s is the saturation temperature at p3 T3 = Supersaturated steam temperature at point 3 which is the limit of supersaturation. Supersaturated vapour behaves like supersaturated steam (n = 1.3). 3 3s p p

62. 62. VANITA THAKKAR - BIT 62 Important Note : Problems on supersaturated flow cannot be solved on Mollier Chart UNLESS Wilson Line is drawn on it.

63. 63. VANITA THAKKAR - BIT 63 EFFECT OF VARIATION IN BACK PRESSURE Nozzles are designed for maximum discharge for given area. When exit pressure(p2) differs from the value for which the nozzle is designed (p*), the flow conditions in the nozzle change. When pb < p*, : UNDEREXPANDING NOZZLE - Expansion of fluid to design pressure inside nozzle; At outlet fluid expands violently and irreversibly down to pb.

64. 64. VANITA THAKKAR - BIT 64 EFFECT OF VARIATION IN BACK PRESSURE (contd.) When pb > p*, : OVEREXPANDING NOZZLE. In Convergent Nozzle : Reduction in mass flow rate from the nozzle. In C-D Nozzle : Expansion followed by Recompression.

65. 65. VANITA THAKKAR - BIT 65 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : CONVERGENT NOZZLE Consider a convergent nozzle connected to a large reservoir of fluid. The reservoir is assumed to be so large that the inlet flow conditions to the nozzle remain constant. The back pressure (pb) is varied by a valve - as shown in the figure. When inlet pressure, p1 = pb : No fluid flow - curve (a). On reducing pb : flow starts.

66. 66. VANITA THAKKAR - BIT 66 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : CONVERGENT NOZZLE With reduction in pb : mass flow rate and velocity increase; pb > p* - curve (b)  OVEREXPANSION. When pb = p* : maximum mass flow rate / discharge through the nozzle - curve (c) : CHOKED FLOW through the nozzle. Upto this point and excluding this point : OVEREXPANDING CONDITIONS.

67. 67. VANITA THAKKAR - BIT 67 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : CONVERGENT NOZZLE With further reduction in pb i.e. pb < p* : mass flow rate, velocity and specific volume do not change. The fluid expands violently and irreversibly outside the nozzle to pb : UNDEREXPANSION, during which the pressure oscillates and shock wave is formed.

68. 68. VANITA THAKKAR - BIT 68 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE Consider a C-D nozzle connected to a large reservoir of fluid. The reservoir is assumed to be so large that the inlet flow conditions to the nozzle remain constant. The back pressure (pb) is varied by a valve - as shown in the figure. When inlet pressure, p1 = pb : No fluid flow - curve (a). On reducing pb : flow starts.

69. 69. VANITA THAKKAR - BIT 69 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE With reduction in pb : mass flow rate and velocity increase; pb > p* - curve (a). Here : Throat pressure is > p*. Velocity at throat is subsonic. Divergent portion acts as Subsonic Diffuser. Nozzle acts as Venturimeter.

70. 70. VANITA THAKKAR - BIT 70 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE With further reduction in pb : When throat pressure = p* : maximum mass flow rate / discharge through the nozzle - curve (b) : CHOKED FLOW through the nozzle.

71. 71. VANITA THAKKAR - BIT 71 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE On Further reduction in pb - Curve (c) : No change in the conditions at throat. Mass flow rate remains constant. Fluid velocity increases in the divergent portion, making velocity supersonic. At some point, due to divergence, supersonic steam is decelerated => shock wave is generated. Shock wave : Abrupt rise in pressure, increase in entropy and velocity reduces from supersonic to subsonic.

72. 72. VANITA THAKKAR - BIT 72 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE On Further reduction in pb : Shock wave travels down the nozzle. A stage comes when pb = design exit pressure - Curve (d). In this condition, flow is accelerated continuously from sonic velocity at the throat to supersonic velocity at exit.

73. 73. VANITA THAKKAR - BIT 73 EFFECT OF VARIATION IN BACK PRESSURE (contd.) : C-D NOZZLE Finally, on reduction in pb below designed value : Expansion takes place outside the nozzle, as in convergent nozzle : UNDEREXPANSION - Curve (e) - a series of irreversible compressions through shock-waves, alternated with irreversible expansions, until the pressure = pb.

74. 74. VANITA THAKKAR - BIT 74 THANKS !!! VANITA THAKKAR ASSISTANT PROFESSOR DEPARTMENT OF MECHANICAL ENGINEERING, FACULTY OF TECHNOLOGY AND ENGINEERING, CHAROTAR UNIVERSITY OF SCIENCE AND ENGINEERING, CHANGA, DIST. : ANAND (GUJARAT)

# data[].attributes.attachment_link.description
A presentation on Steam Nozzles. 1. LECTURE NOTES - POWER PLANT ENGINEERING STEAM NOZZLES VANITA THAKKAR ASSOCIATE PROFESSOR MECHANICAL ENGINEERING DEPARTMENT, BABARIA INSTITUTE OF TECHNOLOGY, VARNAMA, VADODARA 2. VANITA THAKKAR - BIT 2 INTRODUCTION  A Power Plant / Power Station is an industrial facility for generation of Electric Power.

# data[].attributes.attachment_link.readable_text
A steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft

1. 1. Steam Turbines Unit-4

2. 2. Definition A steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft.

3. 3. According to the action of steam:  Impulse turbine: In impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor. The blades change the direction of steam flow without changing its pressure. The force due to change of momentum causes the rotation of the turbine shaft. Ex: De-Laval, Curtis and Rateau Turbines  Reaction turbine: In reaction turbine, steam expands both in fixed and moving blades continuously as the steam passes over them. The pressure drop occurs continuously over both moving and fixed blades.  Combination of impulse and reaction turbine

4. 4. According to the number of pressure stages:  Single stage turbines: These turbines are mostly used for driving centrifugal compressors, blowers and other similar machinery.  Multistage Impulse and Reaction turbines: They are made in a wide range of power capacities varying from small to large. According to the type of steam flow:  Axial turbines: In these turbines, steam flows in a direction parallel to the axis of the turbine rotor.  Radial turbines: In these turbines, steam flows in a direction perpendicular to the axis of the turbine, one or more low pressure stages are made axial.

5. 5. According to the number of shafts:  Single shaft turbines  Multi-shaft turbines According to the method of governing:  Turbines with throttle governing: In these turbines, fresh steam enter through one or more (depending on the power developed) simultaneously operated throttle valves.  Turbines with nozzle governing: In these turbines, fresh steam enters through one or more consecutively opening regulators.  Turbines with by-pass governing: In these turbines, the steam besides being fed to the first stage is also directly fed to one, two or even three intermediate stages of the turbine.

6. 6. According to the heat drop process:  Condensing turbines with generators: In these turbines, steam at a pressure less than the atmospheric is directed to the condenser. The steam is also extracted from intermediate stages for feed water heating). The latent heat of exhaust steam during the process of condensation is completely lost in these turbines.  Condensing turbines with one or more intermediate stage extractions: In these turbines, the steam is extracted from intermediate stages for industrial heating purposes.  Back pressure turbines: In these turbines, the exhaust steam is utilized for industrial or heating purposes. Turbines with deteriorated vacuum can also be used in which exhaust steam may be used for heating and process purposes.  Topping turbines: In these turbines, the exhaust steam is utilized in medium and low pressure condensing turbines. These turbines operate at high initial conditions of steam pressure and temperature, and are mostly used during extension of power station capacities, with a view to obtain

7. 7. According to the steam conditions at inlet to turbine:  Low pressure turbines: These turbines use steam at a pressure of 1.2 ata to 2 ata.  Medium pressure turbines: These turbines use steam up to a pressure of 40 ata.  High pressure turbines: These turbines use steam at a pressure above 40 ata.  Very high pressure turbines: These turbines use steam at a pressure of 170 ata and higher and temperatures of 550°C and higher.  Supercritical pressure turbines: These turbines use steam at a pressure of 225 ata and higher.

8. 8. According to their usage in industry:  Stationary turbines with constant speed of rotation: These turbines are primarily used for driving alternators.  Stationary turbines with variable speed of rotation: These turbines are meant for driving turbo-blowers, air circulators, pumps, etc.  Non-stationary turbines with variable speed: These turbines are usually employed in steamers, ships and railway locomotives.

9. 9. Advantages of steam turbines over steam engines 1. The thermal efficiency is much higher. 2. As there is no reciprocating parts, perfect balancing is possible and therefore heavy foundation is not required. 3. Higher and greater range of speed is possible. 4. The lubrication is very simple as there are no rubbing parts. 5. The power generation is at uniform rate & hence no flywheel is required. 6. The steam consumption rate is lesser. 7. More compact and require less attention during operation. 8. More suitable for large power plants. 9. Less maintenance cost as construction and operation is highly simplified due to absence of parts like piston, piston rod, cross head, connecting rod. 10. Considerable overloads can be carried at the expense of slight reduction in overall efficiency.

10. 10. Methods of reducing rotor speed (Compounding of turbines)  If high velocity of steam is allowed to flow through one row of moving blades, it produces a rotor speed of about 30000 rpm which is too high for practical use.  It is therefore essential to incorporate some improvements for practical use and also to achieve high performance.  This is possible by making use of more than one set of nozzles, and rotors, in a series, keyed to the shaft so that either the steam pressure or the jet velocity is absorbed by the turbine in stages. This is called compounding of turbines.  The high rotational speed of the turbine can be reduced by the following methods of compounding: 1)Velocity compounding 2)Pressure compounding, and 3)Pressure-Velocity compounding

11. 11. Lost velocity

12. 12.  It consists of a set of nozzles and a few rows of moving blades which are fixed to the shaft and rows of fixed blades which are attached to the casing.  As shown in figure, the two rows of moving blades are separated by a row of fixed blades.  The high velocity steam first enters the first row of moving blades, where some portion of the velocity is absorbed.  Then it enters the ring of fixed blades where the direction of steam is changed to suit the second ring of moving blades. There is no change in the velocity as the steam passes over the fixed blades.  The steam then passes on to the second row of moving blades where the velocity is further reduced. Thus a fall in velocity occurs every time when the steam passes over the row of moving blades. Steam thus leaves the turbine with a low velocity.  The variation of pressure and velocity of steam as it passes over the moving and fixed blades is shown in the figure. It is clear from the figure that the pressure drop takes place only in the nozzle and there is no further drop of pressure as it passes over the moving blades.  This method of velocity compounding is used in Curtis turbine after it was first proposed by C.G. Curtis.

13. 13.  It consists of a number of fixed nozzles which are incorporated between the rings of moving blades. The moving blades are keyed to the shaft.  Here the pressure drop is done in a number of stages. Each stage consists of a set of nozzles and a ring of moving blades.  Steam from the boiler passes through the first set of nozzles where it expands partially. Nearly all its velocity is absorbed when it passes over the first set of moving blades.  It is further passed to the second set of fixed nozzles where it is partially expanded again and through the second set of moving blades where the velocity of steam is almost absorbed. This process is repeated till steam leaves at condenser pressure.  By reducing the pressure in stages, the velocity of steam entering the moving blades is considerably reduced. Hence the speed of the rotor is reduced. Rateau & Zoelly turbines use this method of compounding.

14. 14. 1) In this method of compounding, both pressure and velocity compounding methods are utilized. 2) The total drop in steam pressure is carried out in two stages and the velocity obtained in each stage is also compounded. 3) The ring of nozzles are fixed at the beginning of each stage and pressure remains constant during each stage. 4) This method of compounding is used in Curtis and More turbines.

15. 15. Pressure-Velocity compounding

16. 16.  It primarily consists of a nozzle or a set of nozzles, a rotor mounted on a shaft, one set of moving blades attached to the rotor and a casing.  A simple impulse turbine is also called De-Laval turbine, after the name of its inventor  This turbine is called simple impulse turbine since the expansion of the steam takes place in one set of nozzles.

17. 17.  In impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor.  The blades change the direction of steam flow without changing its pressure.  The force due to change of momentum causes the rotation of the turbine shaft.  Examples: De-Laval, Curtis and Rateau turbines.

18. 18.  The impulse turbine consists basically of a rotor mounted on a shaft that is free to rotate in a set of bearings.  The outer rim of the rotor carries a set of curved blades, and the whole assembly is enclosed in an airtight case.  Nozzles direct steam against the blades and turn the rotor. The energy to rotate an impulse turbine is derived from the kinetic energy of the steam flowing through the nozzles.  The term impulse means that the force that turns the turbine comes from the impact of the steam on the blades.

19. 19.  The toy pinwheel can be used to study some of the basic principles of turbines. When we blow on the rim of the wheel, it spins rapidly. The harder we blow, the faster it turns.  The steam turbine operates on the same principle, except it uses the kinetic energy from the steam as it leaves a steam nozzle rather than air.  Steam nozzles are located at the turbine inlet. As the steam passes through a steam nozzle, potential energy is converted to kinetic energy.  This steam is directed towards the turbine blades and turns the rotor. The velocity of the steam is reduced in passing over the blades.  Some of its kinetic energy has been transferred to the blades to turn the rotor.  Impulse turbines may be used to drive forced draft blowers, pumps, and main propulsion turbines.

20. 20.  The uppermost portion of the diagram shows a longitudinal section through the upper half of the turbine.  The middle portion shows the actual shape of the nozzle and blading.  The bottom portion shows the variation of absolute velocity and absolute pressure during the flow of steam through passage of nozzles and blades.  The expansion of steam from its initial pressure (steam chest pressure) to final pressure (condenser pressure) takes place in one set of nozzles.  Due to high drop in pressure in the nozzles, the velocity of steam in the nozzles increases.

21. 21.  The steam leaves the nozzle with a very high velocity and strikes the blades of the turbine mounted on a wheel with this high velocity.  The loss of energy due to this higher exit velocity is commonly known as carry over loss (or) leaving loss.  The pressure of the steam when it moves over the blades remains constant but the velocity decreases.  The exit/leaving/lost velocity may amount to 3.3 percent of the nozzle outlet velocity.  Also since all the KE is to be absorbed by one ring of the moving blades only, the velocity of wheel is too high (varying from 25000 to 30000 RPM).  However, this wheel or rotor speed can be reduced by adopting the method of compounding of turbines.

22. 22. 1. Since all the KE of the high velocity steam has to be absorbed in only one ring of moving blades, the velocity of the turbine is too high i.e. up to 30000 RPM for practical purposes. 2. The velocity of the steam at exit is sufficiently high which means that there is a considerable loss of KE.

23. 23. Force in the tangential direction Rate of change of momentum in the tangential direction. Mass per second change in velocity Newtons = = × ( )2 Newtonsw1 wm V V= ± ( ) Newtonsthrust)(axial direction.axialin themomentumofchangeofRatedirectionaxialin theForce 2aa1 VVm −= = ( ) m/s-NbladesonsteambydoneWork 2 uVVm ww1 ±= ( ) kW uVVm ww1 1000 turbineby thedevelopedPower 2± = ( ) ( ) 2 1 ww1 2 1 ww1 V uVV2u mV uVVm 22 2 1blade(s)thetosuppliedEnergy blade(s)on thedoneWork efficiencyBlade ± = ± == ( ) m/s-N 2 1 frictionbladetoduelostEnergy 2 r2 2 r1 VVm −= ( ) ( ) ( ) d ww1 1 ww1 H uVV HHm uVVm 2 2 2 stagepersuppliedenergyTotal blade(s)on thedoneWork efficiencyStage ± = − ± == ringnozzlein thedropHeat=−= 21d HHHwhere

24. 24. From the combined velocity triangle (diagram), we have uVVV rw +== 11111 coscos βα uVVV rw −== 22222 coscos βαand ( )KCV V V VVVVV r r r rrrww +=      +=+=+∴ 1cos cos cos 1coscoscos 11 11 22 11221121 β β β βββ 1 2 r r V V K =where and 1 2 cos cos β β =C ( )( )KCuVVV ww +−=+ 1cos 1121 α(or) ( )( )uKCuV +− 1cos 11 α ratiospeedBlade 1 == V u ρ Rate of doing work per kg of steam per second = ( )( ) 2 1 11 1cos V KCuV b +− = α η∴Diagram efficiency, Let, ( )( )KCb +−= 1cos2 2 1 ραρηThen, Diagram efficiency,

25. 25.  If the values of α1, K and C are assumed to be constant, then diagram efficiency depends only on the value of blade speed ratio, ρ  In order to determine the optimum value of for maximum diagram efficiency,  Then, ρ becomes, ρ = 0= ∂ ∂ ρ ηb 2 cos 1α

26. 26. ( ) ( ) ( ) 2 cos 1 4 cos cos. 2 cos 12 1 2 1 2 1 1 max αα α α η KCKCb +=      −+= Maximum diagram efficiency = ( )( )uKCuV +− 1cos 11 αWork done/kg of steam/second = 2 2u=Then maximum rate of doing work/kg of steam/second Note: If the blade is symmetrical & friction is absent, then, we have β1=β2 and K = C = 1 Then, maximum diagram efficiency, (ηb)max = cos2 α1

27. 27. 2. Reaction turbine  A turbine in which steam pressure decreases gradually while expanding through the moving blades as well as the fixed blades is known as reaction turbine.  It consists of a large number of stages, each stage consisting of set of fixed and moving blades. The heat drop takes place throughout in both fixed and moving blades.  No nozzles are provided in a reaction turbine. The fixed blades act both as nozzles in which velocity of steam increased and direct the steam to enter the ring of moving blades. As pressure drop takes place both in the fixed and moving blades, all the blades are nozzle shaped.  The steam expands while flowing over the moving blades and thus gives reaction to the moving blades. Hence the turbine is called reaction turbine.  The fixed blades are attached to the casing whereas moving blades are fixed with the rotor.  It is also called Parson's reaction turbine.

28. 28. Work output & power in reaction turbine ( ) smNVVmu ww /21 −+ ( ) H VVu ,Efficiency pairperstagetheindropEnthalpy pairperstagetheinsteamofkgperdonework ,Efficiency ww 1000 21 + =∴ = η η ( ) mNVVu ww −+ 21 The work done per kg of steam in the stage (per pair) = The work done per kg of steam per second in the stage (per pair) = ( ) kW VVmu ww 1000 21 + Power developed (per pair) = where, H = Enthalpy drop in the stage per pair in kJ/kg where, m = mass of steam flowing over blades in kg/s

29. 29. Degree of reaction in reaction turbine

30. 30. Work done & efficiency in reaction turbine

31. 31. Work done & efficiency in reaction turbine

32. 32. Impulse turbine vs Reaction turbine Impulse turbine Reaction turbine  The steam completely expands in the nozzle and its pressure remains constant during its flow through the blade passages  The steam expands partially in the nozzle and further expansion takes place in the rotor blades  The relative velocity of steam passing over the blade remains constant in the absence of friction  The relative velocity of steam passing over the blade increases as the steam expands while passing over the blade  Blades are symmetrical  Blades are asymmetrical  The pressure on both ends of the moving blade is same  The pressure on both ends of the moving blade is different  For the same power developed, as pressure drop is more, the number of stages required are less  For the same power developed, as pressure drop is small, the number of stages required are more  The blade efficiency curve is less flat  The blade efficiency curve is more flat  The steam velocity is very high and therefore the speed of turbine is high.  The steam velocity is not very high and therefore the speed of turbine is low.

33. 33. Governing of turbines Governing is the method of maintaining the speed of the turbine constant irrespective of variation of the load on the turbine. A governor is used for achieving this purpose which regulates the supply of steam to the turbine in such a way that the speed of the turbine is maintained as far as possible a constant under varying load conditions. The various methods of governing of steam turbines are: 1) Throttle governing 2) Nozzle governing 3) By-pass governing 4) Combination of (1) & (2) or (2) & (3)

34. 34. Throttle governing

35. 35. Throttle governing

36. 36. 2. Nozzle governing

37. 37. 3. By-pass governing

38. 38. Losses in steam turbines  Residual velocity loss  Losses in regulating valves  Loss due to steam friction in nozzle  Loss due to leakage  Loss due to mechanical friction  Loss due to wetness of steam  Radiation loss

39. 39. Effect of blade friction in steam turbines

40. 40. overall efficiency & reheat factor Reheat factor: It is defined as the ratio of cumulative heat drop to the adiabatic heat drop in all the stages of the turbine. The value of reheat factor depends on the type and efficiency of the turbine, the average value being 1.05. DA BABABA dropheatAdiabatic dropheatCumulative factorReheat 1 332211 ++ == Overall efficiency: It is defined as the ratio of total useful heat drop to the total heat supplied. DA1 332211 h-H CACACA suppliedheatTotal dropheatusefulTotal efficiencyOverall ++ ==

# data[].attributes.attachment_link.authors[].name
ANKIT SAXENA Asst. Prof. @ Dr. Akhilesh Das Gupta Institute of Technology and Management, New Delhi

# data[].attributes.attachment_link.description
A steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft 1. Steam Turbines Unit-4 2.

# data[].attributes.attachment_link.description
Topic : cochran boiler By rajesh goswami

# data[].attributes.attachment_link.title
Steam Power Plant Layout & Working Principle

# data[].attributes.body
Cochran Boiler

# data[].attributes.body
Impulse & Reaction Turbine

# data[].attributes.attachment_link.title
IMPULSE TURBINE AND REACTION TURBINE - ANUNIVERSE 22

# data[].attributes.body
Compounding Of Turbines

# data[].attributes.body
Continuity Eqn, Nozzle Types,Mach No,Use of Nozzles.

# data[].attributes.body
Difference Between

# data[].attributes.attachment_link.title
Boiler Mountings and Accessories in hindi | Boiler mountings in Hindi | Boiler Accessories in Hindi

# data[].attributes.body
Types of Steam

# data[].attributes.body
Working of Turbines

# data[].attributes.body
Quiz 2

# data[].attributes.attachment_link.description
BHARAT 2050 INFO SOLUTIONS VASUDEVAM KUTAMBAKAM

# data[].attributes.body
Classification of IC Engine

# data[].attributes.attachment_link.title
Classification of IC engine|Types of IC engine|Internal Combustion Engine|GTU|IC engine types|Thermo

# data[].attributes.body
Components of IC Engine

# data[].attributes.attachment_link.title
Main parts of an IC ENGINE with explanation

# data[].attributes.body
4 Stroke Diesel Engine

# data[].attributes.attachment_link.title
[HINDI] How 4-Stroke Diesel Engine Works?

# data[].attributes.attachment_link.title
How Diesel Engines Work - Part - 1 (Four Stroke Combustion Cycle)

# data[].attributes.body
Brake Thermal Efficiency

# data[].attributes.body
Engine Faults & Remedies.

# data[].attributes.attachment_link.title
7 Common Diesel engine faults and its rectification

# data[].attributes.body
Gas Turbine Types.

# data[].attributes.attachment_link.title
Gas Turbine | Gas Turbine Explained | Working Principle of gas turbine | Gas turbine in hindi

# data[].attributes.body
Open & Close Cycle Gas Turbine

# data[].attributes.attachment_link.title
Gas turbine Working principle , Open loop and closed loop gas turbine.

# data[].attributes.body
In Detail

# data[].attributes.attachment_link.title
Mod-01 Lec-27 Components of the Gas Turbine Engine

# data[].attributes.body
Pollution Control

# data[].attributes.attachment_link.readable_text
IC engine emission and control of the emissions for minimizing the global warming

1. 1. IC Engine Emissions and Emission Control Unit - III

2. 2. Formation of CO in IC Engines * Formation of CO is well established. * Locally, there may not be enough O2 available for complete oxidation and some of the carbon in the fuel ends up as CO. * The amount of CO, for a range of fuel composition and C/H ratios, is a function of the relative air-fuel ratio. * Even at sufficient oxygen level, high peak temperatures can cause dissociation. * Conversion of CO to CO2 is governed by reaction HCOOHCO  2 * Dissociated CO may freeze during the expansion stroke. The highest CO emission occurs during engine start up (warm up) when the engine is run fuel rich to compensate for poor fuel evaporation.

3. 3. Formation of CO in CI Engines * The mean air-fuel mixture present in the combustion chamber per cycle is far leaner in the diesel engine than in the SI engine. * Due to a lack of homogeneity of the mixture built up by stratification, however, extremely "rich" local zones are exist. * This produces high CO concentrations that are reduced to a greater or lesser extent by post-oxidation. * When the excess-air ratio increases, dropping temperatures cause the post-oxidation rate to be reduced. * The reactions "freeze up". * However, the final CO concentrations of diesel engines therefore are far lower than in SI engines. * The basic principles of CO formation, however, are the same as in SI engine.

4. 4. Hydrocarbon Emission Sources for CI Engines Overmixing of fuel and air - During the ignition delay period evaporated fuel mixes with the air, regions of fuel-air mixture are produced that are too lean to burn. Some of this fuel makes its way out the exhaust. Longer ignition delay more fuel becomes overmixed. Undermixing of fuel and air - Fuel leaving the injector nozzle at low velocity, at the end of the injection process cannot completely mix with air and burn.

5. 5. NOx Formation in I.C. Engines Three chemical reactions form the Zeldovich reaction are: Forward rate constants:      Tk Tk Tk f f f /450exp101.7 /4680exp108.1 /38370exp108.1 10 ,3 7 ,2 11 ,1    Zelodvich reaction is the most significant mechanism of NO formation in IC engines.

6. 6. Particulates * A high concentration of particulate matter (PM) is manifested as visible smoke in the exhaust gases. * Particulates are any substance other than water that can be collected by filtering the exhaust, classified as: * Solid carbon material or soot. * Condensed hydrocarbons and their partial oxidation products. * Diesel particulates consist of solid carbon (soot) at exhaust gas temperatures below 500oC, HC compounds become absorbed on the surface. * In a properly adjusted SI engines soot is not usually a problem . * Particulate can arise if leaded fuel or overly rich fuel-air mixture are used. * Burning crankcase oil will also produce smoke especially during engine warm up where the HC condense in the exhaust gas.

7. 7. 14 The soot formation process is very fast. 10 - 22 C atoms are converted into 106 C atoms in less than 1 ms. Based on equilibrium the composition of the fuel-oxidizer mixture soot , formation occurs when x ≥ 2a (or x/2a ≥ 1) in the following reaction: Mechanism of Formation of Particulates (soot) )()2( 2 2 22 sCaxH y aCOaOHC yx  Experimentally it is found that the critica C/O ratio for onset of soot formation is between 0.5 and 0.8. The CO, H2, and C(s) are subsequently oxidized in the diffusion flame to CO2 and H2O via the following second stage. OHOHCOOsCCOOCO 2222222 2 1 )( 2 1  Any carbon not oxidized in the cylinder ends up as soot in the exhaust!

8. 8. Emissions Control * Three basic methods used to control engine emissions: * 1)Engineering of combustion process -advances in fuel injectors, oxygen sensors, and on-board computers. * 2) Optimizing the choice of operating parameters -two Nox control measures that have been used in automobile engines are spark retard and EGR. * 3) After treatment devices in the exhaust system -catalytic converter. 23

9. 9. 29 Anatomy of Catalytic Converter *All catalytic converters are built in a honeycomb or pellet geometry to expose the exhaust gases to a large surface made of one or more noble metals: platinum, palladium and rhodium. *Rhodium used to remove NO and platinum used to remove HC and CO. Lead and sulfur in the exhaust gas severely inhibit the operation of a catalytic converter (poison).

10. 10. The active catalyst material is impregnated on the surface of catalyst substrate or support. The function of catalyst substrate is to provide maximum possible contact of catalyst with reactants. Following arethe main requirements of catalyst substrate: High surface area per unit volume to keep a small size of the converter Support should be compatible with coating of a suitable material (washcoat) to provide high surface area and right size of pores on its surface for good dispersion and high activity of thecatalyst. Low thermal capacity and efficient heat transfer properties for quick heat-up to working temperatures. Ability to withstand high operating temperatures up to around to 1000º C. High resistance to thermal shocks that could be caused by sudden heat release when HC from engine misfire get oxidized in the converter. Low pressure drop Ability to withstand mechanical shocks and vibrations at the operating temperatures under road conditions for long life and durability The following types of catalysts supports are used; Pellets Monolithic supports Ceramic monoliths Metal monoliths

11. 11. Three way catalytic convertor * A catalyst forces a reaction at a temperature lower than normally occurs. * As the exhaust gases flow through the catalyst, the NO reacts with the CO, HC and H2 via a reduction reaction on the catalyst surface. * NO+CO→½N2+CO2 , NO+H2 → ½N2+H2O, and others * The remaining CO and HC are removed through an oxidation reaction forming CO2 and H2O products (air added to exhaust after exhaust valve). * A three-way catalysts will function correctly only if the exhaust gas composition corresponds to nearly (±1%) stoichiometric combustion. * If the exhaust is too lean - NO is not destroyed * If the exhaust is too rich - CO and HC are not destroyed * A closed-loop control system with an oxygen sensor in the exhaust is used to A/F ratio and used to adjust the fuel injector so that the A/F ratio is near stoichiometric.

12. 12. The oxides of base metals such as copper, chromium, nickel, cobalt etc. have been studied. The base metal oxides are effective only at higher temperatures. In addition, they sinter and deactivate when subjected to high exhaust gas temperatures experienced at high engine loads. Their conversion efficiency is severely reduced by sulphur dioxide produced by sulphur in fuel. The noble metals platinum (Pt), palladium (Pd) and rhodium (Rh) were found to meet the above mentioned performance requirements. In practice, only the noble metals are used although these are expensive. Mixtures of noble metals are used to provide higher reactivity and selectivity of conversion. Following are typical formulations; Pt : Pd in 2:1 ratio for oxidation catalysts (Pt + Pd): Rh in ratio of 5 :1 to 10: 1 for simultaneous oxidation and reduction such as in 3- way catalysts Palladium has higher specific activity than Pt for oxidation of CO, olefins and methane. For the oxidation of paraffin hydrocarbons Pt is more active than Pd. Platinum has a higher thermal resistance to deactivation. Rhodium is used as a NOx reduction catalyst when simultaneous conversion of CO, HC and NO is desired as in the 3-way catalytic converters. The amount of noble metal used typically varies from about 0.8 to 1.8 g/l (25 to 50 g/ft3) of catalytic

13. 13. Properties of Catalyst * The active catalyst material is required to posses the following main characteristics * High specific reaction activity for pollutants * High resistance to thermal degradation * Good cold start performance, and * Low deactivation caused by fuel contaminants and sulphur Other desirable requirements are low * cost.

14. 14. Exhaust Gas Recirculation-EGR * NOx Emissions * In many countries around the world, the emissions of NOx from diesel and gasoline vehicles are restricted. NOx is formed in the combustion chamber of engines, when high temperatures cause oxygen and nitrogen (both found in the air supplied for combustion) to combine. * Exhaust Gas Recirculation * A widely adopted route to reduce NOx emissions is Exhaust Gas Recirculation (EGR). This involves recirculating a controllable proportion of the engine's exhaust back into the intake air. A valve is usually used to control the flow of gas, and the valve may be closed completely if required. * The substitution of burnt gas (which takes no further part in combustion) for oxygen rich air reduces the proportion of the cylinder contents available for combustion. This causes a correspondingly lower heat release and peak cylinder temperature, and reduces the formation of NOx. The presence of an inert gas in the cylinder further limits the peak temperature (more than throttling alone in a spark ignition engine).

15. 15. The gas to be recirculated may also be passed through an EGR cooler, which is usually of the air/water type. This reduces the temperature of the gas, which reduces the cylinder charge temperature when EGR is employed. This has two benefits- the reduction of charge temperature results in lower peak temperature, and the greater density of cooled EGR gas allows a higher proportion of EGR to be used. On a diesel engine the recirculated fraction may be as high as 50% under some operating conditions. Advantages of EGR Reduced NOx Potential reduction of throttling losses on spark ignition engines at part load Improved engine life through reduced cylinder temperatures (particularly exhaust valve life)

16. 16. * Disadvantages and Difficulties of EGR * Since EGR reduces the available oxygen in the cylinder, the production of particulates (fuel which has only partially combusted) is increased when EGR is applied. This has traditionally been a problem with diesel engines, where the trade-off between NOx and particulates is a familiar one to calibrators. * The deliberate reduction of the oxygen available in the cylinder will reduce the peak power available from the engine. For this reason the EGR is usually shut off when full power is demanded, so the EGR approach to controlling NOx fails in this situation. * The EGR valve can not respond instantly to changes in demand, and the exhaust gas takes time to flow around the EGR circuit. This makes the calibration of transient EGR behavior particularly complex- traditionally the EGR valve has been closed during transients and then re-opened once steady state is achieved. However, the spike in NOx / particulate associated with poor EGR control makes transient EGR behavior of interest.

17. 17. * The recirculated gas is normally introduced into the intake system before the intakes divide in a multi-cylinder engine. Despite this, perfect mixing of the gas is impossible to achieve at all engine speeds / loads and particularly during transient operation. For example poor EGR distribution cylinder-to-cylinder may result in one cylinder receiving too much EGR, causing high particulate emissions, while another cylinder receives too little, resulting in high NOx emissions from that cylinder. * Although the term EGR usually refers to deliberate, external EGR, there is also a level of internal EGR. This occurs because the residual combustion gas remaining in the cylinder at the end of the exhaust stroke is mixed with the incoming charge. There is therefore a proportion of internal EGR which must be taken into account when planning EGR strategies. The scavenging efficiency will vary with engine load, and in an engine fitted with variable valve timing a further parameter must be considered.

18. 18. Particulate Trap

# data[].attributes.attachment_link.title
IC engine emission and control of the emissions

# data[].attributes.attachment_link.description
IC engine emission and control of the emissions for minimizing the global warming 1. IC Engine Emissions and Emission Control Unit - III 2. Formation of CO in IC Engines * Formation of CO is well established. * Locally, there may not be enough O2 available for complete oxidation and some of the carbon in the fuel ends up as CO.

# data[].attributes.body
Gas Turbine

# data[].attributes.attachment_link.readable_text
In this slides I have discussed about gas turbine

Assistant Professor at Jahangirabad Educational Trust Group of Institutions

1. 1.  A gas turbine is a machine delivering mechanical power or thrust. It does this using a gaseous working fluid. The mechanical power generated can be used by, for example, an industrial device.  The outgoing gaseous fluid can be used to generate thrust. In the gas turbine, there is a continuous flow of the working fluid. Efficiency is 20 to 30% whereas that of steam power plant is 38 To 48% Major Applications of Gas Turbine 1. Aviation(self contained, light weight don't require cooling 2. Power Generation 3. Oil and Gas industry(cheaper supply of fuel and low installation cost) 4. Marine propulsion 12/31/2016 Jahangirabad institute of technology 1

2. 2. Hot gases move through a multistage gas turbine. Like in steam turbine, the gas turbine also has stationary and moving blades. The stationary blades guide the moving gases to the rotor blades adjust its velocity. The shaft of the turbine is coupled to a generator. 12/31/2016 Jahangirabad institute of technology 2

3. 3. Working principle :  Air is compressed(squeezed) to high pressure by a compressor.  Then fuel and compressed air are mixed in a combustion chamber and ignited.  Hot gases are given off, which spin the turbine wheels.  Gas turbines burn fuels such as oil, natural gas and pulverized(powdered) coal.  Gas turbines have three main parts: i) Air compressor ii) Combustion chamber iii) Turbine 12/31/2016 Jahangirabad institute of technology 3

4. 4. Advantages of Gas turbine power plants. Storage of fuel requires less area and handling is easy.  The cost of maintenance is less.  It is simple in construction. There is no need for boiler, condenser and other accessories as in the case of steam power plants.  Cheaper fuel such as kerosene , paraffin, benzene and powdered coal can be used which are cheaper than petrol and diesel.  Gas turbine plants can be used in water scarcity areas.  Less pollution and less water is required. 12/31/2016 Jahangirabad institute of technology 4

5. 5. Disadvantages of gas turbine power plant 1. 66% of the power developed is used to drive the compressor. Therefore the gas turbine unit has a low thermal efficiency. 2. The running speed of gas turbine is in the range of (40,000 to 100,000 rpm) and the operating temperature is as high as 1100 - 12600C. For this reason special metals and alloys have to be used for the various parts of the turbine. 3. High frequency noise from the compressor is objectionable. 12/31/2016 Jahangirabad institute of technology 5

6. 6.  Pressure Ratio- Ratio of the cycle's highest pressure to its lowest pressure.  Work Ratio: Ratio of network output to the total work developed in the turbine.  Air Ratio: kg of air entering the compressor inlet per unit of cycle net output, Kg/kWh  Compression efficiency: Ratio of work needed for ideal air compressor through a given pressure range to work actually used by the compressor.  Engine Efficiency: It is the ratio of the work actually developed by the turbine expanding hot power gas through a given pressure range to that would be yeilded for ideal expansion conditions  Machine Efficiency: Collective term of engine efficiency and compressor efficiency of turbine and compressor.  Combustion Efficiency: It is the ratio of heat actually released by 1 g of the fuel to heat that would be released by complete perfect combustion.  Thermal Efficiency: It is the percentage of total energy input appearing as net work output of the cycle. 12/31/2016 Jahangirabad institute of technology 6

7. 7. The gas turbine power plants can be classified mainly into two categories. These are :open cycle gas turbine power plant and closed cycle gas turbine power plant. Open Cycle Gas Turbine Power Plant In this type of plant the atmospheric air is charged into the combustor through a compressor and the exhaust of the turbine also discharge to the atmosphere. Closed Cycle Gas Turbine Power Plant In this type of power plant, the mass of air is constant or another suitable gas used as working medium, circulates through the cycle over and over again. 12/31/2016 Jahangirabad institute of technology 7

8. 8. Gas turbines usually operate on an open cycle Air at ambient conditions is drawn into the compressor, where its temperature and pressure are raised. The high pressure air proceeds into the combustion chamber, where the fuel is burned at constant pressure. The high- temperature gases then enter the turbine where they expand to atmospheric pressure while producing power output. Some of the output power is used to drive the compressor. The exhaust gases leaving the turbine are thrown out (not re-circulated), causing the cycle to be classified as an open cycle 12/31/2016 Jahangirabad institute of technology 8

9. 9.  The ideal cycle that the working fluid undergoes in the closed loop is the Brayton cycle. It is made up of four internally reversible processes: 1-2 Isentropic compression;(No change in entropy) 2-3 Constant-pressure heat addition; 3-4 Isentropic expansion; 4-1 Constant-pressure heat rejection. The T-s diagrams of an ideal Brayton cycle. 12/31/2016 Jahangirabad institute of technology 9

10. 10. 1.Intercooling 2. Reheating 3. Regeneration 12/31/2016 Jahangirabad institute of technology 10

11. 11.  A compressor utilizes the major percentage of power developed by the gas turbine. The work required by the compressor can be reduced by compressing the air in two stages and incorporation a intercooler between the two. 12/31/2016 Jahangirabad institute of technology 11

12. 12.  1-2': LP compression  2'-3: Intercooling  3-4': H.P. compression  4'-5: C.C. Combustion chamber(heating)  5-6': T(Turbine) -Expansion 12/31/2016 Jahangirabad institute of technology 12

13. 13.  Work Ratio is increased  Thermal efficiency decreases but it increases at high pressure ratio. 12/31/2016 Jahangirabad institute of technology 13

14. 14.  The output of gas turbine can be improved by expanding the gasses in two stages with a reheater between the two.  The H.P. turbine drives the compressor and the LP turbine provides useful power output. 12/31/2016 Jahangirabad institute of technology 14

15. 15. 1-2': Compression 2'-3: C.C (heating) 3'-4': Turbine(Expansion) 4'-5: Reheater(heating) 5-6': Turbine(Expansion) 12/31/2016 Jahangirabad institute of technology 15

16. 16.  The exhaust gasses from the turbine carry a large quantity of heat with them since their temperature is far above the ambient temperature.  They can be used to heat air coming from the compressor there by reducing the mass of fuel supplied in the combustion chamber. 12/31/2016 Jahangirabad institute of technology 16

17. 17.  The compression and expansion processes remain the same, but the combustion process is replaced by a constant-pressure heat addition process from an external source.  The exhaust process is replaced by a constant-pressure heat rejection process to the ambient air. 12/31/2016 Jahangirabad institute of technology 17

18. 18. 1-2 : the air is compressed isentropically from lower pressure p1 to the upper pressure p2, temp rising from T1 to T2. 2-3: Heat flows into the system increasing its volume V2 to V3 and temp T2 to T3, pressure remains constant at p2. Heat received = mCp(T3-T2) 3-4: The air is expanded isentropically from p2 to p1, and temp T3 to T4, No heat flow occurs. 4-5: Heat is rejected from the system as volume dec from V4-V1 and temp from T4-T1, pressure remains constant p1. Heat rejected= mCp(T4-T1) 12/31/2016 Jahangirabad institute of technology 18

19. 19.  Merits:  Higher thermal efficiency  Reduced size  No contamination  Improved heat transmission  Lesser Fluid friction  No loss in working medium  Greater output  Inexpensive fuel.  Demerits:  Complexity  Large amount of cooling water is required.  Dependent System  Not economical for moving vehicles as weight /kW developed is high.  Requires the use of very large air heater. 12/31/2016 Jahangirabad institute of technology 19

20. 20.  Gas Turbine and Steam Power Plants:  The combination of gas-turbine-steam cycle aims at utilizing the heat of exhaust gases from the gas turbine thus, improve the overall plant efficiency.  The popular designs are:  1. Heating feed water with exhaust gases.  2. Employing the gases from a supercharged boiler to expand in the gas turbine.  3. Employing the gasses as combustion air in the steam boiler. 12/31/2016 Jahangirabad institute of technology 20

21. 21.  The output heat of the gas turbine flue gas is utilized to generate steam by passing it through a heat recovery steam generator (HRSG), so it can be used as input heat to the steam turbine power plant. This combination of two power generation cycles enhances the efficiency of the plant. While the electrical efficiency of a simple cycle plant power plant without waste heat utilization typically ranges between 25% and 40%, a CCPP can achieve electrical efficiencies of 60% and more. 12/31/2016 Jahangirabad institute of technology 21

22. 22.  The performance of diesel engine can be improved by combining it with exhaust driven gas turbine.  Three combinations: 1. Turbo charging 2. Gas Generator 3. Compound engine 12/31/2016 Jahangirabad institute of technology 22

23. 23. 12/31/2016 Jahangirabad institute of technology 23

# data[].attributes.attachment_link.description
In this slides I have discussed about gas turbine Assistant Professor at Jahangirabad Educational Trust Group of Institutions 1.  A gas turbine is a machine delivering mechanical power or thrust. It does this using a gaseous working fluid. The mechanical power generated can be used by, for example, an industrial device.

# data[].attributes.body
Gas Turbine

# data[].attributes.attachment_link.readable_text
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled toa downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high-pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section
Visit https://www.topicsforseminar.com to Download

1. 1. A GAS TURBINE Prepared By: Anup Mahato

2. 2. CONTENT INTRODUCTION THEORY OF OPERATION BRAYTON CYCLE TYPES OF GAS TURBINE SCALE JET ENGINE MICROTURBINES GAS TURBINE IN SURFACE VEHICLE MARINE APPLICATION NON-MILITARY MARITIME TURBOFAN TURBOPROP ADVANTAGE & DISADVANTAGE CONCLUSION

3. 3. INTRODUCTION A gas turbine, also called a combustion turbine, is a type of internalcombustion engine. It has an upstream rotating compressor coupled toa downstream turbine, and a combustion chamber in-between. A typical axial-flow gas turbine turbojet, the J85

4. 4. THEORY OF OPERATION* Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbines blades, spinning the turbine which powers the compressor and, for some turbines, drives their mechanical output. The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas.

5. 5. BRAYTON CYCLE* The Brayton cycle is a thermodynamic cycle that describes the workings of the gas turbine engine, basis of the airbreathing jet engine and others.

6. 6. EFFICIENCY

7. 7. TYPES OF GAS TURBINE* Jet engines* Turboprop engines* Aeroderivative gas turbines* Amateur gas turbines* Auxiliary power units* Industrial gas turbines for power generation* Compressed air energy storage* Turboshaft engines* Radial gas turbines* Scale jet engines (micro-jets)

8. 8. SCALE JET ENGINE

9. 9. MICROTURBINESAlso known as:Turbo alternatorsTurbogenerator

10. 10. GAS TURBINES IN SURFACE VEHICLES* Gas turbines are often used on ships, locomotives, helicopters, tanks, and to a lesser extent, on cars, buses, and motorcycles.* A key advantage of jets and turboprops for aeroplane propulsion - their superior performance at high altitude compared to piston engines, particularly naturally aspirated ones - is irrelevant in automobile applications. Their power-to-weight advantage, though less critical than for aircraft, is still important.

11. 11. PASSENGER ROAD VEHICLESMore recently, there has been some interest in theuse of turbine engines for hybrid electric cars. Forinstance, a consortium led by micro gas turbinecompany Bladon Jets has secured investment fromthe Technology Strategy Board to develop an UltraLightweight Range Extender (ULRE) for nextgeneration electric vehicles.

12. 12. CONCEPT CARS* Jaguar C-X75 concept car. This electrically powered supercar has a top speed of 204 mph (328 km/h) and can go from 0 to 62 mph (0 to 100 km/h) in 3.4 seconds. It uses Lithium-ion batteries to power 4 electric motors which combine to produce some 780 bhp. It will do around 100 miles on a single charge of the batteries but in addition it uses a pair of Bladon Micro Gas Turbines to re-charge the batteries extending the range to some 560 miles

13. 13. Jaguar C-X75 concept car

14. 14. RACING CARS* Rover and the BRM Formula One team joined forces to produce the Rover-BRM, a gas turbine powered coupe, which entered the 1963 24 Hours of Le Mans, driven by Graham Hill and Richie. It averaged 107.8 mph (173 km/h) and had a top speed of 142 mph (229 km/h). Rover-BRM

15. 15. MOTORCYCLESMTT Turbine SUPERBIKE appeared in 2000 (hence the designation of Y2KSuperbike by MTT) and is the first production motorcycle powered by aturbine engine - specifically, a Rolls-Royce Allison model 250 turbo shaftengine, producing about 283 kW (380 bhp). Speed-tested to 365 km/h or227 mph. Y2K MTT

16. 16. MARINE APPLICATIONSNaval Gas turbines are used in many naval vessels, where they are valued for their high power-to-weight ratio and their ships resulting acceleration and ability to get underway quickly. The first gas-turbine-powered naval vessel was the Royal Navys Motor Gun Boat MGB 2009 (formerly MGB 509) converted in 1947.The Gas turbine from MGB 2009

17. 17. NON-MILITARY MARITIME Gas turbines have been usedexperimentally to power seagoingcommercial vessels since about 1949 (AngloSaxon Petroleum oil tanker "Auris").In July 2000 the Millennium became thefirst cruise ship to be propelled by gasturbines, in a Combined Gas and SteamTurbine configuration. The liner RMS QueenMary 2 uses a Combined Diesel and GasTurbine configuration.

18. 18. TURBOFANLarge jetliners use what are known as turbofan engines, which are nothing more than gas turbines combined with a large fan at the front of the engine.The turbofan is basically the combination of two engines, the turbo portion which is a conventional gas turbine engine.The low specific thrust/high bypass ratio turbofans used in todays civil jetliners (and some military transport aircraft) evolved from the high specific thrust/low bypass ratio turbofans used in such [production] aircraft back in the 1960s.

19. 19. Animation of a 2-spool, high-bypass turbofan. A. Low pressure spool B. High pressure spool C. Stationary components1. Nacelle2. Fan3. Low pressure compressor4. High pressure compressor5. Combustion chamber6. High pressure turbine7. Low pressure turbine8. Core nozzle9. Fan nozzle

20. 20. TURBOPROP A turboprop engine is similar to a turbofan, but instead of a fan there is a conventional propeller at the front of the engine. The output shaft connects to a gearbox to reduce the speed, and the output of the gearbox turns the propeller.A turboprop engine in operation

21. 21. ADVANTAGES OF GAS TURBINE ENGINESVery high power-to-weight ratio, compared to reciprocating engines;Smaller than most reciprocating engines of the same power rating.Moves in one direction only, with far less vibration than a reciprocating engine.Fewer moving parts than reciprocating engines.Low operating pressures.High operation speeds.Low lubricating oil cost and consumption.Can run on a wide variety of fuels.

22. 22. DISADVANTAGES OF GAS TURBINE ENGINESCost is very highLess efficient than reciprocating engines at idle speedLonger startup than reciprocating enginesLess responsive to changes in power demand compared to reciprocating engines

23. 23. THANK YOU

# data[].attributes.attachment_link.description
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled toa downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited.

# data[].attributes.body
Cause & Remedies for IC Engine

# data[].attributes.attachment_link.readable_text
Troubleshooting of internal combustion engine

1. 1. TROUBLESHOOTING OF INTERNAL COMBUSTION ENGINE Present by Six star Group 6 1

2. 2. Group Member name Nur -E- Alam Siddike - 10307050 Arup Mazumder - 10307012 Abul Hasnath - 10307022 K md Brohan - 11307008 Shima - 11307007 Md. Shake Rasel - 10207051 2

3. 3. Objective  To know about Internal Combustion Engine  To know about the trouble of Internal Combustion Engine  Fixed the problem of Internal Combustion Engine 3

4. 4. Engine can avoid many troubles by fallowing the prescribed instructions for starting and operating the engine. Troubleshooter generally associates certain troubles with a particular system or assembly 4

5. 5. Engine fails to start ln general, the troubles that prevent an engine from starting are (1) the engine can neither be cranked nor barred over (2) the engine cannot be cranked, but it can be barred over (3) the engine can be cranked, but it still fails to start. 5

6. 6. Engine do not start for fuel system Problem  Empty fuel tank  Fuel is old, dirty, or contaminated  Faulty wiring and connection problems in the fuel system  Fuel pump not working  Fuel supply hose damaged, distorted, or improperly attached Solution  Fill-up the fuel tank  Change the fuel  Check and repair  Service the pump  repair or replace 6

7. 7. For Petrol engine Problem  Fuel pump not work  Fuel pump pressure low  Fuel line lickage  Carburetor does no work  If EFI engine injector not work  Injector pressure low Solution  Fuel pump repair  Fuel pump repair  Fuel line repair  Carburetor serving  Injector change  Injector change 7

8. 8. Carburator fuel system 8

9. 9. EFI Fuel system 9

10. 10. For Diesel engine Problem  Fuel pump not work  Fuel filter highly jam  High pressure pump not work  Injector not work or pressure very low  Fuel line damage or lickage  Air lock Solution  Fuel pump servicing  Fuel filter change  Pump servicing  Injector change  Fuel line repair or replace  Check the fuel line 10

11. 11. Diesel fuel system 11

12. 12. Engine do not start for Ignition system Problem  Battery is undercharged  Ignition switch faulty  Ignition coil not functional  Distributor not functional  High-tension lead faulty  faulty spark plugs  Loose plug wires Solution  Recharge the battery  Ignition switch repair  Ignition coil replace  Checked and repair  Replace the high-tension lead 12

13. 13. Spark Ignition system 13

14. 14. Engine do not start for Starting System problem  Battery is uncharged  Starting motor not work  Starter solenoid not work  Starter relay not work  Loss wire connection Solution  Battery charge  Motor repair  Repair solenoid  Starter relay change  Check wire connection 14

15. 15. Starting System 15

16. 16. Engine do not start for lubrication system Problem  Main oil pump not work  Oil filter full jam  Engine oil pressure gauge not work  If use low quality oil Solution  Oil pump change  Oil filter change  Oil gauge change  change oil 16

17. 17. Lubricating system 17

18. 18. Engine Can Be Cranked, but Fails to Start  Possible causes:  Fuel supply hose damaged, distorted, or improperly attached  Fuel tank empty  Fuel filter is clogged up  Fuel is old, dirty, or contaminated  Fuel supply hose damaged, distorted, or improperly attached  Closed fuel tank vent  Inoperative, or clogged thermostat  Wrong engine oil  Spark plugs defective, wrong, plugged, or incorrect spark-plug gap Solution  Fuel supply hose change  Fill-up the fuel tank  Filter change  Change the fuel  Servicing the fuel system  Clear the vent  Change the spark plug 18

19. 19. Engine start but not run smoothly Problem  Compression lick  Engine head gasket lick  Piston ring defect  Ignition coil defect  Spark plug defect  Injector defect  Air filter jam  If EFI(Electronic Fuel Injection)engine sensors defect Solution  Compression ring change  Head gasket change  Piston ring change  Ignition coli change  Air filter change  Injector change 19

20. 20. Engine knocks Problem  clogged Carburetor  Ignition Distributor problems  plugged fuel Injectors  Valve timing fails, or faulty  failed or loose timing belt tensioner  lean air-to-fuel mixture  using fuel of lower than recommended Octane Rating Solution  Servicing the  carburetor  Change distributor or servicing  Change injector  Adjust timing belt setting  Adjust ideal speed setting  Change the fuel 20

21. 21. Engine knocks Problem  Anti-Knock sensors malfunction  Engine is too hot  Carbon deposits in the combustion chamber, pistons  Faulty or defective main crankshaft bearings  water pump bearing is worn out  Flywheel is broken or has cracks Solution  Sensor change  Check thermostat  Clean carbon from combustion chamber , piston  Change main bearing  Change water pump bearing  Fly wheel change 21

22. 22. Engine smokes Problem  engine is burning oil  worn or broken piston rings  worn valve guide or valve guide seals  leaking head gasket  broken or cracked engine head  Air/fuel mixture is too rich  leaky fuel injector  Solution  Change the oil grade  Change piston ring  Change valve guide or seals  Change head gasket  Change or servicing engine head  Change injector 22

23. 23. Thanks To ALL 23

24. 24. Any question ??????? 24

Recommended

# data[].attributes.attachment_link.title
Troubleshooting of internal combustion engine

# data[].attributes.attachment_link.description
Troubleshooting of internal combustion engine 1. TROUBLESHOOTING OF INTERNAL COMBUSTION ENGINE Present by Six star Group 6 1 2. Group Member name Nur -E- Alam Siddike - 10307050 Arup Mazumder - 10307012 Abul Hasnath - 10307022 K md Brohan - 11307008 Shima - 11307007 Md. Shake Rasel - 10207051 2 3.

# data[].attributes.body
IC Engine

# data[].attributes.attachment_link.readable_text
internal combustion engines

1. 1. INTERNAL COMBUSTION ENGINE Prepared by: Pradeep Kumar Gupta Assistant Professor Department of Mechanical Engineering

2. 2. Engine A device which transforms one form of energy into another form is known as engine. Most of the engines convert thermal energy of fuel into mechanical work and therefore they are known as heat engines. Internal Combustion (IC) engine classification The Internal Combustion engine can be classified by various ways 1. According to engine design. a. Reciprocating engines, b. Rotary engines. 2. According to working cycle. a. Engines based on Otto cycle (spark-ignition or S. I. engines), b. Engines based on diesel cycle (compression-ignition or C. I. engines). 3. According to number of strokes. a. Four-stroke engines (S. I. engines and C. I. engines) b. Two -stroke engines (S. I. engines and C. I. engines)

3. 3. 4.According to fuel. a. Petrol (or Gasoline), b. compressed natural gas (CNG), c. Liquefied petroleum gas (LPG), d. Diesel e. Alcohols (methanol, ethanol). 5.According to fuel supply and mixture preparation. a. Carbureted types, fuel supplied through carburetor. b. Injection type. (i)Fuel injected into inlet ports or inlet manifold. (ii)Fuel injected into the cylinder just before ignition. 6.According to method of ignition. a. Battery ignition b. Magneto ignition. 7.According to method of cooling. a. Water cooled b. Air cooled 8.According to cylinder arrangement. a. Inline engine, b. V engine, c. Radial engine 9.According to valve or port design and location. a. Overhead (I head), b. Side valve (L head) valves; In two stroke engines: - Cross scavenging, loop scavenging, uniflow scavenging.

4. 4. Various parts of I.C. Engines Spark Ignition Engine

5. 5. Various parts of I.C. Engines Compression Ignition Engine

6. 6. * Terminology used in internal combustion engine * Cylinder bore: The nominal inner diameter of the working cylinder is known as cylinder bore. It is represented by 'D'. * Piston area: The area of a circle of diameter equal to the cylinder bore is known as piston area. It is represented by 'A'. * Stroke: The nominal distance through which a piston moves between two successive reversals of its direction of motion is known as stroke. It is represented by 'L'. * Dead centre: The position of the piston and moving parts which are mechanically connected to it at the moment when the direction of the piston motion is reversed at either point of the stroke is known as dead centre. There are two types of dead centres. These are as follows: * Top dead centre: In vertical engine, it is the dead centre when the piston is farthest from the crankshaft. It is written as TDC. In horizontal engine it is known as Inner dead centre and is written as IDC. * Bottom dead centre: In vertical engine, it is the dead centre when the piston is nearest to the crankshaft. It is written as BDC. In horizontal engine it is known as outer dead centre and is written as ODC.

7. 7. * Swept or displacement volume: The volume swept by the piston when moving from one dead Centre to other is known as swept or displacement volume. It is represented by vs. Mathematically it is written as, 𝑣𝑠 = 𝐴. 𝐿 Where, A= cross sectional area in m2, L= stroke length in m. * Clearance volume: The nominal volume of the cylinder above the piston when the piston is at its top most position (at TDC). It is represented by vc. * Total or cylinder volume: The sum of swept and clearance volume is known as cylinder or total volume. It is represented by v. 𝑣 = 𝑣𝑠. 𝑣𝑐 * Compression ratio: It is defined as the ratio of total cylinder volume to the clearance volume. It is represented by 'r'. Mathematically it is written as,

8. 8. * Compression ratio, 𝑟 = 𝑇𝑜𝑡𝑎𝑙 𝑣𝑜𝑙𝑢𝑚𝑒 𝐶𝑙𝑒𝑎𝑟𝑎𝑛𝑐𝑒 𝑣𝑜𝑙𝑢𝑚𝑒 = 𝑣𝑐 + 𝑣𝑠 𝑣𝑐 * Cubic capacity or Engine capacity: The swept volume of a cylinder multiplied by number of cylinders in an engine is known as cubic capacity or engine capacity. Mathematically it is written as, 𝐶𝑢𝑏𝑖𝑐 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 = 𝑣𝑠. 𝑛 Where, 𝑛 = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟𝑠 𝑖𝑛 𝑎𝑛 𝑒𝑛𝑔𝑖𝑛𝑒.

9. 9. Four-Stroke Spark-Ignition Engine (S.I. Engine)

10. 10. Ideal and Actual Indicator diagram for S.I. Engine

11. 11. Four-Stroke Spark-Ignition Engine (S.I. Engine)

12. 12. Four-Stroke Compression Ignition Engine (C.I. Engine)

13. 13. Indicator diagram for C.I. Engine.

14. 14. Four-Stroke Compression Ignition Engine (C.I. Engine)

15. 15. TWO-STROKE ENGINE

16. 16. TWO-STROKE ENGINE

17. 17. Difference between Two stroke and four stroke engine S. N. Two Stroke Engines Four Stroke Engines 1 The cycle is completed in 2 strokes of the piston or in 1 revolution of the crankshaft. The cycle is completed in 4 strokes of the piston or in 2 revolution of the crankshaft. 2 Lighter flywheel is needed. Heavier flywheel is needed. 3 Because of 1 power stroke for 1 revolution, power produced for same size engine is more. Because of 1 power stroke for 2 revolutions, power produced for same size engine is small. 4 The same power engine is light and compact. The same power engine is heavy and bulky. 5 Greater cooling and lubrication is required. Such engines are subjected to more wear and tear. Lesser cooling and lubrication is required. Such engines are subjected to less wear and tear. 6 Such Engines contain ports. Such engines contain valve and valve mechanism. 7 Initial cost is low. Initial cost is high. 8 Volumetric efficiency is low. Volumetric efficiency is high. 9 Lower thermal efficiency. Higher thermal efficiency.

18. 18. Comparison between SI and CI Engines

19. 19. Comparison between SI and CI Engines S. N. Spark ignition (S.I.) engine Compression ignition (C.I.) engine 1 Such engine operates on Otto cycle. Such engine operates on Diesel cycle. 2 Fuel with high self ignition temperature (Petrol and gas) is used as a working substance. Fuel with high self ignition temperature (Diesel and vegetable oils) is used as a working substance. 3 Air-fuel (A/F) ratio lies between 10:1 to 20:1. Air-fuel (A/F) ratio lies between 18:1 to 100:1. 4 Fuel is ignited by the spark plug within the engine cylinder. Fuel is ignited by the high temperature of compressed air within the engine cylinder. 5 Fuel supply by the carburetor. Fuel supply by the injector. 6 High operating speed (Range-2000 to 6000 rpm). Comparatively low operating speed (Range- 400 to 3500 rpm). 7 Less maintenance required. More maintenance required. 8 Noise produced is less. Comparatively high. 9 Low capital cost. Comparatively high capital cost.

20. 20. Efficiencies of I.C. Engine Mechanical Efficiency: Mechanical efficiency is defined as the ratio of brake power (B.P.) to the indicated power. It is expressed by 𝜂 𝑚𝑒𝑐ℎ. Mathematically it is written as, 𝜂 𝑚𝑒𝑐ℎ = 𝐵. 𝑃. 𝐼. 𝑃. Where, B.P. = Brake Power and I.P. = Indicated power Brake power is defined as the power available at crankshaft. Mathematically it is written as, 𝐵. 𝑃. = 2𝜋𝑁𝑇 60 𝑊𝑎𝑡𝑡 Where, N= shaft rotation in rpm, T=Torque in Nm. Indicate power is defined as the power developed by engine cylinder. Mathematically it is written as, 𝐼. 𝑃. = 𝑃 𝑚 𝐿𝐴𝑁𝑛 60 𝑊𝑎𝑡𝑡 Where, Pm= mean effective pressure in N/m2, L= stroke length in m, A= Cross- sectional area of cylinder in m2, N= engine speed in rpm, n= number of cylinders. Friction power is defined as the power lost due to friction and it is measured by the difference between I.P. and B.P. It is expressed by F.P. Friction Power (F.P.) = Indicated power (I.P.)- Brake power (B.P.)

21. 21. Indicated Thermal Efficiency: Indicated thermal efficiency is defined as the ratio of indicated power to the fuel energy. It is expressed by 𝜂𝑖𝑡ℎ. Mathematically it is written as, 𝜂𝑖𝑡ℎ = 𝐼. 𝑃. 𝑖𝑛 𝑘𝐽/𝑠 𝐹𝑢𝑒𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛 𝑘𝐽/𝑠 𝜂𝑖𝑡ℎ = 𝐼. 𝑃. 𝑖𝑛 𝑘𝐽/𝑠 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑓𝑢𝑒𝑙 𝑝𝑒𝑟 𝑠𝑒𝑐.× 𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑣𝑎𝑙𝑢𝑒 𝑜𝑓 𝑓𝑢𝑒𝑙 𝜂𝑖𝑡ℎ = 𝐼. 𝑃. 𝑚 𝑓 × 𝐶

22. 22. Brake Thermal Efficiency: Brake thermal efficiency is defined as the ratio of brake power to the fuel energy. It is expressed by 𝜂 𝑏𝑡ℎ. Mathematically it is written as, 𝜂 𝑏𝑡ℎ = 𝐵. 𝑃. 𝑖𝑛 𝑘𝐽/𝑠 𝐹𝑢𝑒𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛 𝑘𝐽/𝑠 𝜂 𝑏𝑡ℎ = 𝐵. 𝑃. 𝑖𝑛 𝑘𝐽/𝑠 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑓𝑢𝑒𝑙 𝑝𝑒𝑟 𝑠𝑒𝑐.× 𝐶𝑎𝑙𝑜𝑟𝑖𝑓𝑖𝑐 𝑣𝑎𝑙𝑢𝑒 𝑜𝑓 𝑓𝑢𝑒𝑙 𝜂 𝑏𝑡ℎ = 𝐵. 𝑃. 𝑚 𝑓 × 𝐶

23. 23. Volumetric Efficiency: Volumetric efficiency is defined as the ratio of volume of fuel inlet during the suction stroke to the swept volume of the piston. It is expressed by 𝜂 𝑣. Mathematically it is written as, 𝜂 𝑣 = 𝑣𝑖 𝑣𝑠 Where, 𝑣𝑖= volume of fuel inlet, 𝑣𝑠= swept volume.

24. 24. Relative efficiency: Relative efficiency is defined as the ratio of indicated thermal efficiency to the air standard efficiency. It is expressed by 𝜂 𝑅. Mathematically it is written as, 𝜂 𝑅 = 𝐼𝑛𝑑𝑖𝑐𝑎𝑡𝑒𝑑 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 (𝜂𝑖𝑡ℎ) 𝐴𝑖𝑟 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 Where air standard efficiency is the efficiency of Otto cycle and Diesel cycle in case of S.I. and C.I. engines respectively, as described in chapter 5 as shown below. 𝜂 = 1 − 1 𝑟 𝛾−1 ... ... ... ... ... ... ... ... ... . . 𝑖𝑛 𝑐𝑎𝑠𝑒 𝑜𝑓 𝑆. 𝐼. 𝐸𝑛𝑔𝑖𝑛𝑒 𝜂 = 1 − 1 𝑟 𝛾−1 𝜑 𝛾 − 1 𝛾(𝜑 − 1) ... ... ... ... ... ... 𝑖𝑛 𝑐𝑎𝑠𝑒 𝑜𝑓 𝐶. 𝐼. 𝐸𝑛𝑔𝑖𝑛𝑒

25. 25. Specific Fuel Consumption: It is defined as the ratio of mass of fuel per hour to the power. When it is represented by the ratio of mass of fuel per hour to the indicated power then it is termed as indicated specific fuel consumption and written as isfc. Similarly, when it is represented by the ratio of mass of fuel per second to the brake power then it is termed as brake specific fuel consumption and written as bsfc. 𝑖𝑠𝑓𝑐 = 𝑚 𝑓 𝐼. 𝑃. 𝑘𝑔/𝑘𝑊ℎ 𝑏𝑠𝑓𝑐 = 𝑚 𝑓 𝐵. 𝑃. 𝑘𝑔/𝑘𝑊ℎ

26. 26. Otto cycle German engineer Nicholas A. Otto in 1876. It is also known as constant volume cycle, since the heat is received and rejected at constant volume.

27. 27. Isentropic compression (Process 1-2): The air is compressed isentropically from temperature T1 to temperature T2 as shown curve 1-2 on P-v and T-s diagram. We know that, no heat is absorbed or rejected during isentropic process. Constant volume heat addition process (Process 2-3): The heat is absorbed by the air at constant volume from temperature T2 to a temperature T3 as shown curve 2-3 on P-v and T-s diagram. The heat absorbed by the air during the process is given by 𝑄 𝐴 𝑜𝑟 𝑄2−3 = 𝑚𝑐 𝑣 𝑇3 − 𝑇2 Isentropic expansion (Process 3-4): The air is expanded isentropically from temperature T3 to temperature T4 as shown curve 3-4 on P-v and T- s diagram. We know that, no heat is absorbed or rejected during isentropic process. Constant volume heat rejection process (Process 4-1): The heat is rejected by the air at constant volume from temperature T4 to a temperature T1 as shown curve 4-1 on P-v and T-s diagram. The heat rejected by the air during the process is given by 𝑄 𝑅 𝑜𝑟 𝑄4−1 = 𝑚𝑐 𝑣(𝑇4 − 𝑇1)

28. 28. The work done during the cycle; 𝑊 = Heat absorbed - Heat rejected = 𝑄2−3 − 𝑄4−1 = 𝑚𝑐 𝑣 𝑇3 − 𝑇2 − 𝑚𝑐 𝑣 𝑇4 − 𝑇1 Air standard efficiency, 𝜂 = 𝑊𝑜𝑟𝑘 𝑑𝑜𝑛𝑒 𝐻𝑒𝑎𝑡 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = 𝑚𝑐 𝑣 𝑇3 − 𝑇2 − 𝑚𝑐 𝑣 𝑇4 − 𝑇1 𝑚𝑐 𝑣 𝑇3 − 𝑇2 = 1 − 𝑇4 − 𝑇1 𝑇3 − 𝑇2 = 1 − 𝑇1 𝑇4 𝑇1 − 1 𝑇2 𝑇3 𝑇2 − 1 ... ... ... ... ... ... ... . . (𝑖)

29. 29. For isentropic compression process 1-2 𝑃1 𝑣1 𝛾 = 𝑃2 𝑣2 𝛾 𝑃1 𝑃2 = 𝑣2 𝑣1 𝛾 ... ... ... ... ... ... ... ... (𝑖𝑖) Also from general gas equation we know that, 𝑃1 𝑣1 𝑇1 = 𝑃2 𝑣2 𝑇2 𝑜𝑟 𝑃1 𝑃2 = 𝑇1 𝑇2 . 𝑣2 𝑣1 ... ... ... (𝑖𝑖𝑖) From equation (ii) and (iii) 𝑣2 𝑣1 𝛾 = 𝑇1 𝑇2 . 𝑣2 𝑣1 𝑇1 𝑇2 = 𝑣2 𝑣1 𝛾 . 𝑣2 𝑣1 −1 = 𝑣2 𝑣1 𝛾−1 𝑜𝑟 𝑇1 𝑇2 = 𝑣2 𝑣1 𝛾−1 = 1 𝑟 𝛾−1 ... ... ... ... ... (𝑖𝑣)

30. 30. Where 𝑟 = 𝐶𝑜𝑚𝑝𝑟𝑒𝑠𝑠𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜 = 𝑣1 𝑣2 Similarly for isentropic expansion process 3-4 𝑇4 𝑇3 = 𝑣3 𝑣4 𝛾−1 = 1 𝑟 𝛾−1 ... ... ... ... ... ... ... 𝑣 Where 𝑟 = 𝐸𝑥𝑝𝑎𝑛𝑠𝑖𝑜𝑛 𝑟𝑎𝑡𝑖𝑜 = 𝑣4 𝑣3 From equation (iv) and (v), we can write, 𝑇1 𝑇2 = 𝑇4 𝑇3 = 1 𝑟 𝛾−1 𝑜𝑟 𝑇4 𝑇1 = 𝑇3 𝑇2 Substituting the value of 𝑇4 𝑇1 in equation (i) 𝜼 = 𝟏 − 𝑻 𝟏 𝑻 𝟐 = 𝟏 − 𝑻 𝟒 𝑻 𝟑 = 𝟏 − 𝟏 𝒓 𝜸−𝟏

31. 31. Diesel cycle

32. 32. Isentropic compression (Process 1-2): The air is compressed isentropically from temperature T1 to temperature T2 as shown curve 1-2 on P-v and T-s diagram. We know that, no heat is absorbed or rejected during isentropic process. Constant pressure heat addition process (Process 2-3): The heat is absorbed by the air at constant pressure from temperature T2 to a temperature T3 as shown curve 2-3 on P-v and T-s diagram. The heat absorbed by the air during the process is given by 𝑄 𝐴 𝑜𝑟 𝑄2−3 = 𝑚𝑐 𝑝(𝑇3 − 𝑇2) Where, 𝑐 𝑝 = 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 ℎ𝑒𝑎𝑡 𝑎𝑡 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒. Isentropic expansion (Process 3-4): The air is expanded isentropically from temperature T3 to temperature T4 as shown curve 3-4 on P-v and T-s diagram. We know that, no heat is absorbed or rejected during isentropic process. Constant volume heat rejection process (Process 4-1): The heat is rejected by the air at constant volume from temperature T4 to a temperature T1 as shown curve 4-1 on P-v and T-s diagram. The heat rejected by the air during the process is given by 𝑄 𝑅 𝑜𝑟 𝑄4−1 = 𝑚𝑐 𝑣(𝑇4 − 𝑇1) Where, 𝑐 𝑣 = 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 ℎ𝑒𝑎𝑡 𝑎𝑡 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑣𝑜𝑙𝑢𝑚𝑒.

33. 33. The work done during the cycle; 𝑊 = Heat absorbed - Heat rejected = 𝑄2−3 − 𝑄4−1 = 𝑚𝑐 𝑝 𝑇3 − 𝑇2 − 𝑚𝑐 𝑣(𝑇4 − 𝑇1) Air standard efficiency, 𝜂 = 𝑊𝑜𝑟𝑘 𝑑𝑜𝑛𝑒 𝐻𝑒𝑎𝑡 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 = 𝑚𝑐 𝑝 𝑇3 − 𝑇2 − 𝑚𝑐 𝑣(𝑇4 − 𝑇1) 𝑚𝑐 𝑝 𝑇3 − 𝑇2 = 1 − 𝑐 𝑣 𝑐 𝑝 𝑇4 − 𝑇1 𝑇3 − 𝑇2 = 1 − 1 𝛾 𝑇4 − 𝑇1 𝑇3 − 𝑇2 ... ... ... ... ... ... ... . . (𝑖)

34. 34. We know that, the compression ratio, 𝑟 = 𝑣1 𝑣2 Cut-off ratio, 𝜑 = 𝑣3 𝑣2 Expansion ratio, 𝛼 = 𝑣4 𝑣3 = 𝑣1 𝑣3 = 𝑣1 𝑣2 × 𝑣2 𝑣3 = 𝑟 𝜑 ... ... ... ... ... ... ... . . (𝑖𝑖) (Because 𝑣1 = 𝑣4) For constant pressure heating process 2-3, according to Charles's law 𝑣2 𝑇2 = 𝑣3 𝑇3 𝑇3 = 𝑇2 × 𝑣3 𝑣2 = 𝑇2 × 𝜑 ... ... ... ... ... ... ... (𝑖𝑖𝑖)

35. 35. Similarly, for isentropic expansion process 3-4 𝑇4 𝑇3 = 𝑣3 𝑣4 𝛾−1 = 1 𝛼 𝛾−1 = 𝜑 𝑟 𝛾−1 𝑜𝑟 𝑇4 = 𝑇3 𝜑 𝑟 𝛾−1 = 𝑇2 × 𝜑 𝜑 𝑟 𝛾−1 ... ... ... ... ... (𝑖𝑣) For isentropic compression process 1-2 𝑇2 𝑇1 = 𝑣1 𝑣2 𝛾−1 = 𝑟 𝛾−1 𝑜𝑟 𝑻 𝟐 = 𝑻 𝟏 𝒓 𝜸−𝟏 ... ... ... ... ... ... ... ... (𝒗)

36. 36. On substitution of the value of T2 in equation (iii) and (iv), we get, 𝑻 𝟑 = 𝑻 𝟏 𝒓 𝜸−𝟏 × 𝝋 ... ... ... ... ... . (𝒗𝒊) 𝑇4 = 𝑇1 𝑟 𝛾−1 × 𝜑 𝜑 𝑟 𝛾−1 𝑻 𝟒 = 𝑻 𝟏 𝝋 𝜸 ... ... ... ... ... ... (𝒗𝒊𝒊) On substitution of the value of T2, T3 and T4 in equation (i), we get, 𝜂 = 1 − 1 𝛾 𝑇1 𝜑 𝛾 − 𝑇1 𝑇1 𝑟 𝛾−1 × 𝜑 − 𝑇1 𝑟 𝛾−1 𝜂 = 1 − 1 𝑟 𝛾−1 𝜑 𝛾 − 1 𝛾(𝜑 − 1)

# data[].attributes.attachment_link.description
internal combustion engines 1. INTERNAL COMBUSTION ENGINE Prepared by: Pradeep Kumar Gupta Assistant Professor Department of Mechanical Engineering 2. Engine A device which transforms one form of energy into another form is known as engine. Most of the engines convert thermal energy of fuel into mechanical work and therefore they are known as heat engines.

# data[].attributes.body
Efficiency of IC Engine

# data[].attributes.attachment_link.readable_text
in this presentation , the different engine inefficiencies has been discussed including all sort of friction losses which affects the brake power of the engine. It includes volumetric efficiency, thermal efficiency, IMEP, BMEP, brake power etc.

Vice Chairman, AICTE, Ministry of HRD, Govt. of India

1. 1. ENGINE EFFICIENCIES Prof. (Dr.) M P Poonia Director NITTTR, Chandigarh

2. 3. 1. Indicated and Brake Mean Effective Pressure 2. Indicated Power, IP 3. Brake Power, BP 4. Mechanical Efficiency 5. Friction Power 6. Indicated Thermal Efficiency 7 Brake Thermal Efficiency Performance Parameters

3. 4. 8. Specific Fuel Consumption 9. 10 Heat Balance 11. Fuel Air-Ratio 12. Equivalence Ratio Performance Parameters Volumetric Efficiency

4. 5. IDEAL P-V Diagram Average IMEP 4-12 bar

5. 6. Actual P-V Diagram PMEP = IMEP (g) AREA 1 AREA2 IMEP (n)= AREA1-AREA2 BMEP= IMEP (n)-FMEP

6. 7. Metric Horse Power 1 hp= 735.5 W

7. 8. The indicated power is the power actually developed by the engine cylinder. INDICATED POWER (IP)

8. 9. The indicated power is the power actually developed by the engine cylinder. IP= 𝑷 𝒎 ×𝑳×𝑨×𝑵 𝟏𝟐𝟎 Where IP= Indicated Power, W Pm= Mean Effective Pressure N/m2 L = Stroke Length , m A = Piston Top Area , m2 N = Engine RPM

9. 10. BRAKE POWER : The brake power is the power available at the crankshaft of the engine. Indicated Power BP

10. 11. BRAKE POWER (BP) ɳm= 𝑩𝑷 𝑰𝑷 BP= ɳm× IP = ɳm×𝑷 𝒎 ×𝑳×𝑨×𝑵 𝟏𝟐𝟎 = BMEP×𝑳×𝑨×𝑵 𝟏𝟐𝟎 BP= 𝟐𝝿𝑵𝑻 𝟔𝟎 Where: T=Torque in N-m N= Rotational Speed in Minutes BP=Brake Power in watt

11. 12. BRAKE POWER (BP)

12. 13. Mechanical Efficiency

13. 14. Mechanical Efficiency (i)

14. 15. Mechanical Efficiency

15. 16. Friction Losses 1.Crank Shaft Bearing

16. 17. Friction Losses 2. Connecting Rod Bearing

17. 18. Friction Losses 3. Cylinder Piston Assembly

18. 19. Friction Losses 4. Piston Rings

19. 20. Friction Losses 5. Valve Train

20. 21. Friction Losses 5. Oil Pump

21. 22. Friction Losses 6. Water Pump

22. 23. Friction Losses 7. Generator and Starter Motor

23. 24. S I Engine Friction

24. 25. Friction Power

25. 26. Thermal Efficiency

26. 27. Typically Gasoline Engines will have an sfc of about 0.3kg/kW-h Specific Fuel Consumption(SFC)

27. 28. Volumetric Efficiency * Volumetric efficiency is a comparison of the actual volume of air-fuel mixture drawn into an engine to the theoretical maximum volume that could be drawn in. * Volumetric efficiency is expressed as a percentage

28. 29. Volumetric Efficiency

29. 30. Heat Balance

30. 31. Heat Balance

31. 32. Air Fuel Ratio

32. 33. Air Fuel Ratio

33. 34. Air Fuel Ratio Rich mixture - more fuel than necessary (AF) mixture < (AF)stoich Lean mixture - more air than necessary (AF) mixture > (AF)stoich

34. 35. Air Fuel Ratio

35. 36. It shows the deviation of an actual mixture from stoichiometric conditions. Equivalence Ratio (ɸ) actual stoich stoich actual AF AF FA FA )( )( )( )( 

36. 37. The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called a) mechanical efficiency b) overall efficiency c) relative efficiency d) volumetric efficiency Answer: d FAQ

37. 38. FAQ Explanation: Volumetric efficiency is the ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston while mechanical efficiency is the ratio of the brake power to the indicated power and relative efficiency is the ratio of the indicated thermal efficiency to the air standard efficiency whereas overall efficiency is the ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time.

38. 39. Which one of the following event would reduce volumetric efficiency of an engine? a) Inlet valve closing after bdc b) inlet valve closing before bdc c) inlet valve opening before tdc d) exhaust valve closing after tdc Answer: b Explanation: Volumetric efficiency of an engine is reduced by closing inlet valve before bdc. FAQ

Recommended

# data[].attributes.attachment_link.description
in this presentation , the different engine inefficiencies has been discussed including all sort of friction losses which affects the brake power of the engine. It includes volumetric efficiency, thermal efficiency, IMEP, BMEP, brake power etc. Vice Chairman, AICTE, Ministry of HRD, Govt. of India 1. ENGINE EFFICIENCIES Prof.

# data[].attributes.body
IC Engine

# data[].attributes.attachment_link.readable_text
TO COVER ALL TOPICS OF I.C ENGINES ASSEMBLY AND DISASSEMBLY

1. 1. 1 Assembly, Disassembly and Maintenance of IC Engines Dr. B Harisankar Associate Professor Mechanical Engineering Department Vignan's Institute of Information Technology

2. 2. 2 Introduction Heat Engine: *Heat Engine is a machine which converts heat energy supplied to it into mechanical work. *Heat energy is supplied to the engine by burning the fuel.

3. 3. 3 Classification of Heat Engines *Internal Combustion Engines (IC Engines) In IC engines, combustion of fuel takes place inside the engine cylinder. Examples: Diesel Engines, Petrol Engines, Gas engines. *External Combustion Engines (EC Engines) In EC engines, combustion of fuel takes place outside the working cylinder. Examples: Steam Engines and Steam turbines

4. 5. 5 Classification of IC Engines IC Engines are classified into, (1) Cycle of operation (No of Strokes per cycle) * Two Stroke cycle Engines * Four Stroke Cycle Engines (2) Thermodynamic Cycle or Method of Heat addition: * Otto Cycle Engines (Combustion at constant volume) * Diesel Cycle Engines (Combustion at constant Pressure) * Semi Diesel Engines (Dual Combustion Engines)

5. 6. 6 Classification of IC Engines (3) Types of Fuel Used : * Petrol Engines * Diesel Engines * Gas Engines (4) Ignition Method : * Spark Ignition (SI) * Compression Ignition (CI)

6. 7. 7 Classification of IC Engines (5) Cooling System: *Air cooled Engines *Water Cooled Engines (6) Valves Location : *L head (Side valve) engine *T Head (Side valve) engine * I head (over head valve) engine *F head (over head inlet and side exhaust) engine

7. 8. 8 I.C ENGINE TERMINOLGOGY The standard terms used in I.C Engines are 1. Bore: Inside diameter of the cylinder is termed as Bore. 2. Top Dead Center (TDC): The extreme position reached by the piston at the top of the cylinder in the vertical engine is called Top Dead center. 3. Bottom Dead Center (BDC): The extreme position reached by the piston at the Bottom of the cylinder in the vertical engine is called Bottom Dead center.

8. 9. 9 I.C ENGINE TERMINOLGOGY 4. Stroke: The nominal distance travelled by the piston in the cylinder between the extreme upper and lower positions of the piston (TDC &BDC) is termed as stroke. 5. Compression ratio (r): It is the ratio of Maximum cylinder volume to the Clearance volume. 6. Cylinder volume (v): It is the sum of swept volume and the Clearance volume. V = Vs + Vc

9. 10. 10 I.C ENGINE TERMINOLGOGY 7. Swept volume (Vs): It is the volume of space generated by the movement of piston from one dead center to another dead center. 8. Clearance Volume( Vc): It is the space in the cylinder, when the piston is at Top Dead Center

10. 11. 11 Main Components of IC Engine

11. 12. 12 Main Components of IC Engines Cylinder Block: *It is the main block of the engine. *It contains cylinders accurately finished to accommodate pistons *The cylinder block houses crank, camshaft, piston and other engine parts. *In water cooled engines, the cylinder block is provided with water jackets for the circulating cooling water. *The materials used for cylinder are grey cast iron, aluminium alloys etc., *It is usually made of a single casting

12. 13. 13 Main Components of IC Engines Cylinder block of motor Cylinder block of cycle Car

13. 14. 14 Main Components of IC Engines Cylinder Head: *The cylinder head is bolted to the cylinder Block by means of studs. *The water jackets are provided for cooling water circulation. *The materials used for cylinder head are cast iron, aluminium alloy etc., *This is also generally made of single cast iron.

14. 15. 15 Main Components of IC Engines Cylinder Liners: The liner is a sleeve which is fitted into the cylinder bore. It provides wear resisting surface for the cylinder bores. Liners are classified into (a) Wet liner (b) Dry liner

15. 16. 16 Main Components of IC Engines Cylinder Liners Wet Liner : These liners are surrounded or wetted by cooling water. It provides wear resisting surface for the piston to reciprocate. Also it acts as a seal for the water jacket.

16. 17. 17 Main Components of IC Engines Dry Liner :Dry liners have metal to metal contact with the cylinder block. They are not directly in touch with the cooling water. Liner Materials: *Liner material should withstand abrasive wear and corrosive. *Chromium plated mild steel tubes are used as liners.

17. 18. 18 Main Components of IC Engines Crankcase : It may be cast integral with the cylinder block. Some times, it is cast separately and then attached to the block. These materials are used for crank case are cast iron, aluminium alloys or alloy steels.

18. 19. 19 Main Components of IC Engines Oil pan or oil sump: Oil sump is the bottom part of the engine. It contains lubricating oil. A drain plug is provided the oil sump to drain out the oil. It is made of the pressed sheet.

19. 20. 20 Main Components of IC Engines Piston : The piston serves the following purposes * It acts as a movable gas tight seal to keep the gases inside the cylinder *It transmits the force of explosion in the cylinder to the crankshaft through the connecting rod. *Some of the materials used for piston are cast iron, aluminium alloy, chrome nickel alloy, nickel iron alloy and cast steel.

20. 21. 21 Main Components of IC Engines Piston rings : Piston rings are inserted in the grooves provided in the piston. Two types of piston rings are used in the piston. 1. Compression rings 2. Oil rings or oil control rings.

21. 22. 22 Main Components of IC Engines Compression rings : * Compression rings provide an effective seal for the high pressure gases inside the cylinder. * They prevent the leakage of high pressure gases from the combustion chamber into the crank case. * Each piston is provided with atleast * two compression rings.

22. 23. 23 Main Components of IC Engines Oil rings : * Oil rings wipe off the excess oil from the cylinder walls. * It also returns excess oil to the oil sump, through the slots provided in the rings. The materials used for piston rings should be wear resistant. Normally piston rings are made of alloy steel iron containing silicon, manganese alloy steels etc.,

23. 24. 24 Main Components of IC Engines Connecting Rod: * It connects the piston and crank shaft. * It transmits the force of explosion during power stroke to the crankshaft. * The connecting rod has bearings at both ends. * The small end of the connecting has a solid or split eye and contains a bush. * This end is connected to the piston by means of a gudgeon pin. * The other end is called as big end of the connecting rod. * The connecting rods must withstand heavy thrusts. * Hence it must have strength and rigidity. * They are usually drop forged I sections. * The materials used are plain carbon steel, aluminium alloys, nickel alloy steels etc,

24. 25. 25 Main Components of IC Engines Crank Shaft : * It is the main rotating shaft of the engine. * Power is obtained from the crank shaft. * The crank shaft is combination with connecting rod converts reciprocating motion of the piston into rotary motion. * The crank shaft is held in position by the main bearings. * There are two main bearings to support the crank shaft. * The materials used for crank shaft are billet steel, carbon steel, nickel chrome and other heat treated alloy steels.

25. 26. 26 Main Components of IC Engines Camshaft: * Camshaft contains number of cams. * It is used to convert rotary motion into linear or straight line motion. * It has so many cams as the number of valves in an engine. * An additional cam is also provided to drive the fuel pump. * A gear is provided in the cam shaft to drive the distributor or oil pump. * The opening and closing of the engine valves are controlled by the cams provided on the cam shaft.

26. 27. 27 Petrol Engines Classification of Petrol Engines *Two Stroke cycle Petrol Engines *Four Stroke cycle petrol Engines

27. 28. 28 Four stroke cycle Petrol Engines Construction : *A piston reciprocates inside the cylinder *The piston is connected to the crank shaft by means of a connecting rod and crank. * The inlet and exhaust valves are Mounted on the cylinder head. *A spark is provided on the cylinder Head. * The fuel used is petrol

28. 29. 29 Four Stroke Petrol Engine- Working

29. 30. 30 Four Stroke Petrol Engine - Working (a) Suction Stroke (First Stroke of the Engine) * Piston moves down from TDC to BDC * Inlet valve is opened and the exhaust valve is closed. * Pressure inside the cylinder is reduced below the atmospheric pressure. * The mixture of air fuel is sucked into the cylinder through the inlet valve

30. 31. 31 Four Stroke Petrol Engine - Working (b) Compression Stroke : (Second Stroke of the piston) * Piston moves up from BDC to TDC * Both inlet and exhaust valves are closed. * The air fuel mixture in the cylinder is compressed.

31. 32. 32 Four Stroke Petrol Engine - Working (c) Working or Power or Expansion Stroke: (Third Stroke of the Engine) * The burning gases expand rapidly. They exert an impulse (thrust or force) on the piston. The piston is pushed from TDC to BDC * This movement of the piston is converted into rotary motion of the crankshaft through connecting rod. * Both inlet and exhaust valves are closed.

32. 33. 33 Four Stroke Petrol Engine - Working (d) Exhaust Stroke (Fourth stroke of the piston) * Piston moves upward from BDC * Exhaust valve is opened and the inlet valve is closed. * The burnt gases are forced out to the atmosphere through the exhaust valve (Some of the burnt gases stay in the clearance volume of the cylinder) * The exhaust valve closes shortly after TDC * The inlet valve opens slightly before TDC and the cylinder is ready to receive fresh charge to start a new cycle.

33. 34. 34 Four Stroke Petrol Engine - Working Summary : * Compression ratio varies from 5 to 8 * The pressure at the end of compression is about 6 to 12 bar. * The temperature at the end of the compression reaches 250o C to 350o C

34. 35. 35 Four Stroke Diesel Engine

35. 36. 36 Four Stroke Diesel Engine Construction: *A piston reciprocates inside the cylinder *The piston is connected to the crankshaft by means of a connecting rod and crank. * The inlet and exhaust valves are mounted on the cylinder head. *A fuel injector is provided on the cylinder head *The fuel used is diesel.

36. 37. 37 Four Stroke Diesel Engine - Working (a) Suction Stroke (First Stroke of the piston) * Piston moves from TDC to BDC * Inlet valve is opened and the exhaust valve is closed. * The pressure inside the cylinder is reduced below the atmospheric pressure. * Fresh air from the atmosphere is sucked into the engine cylinder through air cleaner and inlet valve.

37. 38. 38 Four Stroke Diesel Engine - Working (b) Compression stroke (Second stroke of the piston) * Piston moves from BDC to TDC * Both inlet and exhaust valves are closed. * The air is drawn during suction stroke is compressed to a high pressure and temperature

38. 39. 39 Four Stroke Diesel Engine - Working (c) Working or power or expansion stroke (Third stroke of the piston) * The burning gases (products of combustion) expand rapidly. * The burning gases push the piston move downward from TDC to BDC * This movement of piston is converted into rotary motion of the crank shaft through connecting rod. * Both inlet and exhaust valves are closed.

39. 40. 40 Four Stroke Diesel Engine - Working (d) Exhaust Stroke (Fourth stroke of the piston) * Piston moves from BDC to TDC * Exhaust valve is opened the inlet valve is closed. * The burnt gases are forced out to the atmosphere through the exhaust valve. (some of the burnt gases stay in the clearance volume of the cylinder) * The exhaust valve closes shortly after TDC * The inlet valve opens slightly before TDC and the cylinder is ready to receive fresh air to start a new cycle.

40. 41. 41 Two Stroke cycle Petrol Engines

41. 42. 42 Two Stroke cycle Petrol Engines working

42. 43. 43 Two Stroke Cycle Petrol Engine - Construction Construction : *A piston reciprocates inside the cylinder *It is connected to the crankshaft by means of connecting rod and crank *There are no valves in two stroke engines, instead of valves ports are cut on the cylinder walls. *There are three ports, namely inlet, exhaust and transfer ports. *The closing and opening of the ports are obtained by the movement of piston. The crown of piston is made in to a shape to perform this. *A spark plug is also provided.

43. 44. 44 Two stroke cycle Petrol Engines - Working First Stroke : (Compression, ignition and inductance) (Upward stroke of piston) (a) compression: * The piston moves up from Bottom Dead Centre (BDC) to Top Dead Centre (TDC) * Both transfer and exhaust ports are covered by the piston. * Air fuel mixture which is transferred already into the engine cylinder is compressed by moving piston. * The pressure and temperature increases * at the end of compression.

44. 45. 45 Two stroke cycle Petrol Engines - Working First Stroke : (Compression, ignition and inductance) (Upward stroke of piston) (b) Ignition and Inductance: * Piston almost reaches the top dead centre *The air fuel mixture inside the cylinder is ignited by means of an electric spark produced by a spark plug *At the same time, the inlet port is uncovered by the plane. *Fresh air fuel mixture enters the crankcase through the inlet port.

45. 46. 46 Two stroke cycle Petrol Engines - Working Second Stroke: (Downward Stroke of the engine) : (c)Expansion and Crankcase compression *The burning gases expand in the cylinder *The burning gases force the piston to move down. Thus useful work is obtained. *When the piston moves down, the air fuel mixture in the crankcase is partially compressed. This compression is known as Crank case compression.

46. 47. 47 Two stroke cycle Petrol Engines - Working Second Stroke: (Downward Stroke of the engine) : (d) Exhaust and transfer: *At the end of expansion, exhaust port is uncovered. *Burnt gases escape to the atmosphere. *Transfer port is also opened. The partially compressed air fuel mixture enters the cylinder through the transfer port. *The crown of the piston is made of a deflected shape. So the fresh charge entering the cylinder is deflected upwards in the cylinder. *Thus the escape of fresh charge along with the exhaust gases is reduced.

47. 48. 48 Two stroke cycle Diesel Engines- Construction Construction : * Two stroke cycle diesel engines require air supply *This air is used to blow out the exhaust gases and to fill the cylinder with clean air *This air is supplied by a blower or air compressor which is driven by engine itself. *These engines may be valve or port type. *A plate is provided in the crank case to admit air into the crank case. *Transfer and exhaust ports are provided in the cylinder. *These ports are covered and uncovered by the moving piston.

48. 49. 49 Two stroke cycle Diesel Engines- Working First Stroke (Upward Stroke of the piston) (a) Compression and inductance: * The piston moves upwards from Bottom Dead Centre (BDC) to Top Dead Centre (TDC). * Both transfer and exhaust ports are covered. * Air which is transferred already into the engine cylinder is compressed by moving piston. * The pressure and temperature of the air increases. * At the same time, fresh air is admitted into the crankcase through the plate valve (reed valve)

49. 50. 50 Two stroke cycle Diesel Engines- Working First Stroke (Upward Stroke of the piston) (b) Ignition and inductance. * Piston almost reaches the top dead centre. * The fuel is injected into the hot compressed air inside the cylinder. The fuel mixed with hot air and burns. * The admission of fresh air into the crankcase continues till the piston reaches the top centre.

50. 51. 51 Two stroke cycle Diesel Engines- Working Second Stroke (Downward Stroke of the piston) (c) Expansion and crank case compression: *The burning gases expand in the cylinder. *Burning gases force the piston to move down. Thus useful work is obtained. *At the same time, the air in the crank case is compressed by the movement of the piston. *All the ports and the plate valve are in closed position

51. 52. 52 Two stroke cycle Diesel Engines- Working Second Stroke (Downward Stroke of the piston) (d) Exhaust and Transfer: * At the end of expansion, the exhaust port is uncovered. *The burnt escape to the atmosphere through the exhaust port. *Transfer port is also uncovered shortly after the exhaust port is opened. *The partially compressed air from crank case enters the cylinder the transfer port. *This air is deflected upwards by the deflected shape of the piston. *Thus the entering air helps in forcing out the combustion products from the cylinder *The plate valve remains during this period.

52. 53. 53 Scavenging Scavenging : *It is the process of forcing out the burnt exhaust gases from the cylinder for admitting the fresh charge into the cylinder. *This action takes place in the two stroke cylinder.

53. 54. 54 Scavenging Process * The charge (air fuel mixture or air) enters the engine cylinder from the crank case at a pressure higher than the exhaust gases. * This fresh charge forces the exhaust gases to the atmosphere through the exhaust port. * During the period both the transfer and exhaust ports are kept open for a short period. * Hence there is a possibility of the fresh charge escaping out with the burnt gases. * This is over come by designing the piston to have a deflected shape. * This shape of piston deflects the fresh charge upward in the engine cylinder. *It also helps out in forcing out the exhaust gases to atmosphere. *This process is known as Scavenging.

54. 55. 55 Comparison between SI and CI Engines (General Comparison) S.No . Spark Ignition Engines (SI) Compression Ignition Engines (CI) 1 It draws air fuel mixture into the cylinder during suction stroke It draws only air into the cylinder during suction stroke. 2 Petrol engines operate with low pressure and temperature Diesel engines operate with high pressure and temperature 3. Pressure ranges from 6 to 12 bar Temperature ranges from 250o to 300o C Pressure ranges from 35 to 40 bar Temperature ranges from 600o to 700o C

55. 56. 56 Comparison between SI and CI Engines (General Comparison) S.No . Spark Ignition Engines (SI) Compression Ignition Engines (CI) 4 It is fitted with carburettor and spark plugs It is fitted with fuel injection pump and injectors 5 The burning of fuel takes place at constant volume The burning of fuel takes place at constant pressure 6. Ignition of air fuel mixture takes place by an electric spark produced by spark plug Ignition of air fuel takes placed by a injection of fuel into the hot compressed air.

56. 57. 57 Comparison between SI and CI Engines (General Comparison) S.No. Spark Ignition Engines (SI) Compression Ignition Engines (CI) 7 Petrol engines are quality governed engines. The speed of petrol engines are controlled by varying the quantity of air fuel mixture. Diesel engines are quantity governed engines. The speed of diesel engines are controlled by varying quality of air fuel mixture. (rich or weak mixture) 8 Petrol engines are widely used in automobiles and aeroplanes etc., Diesel engines are widely used in heavy vehicles, such as buses, lorries, trucks etc.,

57. 58. 58 Comparison between SI and CI Engines (Merits and Demerits) S.No. Spark Ignition Engines (SI) Compression Ignition Engines (CI) 1 Merits: Otto cycle is employed in petrol engine. Otto cycle is more efficient for a given compression ratio. Demerits: Diesel engines works on diesel cycle. Diesel cycle is less efficient than Otto cycle for a given compression ratio. 2 Operating speed is more. Speed range is 3000 to 6000 rpm Operating speed is less. Speed range is 400 to 3500 rpm. 3. Starting is easy, since cranking effort required is less Starting is difficult since more cranking effort is required.

58. 59. 59 Comparison between SI and CI Engines (Merits and Demerits) S.No. Spark Ignition Engines (SI) Compression Ignition Engines (CI) 4 Merits: Initial cost and maintenance cost are less Demerits: More initial and maintenance costs since the construction is heavy and sturdy. 5 Produces less noise. Produces more noise. 6 Weight per unit power is less Weight per unit power is more.

59. 60. 60 Comparison between SI and CI Engines (Merits and Demerits) S.No. Spark Ignition Engines (SI) Compression Ignition Engines (CI) 4 Demerits: Thermal efficiency is less, since compression ratio is limited. 5 - 8 Merits: Thermal efficiency is high since compression ratio is high. 12 to 18. 5 Specific fuel consumption is more. Specific fuel consumption is less 6 The fuel used is petrol. It is costlier than diesel. It is volatile and fire hazard is more The fuel used is diesel. It is cheaper than petrol. It is less volatile and fire hazard is less.

60. 61. 61 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No. Two Stroke Cycle Engine Four Stroke Cycle Engine 1 Merits: One power stroke in one revolution of the crankshaft Demerits: One power stroke in two revolutions of the crank shaft 2 Power developed for the same engine speed theoretically twice that of a four stroke engine Power developed for the same engine speed is theoretically half that of two stroke engine. 3 Simple design and lighter in construction for the same power For the same power complicated design and heavier in construction

61. 62. 62 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No. Two Stroke Cycle Engine Four Stroke Cycle Engine 4 Merits: Uniform torque is obtained. Hence a lighter fly wheel can be used Demerits: Non uniform torque on the crankshaft. Hence a heavier flywheel is required for balancing. 5 Design of ports is simpler. Hence initial cost is less Design valve mechanism is difficult. Hence initial cost is more. 6 Mechanical efficiency is high. No moving parts like cam, follower, rocker Mechanical efficiency is less. Power is lost due to friction caused by valve mechanism

62. 63. 63 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No. Two Stroke Cycle Engine Four Stroke Cycle Engine 7 Merits: Starting is easy Demerits: Starting is not so easy 8 These engines are generally air cooled These engines are generally water cooled.

63. 64. 64 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No . Two Stroke Cycle Engine Four Stroke Cycle Engine 1 DeMerits: Consumption of lubricating oil is more, because less time is available to remove the heat Merits: Consumption of lubricating oil is less, because more time is allowed for removing heat from the cylinder. 2 More wear and tear of moving parts. Less wear and tear of parts is less 3 Some of the fresh air fuel mixture may escape with exhaust gases. Hence fuel consumption is more Fuel cannot escape with exhaust gases. Hence fuel consumption is less.

64. 65. 65 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No . Two Stroke Cycle Engine Four Stroke Cycle Engine 4 DeMerits: Thermal efficiency is less. Merits: Thermal efficiency is more. 5 It produces more noise due to sudden release of exhaust gases Noise is less is less. Exhaust gases are released in separate stroke. 6 Scavenging is poor, since exhaust port is open only for a short time Scavenging is better, since there is a separate exhaust stroke for the removal of exhaust gases

65. 66. 66 Comparison between Four stroke cycle and two stroke cycle engine (Merits and Demerits) S.No. Two Stroke Cycle Engine Four Stroke Cycle Engine 7 Merits: Poor scavenging leads to mixing of fresh charge with exhaust gases. This results in poor performance, slow running Demerits: Better performance and efficiency is more 8 Used in light vehicles, like bikes, scooters, mopeds, etc., Used in heavy vehicles, like buses, lorries, trucks etc.,

66. 68. 68 Animation of Crank shaft , connecting rod and piston

67. 69. Disassembly of IC Engine Engine removal *Disconnect battery cables *Remove the hood *Remove air cleaner *Label all wires and vacuum lines *Drain coolant and oil *Remove the radiator *Remove the distributor and spark plug wiring 69

68. 72. Engine Disassembly * Important steps - Remove clutch parts - Remove hybrid armature (puller required) - Mount engine to a stand - Remove coolant pump - Remove oil pan - Remove valve covers 72

69. 73. Thank you 73

# data[].attributes.attachment_link.description
TO COVER ALL TOPICS OF I.C ENGINES ASSEMBLY AND DISASSEMBLY 1. 1 Assembly, Disassembly and Maintenance of IC Engines Dr. B Harisankar Associate Professor Mechanical Engineering Department Vignan's Institute of Information Technology 2. 2 Introduction Heat Engine: *Heat Engine is a machine which converts heat energy supplied to it into mechanical work.

# data[].attributes.body
Components of IC Engine

# data[].attributes.attachment_link.readable_text
About components of Internal Combustion Engine.

1. 1. COMPONENTS OF IC ENGINE Prince Singh

2. 2. ENGINE COMPONENTS

3. 3. ENGINE BLOCK # Body of an engine containing the cylinders. # Normally made of ALUMINUM or CAST IRON. # Old engine also have a case for water jackets.

4. 4. CAMSHAFT # Rotating shaft used to push open valves at proper timing in engine cycle. # Can be control HYDRAULICALLY or MECHANICALLY. # Modern engine have more then two cams.

5. 5. CRANKSHAFT # Mostly they made of forged steel or cast iron. # It is attached with the engine block by MAIN BEARING. # Rotates in circular motion # Having crank weights attached with crankshaft # It through which engine is work output supply to the system. # It rotate by which work

6. 6. CONNECTING ROD # Rod connecting the piston with rotating crankshaft. # Provided the contact from piston to the crankshaft. # Usually made of STEEL or ALLOY FORGED but in small engine it can be made of ALUMINUM.

7. 7. PISTON # A cylindrical-shaped mass that reciprocate back and forth in the cylinder transmitting force to the crankshaft. # The top of the piston is called CROWN and the sides are called SKIRT. # PISTON is made up of cast iron, steel or aluminum. # Aluminum piston are light . Used for light engine . # Piston is one of the important component of engine.

8. 8. PISTON RING # Metal ring that fixed into a circumferential grooves around the piston. # Made up of highly polished chromed steel # It make a seal between piston and cylinder walls. # It also used for lubrication purpose.

9. 9. VALVES # Used to allow the flow into and out of the cylinder at proper time in the cycle . # VALVES are made of forged steel. # Two stroke engine do not have valves they have ports system (slot).

10. 10. VALVE SPRING # The spring which attached at the valve. # Push back the valve / closed the valve.

11. 11. CYLINDER OR COMBUSTION CHAMBER # The end of the cylinder between head and piston face where combustion take place.

12. 12. CRANKCASE # The part of the engine block surrounding the rotating shaft. # The oil pan makes up part of the crank case housing.

13. 13. CARBURETOR # CARBURETOR is used for making a air and fuel mixture . # It is replaced by EFI system. # A proper mixture is needed for proper combustion so that carburetor used. # It mixing up the fuel and air . # Making a rich or lean mixture as requirement.

14. 14. RADIATOR # It is an HEAT EXCHANGER. # It is usually mounted in front of the engine in the flow of the air. # Used to cool down the engine and run proper thermodynamic cycle.

15. 15. SPARK PLUG # Electric device used to initiate combustion in SI engine. # Made up of the metal surrounded by the ceramic insulation. # Spark plugs only used in SI engine

16. 16. INTAKE MANIFOLD # Piping system which delivers incoming air to the cylinder. # They made up of cast metal ,plastic or composite materials. # In IS engine fuel added to the air in intake manifold.

17. 17. EXHAUST MANIFOLD # Piping system which carry exhaust gases away from the system. # Made up of CAST IRON.

18. 18. FLYWHEEL # To store the energy , provide energy when it is needed and store. # It keeps the engine rotating.

19. 19. FUEL INJECTOR # A pressurized nozzle which spray the fuel into the incoming air on SI engine. # Injector directly spray at the combustion chamber. # It is placed at the centre of the combustion chamber.

20. 20. OIL PAN # Oil reservoir usually bolted at the bottom of the crankcase. # Act as a oil sump.

21. 21. OIL PUMP # Pump used to distribute oil from oil pan to the required point for lubrication purpose.

22. 22. OIL FILTER # To filter the oil. # Clean oil is need for proper lubrication.

23. 23. STARTER Starter is an electrical device which is used to provide initial torque to the engine at the time of start.

24. 24. TURBO CHARGER # Turbine compressor used to compress incoming air into the engine. # The turbine is powered by the exhaust flow of the engine so it take very little useful work from engine.

25. 25. THANK YOU

Recommended

# data[].attributes.attachment_link.description
About components of Internal Combustion Engine. 1. COMPONENTS OF IC ENGINE Prince Singh 2. ENGINE COMPONENTS 3. ENGINE BLOCK # Body of an engine containing the cylinders. # Normally made of ALUMINUM or CAST IRON. # Old engine also have a case for water jackets. 4.

# data[].attributes.body
Steam Turbines

# data[].attributes.attachment_link.readable_text
Presentation on types of Steam Turbines.

Mechanical Engineer :- Power Engineer at Self Research

1. 1. STEAM TURBINES

2. 2. DEFINITION A steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft.

3. 3. APPLICATIONS OF STEAM TURBINES  Power Generation  Transport

4. 4. CLASSIFICATION OF STEAM TURBINES According to the action of steam:  Impulse turbine: In impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor. The blades change the direction of steam flow without changing its pressure. The force due to change of momentum causes the rotation of the turbine shaft. Ex: De-Laval, Curtis and Rateau Turbines  Reaction turbine: In reaction turbine, steam expands both in fixed and moving blades continuously as the steam passes over them. The pressure drop occurs continuously over both moving and fixed blades.  Combination of impulse and reaction turbine

5. 5. CLASSIFICATION OF STEAM TURBINES According to the number of pressure stages:  Single stage turbines: These turbines are mostly used for driving centrifugal compressors, blowers and other similar machinery.  Multistage Impulse and Reaction turbines: They are made in a wide range of power capacities varying from small to large. According to the type of steam flow:  Axial turbines: In these turbines, steam flows in a direction parallel to the axis of the turbine rotor.  Radial turbines: In these turbines, steam flows in a direction perpendicular to the axis of the turbine, one or more low pressure stages are made axial.

6. 6. CLASSIFICATION OF STEAM TURBINES According to the number of shafts:  Single shaft turbines  Multi-shaft turbines According to the method of governing:  Turbines with throttle governing: In these turbines, fresh steam enter through one or more (depending on the power developed) simultaneously operated throttle valves.  Turbines with nozzle governing: In these turbines, fresh steam enters through one or more consecutively opening regulators.  Turbines with by-pass governing: In these turbines, the steam besides being fed to the first stage is also directly fed to one, two or even three intermediate stages of the turbine.

7. 7. CLASSIFICATION OF STEAM TURBINES According to the heat drop process: Condensing turbines with generators: In these turbines, steam at a pressure less than the atmospheric is directed to the condenser. The steam is also extracted from intermediate stages for feed water heating). The latent heat of exhaust steam during the process of condensation is completely lost in these turbines. Condensing turbines with one or more intermediate stage extractions: In these turbines, the steam is extracted from intermediate stages for industrial heating purposes. Back pressure turbines: In these turbines, the exhaust steam is utilized for industrial or heating purposes. Turbines with deteriorated vacuum can also be used in which exhaust steam may be used for heating and process purposes. Topping turbines: In these turbines, the exhaust steam is utilized in medium and low pressure condensing turbines. These turbines operate at high initial conditions of steam pressure and temperature, and are mostly used during extension of power station capacities, with a view to obtain better efficiencies.

8. 8. CLASSIFICATION OF STEAM TURBINES According to the steam conditions at inlet to turbine:  Low pressure turbines: These turbines use steam at a pressure of 1.2 ata to 2 ata.  Medium pressure turbines: These turbines use steam up to a pressure of 40 ata.  High pressure turbines: These turbines use steam at a pressure above 40 ata.  Very high pressure turbines: These turbines use steam at a pressure of 170 ata and higher and temperatures of 550C and higher.  Supercritical pressure turbines: These turbines use steam at a pressure of 225 ata and higher.

9. 9. CLASSIFICATION OF STEAM TURBINES According to their usage in industry:  Stationary turbines with constant speed of rotation: These turbines are primarily used for driving alternators.  Stationary turbines with variable speed of rotation: These turbines are meant for driving turbo-blowers, air circulators, pumps, etc.  Non-stationary turbines with variable speed: These turbines are usually employed in steamers, ships and railway locomotives.

10. 10. ADVANTAGES OF STEAM TURBINES OVER STEAM ENGINES 1. The thermal efficiency is much higher. 2. As there is no reciprocating parts, perfect balancing is possible and therefore heavy foundation is not required. 3. Higher and greater range of speed is possible. 4. The lubrication is very simple as there are no rubbing parts. 5. The power generation is at uniform rate & hence no flywheel is required. 6. The steam consumption rate is lesser. 7. More compact and require less attention during operation. 8. More suitable for large power plants. 9. Less maintenance cost as construction and operation is highly simplified due to absence of parts like piston, piston rod, cross head, connecting rod. 10. Considerable overloads can be carried at the expense of slight reduction in overall efficiency.

11. 11. IMPULSE TURBINE VS REACTION TURBINE Impulse turbine Reaction turbine  The steam completely expands in the nozzle and its pressure remains constant during its flow through the blade passages  The steam expands partially in the nozzle and further expansion takes place in the rotor blades  The relative velocity of steam passing over the blade remains constant in the absence of friction  The relative velocity of steam passing over the blade increases as the steam expands while passing over the blade  Blades are symmetrical  Blades are asymmetrical  The pressure on both ends of the moving blade is same  The pressure on both ends of the moving blade is different  For the same power developed, as pressure drop is more, the number of stages required are less  For the same power developed, as pressure drop is small, the number of stages required are more  The blade efficiency curve is less flat  The blade efficiency curve is more flat  The steam velocity is very high and therefore the speed of turbine is high.  The steam velocity is not very high and therefore the speed of turbine is low.

12. 12. IMPULSE TURBINE VS REACTION TURBINE

13. 13. SIMPLE IMPULSE TURBINE

14. 14. IMPULSE PRINCIPLE  The impulse turbine consists basically of a rotor mounted on a shaft that is free to rotate in a set of bearings.  The outer rim of the rotor carries a set of curved blades, and the whole assembly is enclosed in an airtight case.  Nozzles direct steam against the blades and turn the rotor. The energy to rotate an impulse turbine is derived from the kinetic energy of the steam flowing through the nozzles.  The term impulse means that the force that turns the turbine comes from the impact of the steam on the blades.

15. 15. IMPULSE PRINCIPLE The toy pinwheel can be used to study some of the basic principles of turbines. When we blow on the rim of the wheel, it spins rapidly. The harder we blow, the faster it turns. The steam turbine operates on the same principle, except it uses the kinetic energy from the steam as it leaves a steam nozzle rather than air. Steam nozzles are located at the turbine inlet. As the steam passes through a steam nozzle, potential energy is converted to kinetic energy. This steam is directed towards the turbine blades and turns the rotor. The velocity of the steam is reduced in passing over the blades. Some of its kinetic energy has been transferred to the blades to turn the rotor. Impulse turbines may be used to drive forced draft blowers, pumps, and main propulsion turbines.

16. 16. BASICS OF IMPULSE TURBINE  In impulse turbine, steam coming out through a fixed nozzle at a very high velocity strikes the blades fixed on the periphery of a rotor.  The blades change the direction of steam flow without changing its pressure.  The force due to change of momentum causes the rotation of the turbine shaft.  Examples: De-Laval, Curtis and Rateau turbines.

17. 17. CONSTRUCTION & WORKING PRINCIPLE OF IMPULSE PRINCIPLE It primarily consists of a nozzle or a set of nozzles, a rotor mounted on a shaft, one set of moving blades attached to the rotor and a casing. A simple impulse turbine is also called De-Laval turbine, after the name of its inventor This turbine is called simple impulse turbine since the expansion of the steam takes place in one set of nozzles.

18. 18. IMPULSE PRINCIPLE

19. 19.  The uppermost portion of the diagram shows a longitudinal section through the upper half of the turbine.  The middle portion shows the actual shape of the nozzle and blading.  The bottom portion shows the variation of absolute velocity and absolute pressure during the flow of steam through passage of nozzles and blades.  The expansion of steam from its initial pressure (steam chest pressure) to final pressure (condenser pressure) takes place in one set of nozzles.  Due to high drop in pressure in the nozzles, the velocity of steam in the nozzles increases. IMPULSE TURBINE

20. 20. IMPULSE TURBINE  The steam leaves the nozzle with a very high velocity and strikes the blades of the turbine mounted on a wheel with this high velocity.  The loss of energy due to this higher exit velocity is commonly known as carry over loss (or) leaving loss.  The pressure of the steam when it moves over the blades remains constant but the velocity decreases.  The exit/leaving/lost velocity may amount to 3.3 percent of the nozzle outlet velocity.  Also since all the KE is to be absorbed by one ring of the moving blades only, the velocity of wheel is too high (varying from 25000 to 30000 RPM).  However, this wheel or rotor speed can be reduced by adopting the method of compounding of turbines.

21. 21. DISADVANTAGES OF IMPULSE TURBINE 1. Since all the KE of the high velocity steam has to be absorbed in only one ring of moving blades, the velocity of the turbine is too high i.e. up to 30000 RPM for practical purposes. 2. The velocity of the steam at exit is sufficiently high which means that there is a considerable loss of KE.

22. 22. VELOCITY DIAGRAM / VELOCITY TRIANGLE INLET VELOCITY TRIANGLE OUTLET VELOCITY TRIANGLE

23. 23. COMBINED VELOCITY TRIANGLE

24. 24. NOTATIONS

25. 25. WORK OUTPUT, POWER, BLADE EFFICIENCY & STAGE EFFICIENCY Force in the tangential direction  Rate of change of momentum in the tangential direction.   Mass per second change in velocity Newtons   Newtons w1 w2  m V V Force in the axial direction  Rate of change of momentum in the axial direction. (axial thrust)   Newtons a1 a2  m V V Work done by steam on blades   N -m/s 2 m V V u w1 w     kW m V V u w1 w Power developed by the turbine 2   1000     m V V u 2 2 2u V V u w1 w 2 1 w1 w 2 1 V mV 1 2 Work done on the blade(s) Energy supplied to the blade(s) Blade efficiency        N-m/s 1 Energy lost due to blade friction 2 2 r2 2 r1  mV V       m V V u 2 V V u w1 w d  w1 w 1 H 2 m H H 2 Work done on the blade(s) Total energy supplied per stage Stage efficiency         Heat drop in the nozzle ring d 1 2 where H H H

26. 26. MAXIMUM WORK & MAXIMUM DIAGRAM EFFICIENCY From the combined velocity triangle (diagram), we have V V V u w r    1 1 1 1 1 cos cos V V V u w r    2 2 2 2 2 and cos cos V  KC V r   cos  2 2 V V V V V r       cos 1 cos cos cos 1 1 1    w 1 w 2 r 1 1 r 2 2 r 1 1  V r    cos  1 1    2 1 r V r V K  where and  2 1 cos cos  C  V V V u KC w w   cos  1 1 2 1 1 (or)  V cos  u1 KCu 1 1  Rate of doing work per kg of steam per second = V u KC 1 1 cos 1 Blade speed ratio u   V 1     2 1 V b     Diagram efficiency,  Let,   KC b  2 cos  1 2 1 Then, Diagram efficiency,    

27. 27. MAXIMUM WORK & MAXIMUM DIAGRAM EFFICIENCY  If the values of 1, K and C are assumed to be constant, then diagram efficiency depends only on the value of blade speed ratio,   In order to determine the optimum value of for maximum diagram efficiency,  0   b    Then,  becomes,  = cos 1  2

28. 28. MAXIMUM WORK & MAXIMUM DIAGRAM EFFICIENCY cos Maximum diagram efficiency = cos         cos 2 1 1 2 1 4   .cos  2 2 1 2 1 1 max      KC KC b     Note: If the blade is symmetrical & friction is absent, then, we have 1=2 and K = C = 1 Then, maximum diagram efficiency, (b)max = cos21 V cos u1 KCu 1 1 Work done/kg of steam/second =  2 Then maximum rate of doing work/kg of steam/second  2u

29. 29. METHODS OF REDUCING ROTOR SPEED (COMPOUNDING OF TURBINES) If high velocity of steam is allowed to flow through one row of moving blades, it produces a rotor speed of about 30000 rpm which is too high for practical use. It is therefore essential to incorporate some improvements for practical use and also to achieve high performance. This is possible by making use of more than one set of nozzles, and rotors, in a series, keyed to the shaft so that either the steam pressure or the jet velocity is absorbed by the turbine in stages. This is called compounding of turbines. The high rotational speed of the turbine can be reduced by the following methods of compounding: 1) Velocity compounding 2) Pressure compounding, and 3) Pressure-Velocity compounding

30. 30. METHODS OF REDUCING ROTOR SPEED (VELOCITY COMPOUNDING)

31. 31. METHODS OF REDUCING ROTOR SPEED (VELOCITY COMPOUNDING)  It consists of a set of nozzles and a few rows of moving blades which are fixed to the shaft and rows of fixed blades which are attached to the casing.  As shown in figure, the two rows of moving blades are separated by a row of fixed blades.  The high velocity steam first enters the first row of moving blades, where some portion of the velocity is absorbed.  Then it enters the ring of fixed blades where the direction of steam is changed to suit the second ring of moving blades. There is no change in the velocity as the steam passes over the fixed blades.  The steam then passes on to the second row of moving blades where the velocity is further reduced. Thus a fall in velocity occurs every time when the steam passes over the row of moving blades. Steam thus leaves the turbine with a low velocity.  The variation of pressure and velocity of steam as it passes over the moving and fixed blades is shown in the figure. It is clear from the figure that the pressure drop takes place only in the nozzle and there is no further drop of pressure as it passes over the moving blades.  This method of velocity compounding is used in Curtis turbine after it was first proposed by C.G. Curtis

32. 32. METHODS OF REDUCING ROTOR SPEED ADVANTAGES (VELOCITY COMPOUNDING) 1) The arrangement has less number of stages and hence less initial cost 2) The arrangement requires less space 3) The system is reliable and easy to operate 4) The fall of pressure in the nozzle is considerable, so the turbine itself need not work in high pressure surroundings and the turbine housing need not be very strong DISADVANTAGES 1) More friction losses due to very high velocity in the nozzles 2) Less efficiency because ratio of blade velocity to steam velocity is not optimum 3) Power developed in the later rows is only fraction of first row. Still all the stages require same space, material and cost.

33. 33. METHODS OF REDUCING ROTOR SPEED (PRESSURE COMPOUNDING)

34. 34. METHODS OF REDUCING ROTOR SPEED (PRESSURE COMPOUNDING)  It consists of a number of fixed nozzles which are incorporated between the rings of moving blades. The moving blades are keyed to the shaft.  Here the pressure drop is done in a number of stages. Each stage consists of a set of nozzles and a ring of moving blades.  Steam from the boiler passes through the first set of nozzles where it expands partially. Nearly all its velocity is absorbed when it passes over the first set of moving blades.  It is further passed to the second set of fixed nozzles where it is partially expanded again and through the second set of moving blades where the velocity of steam is almost absorbed. This process is repeated till steam leaves at condenser pressure.  By reducing the pressure in stages, the velocity of steam entering the moving blades is considerably reduced. Hence the speed of the rotor is reduced. Rateau & Zoelly turbines use this method of compounding.

35. 35. METHODS OF REDUCING ROTOR SPEED (PRESSURE-VELOCITY COMPOUNDING) 1) In this method of compounding, both pressure and velocity compounding methods are utilized. 2) The total drop in steam pressure is carried out in two stages and the velocity obtained in each stage is also compounded. 3) The ring of nozzles are fixed at the beginning of each stage and pressure remains constant during each stage. 4) This method of compounding is used in Curtis and More turbines.

36. 36. METHODS OF REDUCING ROTOR SPEED (PRESSURE-VELOCITY COMPOUNDING)

37. 37. REACTION TURBINE A turbine in which steam pressure decreases gradually while expanding through the moving blades as well as the fixed blades is known as reaction turbine. It consists of a large number of stages, each stage consisting of set of fixed and moving blades. The heat drop takes place throughout in both fixed and moving blades. No nozzles are provided in a reaction turbine. The fixed blades act both as nozzles in which velocity of steam increased and direct the steam to enter the ring of moving blades. As pressure drop takes place both in the fixed and moving blades, all the blades are nozzle shaped. The steam expands while flowing over the moving blades and thus gives reaction to the moving blades. Hence the turbine is called reaction turbine. The fixed blades are attached to the casing whereas moving blades are fixed with the rotor. It is also called Parson's reaction turbine.

38. 38. REACTION TURBINE

39. 39. WORK OUTPUT & POWER IN REACTION TURBINE The work done per kg of steam in the stage (per pair) = muV V N m s w w / 1 2   where, m = mass of steam flowing over blades in kg/s 1 2  Power developed (per pair) = work done per kg of steam in the stage per pair   u V V 1 2  H  Efficiency, Enthalpy drop in the stage per pair Efficiency, w w 1000     uV V N m w w   1 2 The work done per kg of steam per second in the stage (per pair) =   kW mu V Vw w 1000 where, H = Enthalpy drop in the stage per pair in kJ/kg

40. 40. DEGREE OF REACTION IN REACTION TURBINE

41. 41. WORK DONE & EFFICIENCY IIN REACTION TURBINE

42. 42. WORK DONE & EFFICIENCY IN REACTION TURBINE

43. 43. WORK DONE & EFFICIENCY IN REACTION TURBINE

44. 44. GOVERNING OF TURBINES Governing is the method of maintaining the speed of the turbine constant irrespective of variation of the load on the turbine. A governor is used for achieving this purpose which regulates the supply of steam to the turbine in such a way that the speed of the turbine is maintained as far as possible a constant under varying load conditions. The various methods of governing of steam turbines are: 1) Throttle governing 2) Nozzle governing 3) By-pass governing 4) Combination of (1) & (2) or (2) & (3)

45. 45. GOVERNING OF TURBINES (THROTTLE GOVERNING)

46. 46. GOVERNING OF TURBINES (THROTTLE GOVERNING) WILLIAN'S LINE

47. 47. GOVERNING OF TURBINES (NOZZLE GOVERNING)

48. 48. GOVERNING OF TURBINES (BY-PASS GOVERNING)

49. 49. LOSSES IN STEAM TURBINES  Residual velocity loss  Losses in regulating valves  Loss due to steam friction in nozzle  Loss due to leakage  Loss due to mechanical friction  Loss due to wetness of steam  Radiation loss

50. 50. EFFECT OF BLADE FRICTION IN STEAM TURBINES

51. 51. OVERALL EFFICIENCY & REHEAT FACTOR Reheat factor: It is defined as the ratio of cumulative heat drop to the adiabatic heat drop in all the stages of the turbine. The value of reheat factor depends on the type and efficiency of the turbine, the average value being 1.05. A B A B A B 1 1 2 2 3 3   A D Cumulative heat drop Adiabatic heat drop Reheat factor 1   Overall efficiency: It is defined as the ratio of total useful heat drop to the total heat supplied. A C A C A C 1 1 2 2 3 3 H - h A1 D Total useful heat drop Total heat supplied Overall efficiency    

# data[].attributes.attachment_link.description
Presentation on types of Steam Turbines. Mechanical Engineer :- Power Engineer at Self Research 1. STEAM TURBINES 2. DEFINITION A steam turbine is a prime mover in which the potential energy of the steam is transformed into kinetic energy and later in its turn is transformed into the mechanical energy of rotation of the turbine shaft.

# data[].attributes.body
Syllabus

# data[].attributes.body
Syllabus

# data[].attributes.body
Expt_3&4(NIT,SURTHKAL, KARNATAKA)

# data[].attributes.body
All Students are requested to complete the above EXPT and submit Attempted Quiz Screen shot and Assignment Questions written on plain paper by Email to rcvani11@gmail.com after completion of the Experiment.

# data[].attributes.body
All Students are requested to complete above experiment and submit as per Experiment 1.

# data[].attributes.headline
For Reference Video Lecture (IIT Roorkee)

# data[].attributes.subject
For Reference Video Lecture (IIT Roorkee)

# data[].attributes.attachment_link.description
Lecture Series on Strength of Materials by Dr.S.P.Harsha, Department of Mechanical & Industrial Engineering, IIT Roorkee.

# data[].attributes.attachment_caption
Mechanical properties of material (Part 2)

# data[].attributes.headline
Mechanical Properties of Materials Ref Video by NIT NAGPUR.

# data[].attributes.subject
Mechanical Properties of Materials Ref Video by NIT NAGPUR.

# data[].attributes.attachment_link.title
Mechanical properties of material (Part 2)

# data[].attributes.headline
Stress System Reference Video by NIT NAGPUR.

# data[].attributes.subject
Stress System Reference Video by NIT NAGPUR.

# data[].attributes.attachment_caption
Definition of Stress strain shear stress elasticity plasticity and ductility || mechanic of solid

# data[].attributes.attachment_link.title
Definition of Stress strain shear stress elasticity plasticity and ductility || mechanic of solid

# data[].attributes.attachment_caption
CE-3I MOS UNIT 3 TOPIC 1 ELASTIC CONSTANTS

# data[].attributes.attachment_link.title
CE-3I MOS UNIT 3 TOPIC 1 ELASTIC CONSTANTS

# data[].attributes.attachment_caption
ME3I SOM VIDEO 4.1(Introduction to Shear force and Bending Moment

# data[].attributes.headline
Shear Force & BM (Shri Asish Umarkar,NIT, Nagpur)

# data[].attributes.subject
Shear Force & BM (Shri Asish Umarkar,NIT, Nagpur)

# data[].attributes.attachment_link.title
ME3I SOM VIDEO 4.1(Introduction to Shear force and Bending Moment

# data[].attributes.body
All Students are requested to complete Both Quiz(Send Pic) and 5 Q Assignment and send by Email to rcvani11@gmail.com.