# data[].attributes.headline
combustion, a chemical reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light in the form of flame.

# data[].attributes.subject
combustion, a chemical reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light in the form of flame.

# data[].attributes.body
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/combustion

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Principles of Combustion

The processes involved are the initial heating of the particles and release of moisture, further heating and release of volatile species and their combustion, and finally the combustion of the char (solid residual).

The nature of biomass can greatly enhance solid combustion as it is generally very reactive and has a much higher volatile content when compared to coal. However, it can also provide some big challenges: many biofuels are extremely wet, and as stated it is important that the solid particles are heated up to their ignition temperature. Green wood can have a moisture content up to 70%, so the amount of useful heat is low and the drying process before combustion can commence can be quite long. For this reason, the traditional pulverized combustion system is not ideal for the burning of this very wet material and the preferred technology is a longer combustion process such as the grate or fluid bed.

Good combustion relies on the oxidation of the organic material in the biomass. It is important to have a combination of high temperature (> 800°C), oxygen availability, and reactive organic material of the correct size. Problems occur when this is scaled up to industrial scale as the fuel has to be at the correct size for complete combustion (dependent on combustor design), oxygen has to be available to the fuel at each burner/injector, and the rate of combustion has to be controlled to minimize the emissions of NO and minimize ash sintering problems. The properties of biomass materials considered for power generation are significantly different from those of coal. Biomass shows greater variation as a class and can impact adversely on the performance of the combustion system. There are numerous texts available that can give a more detailed discussion of biomass combustion (see, e.g., Van Loo and Koppejan, 2002).

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780124095489110140

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780124095489015633

Gas Chromatography/Combustion/Isotope Ratio Mass Spectrometry

GC/C/IRMS ascertains the relative ratio of light stable isotopes of carbon ( ¹³C/ ¹²C), hydrogen ( ²H/ ¹H), nitrogen ( ¹⁵N/ ¹⁴N), or oxygen ( ¹⁸O/ ¹⁶ O) in individual chemical compounds separated from complex mixtures. The ratio of these isotopes in natural materials is different from that in synthetic materials; hence, GC/C/IRMS can determine whether an analyte is synthetic. The primary prerequisite is that the compounds of the sample mixture be amenable to GC, that is, suitably volatile and thermally stable. Some polar compounds require further chemical modification or transformation (derivatization); in such cases, the relative stable isotope ratio of the derivatization agent must also be determined.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780128134429000109

Abstract

Combustion toxicity research is the study of the adverse health effects caused by exposure to fire atmospheres. A fire atmosphere is defined as all of the effluents generated by the thermal decomposition of materials or products regardless of whether that effluent is produced under smoldering, nonflaming, or flaming conditions. The objectives of combustion toxicity research are to identify potentially harmful products from the thermal degradation of materials, to distinguish those materials that produce unusual or greater quantities of toxic combustion products, to determine the best measurement methods for the identification of the toxic products as well as the degree of toxicity, to determine the effect of different fire exposures on the composition of the toxic combustion products, and to establish the physiological effects of such products on living organisms. The ultimate goals of this field of research are to reduce human fire fatalities due to smoke inhalation, to determine effective treatments for survivors, and to prevent unnecessary suffering of fire casualties caused by smoke inhalation.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780123864543005960

Sulfur Dioxide

Combustion of sulfur-containing fuels, including coal and petroleum, produces sulfur dioxide (SO ₂), a highly water-soluble gas that is readily absorbed in the mucosa of the eyes and upper respiratory tract. SO ₂ is a strong irritant that leads to local inflammation. SO ₂ can also bind to organic PM and affect the distal airways. SO ₂ increases vascular distention, mucosal edema, smooth muscle contraction, and intraairway secretions. Lung function in healthy individuals is relatively resistant to the effects of considerable doses of SO ₂ (5 ppm), but even lower doses (e.g., <1 ppm) elicit acute and substantial bronchoconstriction in some asthmatic patients. Although SO ₂ causes multiple respiratory symptoms, it does not seem to be independently responsible for air pollution-related mortality.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9781455707928000805

# data[].attributes.attachment_link.description
The processes involved are the initial heating of the particles and release of moisture, further heating and release of volatile species and their combustion, and finally the combustion of the char (solid residual). The nature of biomass can greatly enhance solid combustion as it is generally very reactive and has a much higher volatile content when compared to coal.

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Chemistry & Biochemistry - Department of Chemistry & Biochemistry

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Department of Chemistry & Biochemistry
95 Chieftan Way Room 118 DLC
Florida State University
Tallahassee, FL 32306-4390

# data[].attributes.attachment_link.readable_text
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel.

In chemistry we call the type of reaction that produces fire a combustion reaction. Combustion is a high-temperature exothermic (heat releasing) redox (oxygen adding) chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Whenever we complete a combustion reaction a hydrocarbon (compound of C and H) there are generally the same products formed: CO ₂ and H ₂ O.

The fuel you burn in your car's engine contains octane, C ₈H ₁₈. When octane is burned, the products are CO ₂ and H ₂ O.

The key ingredient to the process is the availability of oxygen. Combustion cannot take place in an atmosphere devoid of oxygen.

So if you have a bottle of gasoline (octane) sitting around and open to the atmosphere which contains oxygen, why doesnt it just burst into flames?

The answer to this question is the need to overcome the activation energy of the reaction, which means that it requires energy at first to "jump start" the process. In your car, the distributor and battery provide this starting energy by creating an electrical "spark". Other sources of initial energy can come from the Sun, matches, friction, etc.

The combustion reaction itself is quite exothermic.

Exothermic Reactions

When heat is produced in the process of a chemical reaction this is known as an Exothermic Reaction.

Endothermic Reactions

When heat is absorbed from the reacting substances this is known as an Endothermic Reaction.

But remember, whether endothermic or exothermic, both types of reactions still require an Activation Energy to begin.

# data[].attributes.attachment_link.description
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction.

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What is Fire? Combustion Reaction Tutorial | kinetic & potential energy, heat & light | Chemistry

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yur

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Whoosh Bottle Combustion Reaction in Slow-Mo

# data[].attributes.attachment_link.readable_text
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel.

In chemistry we call the type of reaction that produces fire a combustion reaction. Combustion is a high-temperature exothermic (heat releasing) redox (oxygen adding) chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Whenever we complete a combustion reaction a hydrocarbon (compound of C and H) there are generally the same products formed: CO ₂ and H ₂ O.

The fuel you burn in your car's engine contains octane, C ₈H ₁₈. When octane is burned, the products are CO ₂ and H ₂ O.

The key ingredient to the process is the availability of oxygen. Combustion cannot take place in an atmosphere devoid of oxygen.

So if you have a bottle of gasoline (octane) sitting around and open to the atmosphere which contains oxygen, why doesnt it just burst into flames?

The answer to this question is the need to overcome the activation energy of the reaction, which means that it requires energy at first to "jump start" the process. In your car, the distributor and battery provide this starting energy by creating an electrical "spark". Other sources of initial energy can come from the Sun, matches, friction, etc.

The combustion reaction itself is quite exothermic.

Exothermic Reactions

When heat is produced in the process of a chemical reaction this is known as an Exothermic Reaction.

Endothermic Reactions

When heat is absorbed from the reacting substances this is known as an Endothermic Reaction.

But remember, whether endothermic or exothermic, both types of reactions still require an Activation Energy to begin.

# data[].attributes.attachment_link.description
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction.

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*The alkanes are insoluble in water but are soluble in non-polar solvents. Fuel + Oxyen --> Carbon dioxide and water
*There are weak dispersion forces between molecules as evidenced by their low melting and boiling points.
*Most reactions involving alkanes are either combustion or substitution .
​*
*Eg: CH4 (g) + 2O2 (g) → CO2 (g) + 2H20 (g) + energy
methane Combustion:
*

Chlorine atoms take the place of one or more of the hydrogen atoms.
*Eg: CH4 (g) + Cl2 (g) → CH3Cl (g) + HCl (g)
methane chloromethane
​ Substitution:

Methane combustion diagram ​By Jynto Robert A. Rohde Jacek FH Jynto [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
​

Methane substitution diagram V8rik at English Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons​

# data[].attributes.attachment_link.description
The alkanes are insoluble in water but are soluble in non-polar solvents. Fuel + Oxyen --> Carbon dioxide and water*There are weak dispersion forces between molecules as evidenced by their low melting and boiling points. *Most reactions involving alkanes are either combustion or substitution .

# data[].attributes.body
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/combustion

# data[].attributes.attachment_link.readable_text
Principles of Combustion

The processes involved are the initial heating of the particles and release of moisture, further heating and release of volatile species and their combustion, and finally the combustion of the char (solid residual).

The nature of biomass can greatly enhance solid combustion as it is generally very reactive and has a much higher volatile content when compared to coal. However, it can also provide some big challenges: many biofuels are extremely wet, and as stated it is important that the solid particles are heated up to their ignition temperature. Green wood can have a moisture content up to 70%, so the amount of useful heat is low and the drying process before combustion can commence can be quite long. For this reason, the traditional pulverized combustion system is not ideal for the burning of this very wet material and the preferred technology is a longer combustion process such as the grate or fluid bed.

Good combustion relies on the oxidation of the organic material in the biomass. It is important to have a combination of high temperature (> 800°C), oxygen availability, and reactive organic material of the correct size. Problems occur when this is scaled up to industrial scale as the fuel has to be at the correct size for complete combustion (dependent on combustor design), oxygen has to be available to the fuel at each burner/injector, and the rate of combustion has to be controlled to minimize the emissions of NO and minimize ash sintering problems. The properties of biomass materials considered for power generation are significantly different from those of coal. Biomass shows greater variation as a class and can impact adversely on the performance of the combustion system. There are numerous texts available that can give a more detailed discussion of biomass combustion (see, e.g., Van Loo and Koppejan, 2002).

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780124095489110140

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780124095489015633

Gas Chromatography/Combustion/Isotope Ratio Mass Spectrometry

GC/C/IRMS ascertains the relative ratio of light stable isotopes of carbon ( ¹³C/ ¹²C), hydrogen ( ²H/ ¹H), nitrogen ( ¹⁵N/ ¹⁴N), or oxygen ( ¹⁸O/ ¹⁶ O) in individual chemical compounds separated from complex mixtures. The ratio of these isotopes in natural materials is different from that in synthetic materials; hence, GC/C/IRMS can determine whether an analyte is synthetic. The primary prerequisite is that the compounds of the sample mixture be amenable to GC, that is, suitably volatile and thermally stable. Some polar compounds require further chemical modification or transformation (derivatization); in such cases, the relative stable isotope ratio of the derivatization agent must also be determined.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780128134429000109

Abstract

Combustion toxicity research is the study of the adverse health effects caused by exposure to fire atmospheres. A fire atmosphere is defined as all of the effluents generated by the thermal decomposition of materials or products regardless of whether that effluent is produced under smoldering, nonflaming, or flaming conditions. The objectives of combustion toxicity research are to identify potentially harmful products from the thermal degradation of materials, to distinguish those materials that produce unusual or greater quantities of toxic combustion products, to determine the best measurement methods for the identification of the toxic products as well as the degree of toxicity, to determine the effect of different fire exposures on the composition of the toxic combustion products, and to establish the physiological effects of such products on living organisms. The ultimate goals of this field of research are to reduce human fire fatalities due to smoke inhalation, to determine effective treatments for survivors, and to prevent unnecessary suffering of fire casualties caused by smoke inhalation.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9780123864543005960

Sulfur Dioxide

Combustion of sulfur-containing fuels, including coal and petroleum, produces sulfur dioxide (SO ₂), a highly water-soluble gas that is readily absorbed in the mucosa of the eyes and upper respiratory tract. SO ₂ is a strong irritant that leads to local inflammation. SO ₂ can also bind to organic PM and affect the distal airways. SO ₂ increases vascular distention, mucosal edema, smooth muscle contraction, and intraairway secretions. Lung function in healthy individuals is relatively resistant to the effects of considerable doses of SO ₂ (5 ppm), but even lower doses (e.g., <1 ppm) elicit acute and substantial bronchoconstriction in some asthmatic patients. Although SO ₂ causes multiple respiratory symptoms, it does not seem to be independently responsible for air pollution-related mortality.

Read full chapter

URL: https://www.sciencedirect.com/science/article/pii/B9781455707928000805

# data[].attributes.attachment_link.description
The processes involved are the initial heating of the particles and release of moisture, further heating and release of volatile species and their combustion, and finally the combustion of the char (solid residual). The nature of biomass can greatly enhance solid combustion as it is generally very reactive and has a much higher volatile content when compared to coal.

# data[].attributes.body
https://www.chem.fsu.edu/chemlab/chm1020c/Lecture%207/01.php

# data[].attributes.attachment_link.readable_text
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel.

In chemistry we call the type of reaction that produces fire a combustion reaction. Combustion is a high-temperature exothermic (heat releasing) redox (oxygen adding) chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Whenever we complete a combustion reaction a hydrocarbon (compound of C and H) there are generally the same products formed: CO ₂ and H ₂ O.

The fuel you burn in your car's engine contains octane, C ₈H ₁₈. When octane is burned, the products are CO ₂ and H ₂ O.

The key ingredient to the process is the availability of oxygen. Combustion cannot take place in an atmosphere devoid of oxygen.

So if you have a bottle of gasoline (octane) sitting around and open to the atmosphere which contains oxygen, why doesnt it just burst into flames?

The answer to this question is the need to overcome the activation energy of the reaction, which means that it requires energy at first to "jump start" the process. In your car, the distributor and battery provide this starting energy by creating an electrical "spark". Other sources of initial energy can come from the Sun, matches, friction, etc.

The combustion reaction itself is quite exothermic.

Exothermic Reactions

When heat is produced in the process of a chemical reaction this is known as an Exothermic Reaction.

Endothermic Reactions

When heat is absorbed from the reacting substances this is known as an Endothermic Reaction.

But remember, whether endothermic or exothermic, both types of reactions still require an Activation Energy to begin.

# data[].attributes.attachment_link.description
Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction.

# data[].attributes.body
https://www.fi.edu/sparkofscience/make-your-own-combustion-reactions

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Around here, we love experimenting with combustion. But how it does actually work? Science Interpreter Al breaks it down for us. Adult supervision needed.

You will find out about the three main ingredients it takes to form a combustion reaction: fuel, heat, and an oxidizer. You will see a special kind of combustion reaction using aluminum, friction heat, and iron oxide (rust).
Related Topics: chemistry, combustion, fire, chemical reactions

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You will find out about the three main ingredients it takes to form a combustion reaction: fuel, heat, and an oxidizer. You will see a special kind of combustion reaction using aluminum, friction heat, and iron oxide (rust). Related Topics: chemistry, combustion, fire, chemical reactions

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combustion, a chemical reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light in the form of flame. The rate or speed at which the reactants combine is high, in part because of the nature of the chemical reaction itself and in part because more energy is generated than can escape into the surrounding medium, with the result that the temperature of the reactants is raised to accelerate the reaction even more.

A familiar example of a combustion reaction is a lighted match. When a match is struck, friction heats the head to a temperature at which the chemicals react and generate more heat than can escape into the air, and they burn with a flame. If a wind blows away the heat or the chemicals are moist and friction does not raise the temperature sufficiently, the match goes out. Properly ignited, the heat from the flame raises the temperature of a nearby layer of the matchstick and of oxygen in the air adjacent to it, and the wood and oxygen react in a combustion reaction. When equilibrium between the total heat energies of the reactants and the total heat energies of the products (including the actual heat and light emitted) is reached, combustion stops. Flames have a definable composition and a complex structure; they are said to be multiform and are capable of existing at quite low temperatures, as well as at extremely high temperatures. The emission of light in the flame results from the presence of excited particles and, usually, of charged atoms and molecules and of electrons.

Combustion encompasses a great variety of phenomena with wide application in industry, the sciences, professions, and the home, and the application is based on knowledge of physics, chemistry, and mechanics; their interrelationship becomes particularly evident in treating flame propagation.

In general terms, combustion is one of the most important of chemical reactions and may be considered a culminating step in the oxidation of certain kinds of substances. Though oxidation was once considered to be simply the combination of oxygen with any compound or element, the meaning of the word has been expanded to include any reaction in which atoms lose electrons, thereby becoming oxidized. As has been pointed out, in any oxidation process the oxidizer takes electrons from the oxidizable substance, thereby itself becoming reduced (gaining electrons). Any substance at all can be an oxidizing agent. But these definitions, clear enough when applied to atomic structure to explain chemical reactions, are not as clearly applicable to combustion, which remains, generally speaking, a type of chemical reaction involving oxygen as the oxidizing agent but complicated by the fact that the process includes other kinds of reactions as well and by the fact that it proceeds at an unusually fast pace. Furthermore, most flames have a section in their structure in which, instead of oxidations, reduction reactions occur. Nevertheless, the main event in combustion is often the combining of combustible material with oxygen.

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combustion | Definition, Reaction, Analysis, & Facts

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Combustion, a chemical reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light in the form of flame. Combustion is one of the most important of chemical reactions and may be considered a culminating step in the oxidation of certain kinds of substances.

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Roasting marshmallows over an open fire is popular whilst camping and during cookouts. The trick is to get the marshmallow a nice golden brown, without catching it on fire. Too often, the person roasting the marshmallow is not successful, and the marshmallow is seen suddenly burning on the stick-a combustion reaction is taking place right in front of them!

Combustion Reactions

A combustion reaction is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve \(\ce{O_2}\) as one reactant. The combustion of hydrogen gas produces water vapor:

\[2 \ce{H_2} \left( g \right) + \ce{O_2} \left( g \right) \rightarrow 2 \ce{H_2O} \left( g \right)\]

Notice that this reaction also qualifies as a combination reaction.

Figure \(\PageIndex{1}\): Explosion of the Hindenberg. (CC BY-NC; CK-12)

The Hindenberg was a hydrogen-filled airship that suffered an accident upon its attempted landing in New Jersey in 1937. The hydrogen immediately combusted in a huge fireball, destroying the airship and killing 36 people. The chemical reaction was a simple one: hydrogen combining with oxygen to produce water.

Many combustion reactions occur with a hydrocarbon, a compound made up solely of carbon and hydrogen. The products of the combustion of hydrocarbons are carbon dioxide and water. Many hydrocarbons are used as fuel because their combustion releases very large amounts of heat energy. Propane \(\left( \ce{C_3H_8} \right)\) is a gaseous hydrocarbon that is commonly used as the fuel source in gas grills.

\[\ce{C_3H_8} \left( g \right) + 5 \ce{O_2} \left( g \right) \rightarrow 3 \ce{CO_2} \left( g \right) + 4 \ce{H_2O} \left( g \right)\]

Example \(\PageIndex{1}\)
Solution
Step 1: Plan the problem.

Step 2: Solve.

Write the skeleton equation:

Balance the equation.

Summary

A combustion reaction is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat.

Examples of combustion reactions are given.

Contributors and Attributions

CK-12 Foundation by Sharon Bewick, Richard Parsons, Therese Forsythe, Shonna Robinson, and Jean Dupon.

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Roasting marshmallows over an open fire is popular whilst camping and during cookouts. The trick is to get the marshmallow a nice golden brown, without catching it on fire. Too often, the person roasting the marshmallow is not successful, and the marshmallow is seen suddenly burning on the stick-a combustion reaction is taking place right in front of them!

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Combustion Reaction ( Read ) | Chemistry

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Definition and examples of a combustion reaction.

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The Vehicle Technologies Office (VTO) funds research focused on developing a greater understanding of engine combustion and how emissions form within engine cylinders as well as how combustion and emissions depend on factors such as fuel spray characteristics, in-cylinder air motion, and type of fuel. This greater understanding will help researchers develop higher efficiency advanced combustion engines strategies such as low temperature combustion, dilute (lean burn) gasoline combustion, and clean diesel combustion that produce very low engine-out emissions of oxides of nitrogen (NOx) and particulate matter (PM).

Research is focused on three major combustion strategies:

All the combustion approaches and associated critical technical issues VTO addresses are compatible with the industry trend toward engine downsizing and boosting to improve vehicle fuel economy. In addition, it also supports research on materials that can withstand high operating temperatures and pressures needed to capitalize on these engines' potential benefits.

Low-temperature combustion

Low temperature combustion (LTC) is a flameless, staged burning of the fuel (gasoline, diesel, or biofuel) in an engine's combustion chamber at temperatures that are lower than what occurs during conventional engine combustion. Research suggests that LTC has the potential for a 20% efficiency improvement over current diesel engines. The lower temperature, flameless combustion results from compression of a fuel-air mixture that has been diluted with either excess air or recirculated exhaust gas. This process raises the density and temperature of the dilute mixture, and causes it to autoginite (a process known as compression ignition).

With the LTC process, the engine compresses a dilute fuel-air mixture, raising its density and temperature. This process, known as compression ignition, causes the fuel-air mixture to autoignite. To dilute the fuel-air mixture so that it has a lower proportion of fuel in it than conventional combustion would, the engine uses either excess intake air or recirculated exhaust gas.

Staged burning - the other key element of LTC - is achieved by controlling the timing of the autoignition and rate of heat release. This process works to eliminate excessive combustion rates that can cause engine noise and structural damage, especially at higher loads.

VTO is researching a number of forms of LTC, including homogeneous-charge compression ignition (HCCI), premixed-charge compression ignition (PCCI), and reactivity controlled compression ignition (RCCI).

LTC offers a number of advantages over today's engines:

The fuel/air mixture and combustion product properties enable the engine to be more efficient than conventional combustion engines.

Because of the lower combustion temperature, the engine loses less energy through the cylinder walls to the environment. Some of this reduced energy loss allows the cylinder to maintain higher pressure for a longer period of time, enabling the engine to do more work. Some of the energy appears in the form of higher exhaust energy that turbocharging can partly capture.

Gasoline-based LTC does not need to throttle intake air to control load, which is a major cause of inefficiency in today's gasoline spark-ignition engines.

LTC is not restricted by "knock" (explosive, uncontrolled combustion) in the same way gasoline spark-ignition engines are. As a result, LTC allows gasoline engines to have high compression ratios similar to diesels, increasing their fuel economy.

LTC may be able to achieve ultra-low exhaust emissions, which could greatly reduce aftertreatment requirements, cost, and fuel economy penalties.

With a combustion strategy that utilizes LTC, a vehicle fuel economy improvement of 19.4% (over a model year 2015 baseline) was demonstrated in FY19. The details of this evaluation can be found here.

VTO is supporting work to address a number of critical challenges facing the development of low-temperature combustion, such as:

Difficulty controlling the start of combustion, because of the lack of a spark or fuel injection

Expanding the range of engine loads

Managing the heat release rate

Reducing the lack of control during transient events, such as changing loads and acceleration

Reducing potentially higher hydrocarbon (HC) and carbon monoxide (CO) emissions

Understanding if LTC can be more fully effective when combined with fuel that has different specifications than gasoline and diesel

Dilute (or lean-burn) gasoline combustion

In dilute gasoline combustion, a flame moves through either premixed or non-premixed (i.e., stratified) mixtures of fuel and air. In this process, the engine dilutes the fuel with either more air than is required to burn it (excess intake air) or recirculated exhaust gases. The Vehicle Technologies Office's (VTO) research focuses on the non-premixed (stratified) version because it offers the highest potential to improve efficiency. These engines can operate on current gasoline and gasoline/ethanol blends and are primarily for automotive and light truck applications. This combustion technology can offer fuel economy improvements of up to 35% relative to a 2009 baseline gasoline vehicle.

In the stratified version of the process, the vehicle injects fuel directly into the cylinder. It times it so that a properly stratified combustible fuel-air mixture occurs near the spark plug at the time of spark.

Dilute gasoline combustion results in fuel economy improvements because:

The engine uses the amount of fuel injected to control the load rather than restricting the intake air flow (throttling) to control it. Most gasoline vehicles on the road have port-fuel-injected (PFI) gasoline engines that use throttling, which is far less efficient.

At part load, the combustion products allow the engine to carry out work more efficiently compared to conventional engines.

The engine has a lower combustion product temperature at partial loads than a conventional engine would and as a result, loses less heat.

VTO is supporting work to address critical challenges which include:

Determining the most efficient fuel-air mixing strategies, which involve issues with port configurations, fuel-spray characteristics, and mixing characteristics

Initiating ignition and propagating a flame in stratified mixtures

Facing challenges with stochastic misfire and knock (explosive, uncontrolled combustion)

Reducing emissions that are different from those that occur with conventional (PFI) engines

Clean diesel combustion

In clean diesel combustion, the burning process takes place in a process fairly similar to conventional diesel combustion. In conventional diesel combustion (also known as diffusion combustion), the rate at which the fuel spray mixes with air inside the cylinder before it reaches the flame determines the rate at which the fuel and air burn in the flame. In clean diesel combustion, more fuel-air mixing occurs prior to the flame. This enables cleaner combustion that produces less soot as well as retains or improves the high efficiency of diesel engines. Adding recirculated exhaust gas to the intake air stream dilutes the fuel-air mixture, resulting in lower combustion temperatures and reducing the formation of NOx. Because fewer emissions form inside the cylinder, clean diesel engines do not have to rely as heavily on aftertreatment technologies to further reduce emissions.

The Vehicle Technologies Office (VTO) is supporting research to further improve clean diesel combustion and make it cost-competitive for all passenger and commercial vehicles. This requires pushing the state-of-the-art of technologies such as computer-control, multi-pulse fuel injection, high-pressure fuel injection, use of exhaust gas recirculation, and manipulation of in-cylinder gas flows.

VTO's research on clean diesel combustion engines for passenger and commercial vehicles addresses critical challenges which include:

Controlling the amount and temperature of the exhaust gas used for exhaust gas recirculation to minimize emissions

Improving the fuel injectors, injection pressure, and control over the fuel spray and spray types in high-pressure and multi-pulse injection

Improving lifted-flame combustion, which is when the flame that lifts off of the fuel nozzle stabilizes downstream of the fuel jet. Clean diesel engines must maintain auto-ignition of the fuel-lean mixture that is immediately upstream of the flame base.

Improving post-combustion injections for reducing emissions both in-cylinder and through aftertreatment

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The Vehicle Technologies Office (VTO) funds research focused on developing a greater understanding of engine combustion and how emissions form within engine cylinders as well as how combustion and emissions depend on factors such as fuel spray characteristics, in-cylinder air motion, and type of fuel.

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https://www.youtube.com/watch?v=zZ0swLIM5yY

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Core Concepts

In this tutorial you will learn what exactly a combustion reaction is and why it is important. You will also encounter numerous examples of combustion reactions and be able to replicate them on your own.

Topics Covered in Other Articles

What is a Combustion Reaction?

Combustion reactions, often simplified as "combustion," are chemical reactions between a substance and gaseous oxygen. These combustion reactions are exothermic, release energy in the form of heat and/or light, and occur rapidly. Often combustion reactions will produce carbon dioxide and water, but that isn't a technical requirement. For a combustion reaction to initially occur, the reactants must meet the minimum activation energy -this is why fire will be often used to get a reaction started. Combustion reactions will then continue until either one of the reactants is depleted.

Examples of Combustion Reactions

Imagine the wood burning in a fireplace. The wood is fuel which continuously reacts with oxygen in the air in a combustion reaction. The fire produced is energy being released in a long exothermic reaction, while the smoke you see is carbon dioxide. Lastly, the process can end in one of two ways. Either the wood will completely burn up and the fire will stop, or if you were to completely seal off the fireplace, the fire would stop because of a lack in oxygen.

Balancing Combustion Reactions

Combustion is most common between hydrocarbons and oxygen, to produce carbon dioxide and water. Balancing a combustion reaction is actually pretty straightforward!

1. Balance the C atom in the CO₂ with the hydrocarbon on the left

2. Balance the H atom in the H₂O with the hydrocarbon on the left

3. Use the O atoms in the CO₂ and H₂O to balance the O₂ on the left

Remember that chemical reactions don't need to have whole numbers. If your oxygen is preceded by a fraction, not to worry!

Further Reading

Take a deeper dive into the other types of chemical reactions!

Synthesis Reactions

Decomposition Reactions

Single Replacement

Double Replacement

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In this tutorial you will learn what exactly a combustion reaction is and why it is important. You will also encounter numerous examples of combustion reactions and be able to replicate them on your own. Combustion reactions, often simplified as "combustion," are chemical reactions between a substance and gaseous oxygen.

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All combustion reactions fall into the pattern:

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https://www.chem.fsu.edu/chemlab/chm1020c/Lecture%207/01.php

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Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel.

In chemistry we call the type of reaction that produces fire a combustion reaction. Combustion is a high-temperature exothermic (heat releasing) redox (oxygen adding) chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.

Whenever we complete a combustion reaction a hydrocarbon (compound of C and H) there are generally the same products formed: CO ₂ and H ₂ O.

The fuel you burn in your car's engine contains octane, C ₈H ₁₈. When octane is burned, the products are CO ₂ and H ₂ O.

The key ingredient to the process is the availability of oxygen. Combustion cannot take place in an atmosphere devoid of oxygen.

So if you have a bottle of gasoline (octane) sitting around and open to the atmosphere which contains oxygen, why doesnt it just burst into flames?

The answer to this question is the need to overcome the activation energy of the reaction, which means that it requires energy at first to "jump start" the process. In your car, the distributor and battery provide this starting energy by creating an electrical "spark". Other sources of initial energy can come from the Sun, matches, friction, etc.

The combustion reaction itself is quite exothermic.

Exothermic Reactions

When heat is produced in the process of a chemical reaction this is known as an Exothermic Reaction.

Endothermic Reactions

When heat is absorbed from the reacting substances this is known as an Endothermic Reaction.

But remember, whether endothermic or exothermic, both types of reactions still require an Activation Energy to begin.

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Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction.