https://padlet.com/tuchang_981/2jjghkmkw7me en-us 2017-01-22 09:03:25 UTC 2017-03-15 11:07:54 UTC hello@padlet.com tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550487 The earliest known steam engine was the aeolipile. Steam ejected tangentially from nozzles caused a pivoted ball to rotate. Its thermal efficiency was low.]]> 2017-01-22 09:05:17 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550487 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550579 Denis Papin became interested in using a vacuum to generate motive power while working with Christiaan Huygens and Gottfried Leibniz in Paris. From 1690 on Papin began experimenting with a piston to produce power with steam, building model steam engines. He experimented with atmospheric and pressure steam engines, publishing his results in 1707.]]> 2017-01-22 09:07:55 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550579 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550622 The first steam engine to be applied industrially was the "fire-engine" or "Miner's Friend", designed by Thomas Savery in 1698. Savery made two key contributions that greatly improved the practicality of the design. First, in order to allow the water supply to be placed below the engine, he used condensed steam to produce a partial vacuum in the pumping reservoir, and using that to pull the water upward. Secondly, in order to rapidly cool the steam to produce the vacuum, he ran cold water over the reservoir.]]> 2017-01-22 09:09:38 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550622 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550655 It was Thomas Newcomen with his "atmospheric-engine" of 1712 who can be said to have brought together most of the essential elements established by Papin in order to develop the first practical steam engine for which there could be a commercial demand. This took the shape of a reciprocating beam engine installed at surface level driving a succession of pumps at one end of the beam. The engine, attached by chains from other end of the beam, worked on the atmospheric, or vacuum principle.]]> 2017-01-22 09:10:41 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550655 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550684 Watt solved the problem of the water spray by removing the cold water to a different cylinder, placed beside the power cylinder. Once the induction stroke was complete a valve was opened between the two, and any steam that entered the cylinder would condense inside this cold cylinder. This would create a vacuum that would pull more of the steam into the cylinder, and so on until the steam was mostly condensed. The valve was then closed, and operation of the main cylinder continued as it would on a conventional Newcomen engine. As the power cylinder remained at operational temperature throughout, the system was ready for another stroke as soon as the piston was pulled back to the top. Maintaining the temperature was a jacket around the cylinder where steam was admitted. ]]> 2017-01-22 09:11:29 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550684 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550832 The first high-pressure steam engine was invented in 1800 by Richard Trevithick. The importance of raising steam under pressure (from a thermodynamic standpoint) is that it attains a higher temperature. Thus, any engine using high-pressure steam operates at a higher temperature and pressure differential than is possible with a low-pressure vacuum engine. The high-pressure engine thus became the basis for most further development of reciprocating steam technology. 

]]> 2017-01-22 09:15:47 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550832 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550879 Around 1811 Richard Trevithick was required to update a Watt pumping engine in order to adapt it to one of his new large cylindrical Cornish boilers. In a parallel, Arthur Woolf developed a compound engine with two cylinders, so that steam expanded in a high-pressure cylinder before being released into a low-pressure one. Efficiency was further improved by Samuel Groase, who insulated the boiler, engine, and pipes.

]]> 2017-01-22 09:17:35 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550879 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550989 Patented in 1849, the Corliss engine had greatly improved speed control and better efficiency, making it suitable to all sorts of industrial applications, including spinning. Corliss used separate ports for steam supply and exhaust, which prevented the exhaust from cooling the passage used by the hot steam. Corliss also used partially rotating valves that provided quick action, helping to reduce pressure losses. ]]> 2017-01-22 09:21:11 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148550989 tuchang_981 https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148551073 The Porter-Allen engine, introduced in 1862, used an advanced valve gear mechanism. The high speed engine was a precision machine that was well balanced, achievements made possible by advancements in machine tools and manufacturing technology. Porter greatly improved the fly-ball governor by reducing the rotating weight and adding a weight around the shaft. This significantly improved speed control. Porter's governor became the leading type by 1880.]]> 2017-01-22 09:23:18 UTC https://padlet.com/tuchang_981/2jjghkmkw7me/wish/148551073