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Please Help Me Out with this ?
Does A Heat engine work in cyclic process ? Is it possible to design one ? I read somewhere that an engine work in cyclic process and then I read it is not possible to design an heat engine which works in cyclic process and whose only result is to take heat from a body at a single temperature and convert it completely into mechanical work....
please help I am confused
2 Answers
- az_lenderLv 75 years agoFavorite Answer
Yes, a heat engine works in a cyclic process. Yes, it is possible to design one. An internal combustion engine is an example of a heat engine. However, it does not "completely" convert the heat obtained from the burning fuel into mechanical work. Some of the heat is wasted, and the laws of thermodynamics can prove that will always be the case.
- donpatLv 75 years ago
A Heat Engine absorbs heat, QA , from a Heat Source at high temperature, TH,yields some work, WOUT , rejects
heat, QR , to a Heat Sink at low temperature, TL , and has a work input, WIN.
WNET = WOUT - WIN = QA - QR
Eth = thermal efficiency = [ ( WNET ) / ( QA ) ] [ 100 ]
There are many Heat Engine designs and many Heat Engines actually operating. The Kelvin-Planck Statement
of the Second Law of Thermodynamics requires that all Heat Engines reject some portion of the heat absorbed and have a thermal efficiency less than 100 percent.
The Carnot Heat Engine is an Ideal Heat Engine that has the maximum possible thermal efficiency for any given
TH an TL where
Ethmax = EthCarnot = ( TH - TL ) / ( TH )
The above temperatures are to be absolute temperatures, K or R.
