- #1
FranzDiCoccio
- 342
- 41
Hi,
I was revisiting my (high school level) understanding of thermodynamic cycles and I think I still have some doubts. Last year and more recently I posted a few questions which surely helped me, but I think I need more clarifications.
In a nutshell, what I'd like to know is the following: suppose you have a reversible heat engine that operates (i.e. exchanges heat) between two reservoirs.
Is that machine necessarily a Carnot engine? That is a machine operating according to Carnot's cycle (adiabatic, isothermal, adiabatic, isothermal)?
Would this mean that any non-Carnot engine transferring heat between two reservoirs is not reversible, not even in the ideal situation where mechanical friction causing dissipation has been entirely removed?
For instance: suppose you have a heat engine operating between two reservoirs via a isobaric-adiabatic-isobaric-adiabatic cycle. Suppose all the mechanical parts are perfectly ideal, with no friction and hence no dissipation.
That would not be a reversible engine anyways?
Is this because of the non reversibility of spontaneous heat flow?
I'm asking all this because my textbook gives a version of Carnot's theorem generically referring to "a reversible heat engine operating between two temperatures", whereas other versions of the theorem I found explicitly refer to "a Carnot engine".
Now, a Carnot engine surely fits the description. But the wording in my book kind of leaves other possibilities open, like there were reversible cycles other than Carnot's.
Thanks a lot for your help.
Franz
I was revisiting my (high school level) understanding of thermodynamic cycles and I think I still have some doubts. Last year and more recently I posted a few questions which surely helped me, but I think I need more clarifications.
In a nutshell, what I'd like to know is the following: suppose you have a reversible heat engine that operates (i.e. exchanges heat) between two reservoirs.
Is that machine necessarily a Carnot engine? That is a machine operating according to Carnot's cycle (adiabatic, isothermal, adiabatic, isothermal)?
Would this mean that any non-Carnot engine transferring heat between two reservoirs is not reversible, not even in the ideal situation where mechanical friction causing dissipation has been entirely removed?
For instance: suppose you have a heat engine operating between two reservoirs via a isobaric-adiabatic-isobaric-adiabatic cycle. Suppose all the mechanical parts are perfectly ideal, with no friction and hence no dissipation.
That would not be a reversible engine anyways?
Is this because of the non reversibility of spontaneous heat flow?
I'm asking all this because my textbook gives a version of Carnot's theorem generically referring to "a reversible heat engine operating between two temperatures", whereas other versions of the theorem I found explicitly refer to "a Carnot engine".
Now, a Carnot engine surely fits the description. But the wording in my book kind of leaves other possibilities open, like there were reversible cycles other than Carnot's.
Thanks a lot for your help.
Franz