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[Phys-L] Carnot (?) efficiency of non-Carnot cycles



I'm a bit confused about efficiency. For a Carnot cycle, we have two
isothermal steps and two adiabatic steps. The efficiency is then found to
be 1 - Tcold/Thot.

Okay but what about a non-Carnot but still reversible cycle. To be
specific, let's consider a Stirling cycle with two isothermal and two
isochoric steps. Note that heat is input at both an isothermal and an
isochoric step. I assume their sum is what we should call Qhot. But that
means Qhot is not connected to just Thot. However, since every step is
reversible, we should still have a maximum efficiency. Would you still call
that the "Carnot" efficiency? Or is there some other word that means
"maximum theoretical efficiency"? Is there a general formula analogous to 1
- Tcold/Thot but with some kind of temperatures averaged over all steps in
which heat is input or output to the system?

I'm a bit surprised intro textbooks don't discuss ideal efficiencies for
non-Carnot cycles. Have I missed something?

--
Carl E Mungan, Assoc Prof of Physics 410-293-6680 (O) -3729 (F)
Naval Academy Stop 9c, 572C Holloway Rd, Annapolis MD 21402-1363
mailto:mungan@usna.edu http://usna.edu/Users/physics/mungan/