# Thermodynamics Help- Proving Carnot Cycle

1. Oct 19, 2011

### Spoolx

Given:

A Heat engine goes through a Carnot Cycle as the following states:

State 2 to 3: air compresses adiabatically (pressure increasing)

State 3 to 4: air expanded under isobaric process

State 4 to 1: air goes under adiabatic expansion process

State 1 to 2: air goes under an isobaric compression

Expression :

efficiency = 1-(v1/v4)^gamma(v4/v3)

Find:

1: Plot P-V and T-V diagram of the cycle

2: Prove that the efficiency of this cycle given by expression (1)

3: Determine the net work done by this cycle as function of pressure and volume.

Thank you

2. efficiency = 1-TL/TH
efficiency = 1-(v1/v4)^gamma(v4/v3)

3. I have done the graphs correctly, I am not expecting anyone to do it for me, just some guidance on the right direction to start.

2. Oct 20, 2011

### rude man

What does it tell you that it's a Carnot cycle with the isothermals also isobars?

(I hope γ is latent heat, otherwise I'd be stumped too. Usually γ is Cp/Cv. If this is the case here, then the cycle could not be a Carnot since for a Carnot the top & bottom curves are not isobars. You can only have isobars and isotherms simultaneously if the working substance is part liquiod and part vapor. So we must be dealing with partly liquefied air. At least that's my understanding.)

Last edited: Oct 20, 2011