# Homework Help: Efficiency of Stirling heat engines

1. Apr 13, 2014

### mysticwolves

Not sure if this should be posted in the general physics forums or in the hw/coursework section.

I'm in my second semester of general physics and have to do a class project. For my project I built an alpha type Stirling engine. In the paper I need to write I need to explain how it works using physics. I'm am stuck on the second law of thermodynamics and finding the efficiency (real and ideal) of a Stirling heat engine. I also need to compare the Stirling engine to the carnot engine.

I know the efficiency of a carnot is effc= 1-(Tc/Th).

What formula is used to calculate the the real efficiency of a Stirling heat engine?

2. Apr 13, 2014

### Staff: Mentor

Welcome to the PF.

What have you been reading about the Stirling engine? What equations and derivations have you seen so far for its efficiency?

3. Apr 13, 2014

### mysticwolves

I have been searching Google for various information. On a few sites they use the carnot efficiency for Stirling engines which I wasn't sure if that was the correct equation. On other sites the equations used calculus that I haven't used before.

4. Apr 14, 2014

### mysticwolves

I know these equations for efficiency:

effc=1-(Tc/Th)

eff=W/Qin