# Heat Engine - Maximum Efficiency

1. Apr 9, 2009

### science.girl

1. The problem statement, all variables and given/known data
A heat engine operates between a reservoir at 25 degrees Celsius and one at 375 degrees Celsius. What is the maximum efficiency possible for this engine?

2. Relevant equations

e = $$\frac{Qc}{Qh}$$

3. The attempt at a solution

I'm afraid that the equation above requires units in Joules to calculate thermal efficiency. Is there an equation adapted for this situation? Or does this require more figuring?

2. Apr 9, 2009

### Thaakisfox

Just a little more figuring ;) think of the Carnot cycle ;)

3. Apr 9, 2009

### Redbelly98

Staff Emeritus
Check your textbook for another efficiency equation, one involving absolute temperatures rather than Q's.

4. Apr 9, 2009

### Andrew Mason

Efficiency is the ratio of Energy (work) out to Energy (heat flow) in. This is not Qc/Qh

AM