Highest possible efficiency of an engine

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The highest theoretical efficiency of an engine can be calculated using the formula e=(TH-TC)/TH, where TH is the highest temperature and TC is the lowest. In the case of a Stirling engine with a maximum temperature of 700 °C and a minimum of 100 °C, the initial calculation yields an efficiency of 85.7%. However, the expected answer is 61.7%, indicating that additional factors must be considered. The discussion also touches on the importance of using the correct SI unit for temperature in calculations. Understanding these factors is crucial for accurate efficiency assessments in engine performance.
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Homework Statement


The highest theoretical efficiency of an engine is

e=(TH-TC)/TH

where TH is the highest and TC is the lowest temperature during the circuit process. In a test car with a stirling engine the highest temperature during the circuit process is 700 °C and the lowest temperature is 100 °C. Calculate the highest possible efficiency.

Homework Equations


e=(TH-TC)/TH

The Attempt at a Solution


1 – 100/700 = 85,7%

But apparently the answer should be 61,7%. What other factors needs to be included here?
 
Last edited:
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Do you know the SI unit for temperature?
 
Ah yes. Of course. Thank you!
 

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