Maximum efficiency of a heat engine

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SUMMARY

The maximum possible efficiency of a heat engine using surface lake water at 19°C (292K) as a heat source and rejecting waste heat to water at 4.1°C (277.1K) is calculated using the formula eta = 1 - Tc / Th. The correct calculation yields eta = 1 - 277.1K / 292K, resulting in an efficiency of approximately 0.054 or 5.4%. The initial misunderstanding stemmed from incorrect treatment of the equation, specifically in the conversion to Kelvin and the application of the formula.

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  • Knowledge of temperature conversion to Kelvin
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JJones_86
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Homework Statement


Calculate the maximum possible efficiency of a heat engine that uses surface lake water at 19°C as a source of heat and rejects waste heat to the water 0.100 km below the surface where the temperature is 4.1°C.


Homework Equations


eta = 1 - Tc / Th


The Attempt at a Solution



eta = 1 - 277.1K/292K
eta = -.945548


Not sure what I'm doing wrong, am I not supposed to convert to Kelvin??
 
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Nevermind, I've figured out what I did wrong, I was treating the equation like this (1-277.1K)/292K
 

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