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Homework Help: Maximum efficiency of a heat engine

  1. Dec 14, 2008 #1
    1. The problem statement, all variables and given/known data
    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.

    2. Relevant equations
    eta = 1 - Tc / Th

    3. 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??
  2. jcsd
  3. Dec 14, 2008 #2
    Nevermind, I've figured out what I did wrong, I was treating the equation like this (1-277.1K)/292K
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