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Homework Help: Thermodynamics- carnot engine power

  1. Mar 1, 2009 #1
    1. The problem statement, all variables and given/known data

    An ice making plant consists of a reversed Carnot engine extracting heat from a well- insulated box. The temperature in the icebox is -5C and the temperature of ambient air is 30C. Water of an initial temp 30C is placed in the icebox and allowed to freeze and cool to -5C. If the plant makes 10,000kg of ice, what is the mechanical power required?

    2. Relevant equations

    Qwater= c(water)*m*(T2-T1)
    Qfreeze= Latent heat of fusion * m
    Qice= c(ice)*m*(T2-T1)

    n= 1- Q2/Q1

    3. The attempt at a solution

    I calculated Qwater, Qfreeze, and Qice. I am not sure where to go from here
  2. jcsd
  3. Mar 1, 2009 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    Okay, so that gives you the amount of heat that is removed from the water. We need to relate that to the work done.

    What is the c.o.p. (coefficient of performance) for a refrigerator?

    p.s. I see a problem with the way the problem statement is worded. Does it say in how much time the 10,000 kg ice must be made? And, does it ask for mechanical power or mechanical energy?
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