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Homework Help: What is the minimum power required to operate the heat pump?

  1. Dec 4, 2006 #1
    1. The problem statement, all variables and given/known data
    It is proposed to heat a house using a heat pump operating between the house (27 degees) and the outside (-13 degrees). The heat loss from the house is 7kW. What is the minimum power required to operate the heat pump?


    2. Relevant equations



    3. The attempt at a solution
    e=Th/(Th-Tc) =7.5
    W=7000/7.5 =933 W

    Just checking if this is correct or have I made a mistake. Thanks
     
    Last edited: Dec 4, 2006
  2. jcsd
  3. Dec 4, 2006 #2

    OlderDan

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    Since you start out with a dimensionless number, a ratio of temperatures, and equate that to some number of Watts, something is surely wrong. Maybe you just need to rewrite things to make it clear
     
  4. Dec 4, 2006 #3
    I have moved the equation now. If you look at the question you will see that 7000 has units of watts. Is it wrong anyway?
     
  5. Dec 4, 2006 #4

    OlderDan

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    That looks better. It woudl be better still if you had units of W on the 7000.
     
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