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I need some clarification Thermo Cycle

  1. Sep 22, 2008 #1
    I need some clarification!! Thermo Cycle

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

    One kg of Refrigerant 22, initially at p1=.9MPa, u1=232.92 kJ/kG, is contained within a rigid closed tank. The tank is fitted with a paddle wheel that transfers energy to the refrigerant at a constant rate 0.1kW. Heat transfer from the refrigerant to its surroundings occurs at a rate Kt, in kW, where K is a constant, in kW/minute, and t is time in minutes. After 20 minutes of stirring, the refrigerant is at p2=1.2 MPa, u2=276.67 kJ/kG. No overall changes in KE or PE occur. (a) For the refrigerant, determine the Work and Heat transfer, each in kJ. (b) Determine the value of the constant K appearing in the given heat-transfer relation in kW/min.



    2. Relevant equations

    U2-U1=Q-W
    W=int p*dV





    3. The attempt at a solution

    I guess what I really need is some clarification on the term "energy transfered in." Is this a rate of WORK?
     
    Last edited: Sep 22, 2008
  2. jcsd
  3. Sep 22, 2008 #2
    Re: I need some clarification!! Thermo Cycle

    Can anyone give me a hint before I go to bed? Then I can mull it over and attack this problem on the subway tomorrow! :smile:
     
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