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Thermodynamics/stirling engines

  1. Oct 30, 2012 #1
    1. The problem statement, all variables and given/known data

    Helium Gas (Cv=12.5) has initial temperature T1, pressure P1, and volume V1. It follows a stirling engine cycle, namely it is 1)heated at constant volume to a temperature T2 then is 2)expanded isothermally to volume V2. 3) It is then returned to a temperature T1 by an isochoric process, then 4) returned to volume V1 by an isothermal process

    2. Relevant equations

    Q=deltaU+W
    pv=nRT
    Q=nCvdeltaT


    3. The attempt at a solution

    Because processes 1 and 3 are isochoric, that means there is no work done, so I neglected the calculations from those two processes. For both process 2 and 4 i set Q=W because it is isothermal and I believe we assume that it is an ideal gas. I tried using Q=nCvdeltaT to solve for Q of the two processes, and then subtract them from each other, but I found I would end up with

    nCvT2-nCvT1
    net work=nCv(T2-T1)

    It seems too simple, am I doing something wrong?
     
  2. jcsd
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