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Thermodynamics system

  1. Oct 20, 2014 #1
    1. The problem statement, all variables and given/known data
    Design an explicit system which does the following: It goes adiabatically and reversibly from state A to B. Then it returns from state B to state A probably irreversibly and receiving some heat from the outside world on the way. It cant give out heat.

    2. Relevant equations
    [itex]PV^{\gamma}=c[/itex] for an adiabatic process
    [itex]PV=c[/itex] for an isothermal process

    3. The attempt at a solution

    I attempted to draw various 3 step PV diagrams using isobaric and isochoric steps but they all gave out heat. The only way I can think of doing this is if the adiabatic process is the same as an isothermal process i.e
    [itex]PV^{\gamma}=PV[/itex]
    [itex]\gamma=1[/itex]
    [itex]C_p=C_v[/itex]

    But this can't be true for an ideal gas so I have no idea.
     
  2. jcsd
  3. Oct 20, 2014 #2

    DrClaude

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    Staff: Mentor

    Doesn't that depend on the direction of the process?
     
  4. Oct 20, 2014 #3
    Yes but amn't I forced into a direction that gives out heat after an adiabatic process then a process which takes in heat if I want to get back to the start?
     
  5. Oct 21, 2014 #4

    DrClaude

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    Staff: Mentor

    I haven't worked out the details, but if your adiabatic process is an expansion, can't you go back to state A without any heat leaving the system?
     
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