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Properties of Pure Substance

  1. Sep 12, 2008 #1
    A piston-cylinder device contains 0.85 kg of refrigerant 134a at -10 degrees celsius. The piston that is free to move has a mass of 12 kg and diameter of 25 cm. The local atmospheric pressure 88 kPa. Now, heat is transferred to refrigerant 134a until the temperature is 15 degrees celsius. Determine
    (a)the final pressure
    (b)the change in the volume of the cylinder and
    (c)the change in enthalpy of the refrigerant 134a

    I did part a and got it to be 90.4 kPa as P1 = P2, a value of which I am about 95% sure being correct.

    As for part b, I deduce that I should use the tables in some method but I'm stumped with how to proceed. I tried to calculate the V of initial and final to get delta V but im stuck at this equation

    V = mv

    So I figure i may have to use -10 degrees celsius and 90.4 kPa to get the specific volume at the initial state and 90.4 kPa and 15 degrees celsius to get specific volume at the final state.

    Plz pt me in the right direction if you can.
  2. jcsd
  3. Sep 15, 2008 #2
    c'mon guys its been over two days an no help....oh man
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