Refrigerant 12 in a piston-cylinderassembly undergoes two processes in series. A

Question

Refrigerant 12 in a piston-cylinderassembly undergoes two processes in series. At the initial state,p1 = 90 lbf/in2 and the quality is 100%.Process 1-2 occurs at constant volume until the temperature isT2 = 200F. The second process, from state 2 to state 3,occurs at constant temperature, with Q2-3 = -60.9 Btu,until V3 = 0.6ft3. Kinetic and potentialenergy effects are negligible. For 2.2 lb of refrigerant,determine, in Btu

1)      the heat transfer forprocess1-2                                      

2)      the work for process 2-3

Explanation / Answer

At the initial state, p1 = 90lbf/in2 quality x = 100% at state 2: T2 = 200F take properties from the saturated R-12 tablesat  p1 = 90 lbf/in2 T1 = 40+(50-40)*(90-83.206)/(98.727-83.206) T1 = 44.377F 1)      the heat transfer for process1-2 : constant volumeprocess         for constant volume process heat supplied is givenby        Q1-2= mCv(T2-T1) Q1-2= 2.2x0.131x(200-44.377) Btu Q1-2= 44.85 Btu 2)      the work for process2-3: since it is constant temperature process there fore heat supplied = work done W2-3 =Q2-3 = -60.9Btu by mistake i have taken properties of R-22 but the process isrmains same use R-12 tables by mistake i have taken properties of R-22 but the process isrmains same use R-12 tables

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