Refrigerant 134a vapor in a piston-cylinder assembly undergoes a constant pressu

Question

Refrigerant 134a vapor in a piston-cylinder assembly undergoes a constant pressure process from saturated vapor at 8 bar to 50 degrees C. For the refrigerant, determine the work and heat transfer, per unit mass, each in kJ/kg. Changes in PE and KE are negligible.
T1=31.33 (C) V1 = .02547 m^3/kg u1= 243.78 kJ/kg
T2=50(C) V2 = .02846 m^3/kg u2 = 261.62 kJ/kg
V, u and T1 were taken from the R134a tables in my textbook
8 bar = 800kpa
For Work :
W=p(v2-v1)
800(.02846-.02547) = 2.392 kJ/kg

For heat transfer :
Q=(u2-u1)+w
(261.62-243.78)+2.392 = 20.23 kJ/kg

Explanation / Answer

What ever you have done is absolutely right according to your table values According to my book table values v1=0.025621 m3/kg u1=246.79 kj/kg v2=0.028547 m3/kg u2=263.86 kj/kg w=p(v2-v1)=2.3408 kJ/kg q=u2-u1 +w = 19.41 kJ/kg Only book values differ and the procedure u approached is absolutely right I would suggest , you can use enthalpy change for finding heat transfer.

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