Consider a heat pump that operates on the ideal vapor compression refrigeration cycle with R-134a as the working fluid between the pressure limits of 0.32 MPa and 1.4 MPa. The coefficient of performance of this heat pump is

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Quizplus · Accepted Answer

Solved by EES Software. Solutions can be verified by copying-and-pasting the following lines on a blank EES screen. 
P1=320 "kPa"
P2=1400 "kPa"
P3=P2
P4=P1
s2=s1
h1=ENTHALPY(R134a,x=1,P=P1)
s1=ENTROPY(R134a,x=1,P=P1)
h2=ENTHALPY(R134a,s=s2,P=P2)
h3=ENTHALPY(R134a,x=0,P=P3)
h4=h3
COP_HP=qH/Win
Win=h2-h1
qH=h2-h3
"Some Wrong Solutions with Common Mistakes:"
W1_COP = (h1-h4)/(h2-h1) "COP of refrigerator"
W2_COP = (h1-h4)/(h2-h3) "Using wrong enthalpies, QL/QH"
W3_COP = (h22-h3)/(h22-h1); h22=ENTHALPY(R134a,x=1,P=P2) "Using wrong enthalpy h2 (hg at P2)"

Consider a Heat Pump That Operates on the Ideal Vapor