Repeat Problem 9.117 using EES. Modify your EES program to find the coefficient of performance between pressures of 0.28 and 1.5 MPa. Plot T–s diagrams for the original cycle conditions and for the new conditions. Use the two T–s diagrams to explain the change in the coefficient of performance.

Problem 9.117

Consider an ideal vapor-compression cycle using R-134a and operating between pressures of 0.28 and 1.75 MPa. Determine the coefficient of performance for the cycle for application 

(a) In a refrigerator 

(b) In a heat pump.

Transcribed Image Text:

Temperature (K) 500 400 300 200 0.5 3 0.75 1.0 h = constant 1.75 MPa 4 0.28 MPa 1.25 1.5 Entropy (kJ/kg. K) 2 1 1.75 2.0