Determine the heat pump coefficient of performance for an ideal vapor compression refrigeration cycle operating between 0.653 and 1.342 MPa. The working fluid is R-22. Compare your result with that for the real cycle described in Example 9.14.

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Example 9.14 Heat Pump As shown in the diagram below, a heat pump is used to heat a swimming pool by extracting energy from the ambient air at 295.3 K (72 F) and transferring it to the water in the pool at 283.1K (50F). The heat pump operates with R-22 between 0.653 MPa absolute (~80 psig) and 1.342 MPa (~180 psig) and delivers 24.62 kW (84,000 Btu/hr) to the water. The R-22 vapor is superheated to 291.44 K (65F) before it enters the compressor, and the R-22 liquid is subcooled to 299.78 (80F) at the condenser outlet. The scroll compressor has an isentropic efficiency of 65%. Assuming no losses other than those associated with the compressor, plot the vapor-compression cycle in T-s coordinates and determine the cycle coefficient of performance and the mass flow rate of the refrigerant. (Credit: Mario Tama / Staff / Getty Images News.)