A real heat pump has .02 kg/s of refrigerant-134a flowing through and consumes 3 kW of power. The refrigerant is a mixture at 50% quality and 120 kPa entering the evaporator and leaves at 100 kPa and -20 C. The refrigerant enters the condenser at 1.4 MPa and leaves at 1.2 MPa. Assuming no loss in pressure or temperature in the connecting pipes, determine the temperature, pressure, enthalpy and entropy at all positions in the cycle, the heat transfer coming in and leaving, the COP of this heat pump, the isentropic efficiency of the compressor, and the rate of entropy generation in the compressor and of the throttling process.

A real heat pump has .02 kg/s of refrigerant-134a flowing through and consumes 3 kW of power. The refrigerant is a mixture at 50% quality and 120 kPa entering the evaporator and leaves at 100 kPa and -20 C. The refrigerant enters the condenser at 1.4 MPa and leaves at 1.2 MPa. Assuming no loss in pressure or temperature in the connecting pipes, determine the temperature, pressure, enthalpy and entropy at all positions in the cycle, the heat transfer coming in and leaving, the COP of this heat pump, the isentropic efficiency of the compressor, and the rate of entropy generation in the compressor and of the throttling process.

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

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Why is two-stage compression popular for extra-low-temperature refrigeration systems?
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