A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.29 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of 430 W from the surroundings. The heat exchanger loses no heat to the environment.

A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -30°C by rejecting its waste heat to cooling water that enters the condenser at 18°C at a rate of 0.29 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 65°C and leaves at 42°C. The inlet state of the compressor is 60 kPa and -34°C and the compressor is estimated to gain a net heat of 430 W from the surroundings. The heat exchanger loses no heat to the environment.

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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NOTE: This is a multi-part question. Once an answer is submitted, you will be unable to return to this part. A refrigerator uses refrigerant-134a as the working fluid and operates on the vapor-compression refrigeration cycle. The evaporator and condenser pressures are 100 kPa and 1400 kPa, respectively. The isentropic efficiency of the compressor is 88 percent. The refrigerant enters the compressor at a rate of 0.022 kg/s superheated by 26.37°C and leaves the condenser subcooled by 4.4°C. Problem 11.021.a - Actual refrigeration cycle Determine the rate of heat removal from the refrigerated space, the rate of heat rejection from the refrigerant to the environment, the power input, and the COP. (Take the required values from saturated refrigerant-134a tables.) The rate of heat removal from the refrigerated space is kW. The rate of heat rejection from the refrigerant to the environment is kW. The power input is kW. The COP is .
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