A vapor compression refrigerator using R134a as the refrigerant operates under the following conditions: The refrigerant condenses at 50°C and is then sub-cooled by 10°C to 30°C before expansion. After an isenthalpic expansion, the refrigerant evaporates at -20°C and then superheated by 10°C to 0°C before compression. The refrigerant is compressed to 70°C with entropy of 1.0 kJ/kg.K at the end of the compression. a)With reference to the above operating conditions, draw the cycle on the R134a p-h diagram. b)Calculate the specific refrigerating effect at the evaporating temperature of -20°C. c)Calculate the work input for the compression process. d)Prove the vapor compression is not an isentropic process. e) Calculate the COP of the cycle. f)To produce 5kW cooling, what is the refrigerant flow rate required?

A vapor compression refrigerator using R134a as the refrigerant operates under the following conditions: The refrigerant condenses at 50°C and is then sub-cooled by 10°C to 30°C before expansion. After an isenthalpic expansion, the refrigerant evaporates at -20°C and then superheated by 10°C to 0°C before compression. The refrigerant is compressed to 70°C with entropy of 1.0 kJ/kg.K at the end of the compression. a)With reference to the above operating conditions, draw the cycle on the R134a p-h diagram. b)Calculate the specific refrigerating effect at the evaporating temperature of -20°C. c)Calculate the work input for the compression process. d)Prove the vapor compression is not an isentropic process. e) Calculate the COP of the cycle. f)To produce 5kW cooling, what is the refrigerant flow rate required?

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

Chapter45: Domestic Refrigerators And Freezers

Section: Chapter Questions

Problem 12RQ: Refrigerators currently being manufactured in the United States are using______as their refrigerant.

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