2. A freezer of 20 TR capacity has evaporator and condenser temperatures of - 30°C and 25°C respectively. The refrigerant R-12 is sub-cooled by 4°C before it enters the expansion valve and is superheated by 5°C before leaving the evaporator. The compression is isentropic and the valve throttling and clearance are to be neglected. If a six-cylinder, single acting compressor with stroke equal to bore running at 1000 r.p.m. is used, determine: A- C.O.P. of the refrigerating system, B- Mass of refrigerant to be circulated per min, C- Theoretical piston displacement per minute and D- Theoretical bore and stroke of the compressor.

2. A freezer of 20 TR capacity has evaporator and condenser temperatures of - 30°C and 25°C respectively. The refrigerant R-12 is sub-cooled by 4°C before it enters the expansion valve and is superheated by 5°C before leaving the evaporator. The compression is isentropic and the valve throttling and clearance are to be neglected. If a six-cylinder, single acting compressor with stroke equal to bore running at 1000 r.p.m. is used, determine: A- C.O.P. of the refrigerating system, B- Mass of refrigerant to be circulated per min, C- Theoretical piston displacement per minute and D- Theoretical bore and stroke of the compressor.

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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