A refrigerant 22 refrigeration carries a load of 82 kW at an evaporator pressure of 354 kPa and a condenser pressure of 1460 kPa. The liquid refrigerant is subcooled by 4 degrees before entering the expansion valve and the vapor is superheated by 5 degrees before entering the compressor. The stroke-to-bore ratio of the twin-cylinder compressor is 1.20 and the actual volumetric efficiency is 81 percent. Determine: a. The mass flowrate of the cooling water in the condenser for a 7-degree change in temperature, b. The bore and stroke

A refrigerant 22 refrigeration carries a load of 82 kW at an evaporator pressure of 354 kPa and a condenser pressure of 1460 kPa. The liquid refrigerant is subcooled by 4 degrees before entering the expansion valve and the vapor is superheated by 5 degrees before entering the compressor. The stroke-to-bore ratio of the twin-cylinder compressor is 1.20 and the actual volumetric efficiency is 81 percent. Determine: a. The mass flowrate of the cooling water in the condenser for a 7-degree change in temperature, b. The bore and stroke

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 20RQ: Welded ______sealed compressors are normally used in household refrigerators.

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Welded ______sealed compressors are normally used in household refrigerators.
A refrigerant 22 refrigeration system carries a load of 82 kW at an evaporator pressure of 354 kPa and a condenser pressure of 1460 kPa. The liquid refrigerant is subcooled by 4 degrees before entering the expansion valve and the vapor is superheated by 5 degrees before entering the compressor. The compressor operates at 28 r/s. The stroke-to-bore ratio of the twin-cylinder compressor is 1.20 and the actual volumetric efficiency is 82 per cent. Determine (a) mass flow rate of refrigerant, (b) mass flow rate of cooling water in the condenser for a 7-degree change in temperature, and (c) the bore and stroke. Ans. (a) 0.5025 kg/s, (b) 3.43 kg/s, (c) 9.2 x 11 cm
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.
A four-cylinder refrigerant 12 compressor operates between evaporator and condenser temperature of 4°C and 43°C. It is to carry a load of 20 tons of refrigeration at 1200 rpm. If the average piston speed is 213 m/min and the actual volumetric efficiency is 80%. What should be the bore and stroke of the compressor?
vi) The vapour-compression heat pump system below uses a heat exchanger to superheat the vapour entering the compressor while sub-cooling the liquid exiting the condenser. The refrigerant used (R134a) is at -10.1°C in the evaporator and is sub-cooled by 11.3°C at the throttle valve entrance. If the condenser pressure is 800 kPa, the maximum temperature reached by the refrigerant throughout the cycle is closest to: Condenser Compressor Heat exchanger Throttle Evaporator work ratin n
Catalogue data for R-32 compressor with a displacement of 80 L/s show the capacity to be 8 tons when the suction conditions are 0.2 MPa and -20°C and condensing temperature is 50°C. The refrigerant leaves the condenser as saturated liquid. Calculate the actual volumetric efficiency and the brake work of the compressor if the compressor efficiency is 65%. By using the R-32 chart provided. Please help me! answering this problem.
A refrigerant 22 vapor compression system includes a liquid-to-suction heat exchanger in the system. The heat exchanger cools the saturated liquid from the condenser from 32°C to 21°C with vapor which comes from the evaporator at -10°C. The compressor is capable of pumping 20 L/sec of refrigerant. What is the enthalpy of the refrigerant at the suction of the compressor neglecting the heat exchanger? What is the isenthalpic value of the refrigerant in the system neglecting the heat exchanger? What is the refrigerant's enthalpy after compression? What is the COP of the system neglecting the heat exchanger? What is the enthalpy of the refrigerant before it enters in the expansion valve? What is the approximate enthalpy of the refrigerant at the suction of the compressor? What is the estimated enthalpy of the refrigerant after compression? What is the COP of the system? What is the refrigerating capacity of the system in TOR if: a.) without hex and b.) with hex?
3. A vapour compression refrigeration system of 2400 kJ/min capacity works at an evaporator temperature of 263 K and a condenser temperature of 303 K. The refrigerant used is R-12 and is subcooled by 6°C before entering the expansion valve and vapour is superheated by 7°C before leaving the evaporator coil. The compression of refrigerant is reversible adiabatic. The refrigeration compressor is two-cylinder, single acting with stroke equal to 1.25 times the bore and runs at 1000 r.p.m. Determine: 1. Refrigerating effect per kg ; 2. Mass of refrigerant circulated per minute ; 3. Theoretical piston displacement per minute; 4. Power required to run the com pressor; 5. Heat removed in through condenser; and 6. Bore and stroke of the compressor.
13. A food storage locker requires a refrigeration system of 2500 kJ/min capacity at an evaporator temperature of – 10°C and a condenser temperature of 30°C. The refrigerant used is Freon-12 and sub-cooled by 5°C before entering the expansion valve and vapour is superheated by 6°C before leaving the evaporator coil. The compression of refrigerant is reversible adiabatic. The refrigeration compressor is two-cylinder single- acting with stroke equal to 1.3 times the bore and operates at 975 r.p.m. Determine (using thermodynamic tables of properties for Freon-12): (i) Refrigerating effect per kg. (ii) Mass of refrigerant to be circulated per minute. (iii) Theoretical piston displacement per minute. (iv) Theoretical power required to run the compressor, in kW. (v) Heat removed through the condenser per minute. (vi) Theoretical bore and stroke of compressor. Properties of Freon-12 Saturation Absolute Enthalpy Entropy Specific volume of temp. pressure Liquid kJ/kg Vapour kJ/kg °C vapour…
Aa 3. A vapour compression refrigeration system of 2400 kJ/min capacity works at an evaporator temperature of 263 K and a condenser temperature of 303 K. The refrigerant used is R-12 and is subcooled by 6°C before entering the expansion valve and vapour is superheated by 7°C before leaving the evaporator coil. The compression of refrigerant is reversible adiabatic. The refrigeration compressor is two-cylinder, single acting with stroke equal to 1.25 times the bore and runs at 1000 r.p.m. Determine: 1. Refrigerating effect per kg ; 2. Mass of refrigerant circulated per minute; 3. Theoretical piston displacement per minute ; 4. Power required to run the com pressor; 5. Heat removed in through condenser ; and 6. Bore and stroke of the compressor. I want the solution on a piece of paper and using the diagram الأصدقاء المقربون
Q2: A simple R134a vapor compression system operates between 40°C condensing temperature and-10°C evaporating temperature. The system compressor has a piston displacement of 3 m'/min and volumetric efficiency of 75%. The temperature of vapor leaving the compressor is 60°C. The liquid refrigerant is subcooled by 10°C before entering to the expansion device. Calculate: a. Refrigerant mass flow rate. b. Refrigeration capacity. c. Indicated power. d. The COP.
A refrigeration system using refrigerant 12 is to have a refrigerating capacity of 80 kW. The cycle is a standard vapor-compression cycle in which the evaporating temperature is -15°C and the condensing temperature 30°C. Determine the volume flow of refrigerant measured in liters per second at the inlet to the compressor.