A two-stage compression refrigeration system with an adiabatic liquid-vapor separation unit like that in the figure uses refrigerant-134a as the working fluid. The system operates the evaporator at 100 psia the condenser at 300 psia, and the separator at 200 psia. The compressors use 29 kW of power. Determine the rate of cooling provided by the evaporator and the COP of this cycle. The refrigerant is a saturated liquid at the inlet of each expansion valve and a saturated vapor at the inlet of each compressor, and the compressors are isentropic. (Take the required values from saturated refrigerant-134a tables.) Compressor Compressor m6 m₂ Condenser Separator Evaporator The rate of cooling provided by the evaporator is ↓ Btu/h, and the COP of the refrigerator is

A two-stage compression refrigeration system with an adiabatic liquid-vapor separation unit like that in the figure uses refrigerant-134a as the working fluid. The system operates the evaporator at 100 psia the condenser at 300 psia, and the separator at 200 psia. The compressors use 29 kW of power. Determine the rate of cooling provided by the evaporator and the COP of this cycle. The refrigerant is a saturated liquid at the inlet of each expansion valve and a saturated vapor at the inlet of each compressor, and the compressors are isentropic. (Take the required values from saturated refrigerant-134a tables.) Compressor Compressor m6 m₂ Condenser Separator Evaporator The rate of cooling provided by the evaporator is ↓ Btu/h, and the COP of the refrigerator is

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

Chapter22: Condensers

Section: Chapter Questions

Problem 7RQ: When a standard-efficiency air-cooled condenser is used, the condensing refrigerant will normally be...

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When a standard-efficiency air-cooled condenser is used, the condensing refrigerant will normally be higher in temperature than the entering air temperature.
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A food storage locker requires a refrigeration system of 2,400 kJ/min capacity at an evaporator temperature of -10OC and a condenser temperature of 30OC. The refrigerant used is freon-12 and sub-cooled by 6OC before entering the expansion valve and vapor is superheated by 7OC before leaving the evaporator coil. The compression of refrigerant is isentropic. The refrigeration compressor is two-cylinder, single-acting with stroke equal to 1.25 times the bore diameter and operates at 1000 rpm. Determine: (a) refrigerating effect, (b) mass of refrigerant to be circulated, (c) theoretical piston displacement per minute, (d) theoretical power to run the compressor in kW, (e) heat removed from the condenser per min. (f) theoretical bore and stroke of compressor.
: In a conventional refrigeration cycle which uses Freon-12 as the refrigerant, the temperatureof the evaporating fluid is -20°C. It leaves the evaporator as saturated vapor at -20°C and enters thecompressor. The pressure in the condenser is 1.30 MPa. The liquid leaves the condenser and enters theexpansion valve at 40°C. It is proposed to modify this cycle by adding a heat exchanger that would superheatthe suction vapor to 25°C Compare the coefficient of performance of these two cycles What is the temperature of the refrigerant entering the expansion valve with the heatexchanger? For a load of 50 kW, determine the volume flow rate for both cycles. inlcude PH diagram and TS diagram, show complete solution
A vapor compression refrigeration cycle uses refrigerant-134a as its working fluid. The condenser pressure is 800 kPa and the evaporator temperature is -20 C. The compressor has an isentropic efficiency of 80 percent. The mass flow rate is 1.7489 kg/s. In the question that follows, select the answer that is closest to the true value. What is the heat going to the evaporator in units of kW?
The required refrigeration capacity of a vapour compression refrigeration system (with R-22 as refrigerant) is 100 kW at –30 C evaporator temperature. Initially the system was single-stage with a single compressor compressing the refrigerant vapour from evaporator to a condenser operating at 1500 kPa pressure. Later the system was modified to a two-stage system operating on the cycle shown below.At the intermediate pressure of 600 kPa there is intercooling but no removal of flash gas. Find: a) Power requirement of the original single-stage system; b) Total power requirement of the two compressors in the revised two-stage system.Assume that the state of refrigerant at the exit of evaporator, condenser and intercooler is saturated, and the compression processes are isentropic.
The required refrigeration capacity of a vapor compression refrigeration system (with R-22 as refrigerant) is 100 kW at –30oC evaporator temperature. Initially the system was single-stage with a single compressor compressing the refrigerant vapor from evaporator to a condenser operating at 1500 kPa pressure. Later the system was modified to a two- stage system operating on the cycle shown below. At the intermediate pressure of 600 kPa there is intercooling but no removal of flash gas. Find: a) Power requirement of the original single-stage system; b) Total power requirement of the two compressors in the revised two-stage system.
Figure below shows a two-stage vapor-compression refrigeration system with ammoniaas the working fluid. The system uses a direct-contact heat exchanger to achieve intercooling. Theevaporator has a refrigerating capacity of 30 tons and produces −20°F saturated vapor at its exit.In the first compressor stage, the refrigerant is compressed adiabatically to 80 lbf/ in 2 , which is thepressure in the direct contact heat exchanger. Saturated vapor at 80 lbf/ in 2 enters the secondcompressor stage and is compressed adiabatically to 250 lbf/ in 2 . Each compressor stage has anisentropic efficiency of 85%. There are no significant pressure drops as the refrigerant passesthrough the heat exchangers. Saturated liquid enters each expansion valve. Determinea) the ratio of mass flow rates, ?̇ 3 /?̇ 1b) the power input to each compressor stage, in horsepower.c) the coefficient of performance.
Use ashrae for refregerant In a conventional refrigeration cycle which uses Freon12 as the refrigerant, the temperature of the evaporating fluid is -20°C. It leaves the evaporator as saturated vapor at -20°C and enters the compressor. The pressure in the condenser is 1.30 MPa. The liquid leaves the condenser and enters the expansion valve at 40"C. It is proposed to modify this cycle by adding a heat exchanger that would superheat the suction vapor to 25°C. Compare the coefficient of performance of these two cycles. What is the temperature of the refrigerant entering the expansion valve with the heat exchanger? For a load of 50kW, determine the vol ume flow rate for both cycles. Ans. 2.79, 2.80, 12°C, 0.0522m3/s, 0.0523 m3/s