In a conventional refrigeration cycle which uses Freon- 12 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 volume flow rate for both cycles. Ans. 2.79, 2.80, 12°C, 0.0522m³/s, 0.0523 m³/s

In a conventional refrigeration cycle which uses Freon- 12 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 volume flow rate for both cycles. Ans. 2.79, 2.80, 12°C, 0.0522m³/s, 0.0523 m³/s

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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: 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
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Consider a two-stage compression refrigeration system operating between the pressure limits of 1.2 MPa and 0.16 MPa. The working fluid is refrigerant-134a. The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.7 MPa. Part of the refrigerant evaporates and the remainder is mixed with the refrigerant leaving the low-pressure compressor. The mixture is then compressed to the condenser pressure by the high-pressure compressor. The liquid in the flash chamber is throttled to the evaporator pressure, and it cools the refrigerated space as It vaporizes in the evaporator. Assume that the refrigerant leaves the evaporator as saturated vapor and both compressors are isentropic. a) Draw the 'T-S' Diagram and state the assumptions b) Determine the fraction of the refrigerant that evaporates as it is throttled to the flash chamber (x_e).
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