The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.6 MPa in a two-stage cascade refrigeration system operating between the pressure limits of 1.6 MPa and 240 kPa with refrigerant-134a as the working fluid. Part of the refrigerant evaporates during this flashing process, and this vapor 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 cools the refrigerated space as it vaporizes in the evaporator. The mass flow rate of the refrigerant through the low-pressure compressor is 0.25 kg/s. Assuming the refrigerant leaves the evaporator as a saturated vapor and the isentropic efficiency is 90 percent for both compressors. i) determine the mass flow rate of the refrigerant through the high-pressure compressor, ii) calculate the rate of heat removal from the refrigerated space, iii) find the COP of this refrigerator, and iv) Develop a refrigerator operated on a single-stage cycle between the same pressure limits with the same compressor efficiency and the same flow rate as in part (a).

The refrigerant leaves the condenser as a saturated liquid and is throttled to a flash chamber operating at 0.6 MPa in a two-stage cascade refrigeration system operating between the pressure limits of 1.6 MPa and 240 kPa with refrigerant-134a as the working fluid. Part of the refrigerant evaporates during this flashing process, and this vapor 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 cools the refrigerated space as it vaporizes in the evaporator. The mass flow rate of the refrigerant through the low-pressure compressor is 0.25 kg/s. Assuming the refrigerant leaves the evaporator as a saturated vapor and the isentropic efficiency is 90 percent for both compressors. i) determine the mass flow rate of the refrigerant through the high-pressure compressor, ii) calculate the rate of heat removal from the refrigerated space, iii) find the COP of this refrigerator, and iv) Develop a refrigerator operated on a single-stage cycle between the same pressure limits with the same compressor efficiency and the same flow rate as in part (a).

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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