Refrigerant-134a enters the compressor of a refrigerator as superheated vapour at 0.20 MPa and 25°C at a rate of 0.07 kg/s, and it leaves at 1.2 MPa and 100°C. The refrigerant is cooled in the condenser to 44°C and 1.2 MPa, and it is throttled to 0.20 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, 2.1 Calculate the rate of heat removal from the refrigerated space and the power input to the compressor, 2.2 Calculate the isentropic efficiency of the compressor, and 2.3 Calculate the Coefficient of Performance of the refrigerator

Refrigerant-134a enters the compressor of a refrigerator as superheated vapour at 0.20 MPa and 25°C at a rate of 0.07 kg/s, and it leaves at 1.2 MPa and 100°C. The refrigerant is cooled in the condenser to 44°C and 1.2 MPa, and it is throttled to 0.20 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, 2.1 Calculate the rate of heat removal from the refrigerated space and the power input to the compressor, 2.2 Calculate the isentropic efficiency of the compressor, and 2.3 Calculate the Coefficient of Performance of the refrigerator

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 12RQ: Refrigerators currently being manufactured in the United States are using______as their refrigerant.

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Refrigerators currently being manufactured in the United States are using______as their refrigerant.
Welded ______sealed compressors are normally used in household refrigerators.
Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and -10oC at rate of 0.05 kg/sec and leave at 0.8 MPa and 50oC. The refrigerant is cooled in the condenser to 26oC and 0.72MPa and is throttled to 0.15MPa. Determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, (b) the isentropic efficiency of the compressor and (c) the coefficient of performance.
Refrigerant R-134a to the compressor of a refrigeration machine It enters at 140 kPa pressure and -10 °C, and exits at 1 MPa pressure. Volumetric flow of the refrigerant entering the compressor It is 0.23 m³/minute. The refrigerant enters the throttling valve at a pressure of 0.95 MPa and at 30 °C, and exits the evaporator as saturated steam at -18 °C. Adiabatic efficiency of the compressor It is 78%. Show the cycle in the T-s diagram. And; a) Calculate the power required to run the compressor. b) Calculate the heat absorbed per unit time from the cooled medium. ( COPSM=? ) c) Calculate, between the evaporator and the compressor, how much the pressure of the refrigerant drops and how much the heat gain.
Refrigerant R-134a enters the compressor of a refrigeration machine at 140 kPa pressure and -10°C temperature and exits at 1 MPa pressure. The volumetric flow of the refrigerant entering the compressor is 0.23 m3/minute. The refrigerant enters the throttling valve at 0.95 MPa pressure and 30°C, exiting the evaporator as saturated steam at -18°C. The adiabatic efficiency of the compressor is 78%. Show the cycle in the T-s diagram. a) Calculate the power required to start the compressor. b) Calculate the heat taken in a unit time from the cooled environment. COP=? c) Calculate between the evaporator and the compressor, how much the pressure of the refrigerant drops, and how much is the heat gain.
The refrigerant R-134a enters the compressor of a refrigeration machine at a pressure of 140kPa and a temperature of -10°C, and exits at a pressure of 1MPa. The volumetric flow rate of the refrigerant entering the compressor is 0.23m3/minute. The refrigerant enters the throttling valve at 0.95MPa pressure and 30 °C, and exits the evaporator as saturated steam at -18 °C. The adiabatic efficiency of the compressor is 78%. Show the cycle in the T-s diagram. a) The power required to operate the compressor, b) Calculate the heat withdrawn from the cooled environment in unit time, COPsm=? c) Calculate how much the pressure of the refrigerant drops between the evaporator and the compressor and how much the heat gain is
A commercial refrigerator using R-134a as a refrigerant is used to keep the cooled environment at -35 C. The refrigerator releases the waste heat to the cooling water that enters the condenser at 18 C at 0.25 kg / s and leaves the condenser at 26 C. The refrigerant enters the condenser at a pressure of 1.2 MPa and a temperature of 50 ° C, and leaves the condenser at the same pressure, supercooled at 5 ° C. Since the compressor consumes 3.3 kW of power, a) Mass flow rate of the refrigerant, b) Cooling load and COP value c) Calculate the minimum power consumed by the compressor for the same cooling load.
Refrigerant-134a is condensed in a refrigeration system by rejecting heat to ambient air at 25°C. R-134a enters the condenser at 700 kPa and 50°C at a rate of 0.05 kg/s and leaves at the same pressure as a saturated liquid. Determine the COP of this refrigeration cycle if the cooling load at these conditions is 6 kW.
A refrigerator using fluid-134a as a work fluid is used to keep the cooling medium at -25 oC. The refrigerator releases the waste heat, which enters the condenser at 18 oC with a flow of 0.30 kg / s and from the condenser at 26 oC to the cooling water. The refrigerant enters the condensate at a pressure of 1.2 MPa and 50 oC, and leaves the condenser at 40 oC at the same pressure. Find a) the mass flow rate of the refrigerant, b) the power consumed by the compressor, c) the COP value, and d) the minimum power that the compressor will consume for the same cooling load.They watch the specific heat of water as ?? = 4.22 ?? / ???.
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