Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, a)Show the cycle on a T-S diagram

Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, a)Show the cycle on a T-S diagram

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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Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, Determine the adiabatic efficiency of the compressor
Refrigerant-134a at a rate of 0.08 kg/s enters the compressor of a refrigerator as superheated vapor at 0.18 MPa and 0 ℃ and leaves at 0.9 MPa and 80 ℃. The refrigerant is cooled in the condenser to 31.3 ℃ and 0.8 MPa and it is throttled to 0.18 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, Determine the coefficient of performance of the refrigerator.
A heat pump using refrigerant-134a heats a house by using underground water at 8°C as the heat source. The house is losing heat at a rate of 60,000 kJ/h. The refrigerant enters the compressor at 280 kPa and 0°C, and it leaves at 1 MPa and 60°C. The refrigerant exits the condenser at 30°C. Investigate the effect of varying the compressor isentropic efficiency over the range [60 to 100 percent]. Plot the power input to the compressor and the electric power saved by using a heat pump rather than electric resistance heating as functions of compressor efficiency and discuss the results.
Refrigerant-134a enters the compressor of a refrigerator at 0.14MPa and -10°C at a rate of 0.05 kg/s and leaves at 0.8 MPa and 50°C. The refrigerant is cooled in the condenser to 26°C and 0.72 MPa and is throttled to 0.15 MPa. 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 of the refrigerator. Answers: (a) 7.93 kW, 2.02 kW, (b) 0.939, (c) 3.93
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.
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at 10°C by rejecting waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 2.3 kW of power, determine the COP?
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at –35°C by rejecting waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 3.3 kW of power, determine the mass flow rate of the refrigerant,
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at –35°C by rejecting waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 3.3 kW of power, determine the refrigeration load.
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at –35°C by rejecting waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 3.3 kW of power, determine the minimum power input to the compressor for the same refrigeration load.
Air enters the compressor of a regenerative gas-turbine engine at 310 K and 100 kPa, where it is compressed to 900 kPa and 650 K. The regenerator has an effectiveness of 80 percent, and the air enters the turbine at 1400 K. For a turbine efficiency of 90 percent, determine (a) the amount of heat transfer in the regenerator and (b) the thermal efficiency. Assume variable specific heats for air.
Consider the following ideal cascade refrigeration system with pressures of 0.9, 0.4, and 0.12 MPa.If the lower cycle transfers 69kW of energy to the upper cycle, determine the mass flowrate of R-134A (in kg/s) in the upper cycle. a.0.3987 b.0.4114 c.0.3600 d.0.4480
A commercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°C by rejecting waste heat to cooling water that enters the condenser at 18°C at a rate of 0.25 kg/s and leaves at 26°C. The refrigerant enters the condenser at 1.2 MPa and 50°C and leaves at the same pressure subcooled by 5°C. If the compressor consumes 3.3 kW of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the COP, and (d) the minimum power input to the compressor for the same refrigeration load.