Q14) An air-conditioner with refrigerant-134a as the working fluid is used to keep a room at 26°C by rejecting the waste heat to the outdoor air at 34°C. The room gains heat through the walls and the windows at a rate of 250 kJ/min while the heat generated by the computer, TV, and lights amounts to 900 W. The refrigerant enters the compressor at 500 kPa as a saturated vapor at a rate of 100 L/min and leaves at 1200 kPa and 50°C. Determine (a) the actual COP,(b) the maximum COP, and (c) the minimum volume flow rate of the refrigerant at the compressor inlet for the same compressor inlet and exit conditions.

Q14) An air-conditioner with refrigerant-134a as the working fluid is used to keep a room at 26°C by rejecting the waste heat to the outdoor air at 34°C. The room gains heat through the walls and the windows at a rate of 250 kJ/min while the heat generated by the computer, TV, and lights amounts to 900 W. The refrigerant enters the compressor at 500 kPa as a saturated vapor at a rate of 100 L/min and leaves at 1200 kPa and 50°C. Determine (a) the actual COP,(b) the maximum COP, and (c) the minimum volume flow rate of the refrigerant at the compressor inlet for the same compressor inlet and exit conditions.

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

Chapter28: Special Refrigeration Applications

Section: Chapter Questions

Problem 15RQ: Why is two-stage compression popular for extra-low-temperature refrigeration systems?

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A refrigeration system with R134a as the working fluid is used to maintain a space at 25°C by absorbing heat from water entering the evaporator at 50°C with atmospheric pressure at a rate of 0.065kg/s and exiting at 40°C. The compression has an isentropic efficiency of 75%. The refrigerant exits the evaporator at 20°C with 0.5542 MPa, while the condenser outlet temperature is 3.8°C.Determine the heat exchange in the evaporator.
: Refrigerant 134a enters a compressor of a vapour compression of a refrigeration cycle at 120Kpa as a saturated vapour and leaves at 900 Kpa and 75oc. The refrigerant leaves the condenser as a saturated liquid. The rate of cooling provided by the system is 18000 Btu/hr. Determine (1) Mass flow rate of R134a (2) The Cop of the cycle (3) Also determine the Cop of the cycle if the expansion valve is replaced by an isentropic turbine. Do you recommend such a replacement for the refrigeration system? (4) Determine the Cop if the evaporator pressure is 160Kpa and otheer values remains the same. (5) Determine the Cop if the condenser pressure is 800 Kpa and other values remain the same.
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A refrigeration system with R134a as the working fluid is used to maintain a space at 25°C by absorbing heat from water entering the evaporator at 50°C with atmospheric pressure at a rate of 0.065kg/s and exiting at 40°C. The compression has an isentropic efficiency of 75%. The refrigerant exits the evaporator at 20°C with 0.5542 MPa, while the condenser outlet temperature is 3.8°C. The heat exchange in the evaporator is 2.717 kW that was the result I obtained, so how do I analyze the effect of the isentropic compression efficiency on the process? I need help please, I am stuck on this homework.
A refrigeration system with R134a as the working fluid is used to maintain a space at 25°C by absorbing heat from water entering the evaporator at 50°C with atmospheric pressure at a rate of 0.065kg/s and exiting at 40°C. The compression has an isentropic efficiency of 75%. The refrigerant exits the evaporator at 20°C with 0.5542 MPa, while the condenser outlet temperature is 3.8°C. The heat exchange in the evaporator is 2.717 kW that was the result I obtained, so what would be the result of the isentropic efficiency of compression on the process? I need help please, I am stuck on this homework.
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