A vapor-compression refrigerator operates as in the right figure using CO₂ as refrigerant. The evaporation is at -10 °C and the condensation is at 20 °C. The efficiency of the compressor is 0.7, and the refrigeration capacity is 1500 kJ/s. Using the P-H diagram below, (a) Estimate the power requirement, the heat transfer rate in the condenser, and the circulation rate of CO2. (b) Estimate the coefficient of performance. (c) Sketch the cycle in the P-H diagram (as accurate as possible). Pressure Entropy [kJ/kg.K] 1.0 20 MPa 18 MPa 15 MPa 13 MPa 10 MPa 9 MPa 8 MPa 7 MPa 6 MPa 5 MPa 4 MPa 3.5 MPa 3MPa 2.5 MPa 2MPa 150 -10°C 0°C P-h diagram for Carbon Dioxide Refrigerant [R744] 1.2 1.3 1.4 1.5 1.1 1.6 10 °C 200 20 °C 30 °C 40 °C سال اگر 1.7 1.8 100 C 120 C 50 °C 60°C 70°C 80 °C 90 °C 250 volume [m³/kg]. 10% 20% 30% 40% 50% 60% 70% 80% 90% 0.002: 300 0.003 0.004 350 Enthalpy (kJ/kg) 400 0.006 450 Throttle valve 4 -0.008 0.01 Condenser 500 1.9 2.0 140 C 160 C 180 C Evaporator Compressor 550 3 plot by izzi 2 2.1 600

A vapor-compression refrigerator operates as in the right figure using CO₂ as refrigerant. The evaporation is at -10 °C and the condensation is at 20 °C. The efficiency of the compressor is 0.7, and the refrigeration capacity is 1500 kJ/s. Using the P-H diagram below, (a) Estimate the power requirement, the heat transfer rate in the condenser, and the circulation rate of CO2. (b) Estimate the coefficient of performance. (c) Sketch the cycle in the P-H diagram (as accurate as possible). Pressure Entropy [kJ/kg.K] 1.0 20 MPa 18 MPa 15 MPa 13 MPa 10 MPa 9 MPa 8 MPa 7 MPa 6 MPa 5 MPa 4 MPa 3.5 MPa 3MPa 2.5 MPa 2MPa 150 -10°C 0°C P-h diagram for Carbon Dioxide Refrigerant [R744] 1.2 1.3 1.4 1.5 1.1 1.6 10 °C 200 20 °C 30 °C 40 °C سال اگر 1.7 1.8 100 C 120 C 50 °C 60°C 70°C 80 °C 90 °C 250 volume [m³/kg]. 10% 20% 30% 40% 50% 60% 70% 80% 90% 0.002: 300 0.003 0.004 350 Enthalpy (kJ/kg) 400 0.006 450 Throttle valve 4 -0.008 0.01 Condenser 500 1.9 2.0 140 C 160 C 180 C Evaporator Compressor 550 3 plot by izzi 2 2.1 600

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

Chapter47: High-pressure, Low-pressure, And Absorption Chilled-water Systems

Section: Chapter Questions

Problem 13RQ: The subcooling temperature in a condenser can be measured by taking the difference between the A....

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Two methods used to power refrigeration compressors on a ship are _____and ____.
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A plant using R134a refrigerant has a cooling capacity of 352 kW of refrigeration. It evaporates at 0 Cand condenses at 35 C, with the 5 of superheat at the evaporator outlet and 5 K of sub-cooling at the condenser outlet. Assuming isentropic compression and ignoring pressure drops in the piping, the evaporator and condenser, determi the following; a) The refrigeration effect b) The mass flow rate of refrigerant ) The compressor power d) The rate of heatrejection at the condenser e) The COP 0 The corresponding Carnot COP g) The percentage Carnot-efficiency
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A vapour absorption refrigeration system works with a generator temperature of 87⁰C, absorber temperature of 37⁰C and evaporator temperature of -13⁰C. (a) Obtain the COP of the system. (b) If the evaporator temperature falls to -18⁰C, what should be the generator temperature so that the system operates with the same COP?
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Problem 4.9. Estimate the maximum possible COP of a household air conditioner. use any reasonable values for the reservior temperatures
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