Refrigerant-134a enters the compressor of a refrigerator at 140kPa and - 10 degrees celsius at a rate of 0.3 m^3/min and leaves at 1 MPa. The isentropic efficiency of the compressor is 78%. The refrigerant enters the throttling valve at 0.95 MPa and 30 degrees celsius and leaves the evaporator as saturated vapour at -18.5 degrees celsius. DETERMINE the coefficient of performance..

Refrigerant-134a enters the compressor of a refrigerator at 140kPa and - 10 degrees celsius at a rate of 0.3 m^3/min and leaves at 1 MPa. The isentropic efficiency of the compressor is 78%. The refrigerant enters the throttling valve at 0.95 MPa and 30 degrees celsius and leaves the evaporator as saturated vapour at -18.5 degrees celsius. DETERMINE the coefficient of performance..

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 20RQ: Welded ______sealed compressors are normally used in household refrigerators.

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Welded ______sealed compressors are normally used in household refrigerators.
4. The refrigerant 134-a enters the compressor of a refrigeration machine as superheated vapor at a flow rate of 0.12 kg/s, a pressure of 0.14 MPa, and a temperature of -10 °C. It exits at a pressure of 0.7 MPa and a temperature of 50 °C. The refrigerant exits the condenser at a temperature of 24 °C and a pressure of 0.65 MPa and is then throttled to a pressure of 0.15 MPa. Show the cycle on a T-s diagram, including the saturated liquid and saturated vapor lines. Also, a) Calculate the heat extracted from the environment per unit time and the power required to operate the compressor, b) The isentropic efficiency of the compressor, c) The coefficient of performance of the refrigeration machine. Note: This is a question from the thermodynamics course. Please provide a clear and prompt solution.
An ammonia refrigeration compressor takes its suction from the evaporator at a temperature of -20oF (-28.9oC) and a quality of 95%. The compressor discharges at a pressure of 100 psi (689.5 kPa), liquid ammonia leaves condenser at 50oF (10oC). Properties of Ammonia: At 689.6 kPa (Tsat = 13.3oC) h = 1,568 kJ/kg; s = 5.7676 kJ/kg.K At 10oC: hf = 246.531 kJ/kg At -28.9oC by interpolation hf = 68.5 kJ/kg; hg = 1424.5 kJ/kg sf = 0.49366; sg = 6.0452Find the COP. a. 4 b. 4.25 c. 5 d. 5.25
An ammonia refrigeration compressor takes its suction from the evaporator at a temperature of -20oF (-28.9oC) and a quality of 95%. The compressor discharges at a pressure of 100 psi (689.5 kPa), liquid ammonia leaves condenser at 50oF (10oC). Properties of Ammonia: At 689.6 kPa (Tsat = 13.3oC)      h = 1,568 kJ/kg; s = 5.7676 kJ/kg.K At 10oC:      hf = 246.531 kJ/kg At -28.9oC by interpolation      hf = 68.5 kJ/kg; hg = 1424.5 kJ/kg             sf = 0.49366; sg = 6.0452Find the heat rejected by the evaporator in kJ/kg. a. 1,356.5 b. 1,568.5 c. 1,321.5 d. 1,125.5
An ammonia refrigeration compressor takes its suction from the evaporator at a temperature of -20oF (-28.9oC) and a quality of 95%. The compressor discharges at a pressure of 100 psi (689.5 kPa), liquid ammonia leaves condenser at 50oF (10oC). Properties of Ammonia: At 689.6 kPa (Tsat = 13.3oC)      h = 1,568 kJ/kg; s = 5.7676 kJ/kg.K At 10oC:      hf = 246.531 kJ/kg At -28.9oC by interpolation      hf = 68.5 kJ/kg; hg = 1424.5 kJ/kg             sf = 0.49366; sg = 6.0452Find the horsepower per ton of refrigeration. a. 1.044 b. 0.987 c. 1.404 d. 0.897
An ammonia refrigeration compressor takes its suction from the evaporator at a temperature of -20oF (-28.9oC) and a quality of 95%. The compressor discharges at a pressure of 100 psi (689.5 kPa), liquid ammonia leaves condenser at 50oF (10oC). Properties of Ammonia: At 689.6 kPa (Tsat = 13.3oC)      h = 1,568 kJ/kg; s = 5.7676 kJ/kg.K At 10oC:      hf = 246.531 kJ/kg At -28.9oC by interpolation      hf = 68.5 kJ/kg; hg = 1424.5 kJ/kg sf = 0.49366; sg = 6.0452Find the heat absorbed by the evaporator in kJ/kg.
An ammonia refrigeration compressor takes its suction from the evaporator at a temperature of -20oF (-28.9oC) and a quality of 95%. The compressor discharges at a pressure of 100 psi (689.5 kPa), liquid ammonia leaves condenser at 50oF (10oC). Properties of Ammonia: At 689.6 kPa (Tsat = 13.3oC) h = 1,568 kJ/kg; s = 5.7676 kJ/kg.K At 10oC: hf = 246.531 kJ/kg At -28.9oC by interpolation hf = 68.5 kJ/kg; hg = 1424.5 kJ/kg sf = 0.49366; sg = 6.0452 Determine the quality of refrigerant upon entering to the evaporator.
A three-stage compressor receives 500 lps of air at 101 kPaa and 27degrees Celcius, anddischarges at 750 kPaa. Determine a) the power required; b) the pressure at eachintercooler; c) the maximum temperature; and d) the heat transferred in each intercooler. e) What is the discharge temperature of a single-stage compressor operating at the sameintake and discharge temperatures?
1. Refrigerant 134-a enters a compressor at 180kPa as a saturated vapor with a flow rate of 0.4m³/min and leaves at 700kPa. The power supplied to the refrigerant during the compression process is 2.5kW. What is the temperature of the refrigerant at the exit of the compressor?
A vapor compression refrigeration cycle undergoes wet compression and maintains the temperatureof the refrigerated space to -25C. The system uses R-12 refrigerant and undergoes isentropicexpansion to the inlet of the evaporator. The compressor discharges the refrigerant at saturatedvapor state at a condensing pressure of 1367 kPa. Determine:a) Determine the enthalpy of all statesb) Determine the quality of refrigerant entering the evaporatorc) Determine the quality of refrigerant leaving the evaporatord) Refrigerant effecte) Work of compressionf) COP If a liquid to suction heat exchanger was installed to prevent wet compression such that it allows 6Csub cooling of refrigerant and superheating to 8C. The expansion of refrigerant is no moreisentropic but isenthalpic. Therefore, determine:g) Enthalpy at different section of the cycleh) COP of the system compared to COP of standard vapor compression cycle.
THERMODYNAMICS A condenser (cooler) takes 0.05 kg/s of R-134a at 200 kPa and 80 degrees Celsius and cools it to 10 degrees Celsius. Assume the exit properties are the same as those of a saturated liquid with the same T. What cooling capacity (kW) does the condenser need to have?
In a refrigerator the pressure in the evaporator us 2.72 kg/cm sq. and the refrigerant entry is 0.12 dry while at the exit 0.91 dry. During the compression, the work done per kg is 17,033 kg-m/kg. Calculate the COP. The rate of refrigerant circulation is 5.64 kg/min. The given latent heat and specific volume at 2.72 kg/cm sq are 320 kcal/kg ang 0.436 cu m/kg.