A:- A commercial refrigerator with refrigerant-134a as shown in Fig. Q3A 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 refrigerante 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, and (c) the COP. 1:2 MPa 5°C subcooled Expansion valve Fig. Q3A Condenser Evaporator Water 18% 1.2 MP 50PC Compressor

A:- A commercial refrigerator with refrigerant-134a as shown in Fig. Q3A 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 refrigerante 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, and (c) the COP. 1:2 MPa 5°C subcooled Expansion valve Fig. Q3A Condenser Evaporator Water 18% 1.2 MP 50PC Compressor

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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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.
An ammonia ice plant operates between a condenser temperature of 35oC andevaporator of –15oC. It produces 10 metric tons of ice per day from water at 30oCto ice at –5oC. Assuming simple saturation cycle, determine the horsepower ofthe motor if the adiabatic efficiency of the compressor ηc = 0.80 and mechanicalefficiency ηm = 0.90. The specific heat of ice is 2.094 kJ/kg.oC and the latent heatis 335 kJ/kg. From the table for ammonia the following enthalpies are: condenserentrance = 1703 kJ/kg, exit = 366.1 kJ/kg; compressor entrance = 1443.9 kJ/kg,exit = 1703 kJ/kg A. 14.55 hp B. 24.55 hp C. 34.55 hp D. 44.55 hp
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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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 with a flow of 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 and supercooled at 5 ₒC. 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.
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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