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 b) Determine the rate of heat removal from the refrigerated space and the power input to the compressor c) Determine the adiabatic efficiency of the compressor d) Determine the coefficient of performance of the refrigerator.

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 b) Determine the rate of heat removal from the refrigerated space and the power input to the compressor c) Determine the adiabatic efficiency of the compressor d) Determine the coefficient of performance of the refrigerator.

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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Condensers in these refrigerators are all_______cooled.
1. A refrigeration system operates on an ideal vapor compression using R-12 with an evaporator temperature of -30°C and condenser exit temperature of 49 30 °C and requires 74.6 kW motor to drive the compressor. What is the capacity of the refrigerator in tons of refrigeration? Enthalpy at condenser entrance = 382 kJ/kg, exit = 248.15 kJ/kg, at evaporator entrance 248.15 KJ/kg, exit = 338.14 kJ/kg.
SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS Example 2:- Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa 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. Disregarding any heat trans fer and pressure drops in the connecting lines between the components; determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, and (b) the coefficient of performance of the refrigerator. Solution: - P 0.14 MPa T=-10 C dut 246.36 kJ/kg OF P 0.8 MPa h2 = 286.69 kJ/kg P 0.72 MPa T= 26 C h3 = 87.83 kJ/kg h3 = h = 87.83 KJ/kg h4 = h3 (throttling) h4 87.83 kJ/kg 0.8 MPa 0.72 MPa/ 26 C 0.15 MPa 0.14 MPa -10°C SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS SAMARRA RING
SUBJECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS Example 2:- Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa 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. Disregarding any heat trans fer and pressure drops in the connecting lines between the components; determine (a) the rate of heat removal from the refrigerated space and the power input to the compressor, and (b) the coefficient of performance of the refrigerator. Solution: - P 0.14 MPa T=-10 C 212 h 246.36 kJ/kg da OF SAMARRA P 0.8 MPa VER h2 = 286.69 kJ/kg O P 0.72 MPa T= 26 C hg = 87.83 kJ/kg h3 =h = 87.83 KJ/kg h4 = h3 (throttling) h4 87.83 kJ/kg 0.8 MPa 50°C 0.72 MPa/ 26 C 0.15 MPa 0.14 MPa -10°C SUBIECT: THERMODYNAMIC COURSE: II ASSI.LACTURE: NATIQ ABBAS RING
Q2: A simple R134a vapor compression system operates between 40°C condensing temperature and-10°C evaporating temperature. The system compressor has a piston displacement of 3 m'/min and volumetric efficiency of 75%. The temperature of vapor leaving the compressor is 60°C. The liquid refrigerant is subcooled by 10°C before entering to the expansion device. Calculate: a. Refrigerant mass flow rate. b. Refrigeration capacity. c. Indicated power. d. The COP.
An ammonia refrigeration compressor takes its suction from the evaporator, at a temperature of-200F and a quality of 95%. The compressor discharges at a pressure of 100 psi, liquid ammonia leaves the condenser at 500F.(a)Determine the heat absorbed by the evaporator in kJ/kg. (b)Determine the heat rejected to the condenser in kJ/kg. (c)Determine the COP. (d)Determine the horsepower per ton of refrigeration. (e)Determine the quality of refrigerant upon entering to the evaporator
3.23: An ideal refrigeration cycle operates with R134a as the working fluid. The temperature of refrigerant in the condenser and evaporator are 40°c and -20°c respectively. The mass flow rate of refrigerant is 0.1 kg/s. Determine the cooling capacity and cop of the plant. Take enthalpy of refrigerant vapour at the end of compression as 276 kJ/kg. 40°C 2 -20°C/ 3 40°C -20°C h
THERMODYNAMICS - Heat Exchanger UPLOAD COMPLETE SOLUTION. Consider a water-cooled condenser in a large refrigeration system in which R-134a is the refrigerant fluid. The refrigerant enters the condenser at 1.0 MPa and 60◦C, at the rate of 0.2 kg/s, and exits as a saturated liquid at 0.95 MPa. Cooling water enters the condenser at 10◦C and exits at 20◦C. Compute for the rate of heat transfer and the rate at which cooling water flows through the condenser.
A system consists of one compressor and two evaporators. One evaporator carries a load of 35kw at 10°c and the other load of 20kw at -5°c. A back pressure value reduces the pressure in the10°c to that of the -5°c evaporator. The condensing temperature is 37°c. The refrigerant is ammonia. A. Determine the enthalpy of the refrigerant leaving the condenser. B. The massflow rate at the low-pressure evaporator. C. The mass flow rate at the high-pressure evaporator.
The large insulated flash chamber of a vacuum refrigeration plant is kept at low temperatureby a steam jet which pumps vapor to a condenser . The condensate pump removes thecondensate formed and an air ejector discharges air from the condenser to an air vent .Warm water returns enters the flash chamber at 13 deg C ; chilled water leaves the flashchamber at 4 deg C . The vapor leaving the flash chamber has a dryness factor of 97% andthe condenser inside temperature is 32 deg C . For 100 tons of refrigeration , determine thequantity in cubic meter per minute of chilled water at 4 deg C that the system can provide .A) 0.45 B) 0.56 C) 9.33 D) 0.75
Refrigerant ammonia enters the compressor of a refrigerator as superheated vapor at 0.14 MPa, -20°C at a rate of 0.04 kg/s, and leaves at 0.8 MPa, 50°C. The refrigerant is cooled in the condenser to 0.75 MPa and is throttled to 0.14 MPa. Disregarding any heat transfer and pressure drops in the connecting lines between the components, determine the rate of heat removal from the refrigerated space. kW
(a) In a refrigerating plant using R12 the vapour leaves the evaporator dry saturated at 1.826 bar and is compressed to 7.449 bar. The temperature of the vapour leaving the compressor is 45°C. The liquid leaves the condenser at 25°C and is throttled to the evaporator pressure. Calculate: (i) the refrigeratig effect; (ii) the specific work input; (iii) the COPref. (b) Compare the results found in (a) with a plant using R134a between the same saturation temperatures, with the same maximum cycle temperature and the same degree of undercooling of the condensate. (121.27 kJ/kg; 29.66 kJ/kg; 4.09; 152.05 kJ/kg; 43.65 kJ/kg; 3.48)