A commercial refrigeration system with refrigerant R-134a as working fluid is used to keep the refrigerated space at -25 °C by rejecting waste heat to cooling water that enters the condenser at 15 °C as saturated liquid, as shown in Figure Q3, leaves at 30 °C as saturated liquid as well and flow rate is 1080 kg/h. The refrigerant enters the compressor at 500 kPa and leaves at 1.4 MPa and 68 °C. The pressure drop inside the condenser is 86 % and the density is 200 kg/m³. Determine : (i) refrigerant mass flow rate, (ii) compressor power input, (iii) the refrigerant load, (iv) coefficient of performance (COP), and (v) COP Carnot refrigerant system and compressor power input at minimum temperature

A commercial refrigeration system with refrigerant R-134a as working fluid is used to keep the refrigerated space at -25 °C by rejecting waste heat to cooling water that enters the condenser at 15 °C as saturated liquid, as shown in Figure Q3, leaves at 30 °C as saturated liquid as well and flow rate is 1080 kg/h. The refrigerant enters the compressor at 500 kPa and leaves at 1.4 MPa and 68 °C. The pressure drop inside the condenser is 86 % and the density is 200 kg/m³. Determine : (i) refrigerant mass flow rate, (ii) compressor power input, (iii) the refrigerant load, (iv) coefficient of performance (COP), and (v) COP Carnot refrigerant system and compressor power input at minimum temperature

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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Q1.2 Consider a two-stage compression refrigeration system operating between the pressure limits of 0.8and0.14 MPa(see Fig. Q 2). The working fluid isrefrigerant -134a. The refrigerant leaves thecondenser as a saturated liquid and is throttled to aflash chamberoperating at0.4 MPa. Part ofthe refrigerant evaporates during this flashing process, and this vapour is mixed with the refrigerantleaving the low-pressure compressor. The mixture is then compressed to the condenser pressure bythe high-pressure compressor. The liquid in the flash chamber is throttled to the evaporator pressure,and it cools the refrigerated space as it vaporizes in the evaporator. Assuming the refrigerant leavesthe evaporator as saturated vapor and both compressors are isentropic, determine(a) the coefficient of performance (COP).Re-draw the schematic diagram and sketch the cycle accurately on a T-s diagram with the propertyvalues labelled at all state points.
A refrigeration system with a capacity of 15 tons of refrigeration, operates at 150 kPa in the evaporator, while in the condenser it is 1000 kPa. If the R-134a refrigerant is in a saturated state, calculate the theoretical power required to operate the compressor. Compressor Power = Answer kW
A vapor-compression refrigeration machine uses refrigerant-134a as much as 2 kg/min with operating conditions leaving the evaporator at a temperature of -14°C and a condenser pressure of 0.8 Mpa. Determine the COP value and cooling load of the machine.
A two-evaporatoor compression refrigeration system like that in the Figure below uses refrigerant-134a as the working fluid. The system operates evaporator 1 at 30 psia, evaporator 2 at 10 psia, and the condeser at 180 psia. The cooling load for evaporator 1 is 9000 Btu/h and that for evaporator 2 is 24,000 Btu/h. Determine the power required to operate the compressor and the COP of this system. The regrigerant is saturated liquid at the exit of the condenser and saturated vapor at the exit of each evaporator, and the compressor is isentropic.
S3
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