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ME 426 Tutorial 1

The document outlines a tutorial for ME 426 on refrigeration and air conditioning, focusing on the analysis of refrigeration cycles using refrigerant-134a. It includes three problems that require determining the coefficient of performance, heat absorbed, network input, heat removal rates, power inputs, and isentropic efficiency. Each problem is accompanied by specific answers for quick reference.

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almajidmohamed3
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28 views1 page

ME 426 Tutorial 1

The document outlines a tutorial for ME 426 on refrigeration and air conditioning, focusing on the analysis of refrigeration cycles using refrigerant-134a. It includes three problems that require determining the coefficient of performance, heat absorbed, network input, heat removal rates, power inputs, and isentropic efficiency. Each problem is accompanied by specific answers for quick reference.

Uploaded by

almajidmohamed3
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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ME 426: Refrigeration and Air Conditioning

Tutorial 1
1. A steady-flow Carnot refrigeration cycle uses refrigerant-134a as the working fluid. The
refrigerant changes from saturated vapor to saturated liquid at 30°C in the condenser as it rejects
heat. The evaporator pressure is 160 kPa. Show the cycle on a T-s diagram relative to saturation
lines and determine:
(a) the coefficient of performance,
(b) the amount of heat absorbed from the refrigerated space, and
(c) the network input.
Answers: (a) 5.64, (b) 147 kJ/kg, (c) 26.1 kJ/kg

2. A refrigerator uses refrigerant-134a as the working fluid and operates on an ideal vapor-
compression refrigeration cycle between 0.12 and 0.7 MPa. The mass flow rate of the
refrigerant is 0.05 kg/s. Show the cycle on a T-s diagram with respect to saturation lines.
Determine:
(a) the rate of heat removal from the refrigerated space and the power input to the compressor,
(b) the rate of heat rejection to the environment, and
(c) the coefficient of performance.
Answers: (a) 7.41 kW,1.83 kW, (b) 9.23 kW, (c) 4.06

3. Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 MPa and
-10°C at a rate of 0.12 kg/s, and it leaves at 0.7 MPa and 50°C. The refrigerant is cooled in the
condenser to 24°C and 0.65 MPa, and it is throttled to 0.15 MPa. Disregarding any heat transfer
and pressure drops in the connecting lines between the components, show the cycle on a T-s
diagram with respect to saturation lines, and 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 COP of the refrigerator.
Answers:(a) 19.4 kW, 5.06 kW, (b) 82.5 percent, (c) 3.83

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