Q5Basic Mechanical Engineering

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Q.5 Define COP of refrigerator.

Answer 1

In reversed thermodynamic cycles (refrigerators and heat pumps), traditional efficiency is completely replaced by a strictly defined dimensionless index known as the Coefficient of Performance (COP). For a standard refrigerator, the primary desired physical output is the heat strictly extracted from the low-temperature refrigerated space ( $Q_{L}$ ).

COP_{R} = \frac{Desired Output}{Required Input} = \frac{Q _{L}}{W _{in}}

According to the rigid First Law of Thermodynamics, the external work input $W_{in}$ strictly equals the total heat rejected ( $Q_{H}$ ) minus the heat absorbed ( $Q_{L}$ ), yielding the expanded mathematical relation: $COP_{R} = \frac{Q _{L}}{Q _{H} - Q _{L}}$ .

Q5Basic Mechanical Engineering

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