Chapter 15, Problem 13Q

To determine

To Explain: The coefficient of performance (COPs) are defined differently for heat pumps and air conditioners.

Answer to Problem 13Q

Solution:

The coefficients of performance (COPs) are defined differently for heat pumps and air conditioners because both the machines have different purposes of operation.

Explanation of Solution

Fora heat pump, the coefficient of performance (COPs) is defined as the ratio of heat transfer to the work required to be done for heat transfer as $k=\frac{Q_H}{W}$ .The main task of the heat pump is to heat the house so, here the heat transfer is $Q_H$ .

For refrigerator, the coefficient of performance (COPs) is defined as the ratio of heat transfer to the work required to be done for heat transfer as $k=\frac{Q_L}{W}$ . The main task of the refrigerator is to cool means removing the heat so, here the heat transfer is $Q_L$ .

Conclusion:

Due to the different interests of two different machines, the coefficient of performance (COPs) are defined differently for heat pumps and air conditioners.