Explanation:

To understand why superheating in the refrigeration cycle decreases the coefficient of performance (COP), we first need to understand what superheating means in the context of refrigeration.

Superheating refers to the process of heating a vapor above its saturation temperature without changing its pressure. In the refrigeration cycle, superheating occurs after the refrigerant leaves the evaporator and enters the compressor. During this process, the refrigerant vapor is heated to a temperature higher than its saturation temperature.

Now let's see why superheating decreases the COP of the refrigeration cycle:

1. Understanding COP:
COP is a measure of the efficiency of a refrigeration system and is defined as the ratio of the desired cooling effect (refrigeration capacity) to the work input required to achieve that cooling effect. Mathematically, COP = refrigeration capacity / work input.

2. Effect of superheating on refrigeration capacity:
When the refrigerant vapor is superheated, its temperature increases. This means that the refrigerant can absorb less heat during the condensation process in the condenser. As a result, the refrigeration capacity decreases.

3. Effect of superheating on work input:
The work input required by the compressor is directly related to the enthalpy difference between the compressor inlet and outlet. Superheating increases the enthalpy of the refrigerant vapor, which in turn increases the work input required by the compressor.

4. Overall effect on COP:
Since superheating decreases the refrigeration capacity and increases the work input, the COP of the refrigeration cycle decreases. This means that the system becomes less efficient in providing cooling for a given amount of work input.

In conclusion, superheating in the refrigeration cycle decreases the COP because it reduces the refrigeration capacity and increases the work input required by the compressor.