Why must refrigerant be superheated before entering the compressor?

Superheating refrigerant before it enters the compressor is essential primarily to protect the compressor from potential damage. When refrigerant enters the compressor, it should be in a vapor state. If liquid refrigerant were to enter the compressor, it could lead to a condition known as "liquid slugging," where the compressor attempts to compress a liquid rather than a vapor. This can result in significant mechanical damage due to the incompressibility of the liquid and the stress it places on the compressor components.

By superheating the refrigerant, it ensures that the refrigerant is fully vaporized before it reaches the compressor, thus preventing liquid from entering and minimizing the risk of damage. This process can also improve the overall efficiency of the refrigeration cycle, but the primary concern is safeguarding the integrity of the compressor.