What is the purpose of having refrigerant slightly superheated in the suction line?

The purpose of having refrigerant slightly superheated in the suction line is primarily to ensure that liquid refrigerant does not enter the compressor. When the refrigerant is superheated, it is entirely in a gaseous state as it approaches the compressor. This is crucial because compressors are designed to handle vapor, and the presence of liquid refrigerant can cause hydraulic lock, leading to compressor damage or failure. Superheating helps maintain the integrity and proper functioning of the compressor by ensuring that it only processes refrigerant vapor, allowing for efficient operation and longevity of the system.

While efficiency, high pressure, and cooling are important aspects of a refrigeration system, they are not directly related to the superheating of the refrigerant in the suction line in the same way that avoiding liquid refrigerant is. Therefore, ensuring that only vapor enters the compressor is the primary benefit of this practice.