What type of refrigerant state is usually desired before it enters the compressor?

The desired state of a refrigerant before it enters the compressor is superheated vapor. This state is preferred because it enhances the efficiency and capacity of the refrigeration cycle. In the superheated state, the refrigerant has absorbed enough heat beyond its boiling point, which ensures that it remains in the vapor phase without the risk of containing any liquid refrigerant. If liquid refrigerant were allowed into the compressor, it could cause damage due to liquid slugging, leading to mechanical failure.

Moreover, starting with superheated vapor allows for more effective compression, as the vapor can be compressed to a higher pressure and temperature, improving the overall efficiency of the cooling process. This is particularly important in systems designed for higher cooling loads or under varying operating conditions, where maintaining a completely vapor state ensures consistent performance and reliability of the system.