What does "subcooling" refer to in refrigeration?

Subcooling refers to the process of cooling the refrigerant below its condensation temperature. In refrigeration systems, once the refrigerant has condensed into a liquid, it can still be at a temperature above the saturation point. By further cooling this liquid refrigerant below this point, subcooling increases the refrigerant's efficiency as it moves through the system. This process ensures that the refrigerant remains in liquid form when it enters the expansion device, which is critical for optimal performance. Subcooling also helps prevent the vaporization of refrigerant in the liquid line and enhances the system's overall capacity and efficiency.

The other options refer to processes contrary to the principles of refrigeration: heating the refrigerant would raise its temperature rather than decrease it; adding heat to the refrigerant implies moving it away from condensation; and charging the system refers to the addition of refrigerant to the system, which is a different concept entirely from subcooling.