The degree of super heat is the difference between the refrigerants evaporating temperature and the temperature of the vapor at the __________ inlet.

The degree of superheat is a critical concept in refrigeration systems, as it measures how much the vapor temperature exceeds its saturation temperature at a given pressure. In this context, the correct choice pertains to the compressor inlet.

When refrigerant vapor exits the evaporator, it is at its evaporating temperature. Superheating occurs when this vapor is heated beyond this temperature before it enters the compressor. The purpose of this superheating is to ensure that only vapor enters the compressor, which prevents potential damage that could occur if liquid refrigerant were to enter it.

By measuring the difference between the refrigerant's evaporating temperature and the temperature of the vapor at the compressor inlet, one can accurately determine the degree of superheat in the system. This is essential for efficient system operation, as it helps optimize performance and prevent compressor failure.

In contrast, the other options refer to different components within the refrigeration cycle. The expansion device controls the flow of refrigerant and lowers its pressure, while the evaporator is where heat exchange occurs and the refrigerant evaporates. The condenser is responsible for rejecting heat and changing the refrigerant back into a liquid state. Therefore, these do not relate directly to the measurement of superheat as it applies to the compressor inlet