In a refrigeration system, what might cause a significant drop in compressor discharge temperature alongside high suction line pressure?

The scenario described involves a significant drop in compressor discharge temperature while experiencing high suction line pressure, which can be closely associated with the functioning of the expansion valve. When the expansion valve is open too wide, it allows an overabundance of refrigerant to flow into the evaporator. This excess refrigerant results in a lower temperature in the compressor discharge because the compressor is working harder but not receiving the expected heat load.

In a refrigeration system, the role of the expansion valve is to regulate the amount of refrigerant entering the evaporator, where it absorbs heat and transforms from a liquid to a vapor. If the valve stays too open, it can lead to subcooling of refrigerant in the evaporator, which means that the refrigerant does not absorb enough heat, thereby allowing the discharge temperature to drop significantly. Simultaneously, due to the high flow of refrigerant and the associated dynamics, the suction line pressure can remain high, since there’s an abundance of refrigerant returning to the compressor.

Understanding the components and their interactions in a refrigeration cycle is crucial for diagnosing the causes of specific temperature and pressure characteristics within the system. This knowledge helps in identifying how operational problems within these components can lead to abnormal functioning of the system.