The air-cooled screw cold water heat pump unit is a central air-conditioning unit that uses air as the cooling medium (summer) and heat source (winter), water as the refrigerant, and adopts a vapor compression refrigeration cycle. The unit has the characteristics of both heating and cooling. It can form a centralized or semi-centralized central air-conditioning system together with fan coil units, air conditioning boxes, and air handlers. It has the characteristics of flexible layout and various control methods.

During refrigeration: the compressor continuously extracts the refrigerant vapor from the evaporator, and after compression by the compressor, the refrigerant changes from low temperature and low pressure vapor to high temperature and high pressure vapor. The high-temperature and high-pressure refrigerant vapor is condensed in the air cooled condenser, and a large amount of heat is released and absorbed by the air. The high-pressure liquid refrigerant condensed by the air cooled condenser is throttled and depressurized by the thermal expansion valve, and turned into a low-pressure refrigerant liquid. The low-pressure refrigerant evaporates in the evaporator and absorbs a lot of heat from the refrigerant water, thereby reducing the temperature of the refrigerant water and achieving the purpose of refrigeration. The low pressure refrigerant vapor is extracted by the compressor, thus forming a refrigeration cycle.