When the unit is refrigerating, the compressor sucks the low-temperature and low-pressure refrigerant in the evaporator into the cylinder, and after the compressor does work, the refrigerant vapor is compressed into high-temperature and high-pressure gas, which
enters the condenser through the exhaust pipe. The high-temperature and high-pressure refrigerant gas exchanges heat with cooling water in the condenser, transferring heat to the cooling water and taking it away, while the refrigerant gas condenses into high-pressure liquid. The high-pressure liquid from the condenser enters the evaporator after being throttled and depressurized by the thermal expansion valve. In the evaporator, the low-pressure liquid refrigerant absorbs the heat of the frozen water and vaporizes, so that the frozen water is cooled down and becomes the required low-temperature water. The vaporized refrigerant gas is sucked in by the compressor again for compression, and then discharged into the condenser, so that it circulates repeatedly, thus realizing the cooling of frozen water.
The chilled water from the unit enters the terminal devices such as fan coil units and variable air volume air conditioners, and exchanges heat with convective air indoors. During this process, the temperature of the water rises due to absorbing the heat of the indoor air (dissipating heat to the indoor air), while the temperature of the indoor air drops after passing through the indoor heat exchanger, driven by the fan, and is sent indoors, thus lowering the indoor air temperature, and the chilled water after the temperature rise re-enters the unit under the action of the water pump.