Water-cooled chiller is a kind of vapor compression refrigerator. It works by energizing the refrigerant vapor via the compressor so that the pressure and temperature increase. Then it is turned to liquid refrigerant of low pressure and temperature by condensing and throttling. When the water chiller is evaporated in the evaporator, it obtains heat from the surrounding (cooling medium, such as cool water) to decrease the temperature of thecarrier so that artificial refrigeration is realized. Therefore, vapor compression refrigeration cycle includes the four necessary processes of compression, condensation, reducing expenditure and evaporation.
The principles are detailed as below:
Compression: After the refrigerant vapor in the evaporator is inhaled by the compressor, the electromotor increases its energy via the rotor of the compressor so that the pressure of refrigerant vapor is increased and it then it enters the condenser. At the same time, the temperature of refrigerant vapor will increase correspondingly after compression.
Condensation: The high-pressure and high-temperature refrigerant vapor from compressor will release heat in the condenser via the cooling water in the pipe. Meanwhile it will be condensed into liquid under the saturation pressure (the corresponding condensation pressure for condensation temperature). In that case, the temperature of cooling water will increase. The temperature of cooling water is directly related to the condensation temperature (condensation pressure).
Reducing expenditure: When the high-pressure and high-temperature liquid refrigerant from the bottom of condenser flows through the throttle device, its pressure will decrease and it will bulge, with both pressure and temperature decreasing. Then the low-pressure and low-temperature liquid enters the evaporator. We need to know what causes high pressure of chiller.
Evaporation: The low-pressure and low-temperature liquid refrigerant turns to gas by deriving energy from the cooling carrier (e.g. cool water). At the same time, the temperature of cooling carrier decreases and the artificial refrigeration is realized. The refrigerant vapor in the evaporator is then inhaled by the compressor for compression. The processes of compression, condensation, reducing expenditure and evaporation will repeat circularly to realize the refrigeration. The cooling capacity is in direct proportion to the suction volume. Therefore, the guiding valve is installed in the compressor for suction volume control of the compressor and evaporating capacity control of the refrigerant, so that the cooling capacity is adjustable in certain range.
