Water-cooled screw units are highly efficient refrigeration equipment with screw compressors at their core, and are widely used in central air conditioning systems and industrial refrigeration fields. Its working principle is based on the vapor compression refrigeration cycle, achieving heat transfer through four core processes (compression, condensation, throttling, and evaporation). The following is a detailed analysis:
Core working principle: Vapor compression refrigeration cycle
Water-cooled screw units achieve heat transfer through the phase change of the refrigerant (liquid to gas conversion), and the specific process is as follows:
Compression process: The low-temperature and low-pressure refrigerant gas is drawn into the cylinder of the screw compressor from the evaporator. The compressor compresses the gas into high-temperature and high-pressure refrigerant gas through the mechanical work of the screw rotor, and the temperature rises significantly at the same time.
Condensation process: High-temperature and high-pressure gas enters the condenser (shell and tube heat exchanger) and exchanges heat with the cooling water. Heat is transferred from the refrigerant to the cooling water. The gas condenses into high-pressure liquid, and the cooling water, after being heated, returns to the cooling tower to dissipate heat.
Throttling process: High-pressure liquid passes through a thermal expansion valve to throttle and reduce pressure, turning into low-pressure and low-temperature liquid. At the same time, part of the liquid vaporizes to form a gas-liquid mixture.
Evaporation process: Low-pressure and low-temperature liquid enters the evaporator (shell and tube heat exchanger), absorbs the heat of the chilled water and vaporizes, cooling the chilled water to the set temperature (such as 7-12℃). The vaporized refrigerant gas is re-drawn into the compressor, completing the cycle.
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