The working principle of a screw chiller unit is as follows: gaseous refrigerant exiting the evaporator undergoes adiabatic compression within the compressor, transforming into a high-temperature, high-pressure state. This compressed gaseous refrigerant then undergoes isobaric cooling and condensation within the condenser. Upon condensing into a liquid state, the refrigerant passes through an expansion valve, where it expands to a lower pressure, becoming a gas-liquid mixture. Within the evaporator, the liquid refrigerant-now at a low temperature and low pressure-absorbs heat from the substance being cooled, reverting once again to a gaseous state. This gaseous refrigerant then flows back through the piping into the compressor, thereby initiating a new refrigeration cycle.
Low-temperature screw chillers are specifically optimized to meet low-temperature requirements. They utilize specialized low-temperature screw compressors designed to intake low-temperature, low-pressure refrigerant. These low-temperature units employ refrigerants with low boiling points-such as R23 (boiling point: -82°C) or R507A (boiling point: -46.7°C). The evaporator features a highly efficient shell-and-tube or spiral-plate structure; the low-temperature refrigerant flows through the interior of the tubes, while the secondary coolant (or heat-carrying medium) circulates on the exterior. As the refrigerant absorbs heat from the secondary coolant, it evaporates, effectively cooling the secondary coolant down to the desired low temperature.
