Screw-compressor chillers due to its key parts screw screw chillers, unit consists of the evaporator refrigerant gas; after by adiabatic compression of compressor, into a State of high temperature and high pressure. Compressed refrigerant gases, in the condenser, isobaric cooling, condensation after condensing into a liquid refrigerant, then through the throttle valve expansion to low-voltage, gas-liquid mixture. Under low temperature and low pressure liquid refrigerant in the evaporator to absorb heat by cold material, back into a gaseous refrigerant. Gaseous refrigerant piping into the compressor again, starting a new cycle. This is the process of refrigeration cycle of four, is the main working principle of screw chillers.