What is the function and principle of an economizer in a propane refrigeration system?

The basic principle of the economizer system is to direct the gas at intermediate pressure generated by the primary throttling process into the compression chamber of the corresponding part of the compressor, while simultaneously recooling the refrigerant coming out of the condenser within the economizer. This approach serves to increase the cooling capacity and improve the coefficient of performance of the refrigeration system. The casing of a screw-type refrigeration compressor equipped with an economizer has a charge port. The liquid refrigerant coming out of the condenser enters the economizer after passing through a throttle valve, where it flashes into a gas at intermediate pressure. This gas then enters the compressor through the charge port, while simultaneously supercooling the liquid refrigerant in the economizer coils. Due to this supercooling, the cooling capacity per unit volume of the liquid refrigerant is higher than that of refrigerant that has not been supercooled. Since the charge port is located after the suction process in the screw teeth is complete, it does not affect the amount of refrigerant drawn in by the screw. Therefore, when the compressor compresses the same mass flow rate of refrigerant, its cooling capacity increases. However, since the increase in cooling capacity is greater than the increase in shaft power, the coefficient of performance improves. In refrigeration systems, screw refrigeration compressors equipped with economizers achieve higher coefficient of performance when operating under low-temperature conditions, compared to those without economizers.

There are two functions: first, to supply air to the compressor, based on a principle similar to that of a two-stage compressor. II. Subcool the refrigerant liquid supplied to the evaporator to increase the cooling capacity