Economizer for ZF CPL Compressors

CPL compressors ZF series high-powered machines are sold together with a number of matching equipment, which of course does not mean that you can not buy a single machine. These supporting equipment contains the economizer, which is often referred to as the plate heat exchanger. What is the working principle of the economizer? Let's learn about it.

Economizer is a heat exchanger, through the refrigerant itself throttling evaporation to absorb heat so that another part of the refrigerant to get subcooled. In the evaporating temperature is relatively low (-25 ℃ or below), the economizer cycle, can improve the efficiency of the compressor compression refrigeration cycle, improve the cooling capacity, reduce the compressor exhaust temperature.

Economizer for fluorine is a dry heat exchanger, part of Freon liquid is throttled and evaporated in the tube and then enters the compressor make-up gas port, and the other part of Freon liquid is subcooled outside the tube.

The heat exchanger leads the refrigerant from the liquid pipeline and expands to the intermediate injection pressure through the expansion valve to exchange heat with the liquid with residual heat refrigerant in the form of counterflow, and the liquid leaving the condenser gets subcooled. The superheated vapor exits the heat exchanger and is then injected into the economizer port where it mixes with the slightly compressed suction gas from the evaporator before being further compressed.

Shell and tube, casing and plate heat exchangers can be used. The cooling capacity of the subcooler can be derived from the difference between the cooling capacity with and without the economizer. The temperature of the subcooled liquid must be at least 10 K higher than the intermediate pressure saturation temperature.

The refrigerant subcooler is suitably installed under the compressor to prevent oil or liquid backflow from the compressor from surging into the compressor during shutdown. In unstable operating conditions or when shutting down the subcooling circuit, the compressor will squeeze some oil out of the economizer injection port, so the liquid injection line should be bent into a curved section.