Liquid-Suction Line Heat Exchangers

Systems that work with capillary tube and expansion valves permit refrigerant migrate in the evaporator during the off cycle. Aldiough suction piping shall be designed and installed so as to reduce the possibility of ingress of liquid refrigerant in the compressor, liquid pressure heat exchanger can be installed in diese systems as an additional security measure against damage of the compressor. Liquid-suction line heat exchanger usually takes die in the form of a cylinder, that is about twice the diameter of the suction line, wrapped the smaller diameter of the liquid line of the pipeline.

Liquid slugs can be a result of the refrigerant migration during the off cycle, overfeeding by the expansion valve during start-up or abrupt changes in the evaporator load. Liquid-intake heat exchanger is designed to intercept any of the liquid flowing through the suction line and evaporate. Energy used in the process of evaporation comes from the warm refrigerant in the liquid line. Heat exchange process also subcools the refrigerant in the liquid line. As the transfer of heat from the suction line heat exchanger subcools liquid refrigerant, improves the cooling capacity of the system as it protects the compressor from a bullet of the liquid refrigerant.

If the system is designed to work with pump down defrost cycle, liquid-suction line heat exchanger is not needed, because the refrigerant is removed from the low side of the system before the compressor cycles off. In these systems, the solenoid valve on the liquid line is installed ahead of tne metering device. This stops the flow of the refrigerant, when the surface temperature is satisfied. Compressor cycles off., as the refrigerant has been removed with the low side of the system and stored in the receiver. This strategy also prevents the migration of liquid if the expansion valve does not close tightly...