Copeland EVI Scrollcompressors are equipped with a vapour injection connection for EconomizerOperation.Economizing can be accomplished by utilising a subcooling circuitsimilar to the circuit shown in Figure 1. This increases the refrigerationcapacity and the system efficiency. The benefits provided will increase as thecompression ratio increases.
The schematic shows a systemconfiguration for the economizer cycle. A heat exchanger is used to provideadditional subcooling to the refrigerant before it enters the evaporator. Thissubcooling process provides the increased capacity gain measured in the system.During the subcooling process, a certain amount of refrigerant is evaporated.This evaporated refrigerant is injected into the compressor and providesadditional cooling at higher compression ratios.
The P-h diagram (Figure 2)shows the theoretical gain in system performance acquired by using theeconomizer cycle. The extension outside of the vapour dome provides theenthalpy increase, enhancing system performance. Although power increases dueto the vapour injection into the compressor, there is still a significantefficiency gain because the capacity gain exceeds the power increase.