Copeland EVI Scroll compressors are equipped with a vapour injection connection for Economizer Operation.Economizing can be accomplished by utilising a subcooling circuit similar to the circuit shown in Figure 1. This increases the refrigeration capacity and the system efficiency. The benefits provided will increase as the compression ratio increases.
The schematic shows a systemconfiguration for the economizer cycle. A heat exchanger is used to provide additional subcooling to the refrigerant before it enters the evaporator. This subcooling 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 provides additional cooling at higher compression ratios.
The P-h diagram (Figure 2)shows the theoretical gain in system performance acquired by using the economizer cycle. The extension outside of the vapour dome provides the enthalpy increase, enhancing system performance. Although power increases due to the vapour injection into the compressor, there is still a significant efficiency gain because the capacity gain exceeds the power increase.