Abstract
From the object to prevent global warming, natural refrigerant, especially CO_2 is considered as an alternative refrigerant to HFC. Moreover, heat pump technology advanced as energy conservation is spreading promoted. We have developed a two-stage rotary compressor for two-stage compression cycle with injecting refrigerant of intermediate pressure. We have proved its high efficiency and the effects of the injection on the condition of high pressure ratio equivalent of ambient low temperature. We have analyzed it in detail and clarified the merit and weak point in comparision with a single rotary compressor.
