DEVELOPMENT OF TWO-PHASE FLOW EXPANDER FOR CO2 HEAT PUMPS AND AIR-CONDITIONERS
We developed a two-phase flow expander for CO2 heat pumps and air-conditioners to improve the performance of transcritical cycle. We selected the swing type as an evaluation result of the existing pump and compressor types from the viewpoints of performance, reliability with two-phase flow, applicable volume, and productivity when applied to expanders. The test results of the newly designed prototype of a two-stage swing expander showed high efficiency in energy recovery. According to the evaluation made by calculation when mounted on a heat pump, the expander gives substantial reduction in heating energy consumption when compared with traditional combustion type heaters.