30 May 2005
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.