Low GWP, Water refrigerant, R718, Condensing ejector, Continuous cooling turbo compressor
Turbo chiller using water as a refrigerant was developed. A refrigeration cycle using water (R718) as a refrigerant has a high theoretical efficiency, but the cycle pressure ratio is high, and the compressor discharge temperature is elevated. Although the conversion of the compressor to a multistage compressor and the addition of an intercooler between each stage are known to lower the discharge temperature and improve performance, the resulting increased size is problematic. To resolve this issue, this study develops a refrigeration cycle that lowers discharge temperature during the compression process without enlarging the device. Using a continuous cooling compressor that compresses refrigerant vapor while continuously cooling it in process and a condensing ejector that condenses the vapor while compressing it, we experimentally verify the performance of each element. Based on the results, we verify the basic principles of a continuous cooling compressor for continuously cooling compressed vapor with refrigerant droplets sprayed by nozzles installed on the impeller. In addition, the condensing ejector uses a high-speed fine refrigerant droplets to transfer momentum to the refrigerant vapor. And thus raises its pressure within a two-phase state and simultaneously condensing refrigerant vapor.