22 May 2008
Application of natural refrigerants in refrigeration and air conditioning has attracted considerable interest in the past decade because of environmental concerns attached with CFC, HCFC and HFCs. In the last ten years, small size compressors using CO2 as the working fluid have been developed for hot water supply systems in Japan. Over 1,000,000 transcritical CO2 heat pump hot water supply units have been installed in residential buildings in Japan. This paper reports on the development of a commercial transcritical CO2 compressor with a nominal power of 25kW and installation of a 60kW size water heat source CO2 heat pump in Europe, Switzerland. The unit was supplied to Zurich City Electric Power Company for heat energy supply to a football training center in Niederhasli. It was supplied in September, 2005 and has been running with no major problems. The paper also introduces a CO2 heat pump application using air as the heat source for producing hot water for a hostel in Japan. The heat pump system with a 30m3 water storage tank and 130kW heating capacity is fully automated to match with load changes.