06 November 2008

CO2 HEAT PUMP HEATING AND WATER HEATER SYSTEMS FOR COLD AREAS


By incorporating a first-stage expansion intermediate-cooling cycle (gas
injection) into a CO2 natural refrigerant heat pump, we have managed to achieve a significant
improvement in heating capacity and energy consumption efficiency under low ambient
temperature conditions. By combining this technology with previously developed technologies
for CO2 heat pump application, including heater-less ice formation prevention technology,
“direct heating” technology that provides direct heat exchange between the CO2 refrigerant
and heating antifreeze, and outlet hot water temperature transition control technology, we
have developed a prototype CO2 natural refrigerant heat pump heating and water heater
system, which enables both heating and hot water to be delivered by a single system. This
report describes the results obtained from performance evaluation tests conducted in our
environmental test laboratory and from monitoring tests in a cold region (Hokkaido, Japan),
and addresses the possibilities of this system for use in a heat pump system application.