22 May 2008

DEVELOPMENT OF MULTI-FUNCTION CO2 HEAT PUMP WATER HEATER


We have succeeded in the development of a hot water supply system with a highefficiency
heat pump using a natural refrigerant (CO2), and also succeeded in its massproduction
for the first time in the world in 2001.After the first product launch, we have
developed a multi-function type, which can be used as a floor-heater and bathroom-heater in
addition to the hot water supply. During development, there was a difficulty that the efficiency
decreased due to the temperature rise of water returned from the heater. However, we have
solved this problem with our ejector cycle technology and the technology of the cascade heat
process, which makes it possible to use the hot water in the storage tank for hot water supply
or heater selectively. Then, we commercialised this multi-function type in 2003.In this paper,
we are reporting the “multi-function CO2 heat pump water heater” characterized by the
ejector cycle technology and the technology of the cascade heat process.