01 September 2013

R744 two-stage compressor for commercial heat pump water heater


The use of heat pump water heaters is becoming more widespread in response to energy conservation requirements.
However, one of the weaknesses of heat pump systems is the drop of heating capacity under low ambient
temperature conditions. This is why heat pump systems are not catching on in cold regions.
This paper describes the development of a high-efficiency compressor for commercial CO2 heat pump water heaters.
The new compressor is the world’s first to employ a two-stage compressor design, a combination of rotary
and scroll compressors that can overcome specific issues of CO2 refrigerant, such as a large pressure difference
and high operating pressure. It is the most suitable compression mechanism for the operating conditions of a heat
pump water heater.
By using this compressor, heating capacity and efficiency can be significantly improved in comparison with conventional
water heaters. These improvements have made it possible to introduce heat pump water heaters in cold
regions.