Developing a Two-Stage Rotary Compressor for CO_2 Heat Pump Systems with Refrigerant Injection

摘要

The reduction of greenhouse gas emissions has been the focus of global attention. As an alternative refrigerant to HFC, CO2 has been considered. As another promising possibility of energy conservation, use of heat pump systems has also been spreading. However, conventional heat pump systems have problems remaining, such as inadequate heating capacity or overheating of the compressor due to reduced performance under ambient low temperature condition. To solve these problems, we developed a two-stage rotary compressor for CO2 heat pump systems, examined the effects of the injection into an intermediate pressure connector under the condition of a high pressure-ratio and offered proof of its high efficiency. We also examined unique performance characteristics of the two-stage rotary compressor by its loss analysis. We clarified the merits of the two-stage rotary compressor's performance compared to those of a single-stage rotary compressor.