关键词: CO2热泵, 跨临界, 采暖, 能效, 经济

Abstract: In order to improve the performance of CO2 transcritical heat pump heating system, a two-stage compression, two gas cooler and vapor injection regenerative system is proposed. Through the establishment of the thermodynamic model, the impact of various factors on the energy efficiency of the system is analyzed combined with the other three CO2 heat pump systems and R134a single-stage compression regenerative system. In addition, by constructing an economic evaluation model that comprehensively considers the initial investment cost and annual operating cost, combined with typical annual meteorological parameters, the total investment situation of each system in different cities during the operating cycle is studied. The results show that the two-stage compression, two gas cooler and vapor injection regenerative system is the optimal system scheme, which has the highest COPh and exceed R134a single-stage compression regenerative system. When the ambient temperature is 0℃ and the temperature of outlet/return water is 65/40 ℃, the theoretical COPh can reach 2.58, which is 9.1% higher than that of R134a system, and 22.5% higher than that of CO2 single-stage compression system, and the compressor discharge temperature doesn’t exceed the existing temperature limit. In the selected sample cities, the total investment cost of all heat pump systems during the operating cycle is the lowest in Shanghai and the highest in Shenyang, which shows that it is greatly affected by the climate region. Due to the high cost of the CO2 compressor, the total investment cost of CO2 heat pump system is higher than that of R134a system. With the improvement of CO2 heat pump technology and the expansion of production scale, when the cost of the compressor is reduced by 80%, the total investment cost of two-stage compression, two gas cooler and vapor injection regenerative system will be lower than that of R134a system.

Key words: CO2 heat pump, transcritical, heating, energy efficiency, economy