Analysis and optimization of injection characteristics and comprehensive performance of low GWP refrigerant HP-1 in high temperature heat pump systems

In the context of low-GWP refrigerants becoming a research hotspot, the environmentally friendly refrigerant HP1 with independent intellectual property rights in China has demonstrated significant advantages in fields such as data centers and 5G base stations. However, there are few applied studies in the field of high-temperature heat pumps (HTHPs), therefore, in this study, HP-1 was utilized in HTHP system and this process was combined with the injection technology. It has been proven to be an effective approach for performance improvement. The injection characteristics of HP-1-based HTHP were analyzed and optimized with a focus on safety, stability, and efficient operation. The application advantages of HP-1 were compared and analyzed in terms of thermodynamic performance and Total Equivalent Warming Impact. The results indicated that there were three types of characteristic injection pressures based on system performance, corresponding to the maximum coefficient of performance (COP), the lowest electronic expansion valve inlet refrigerant temperature, and the lowest exhaust temperature of the compressor. Further, the corresponding control equations for injection pressure were obtained. Based on the safety injection pressure, the optimal COP under injection pressure could effectively improve the COP of the system by 2.1-5.2 %, and the exhaust temperature also increased by 6.1-10.1 %. When the temperature of the heat source was 50 degrees C and the target heating temperature was 120 degrees C, the heating capacity of HP-1 increased by 10.8 % compared with that of R245fa, the COP of the system increased by 2.7 %, and the volume heating capacity increased by 10.3 %. Moreover, the emission reduction effect of HP-1 was significant, and the carbon dioxide emissions were reduced by 15.4-39.1 %. The analysis shows that HP-1 exhibits better performance and environmental characteristics than HFC-245fa. This study is of guiding significance to improve the thermodynamic performance of HTHP, for the safe and efficient operation and energy saving and emission reduction in the industrial field.