Research on Performance of Transcritical CO2 Heat Pump System with Distributed Compression
CO2 heat pump system is one of advancing low-carbon heating technologies, of which performance optimization is helpful to enlarging its application, and the distributed compression system with stepped compression processes can effectively improve the energy efficiency ratio of transcritical CO2 heat pump systems. This paper employs distributed compression cycle theory to construct a model of a transcritical CO2 heat pump system. Through numerical simulation, the effects of key thermodynamic parameters—such as cycle temperatures and pressures—on system performance are analyzed. An exhaustive search method is applied to derive correlations between the optimal intermediate pressure and the system's key thermodynamic parameters. The results indicate that the optimal intermediate pressure in the distributed compression cycle is related to the evaporation temperature, final discharge pressure, and gas cooler outlet temperature. The fitted multivariate correlation achieves a coefficient of determination (R²) of 0.8899. Furthermore, the system performance surpasses that of single-stage transcritical CO2 systems (including those with internal heat exchanger or ejector) and some two-stage systems. This study validates the feasibility of the distributed compression technology and provides theoretical support for the design of high-efficiency transcritical CO2 heat pump systems.