Replacing conventional boilers with an efficient heat pump system is an effective solution to achieving “carbon peaking and carbon neutrality”. In this study

a CO2 heat pump system adopting an ejector to realize dual-temperature evaporation is proposed for cascade utilization of waste heat and high-efficiency heating. Thermodynamic models of the baseline CO2 system (Base)

conventional CO2 ejector system (Ej-Evap1)

and CO2 ejector system with dual-temperature evaporation (Ej-Evap2) are developed based on the pinch method. The maximum coefficient of performance (COP) is achieved at the optimum discharge pressure for the dual-temperature evaporation system. Under the optimum working conditions

the results show that the maximum COP of the Ej-Evap2 system under nominal conditions is 4.84

which is 9.88% higher than that of the base. Double-temperature evaporation can significantly reduce the heat transfer irreversibility loss in the heat absorption process. The irreversible performance index of Ej-Evap2 during the evaporator process is 1.51

which is 24.50% lower than that of the base and Ej-Evap1 systems.