Assessment of Ejector-Expansion Heat Pump Systems with Low GWP Refrigerants for Electric Vehicles

This study addresses the critical challenge of developing efficient thermal management systems for electric vehicles by proposing and evaluating two novel ejector-expansion heat pump configurations: single-evaporator (SEEHP) and dual-evaporator (DEEHP) systems. Through comprehensive thermodynamic analysis across six representative Chinese cities using four refrigerants (R134a, R32, R152a, R290), system performance via coefficient of performance (COP) and lifecycle CO2 emissions were assessed. The results demonstrate significant advantages over conventional (CBHP) and vapor injection (VIHP) systems, particularly in extreme cold conditions. The SEEHP configuration achieves 10–30% COP improvements versus CBHP, while DEEHP shows 7–15% enhancement. The corresponding lifecycle emission reductions reach 9–14% for SEEHP and 2–11% for DEEHP relative to conventional systems. Among the refrigerants, R290 systems achieve the lowest equivalent CO2 emissions due to superior COP in Beijing, Shanghai, Chongqing, Kunming and Guangzhou, whereas R32 systems yield minimal emissions owing to its exceptional heating capacity in Harbin. These findings highlight ejector technology’s potential for substantially improving electric vehicle energy efficiency while reducing environmental impact.