Integrated thermal management system (ITMS) technology for electric vehicles (EV) has become a major industry research direction. However, R290 refrigerants are still not applied on a large scale in EVs. Therefore, we developed a suitable thermal management system for R290 in this study. This architecture adapts an unusual indirect design, which can coordinate the heat between the air conditioner, battery pack, and electric motor. We focused on heat pump air conditioning systems for EV thermal management; thus, we carried out the performance analysis of R290 under the cooling and heating conditions of our ITMS through an experimental approach. The current study explores various aspects affecting the performance of heat-pump air conditioners: refrigerant charge, electronic expansion valve (EXV) opening, compressor speed, and performance between R290 and R134a under different external temperatures. We aim to improve cooling and heating efficiencies. Among these parameters, the EXV opening and compressor speed have the greatest impact on the performance of the ITMS, as evidenced by the optimal EXV opening and lower compressor speed to maximize the coefficient of performance (COP) and increase the heat transfer rate. In addition, this study has shown that, compared to an ITMS equipped with R134a, R290 has a smaller refrigerant charge, better heat transfer rate and COP under heating conditions, and similar performance under cooling conditions.

Electric vehicle (EV) thermal management systems (TMSs) face a critical challenge in adopting environmentally friendly refrigerants, essential for adaptability, thermal safety, driving range optimization, and passenger comfort across wide temperature ranges. This study investigates the use of R290, a low‐cost and environmentally friendly refrigerant, in a secondary‐loop‐based TMS. A system test bench was established to validate the system performance experimentally, and a comparison was made with the system using R134a. The experimental results show that the R290 charge amount is approximately 50% of that of R134a. Under low‐temperature heating condition (0°C), R290 demonstrates significant performance advantages, with heating capacity and coefficient of performance (COP) increasing by up to 67.6% and 36%, respectively, compared to R134a. At extremely low temperatures (−20°C), R290 achieves a COP of 1.24, further showcasing its superior heating performance. Under high‐temperature cooling conditions (35 and 43°C), R290 exhibits slightly lower cooling capacity compared to R134a; however, its performance remains sufficient to meet the operational requirements of a TMS. In summary, the proposed TMS using R290 as the refrigerant demonstrates excellent performance and promising potential for application in EVs across a wide range of operating conditions.