Energetic and driving range investigation of the ejector enhanced CO₂ thermal management system used in electric vehicles

With the rapid development of electric vehicles, CO₂ as a natural refrigerant, can solve the problem of decreasing driving range in winter, and has great application prospects in thermal management systems. However, since the CO₂ operates as a transcritical cycle, the cooling performance is insufficient. In this paper, the ejector was simulated using a non-equilibrium model and a 1-D ejector model was developed. The transcritical CO₂ ejector thermal management system model was developed. The performance of the ejector system in the cabin cooling mode versus the conventional EXV (Electronic Expansion Valve) system at different ambient temperatures was simulated. The results show that there is a maximum 15.22 % improvement in COP (coefficient of performance) at 45 °C. Subsequently, the driving range and energy flow of electric vehicles at different ambient temperatures were simulated, which shows that the ejector system is increasingly effective in driving range improvement as the ambient temperature increases, bringing 19.6 km, 5.28 % improvement at 45 °C. And as the ambient temperature rises, the proportion of thermal management system energy consumption rises gradually, accounting for 45.4 % at 45 °C. The results provide theoretical support and data basis for the electric vehicle driving range extension technology and the application of CO₂ ejector in the thermal management system of electric vehicles.