Application of Vortex Tube for Expansion Device Replacement in R744 Integrated Thermal Management System for Electric Vehicle

The use of conventional fluorinated refrigerants, such as R134a and R1234yf, is being progressively restricted as regulations on persistent substances, including per- and polyfluoroalkyl substances (PFAS), become increasingly stringent. Accordingly, environmentally friendly refrigerants are receiving increasing attention. R744 (carbon dioxide, CO2) is considered a promising alternative for thermal management systems in electric vehicles (EVs) owing to its low global warming potential and favorable environmental characteristics. However, R744 operates under transcritical conditions, and high operating pressure and energy losses during expansion require improved thermal management technologies. The vortex tube has attracted attention as an alternative device because it can separate high-pressure refrigerant into hot and cold streams without moving parts, allowing pressure energy to be utilized as thermal energy. However, most previous studies have focused on energy separation characteristics and performance of the vortex tube as a standalone device, while applications to electric vehicle integrated thermal management system (EVITMS) remain limited. Therefore, this study developed an R744-based integrated thermal management system (ITMS) incorporating the vortex tube. A vehicle-level simulation model reflecting actual driving conditions was established to analyze cabin heating and the thermal management performance of battery and power electronic components and confirm the applicability of vortex tube-based ITMS.