Winter driving range optimization of electric bus based on CO2 thermal management system and thermal energy cascade utilization

Environmental pollution and the energy crisis are intensifying. Pure electric vehicles (EVs) are promising alternatives to traditional internal combustion engine vehicles (ICEVs), but a significant decrease in winter driving range challenges their adoption. This paper proposes an integrated CO 2 thermal management system with a waste heat recovery mode(WHR-CO 2 TMS) for buses, addressing cabin, motor, and battery thermal management . By harnessing motor waste heat and preheating the battery , we optimize winter driving range. The study compares four systems between −20 °C and −10 °C: PTC heating system, CO 2 heat pump system, WHR-CO 2 TMS, WHR-CO 2 TMS with battery preheating. Key findings include: a. Replacing PTC heating system with a CO 2 heat pump system increases driving range by 10.37 %–12.90 %. b. Motor waste heat recovery enhances CO 2 heat pump performance, increasing COP by 6.97 %–11.13 %, and improves driving range by 19.14 %–20.90 %. c. Preheating the battery reduces range decay by 8.73 %–13.26 %, leading to a range improvement of 19.47 %–21.60 % compared to PTC heating system. d. A scheme is proposed to adjust battery preheating based on driving distance and ambient temperature. The results highlight the potential of integrated TMS for enhancing the winter driving range of electric buses. • Proposes a WHR-CO 2 TMS integrating cabin/motor/battery heating, reducing energy consumption vs. PTC/CO 2 heat pump. • CO 2 heat pump replaces PTC heating, cutting energy use 9.42–11.42% and boosting driving range 10.37–12.90% . • Motor waste heat recovery raises CO 2 heat pump COP by 6.97–11.13%, extending driving range 19.14–20.90% vs PTC heating. • Battery preheating via CO 2 reduces range decay 8.73–13.26%, improving driving range 19.47–21.60% over PTC heating. • Optimal battery preheating initial temp increases with driving distance and decreases with colder ambient temperatures.