Thermodynamic analysis and influence mechanism of the key parameters in the dual-evaporative temperature thermal management system

Carbon dioxide (CO2) thermal management systems offer potential advantages for electric vehicles, though their cooling performance requires further optimization. A dual-evaporation-temperature (DET) system, which independently regulates battery and cabin cooling, demonstrates superior energy efficiency compared to conventional single-temperature systems. However, operational constraints arise from uneven energy distribution and coupled thermodynamic effects, complicating system design and control. To well address this, a simulation model is developed and verified using experimental data. Key operational characteristics are examined, with emphasis on compressor displacement design and its influence on performance limitations. Additionally, the coupled effects of coolant temperature and battery heat generation are investigated, alongside system boundary constraints. Furthermore, the DET system is compared with that of the traditional CO2 system, and the energy-saving potential was analyzed. Critical findings indicate that compressor displacement, coolant conditions, and thermal load variations predominantly govern battery cooling capacity by modulating chiller heat transfer dynamics. Excessive cooling demand beyond system capacity induces instability and efficiency degradation. The DET system achieves a 10–21% efficiency improvement over traditional CO2 systems under ambient temperatures of 30–40 °C, contingent upon optimal design and control strategies. The results provide a new guideline for the performance enhancement of the automobile CO2 air conditioning.