Exergy analysis of electric vehicle battery thermal management systems using transcritical CO2 vapour compression cycle

In this paper, performance analysis of a transcritical CO2-based electric vehicle battery thermal management system (EV BTMS) is investigated in a basic single-stage vapour compression cycle along with its various modifications that include internal heat exchanger (IHX), two-stage vapour compression and an intercooler. The system is compared against conventional cycles with various commercial refrigerants including R152a, R134a, R290, R600, R600a, R1234yf and Dimethylether and evaluated with respect to exergy-based thermodynamic, economic and environmental considerations. In the study, the efficiencies of each system and its components are calculated under various conditions and input parameters, and the corresponding component and exergy destruction-based costs and environmental impacts are determined. Based on the analyses, it is found that the exergy efficiency of the transcritical CO2-based system can be improved by up to 22% with two-stage compression and IHX. However, the efficiency of the improved system is still found out to be lower than the compared system using the studied refrigerants.