Experimental and numerical investigation on integrated thermal management for lithium-ion battery pack with composite phase change materials

Highlights: • A novel integrated thermal management system based composite PCM is proposed. • Thermal behaviors of the integrated system and air cooling system are compared. • Effect of air flow rate, ambient temperature and PCM liquid fraction are discussed. • Thermal behaviors of air cooling system in 4 C charge-discharge cycles are analyzed. • Cycle performances of integrated system in 4 C charge-charge cycles are simulated. - Abstract: In this article, a novel composite phase change materials based thermal management system coupled with air cooling was proposed in order to sustain the temperature rise and distribution within desirable ranges of the lithium-ion battery utilized in a hybrid power train. A combined experimental and numerical study was conducted to investigate the effects of air flow rate and phase change material liquid fraction on the thermal behavior of the integrated thermal management system. Comparisons between the integrated system and an air cooling system were implemented under different air flow rates and ambient temperatures. Furthermore, thermal characteristics of both systems during charge-discharge cycles were numerically simulated. The results showed that the cooling effect of the integrated system was obviously better than that of the air cooling system. The variation of the air flow rate and ambient temperature had negligible impact on the heat dissipation of the phase change cooling. After the fully melt of phase change material, the battery temperature did not rise rapidly due to the auxiliary cooling of the cooling air. During 4 C charge-discharge cycles, the temperature rise of the battery pack could be effectively restrained by the air cooling at a flow rate exceeding 300 m³/h. While for the integrated system, good thermal management could be achieved with only 100 m³/h of air flow rate. Especially for the operation mode, i.e., phase change material cooling during the discharge and coupled phase change material and air cooling during the charge, the integrated system could control the maximum temperature of the battery pack below 49.2 °C and reach up to six charge-discharge cycles under no additional battery power consumption.