Latent heat recovery of composite PCM for hybrid BTMSs based on micro-encapsulated phase change slurry

Phase change material (PCM) cooling is widely applied in battery thermal management systems (BTMS) due to high latent heat. To address the long latent heat recovery time of PCM, especially in continuous discharge and charge cycles, a novel hybrid BTMS coupling dual-PCM is designed. The dual-PCM contains the composite PCM as the main heat dissipation and the micro-encapsulated phase change slurry (MEPCS) for latent heat recovery. The experiments are performed to ensure the effectiveness of the hybrid BTMS. The temperature performance of the battery module, solidification rate of composite PCM and pressure drop of the MEPCS are studied as the critical performance indicators. To establish a trade-off between these performance indicators, the interaction effects between inlet velocities and mass concentrations of the MEPCS are investigated. Meanwhile, different ambient temperatures combined with mass concentrations are considered. Results indicate that MEPCS as the coolant has a significant effect on the temperature and solidification performances at low inlet velocity. The higher mass concentration of MEPCS does not mean better heat recovery capacity at the same pressure drop. Considering the fluctuation of the solidification performance, the mass concentration of MEPCS above 10 % is recommended to meet the challenges of different ambient temperatures. The energy efficiency is optimized by adjusting the mass concentration and inlet velocity. The maximum reduction in pressure drop is 39.8 % with high temperature and solidification performances. The solutions can reduce energy consumption and improve the economic benefits for BTMS.