Numerical Investigation of Lithium Battery Using Heat Pipes in Electric Vehicles

The battery thermal management system plays a crucial role for lithium-ion battery in electric vehicles because of its susceptible performance during fast discharging. In this study, the Newman, Tiedemann, Gu, and Kim (NTGK) electrochemical model is applied to investigate the numerical simulation on the temperature distribution within battery when discharging at various rates, which is comprehensively validated with experimental data. Following the verification, a threedimensional heat pipe integrated system (HPIS) is designed with a novel thermal resistance model on the basis of equivalent thermal circuit method. The combination of thermal resistance between pipes and fins at the condenser section greatly predicts the temperature distribution of the system. Then the simulation model is employed to obtain the cooling efficiency of heat pipe (HP) under transient conditions. The temperature difference and maximum temperature of the battery pack under natural and forced air convection are compared. Implementation of insulating board overcomes the thermal runaway and propagation to protect the lithium-ion battery during a rapid discharging rate of adjacent cell. Simulation results reveal that the HPIS-based battery pack not only improves the heat dissipation capability, but also provides the thermal runaway protection to ensure the battery cell safety.