A coupled conjugate heat transfer and CFD model for the thermal runaway evolution and jet fire of 18650 lithium-ion battery under thermal abuse

Thermal runaway (TR) is a major safety concern for lithium-ion batteries.A TR model incorporating the resulting jet fire can aid the design optimization of battery modules.A numerical model has been developed by coupling conjugate heat transfer with computational fluid dynamics (CFD) to capture the cell temperature and internal pressure evolution under thermal abuse, venting and subsequent combustion of 18650 lithium-ion batteries.The lumped model was employed to predict the thermal abuse reactions and jet dynamics, while the vented gas flow and combustion were solved numerically.Model validation has been conducted with newly conducted experimental measurements for the transient flame height of jet fire and temperatures at selected monitoring points on the cell surface and above the cell.The validated model was then used to investigate the effect of the SOCs on the evolution of TR and subsequent jet fires.Increasing SOCs shortens the onset time of TR and enlarges the peak jet velocity.The peak heat release rates and flame height of the jet fire increase with theincrease of the SOC.The developed modelling approach extends the TR model to jet fire.IT can potentially be applied to assist the design of battery modules.