Numerical investigation on the effect of combined convective and radiative heat transfer on thermal runaway propagation in aligned air-cooled cylindrical Li-ion battery modules

The global transition towards widespread electric vehicle (EV) adoption represents a pivotal shift, offering a multitude of environmental, economic, and technological benefits. Although thermal runaway (TR) events have been shown to cause battery fires, ongoing research and the adoption of precautionary driving habits could lead to the introduction of safe battery packs for automobiles. In this study, the propagation characteristics of TR inside an air-cooled 18650 lithium-ion battery (LiB) module in an aligned cell arrangement under different operating conditions were investigated. The investigation incorporated radiation effects using a three-dimensional numerical model validated by experiments with surrogate cells and studies from the literature. The corner cell represented the TR initiation source in the module. The module was also subjected to varying flow and ambient conditions, while the variation in the temperature responses from neighboring cells, the temperature rise rates, the onset time, the TR propagation sequences, and the TR propagation rates were evaluated and a comparative analysis was performed to investigate the effects of radiation. Furthermore, a comprehensive cell-to-cell heat transfer analysis was performed to determine heat transfer within the cells during TR and quantified. The findings of this study offer a greater understanding of the mechanisms behind TRP and contribute to the development of novel and safe battery thermal management designs.