Hot gas impingement and radiation on neighboring surfaces from venting and combustion in a package of 18650 cells

Abstract

A quasi-steady, CFD-based modeling approach is employed to investigate the heat loading within a small package of twenty-five 18650 Li-ion cells. The quasi-steady approach allows for computationally efficient simulations to capture the compressible and turbulent flow field through the safety vent structure and out into the space surrounding a failing cell. Combustion of vent gases leads to high heat loading on neighboring cells and nearby surfaces. Heat transfer mechanisms within the enclosure include convection from hot gases, radiation from the participating medium, and radiation exchange between surfaces. Simulations provide insight into the magnitude of each heat transfer mechanism, and the spatial distribution of heat flux on nearby cells and surfaces within the pack. The complex geometry of the safety vent geometry resulted in an asymmetric jet flow pattern, which induces highly localized impingement heat transfer on specific cells within the enclosure. Radiation from hot surfaces was more significant than radiation from hot gases and soot to neighboring cells. The quasi-steady simulations may be used in the future to develop reduced-order heat transfer models that include the effects of venting and combustion on propagating failure.