Heat transfer experiments and correlations for vent gases emerging from a Li-ion battery and impinging on a flat surface

During thermal runaway of Li-ion battery cells, high-temperature gas jets may impinge onto nearby sur-faces and may increase the risk of a propagating failure. In this paper, heat transfer rates of jets emerging from a cylindrical Li-ion cell and impinging on a flat surface were measured experimentally and empir-ical correlations were developed based on the resulting data. Experiments used compressed air as the working fluid, which issued from the isolated safety vent and impinged on a target plate. Infrared ther-mography was used to obtain the spatially-resolved, convective heat transfer distribution on the target plate. While heat transfer distributions showed local maxima at the site of jet impingement, complex geometric features within the vent resulted in variation in the convection rate when comparing the mul-tiple impinging jets emerging from a single Li-ion cell. Heat transfer correlations were developed in the form of Nusselt number as a function of Reynolds number and may be used in thermal runaway models which seek to include the effects of venting and combustion as an alternative to resolving the impinge-ment heat transfer rates with expensive 3-D computational fluid dynamics simulations.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This paper investigates the impact of high-temperature gas jets from a Li-ion battery cell during thermal runaway on nearby surfaces and the risk of propagating failure. Experimental measurements of heat transfer rates were conducted for jets impinging on a flat surface, and empirical correlations were developed based on the data. It was found that the geometric features of the vent affected the convection rate, highlighting its importance in thermal runaway modeling.