Investigation on flame characteristic of lithium iron phosphate battery fires under different fire source-wall spacing

Lithium-ion batteries (LIBs) fires typically occur within confined spaces, yet there is limited research on the influence of limited entrainment on the jet fire characteristics of LIBs. Hence, this work innovatively carried out a series of thermal runaway (TR) experiments for large prismatic LIBs with various states of charges (SOCs) under different fire source-wall spacing. As revealed, the flame during LIBs combustion was divided into three stages. The average flame height is further proposed to quantify the flame profile at different phases. The mean flame height and heat release rate of LIBs with various SOCs, away from the sidewall for different distance, is analyzed. Moreover, the relationship between dimensionless flame height and dimensionless distance under sidewall conditions is investigated. Critical spacing unaffected by sidewall influence of LIBs jet flame has been provided. The centerline temperature distributions of battery flame under different separation distances from wall to fire center conditions are presented. The radiation distribution on the wall under different separation distances from wall to fire center conditions is shown. The results will contribute to understand the battery fire characteristics and provide inspirations for fire prevention, thus enhancing the overall safety of LIBs.