Study on theoretical analysis method of thermal runaway liquid nitrogen cooling inerting of LPF batteries
The traditional commercial fire extinguishing agent is not effective in suppressing the thermal runaway fire and reigni-tion of lithium ion battery.Liquid nitrogen is an efficient fire extin-guishing agent,and its cooling effect on restraining thermal run-away of lithium-ion batteries has been verified by experiments of many research institutions.However,at present,there is a lack of theoretical analysis methods for the influence of liquid nitrogen fire extinguishing dosage and fire extinguishing efficiency.Based on the theoretical analysis of liquid nitrogen fire extinguishing mechanism,the theoretical analysis and calculation method of liq-uid nitrogen cooling and inerting are studied and determined.In the method,experimental studies on thermal runaway heat re-lease,heat absorption of liquid nitrogen,and inert amount of liq-uid nitrogen were carried out,and the effectiveness of the method was verified by full-scale experiments.Taking the thermal run-away of 280 Ah lithium iron phosphate battery as an example,the minimum amount of liquid nitrogen for inerting explosion suppres-sion and cooling is calculated according to the theoretical analysis method.After 83.39 kg of liquid nitrogen was applied to the ex-plosion test chamber with an effective volume of 38.88 m³,the ex-plosion occurred 48 times at a 24-hour interval.The effectiveness and rationality of the theoretical analysis method are effectively verified by practical cases,and the proposed theoretical analysis method provides evaluation means and methods for the design and effectiveness analysis of liquid nitrogen fire suppression and explo-sion suppression,so as to further effectively enhance the safety of lithium iron phosphate battery storage system.
liquid nitrogenthermal runawaycoolinginertinglithium iron phosphate battery