基于壅塞流的动力电池防爆阀泄压特性的动态仿真

The dynamic simulation of pressure relief characteristics of the power battery vent based on choking flow

防爆阀作为缓解电池系统热失控的被动安全措施,在电芯设计中扮演着非常重要的角色,防爆阀的开启压力、阀体面积及阀体位置对电芯热失控后的泄压过程有着重要影响。本工作主要介绍了动力电池热失控后产热产气导致防爆阀开启的泄压过程,通过理论计算、实验测试及仿真分析相结合的方式,对防爆阀的泄压特性进行了系统阐述与分析。首先,基于流体力学基本原理和方程从理论上对防爆阀的泄压过程进行了分析,阐述了电芯热失控过程中防爆阀开启后的泄压壅塞流基本状态;其次,通过开展无阀电芯的加热热失控和过充热失控两类实验,实验中实时监测了电芯热失控过程中卷芯的温度和电芯的内压,从而得到电芯热失控过程中防爆阀开启前电芯的产热产气速率;最后,对电芯的产热产气及泄压过程进行仿真,基于COMSOL软件,建立了动力电池防爆阀泄压过程的系统模型。且对防爆阀的开启压力、阀体面积及阀体位置等影响因素进行了归类仿真分析,并与实验数据进行了对比验证,得到了较为优化的防爆阀结构设计,为动力电池优化设计提供了一定的参考。

As a passive safety measure to prevent the thermal runaway of the battery system,the vent plays a very essential role in cell design.After the cell has reached thermal runaway,the pressure relief procedure is significantly impacted by the opening pressure,area,and position of the vent.This paper mainly presents the pressure relief process of the vent opening caused by heat and gas production after the cell thermal runaway.Through theoretical calculation,experimental test and simulation analysis,the pressure relief features of the vent are systematically described and analyzed.First,the pressure relief process of the vent is examined theoretically based on the basic principles and equations of fluid mechanics,and the basic state of the pressure relief choke flow after the vent is opened in the process of thermal runaway is expounded;Second,by performing two kinds of experiments of heating thermal runaway and overcharging thermal runaway of the cell,the temperature of the jerry roll and the internal pressure of the cell were monitored in real time,to determine the heat and gas production rate before the vent was opened;Finally,a simulation of the cell's pressure relief,gas production,and heat output are performed.The system model for the vent's pressure relief is built using COMSOL,and impacting elements including the vent's opening pressure,area,and position are categorized and simulated.Additionally,the simulation results and test data from experiments are compared.A more optimized structure design of the vent is obtained,which provides a certain reference for the optimal design of the power battery.