燃料电池汽车车载高压Ⅳ型储氢瓶耐火烧性能仿真

Numerical simulation of fire resistance performance of high-pressure typeⅣhydrogen storage tank for fuel cell vehicle

为了评价Ⅳ型车载储氢瓶在火灾中的安全性,应用计算流体力学方法对70 MPa的Ⅳ型复合材料储氢瓶进行整体与局部耐火烧性能的数值仿真研究。首先,模拟不同火灾情形的燃烧场,获得气瓶表面的热通量分布数据作为传热分析的边界条件;其次,分析气瓶不同位置遭受火烧过程中瓶内氢气及气瓶各部件壁面温度的变化情况,获得温控压力泄放装置(TPRD)开启所需要的时间,预测气瓶高温失效的关键位置,评估气瓶的耐火安全性;最后,基于局部火灾位置对TPRD启动时间的影响分析,提出提高车载高压储氢瓶耐火性能的可行方案。研究结果表明:气瓶耐火性能符合整体火烧试验要求;在油池火灾中,气瓶中间高度靠上方、头尾两端的圆肩部位最有可能先发生失效;瓶内氢气的温度分布对内胆的温度影响不显著;在发展成整体吞没火灾前,远离瓶口区域的局部火灾对TPRD温升的贡献极小,安全风险高。

To evaluate the safety of onboard typeⅣhydrogen storage tanks in fire,numerical simulations of engulfed and localized fire resistance of a 70 MPa typeⅣcomposite hydrogen storage tank were conducted by applying computational fluid dynamics method.Firstly,the heat flux distributions on the surface of the tank were obtained by simulating the combustion fields under different fire conditions,which were then input as boundary conditions of the heat transfer analysis.Then the changes of hydrogen temperature,as well as wall temperature of each part of the tank under different fire conditions were analyzed in order to obtain the time before the temperature-activated pressure relief device(TPRD)opened,predict the critical locations of thermally induced failure,and evaluate the fire resistance performance of the tank.Finally,according to the influence of localized fire locations on the activation time of TPRD,feasible proposals were raised to improve the fire resistance performance of onboard high pressure hydrogen storage tanks.The results show that the fire resistance of the tank meets the requirements of engulfed fire test;in oil pool fire,the round shoulders at upper part of both head and tail of the tank are most likely to fail first;the temperature distribution of hydrogen in the tank has little effect on the temperature of liner;if the localized fire is far from top of the tank,before it develops into engulfed fire,the contribution of the flame to the temperature rise of TPRD is tiny,which presents an extreme risk of safety.