【作者】 王雪莹；

【导师】 李贝；

【作者基本信息】 大连理工大学 ， 安全科学与工程， 2024， 硕士

【摘要】 氢气储运的可靠性是氢燃料电池汽车普及和推广的基础,但是车辆火灾事故场景下储氢气瓶存在潜在失效风险,会给其在全寿命周期内的服役安全带来挑战。本研究在综合采用实验研究、理论分析和统计学量化分析的基础上,深入探究了热负荷诱发Ⅲ型储氢气瓶及缠绕层材料的失效机制。主要工作和结论如下:(1)基于典型Ⅲ型高压复合材料气瓶爆炸试验,确定储氢气瓶爆炸失效过程主要包括物理爆炸、氢气膨胀点火和氢化学爆炸3个阶段。火灾极端条件下特定规格气瓶爆炸失效会同时产生火球、碎片及冲击波。通过与实验结果比较,火球直径理论值与实际直径4.48 m之间的偏差在±8%以内。此外,气瓶爆炸罐体碎片的最大投射距离约46.0 m;冲击波超压随距离衰减,在距离爆炸源2 m到15 m的同一半径方向上冲击波超压从875.33 kPa衰减至7.04 kPa;基于火灾场景下气瓶失效机理,建立了耦合物理爆炸和化学爆炸能量的气瓶爆炸波超压评估模型,该模型在近场区域的预测偏保守,但是在远场区域则相对准确,基于Mills方程预测7～15 m的远场区域峰值超压误差仅在2.8%～26.8%之间,预测精度基本满足工程应用,为氢工程领域安全距离划分提供了重要参考。(2)基于气瓶水压爆破试验、火烧试验、二次水爆试验,对比了不同工况条件下储氢气瓶极限承压能力,建立典型事故场景下储氢气瓶临界失效判据。常温工况下储氢气瓶的实际爆破压力约300%～377%NWP,具有足够的抗爆性能;火烧条件下其承压性能急剧下降约63.1%～67.5%,极易诱发爆破失效;而火烧损伤后恢复至室温的气瓶剩余爆破压力仍能达到256%NWP,仍保留较好的承压性能。此外,建立储氢气瓶极限承压能力影响因素灰色关联模型,定量分析出常温工况下缠绕层设计壁厚与气瓶承压性能的灰色关联度高达0.890,而火烧环境下初始充装压力、缠绕层设计壁厚以及整体火烧阶段的平均压力上升速率对临界失效压力有显著影响。(3)基于TG-DSC同步热分析、稳态热载及原位火烧条件下材料拉伸力学性能试验,深入分析了储氢气瓶缠绕层碳纤维复合材料的热-力学响应特征。碳纤维复合材料在100℃的高温辐射热环境下,抗拉强度仅比室温环境下降约13.2%,但是当环境温度为150℃超过环氧树脂玻璃化转变特征温度110℃时,其抗拉强度大幅度降低约50.9%;探究了碳纤维复合材料力学性能劣化特征与气瓶结构失效行为之间的关系,随火焰暴露时间的增加,碳纤维复合材料的抗拉强度下降约60.34%～67.1%,与典型火烧条件下测得的储氢气瓶临界失效压力的急剧下降约60.3%～67.5%呈现出一致性。更多还原

【Abstract】 The reliability of hydrogen storage and transportation is fundamental for the popularization and promotion of hydrogen fuel cell vehicles.However,the potential failure risk of hydrogen storage tanks in vehicle fire accident scenarios can pose a challenge to ensuring the safety in service throughout entire lifecycle.This study comprehensively investigated the failure mechanisms of Type Ⅲ hydrogen storage tanks and winding layer materials induced by thermal loads,based on a combination of experimental research,theoretical analysis,and statistical quantification.The main work and conclusions were as follows:(1)Based on the explosion test of the typical Ⅲ high-pressure composite tanks,the main failure processes of hydrogen storage tanks during explosion were determined to include three stages: physical explosion,hydrogen expansion ignition,and hydrogen chemical explosion.Under extreme fire conditions,the explosion failure of specific specifications of tanks simultaneously generated fireballs,fragments,and shockwaves.By comparing with the experimental results,the deviation between the theoretical value of the fireball diameter and the actual diameter of 4.48 m was within ±8%.Additionally,the maximum projected distance of tank fragments was approximately 46.0 m.The blast wave overpressure with distance followed a decay pattern,decreasing from 875.33 kPa to 7.04 kPa within the same radial direction from the explosion source at distances of 2 m to 15 m.Based on the failure mechanism of tanks in fire scenarios,a blast wave overpressure assessment model coupling physical explosion and chemical explosion energies was established.While the model tended to be conservative in predicting the near-field area,it demonstrated relative accuracy in the far-field area.Based on the Mills equation,the predicted peak overpressure error in the far-field area of 7-15 m ranges from 2.8% to 26.8%.The prediction accuracy generally met engineering requirements,which could provide references for the determination of safety distances in the field of hydrogen engineering.(2)Based on hydraulic burst tests,bonfire tests,and secondary hydraulic burst tests of tanks,the ultimate pressure-bearing capacity of hydrogen storage tanks under different working conditions was compared.The critical failure criteria for hydrogen storage tanks in typical accident scenarios were established.Under ambient temperature conditions,the actual burst pressure of tanks was approximately 300% to 377% of the nominal working pressure(NWP),which indicated that tanks had a fairly high burst resistance.Under fire exposure conditions,the pressure-bearing performance of tanks sharply declined by around 63.1% to 67.5%,making tanks highly susceptible to bursting failure.However,the residual burst pressure of a tank returned to room temperature after fire damage could still reach 256% NWP,which indicated that the tank retained good pressure-bearing performance.Additionally,a grey relational model was established to analyze the influencing factors on the ultimate pressure-bearing capacity of tanks.It was quantitatively determined that under ambient temperature conditions,the design wall thickness of the winding layer exhibited a high grey relational degree of 0.890 with the pressure-bearing performance of the tanks.Moreover,under fire conditions,factors such as initial filling pressure,design wall thickness of the winding layer,and the average rate of pressure rise during the engulfing fire stage significantly affected the critical failure pressure.(3)Based on TG-DSC simultaneous thermal analysis,steady-state thermal loading mechanical tensile test,and in-situ mechanical tensile tests under fire exposure conditions,the thermal-mechanical response characteristics of carbon fiber composites used in the winding layer of hydrogen storage tanks were comprehensively analyzed.The carbon fiber composites exhibited only a slight decrease in tensile strength of approximately 13.2% when exposed to a high-temperature radiation environment of 100 ℃ compared to room temperature conditions.However,when the environmental temperature exceeded the glass transition characteristic temperature of the epoxy resin at 110 ℃,such as at 150 ℃,the tensile strength decreased significantly by nearly 50.9%.The relationship between the deterioration characteristics of the mechanical properties of carbon fiber composites and the failure behavior of the tank structures was investigated.With increasing exposure time to flames,the tensile strength of carbon fiber composites decreased by ca.60.34% to 67.1%,showing consistency with the sharp decrease of approximately 60.3% to 67.5% in the critical failure pressure of hydrogen storage tanks measured under typical fire exposure conditions.更多还原