车载储氢气瓶气密性试验关键参数研究

Research on Air-tightness Test Key Parameter of Vehicle-mounted Hydrogen Storage Cylinder

车载储氢气瓶作为氢气的重要载体,必须根据相关标准和技术规范进行型式试验,其中,气密性试验是检验车载储氢气瓶泄漏情况的重要环节。虽然国内外颁布的相关标准对气密性试验关键试验参数提出的不同程度的要求,但现行标准对部分试验参数并未提出定量的要求,且缺乏理论依据和数据支撑。基于数值仿真模型,结合试验结果进行验证,分析气瓶气密性试验过程的流场分布特性,结合气密性试验表征参量,研究关键试验参数对气瓶气密性试验结果的影响并获得试验参数优化值。结果表明:(1)随着增压速率的增大,气瓶的压降时间整体呈现出逐渐增加的趋势,且当增压速率大于3 MPa/min时增加幅度尤为明显;(2)随着保压时间的增加,气瓶的压差百分比和压降时间呈现先增加,并在保压时间大于90 s时不再发生变化;(3)当充装温度越低,气瓶气密性试验结果越准确;(4)当试验介质氮气和氦气的比例相近时,气瓶的压降时间和压差百分比最小。

As an important container of hydrogen,vehicle-mounted hydrogen storage cylinders should be type tested according to relevant standards and technical specifications,among which,the air-tightness test is an important process of cylinders leakage detection.Different requirements of the test parameters are given in the standards.However,the quantitative requirements with theoretical basis and data support are lack.In this research,the flow field distribution of the cylinder during the air-tightness test is studied by developing the verified numerical simulation model.Based on the characterization parameters of the air-tightness test,the influence of the test parameters is analyzed and the optimized values are obtained.The results show that:(1)with the increase of pressurization rate,the pressure drop time of the cylinder shows a trend of gradual increase,and the increase is especially obvious when the pressurization rate is greater than 3 MPa/min;(2)With the increase of holding time,the differential pressure percentage and pressure drop time of cylinders increase first and cease to change when the holding time is greater than 90 s;(3)the lower the filling temperature,the more accurate the gas-tightness test results of the cylinder;(4)when the ratio of test medium nitrogen and helium is 1∶1,the pressure drop time and pressure difference percentage of the cylinder is the smallest.