车用液氢气瓶快充过程数值研究

Numerical Study on Fast Filling Process of Vehicle Liquid Hydrogen Cylinder

车用液氢气瓶加注过程中,因加注速度快且气瓶容积小,极易造成过充现象,导致安全事故发生。针对设有气包防过充装置的车载液氢气瓶建立三维对称模型,采用CFD方法对气瓶快速加注过程开展数值仿真。分析了开孔孔径、加注速率、初始充满率和防过充装置容积对防过充装置性能的影响规律。结果表明:开孔孔径是影响防过充装置性能的主要因素,其限制了液体的流通能力;采用6 mm孔径和初始充装量为50%的状况下,充装结束后气瓶都将过充,最大充装率可达98.4%;采用大容积的防过充装置可以为气瓶预留更多的气相安全空间,但同时也会导致充装量不足等问题,当防过充装置容积为100 L时,最终充装量仅有77.2%。

The vehicle liquid hydrogen cylinder is easy to be overfilled due to the fast filling speed and the small size of hydrogen cylinder during the filling process and safety accidents might be caused.A three-dimensional symmetric model is built for vehicle liquid hydrogen cylinder that is equipped with an ullage tank,and a numerical study using CFD simulation method is performed on the fast filling process of vehicle liquid hydrogen cylinder.The effects of hole sizes,filling rate,initial filling rate and volume of overfill prevention device on the performance of the overfill prevention devices are studied.The results have been obtained.The hole sizes have a significant effect on the performance of the overfill prevention device,which limits the flow capacity of liquid.When the hole size is 6mm and the initial filling rate is 50%,the cylinders will be overfilled at the end of filling,and the maximum filling rate can reach 98.4%.The use of large volume overfill prevention devices can reserve more phase for cylinders,but it will also lead to issues such as insufficient filling.When the volume of overfill prevention device is 100L,the final filling rate is only 77.2%.