Numerical study of hydrogen leakage and explosion in hydrogen refueling station with large volume hydrogen storage vessels

Large volume multi-layered high pressure hydrogen storage vessel is one of the vital equipment in hydrogen refueling station. However, the possibility of leakage from container nozzles during service remains a safety concern. In this paper, a leakage model modified by the real gas equation of state and a three-dimensional (3D) computational fluid dynamics (CFD) model based on the real hydrogen refueling station layout are established to simulate the whole process of hydrogen diffusion and explosion after the large volume vessel leak. The influences of leakage direction, leakage height, hydrogen storage pressure and wind speed on the distribution of flammable hydrogen are studied, as well as the scope of overpressure harmful area is respectively predicted when the real hydrogen cloud is ignited at different times. Results indicate that the high-pressure hydrogen jet over 30MPa diffuses in a wide range near the surface under momentum control. And the smaller the leakage source height is, the more obvious the Coanda effect is. In addition, igniting after hydrogen leakage in a very short time (such as 0.5 s) will lead to higher maximum overpressure, and igniting after a long time will form a larger dangerous area. Compared with the seamless hydrogen storage cylinder group, the hydrogen explosion hazard of vertical large volume multi-layered hydrogen storage vessel is significantly alleviated after leakage. Also, setting a certain height of isolation walls outside the hydrogen storage area can effectively reduce the risk and consequences of accidents.