Abstract: To prevent safety accidents resulting from hydrogen storage tank leakage, the CFD software was used to establish a numerical model for the leakage and diffusion of 20 MPa storage tanks in hydrogen refueling stations. The impacts of explosion-proof walls, leakage diameters, and ambient wind speeds on hydrogen leakage diffusion were analyzed. Furthermore, based on the numerical simulation results, the improved A* algorithm was adopted to plan the evacuation path of personnel in the hydrogen refueling station. The results show that after hydrogen strikes explosion-proof walls, its diffusion path of hydrogen is altered. Most of hydrogen diffuses along the left and right sides of the wall, preventing the expansion of the flammable area. The closer to the explosion-proof walls, the larger the profile of the flammable hydrogen cloud, and the greater the risk of explosion. The larger the leakage diameter, the larger the flammable area formed, and the greater the volume of flammable hydrogen gas cloud. When the leakage diameter reaches 5 mm, the flammable area expands to other working units. When the leakage diameter reaches 10 mm, the flammable area expands to the outside of the hydrogen refueling station. When the leakage diameter is 2 mm, the excessively high ambient wind velocity along the leakage direction （5, 8 m/s） is introduced, which is conducive to the diffusion of hydrogen above the explosion-proof wall along the leakage direction. However, the hydrogen is hard to diffuse below the explosion-proof wall, resulting in the accumulation of flammable hydrogen clouds. The diffusion range of hydrogen concentration at 1% volume fraction is defined as the hazardous area. Considering the influence of factors such as wind direction and wind velocity, the improved A* algorithm is adopted to realize the optimal evacuation path planning for maintenance and inspection personnel of hydrogen refueling stations.

Key words: hydrogen storage tank, numerical simulation, explosion-proof wall, leakage diameter, ambient wind velocity, evacuation route