Characterization of Hydrogen Leakage Diffusion in Outdoor Hydrogen Energy Utilization Stations

Driven by the global energy transition and carbon neutrality goals, clean hydrogen energy, as a strategic emerging industry in China, is accelerating from the laboratory to large-scale application. With the continuous development of hydrogen energy, hydrogen refueling stations have emerged as the key hub of the hydrogen energy industry ecosystem. Compared with traditional hydrogen refueling stations, outdoor hydrogen utilization stations with more comprehensive and diversified functions will be put into large-scale use in the future. However, the outdoor hydrogen station is still in the demonstration and experimental stage, and its internal functions are complicated and lacking, while hydrogen itself has the properties of low density, flammability and explosiveness, and if leakage occurs, it will be mixed with air, and in the presence of an ignition source, it may trigger an explosive reaction, which significantly increases the risk, and the related research is relatively scarce. Therefore, in this study, an outdoor hydrogen energy comprehensive utilization station in China is used as a reference object, and CFD numerical simulation calculations are used to investigate the influence of different influencing factors on the spatial and temporal diffusion of hydrogen cloud after a hydrogen leakage accident. The results show that obstacles are the key factors affecting the hydrogen diffusion path and accumulation characteristics, which significantly increase the risk of local accumulation; the leakage pressure directly affects the initial leakage flow rate, and the risk of high-pressure leakage may be reduced in the later stage, while the low-pressure leakage may cause a longer-term safety hazard due to the persistent accumulation characteristics; the ambient wind field has a significant regulatory effect on the hydrogen diffusion behavior, which reduces the overall concentration of the cloud, and the overall concentration of the cloud can be effectively improved by changing its diffusion path, and the overall concentration of the cloud can be reduced by changing its diffusion path. Changing the diffusion path can effectively improve the accumulation of hydrogen clouds at obstacles. When laying out an outdoor hydrogen energy utilization station, the weak points should be oriented parallel or opposite to the local average wind direction, and be arranged in the same direction as the rest of the functional areas, keeping the pipelines and tanks connected in an open area, and improving the safety level of the station.