Investigation on leakage characteristics and consequences of hydrogen-blended gas pipelines based on CFD with the full multicomponent diffusion model

Pipeline transportation of hydrogen-blended natural gas (HBNG) is pivotal for advancing the hydrogen energy industry. However, as pipelines age, accidents such as fires and explosions caused by leaking are becoming more likely. The aim of this study is to evaluate the effect of different influencing factors on the leakage characteristics. The results demonstrate a positive correlation between pressure, aperture, and hydrogen blend ratio (HBR) with HBNG concentration and hazardous area. Conversely, soil porosity is negatively correlated with these characteristics. The hazardous area of upward leakage is the highest, while downward leakage is the smallest. The chemical properties of inert gases are relatively stable and there should be no reaction with other gases. Adding inert gases can increase the lower explosive limit and reduce the risk of leakage. The explosion area exhibits a trend of initial increase, followed by decrease, and then a subsequent increase over time. Of particular note is that it is the first time to discover in this study that adding inert gas can reduce the explosion area within a shorter leakage time. However, in the case of long-term leakage, the addition of inert gas can increase the explosion area.