A novel method for analyzing the leakage and diffusion of hydrogen: First arrival time distribution

Hydrogen energy plays an important role in achieving the carbon peak and carbon neutrality goals. However, owing to its flammability and explosiveness, hydrogen leakage during transportation and use can easily cause severe consequences. Therefore, research on the safety of hydrogen leakage is particularly important. This study proposes a novel method for analyzing the diffusion behavior of hydrogen leakage called first arrival time distribution (FATD). The spatial distribution of the first arrival times of specific concentration values (such as explosion limit and alarm concentration) at each coordinate point in the calculation domain was obtained by processing the concentration field of hydrogen leakage and diffusion via computational fluid dynamics simulations. The hydrogen leakage and diffusion processes were simulated for multiple scenarios using Fluent software, and the method of obtaining the FATD based on the simulations was detailed. The study also analyzed the hydrogen leakage and diffusion processes as well as the effects of mesh quantity and sampling time interval on the FATD; the FATD was additionally applied in actual scenarios to obtain an alarm time distribution for guiding sensor deployment. The results show that the FATD intuitively displays the hydrogen diffusion and evolution processes via specific concentration values in the calculation domain while describing the detailed influences of obstacles on the hydrogen diffusion process. Moreover, the FATD can serve as an indicator of grid independence analysis. This provides a new method for understanding diffusion behavior, reference for accident risk and consequence assessments, and safety guidance for the utilization of hydrogen energy.