Evaluation of Safety Distances for Hydrogen Refueling Stations

Due to the strong increase in the hydrogen use for mobility, hydrogen refueling station (HRS) development is currently a major issue. Having a safe design of those HRS is crucial to prevent any major accident during the deployment of this technology. To accompany this safe development, a generic safety study was achieved. Based on the main scenarios identified in the risk analysis, associated safety distances were evaluated. Those scenarios include mainly tank burst, jet fire, jet explosion and explosion in container. To meet the objective of having relevant distances for all those scenarios, different approaches were used from simple correlation to CFD model.

Several leak diameters, from 10% to full line rupture, and pressures were considered, for both confined and atmospheric leakages. For confined leak, a specific model was applied to highlight the influence of the mixture concentration and turbulence, but also to consider the opening part of the structure, container typically.

Atmospheric dispersion of pressurized hydrogen was modelled using a computational fluid dynamic (CFD) code based on the large eddy simulation turbulence closure. Such an approach is essential to show the strong unsteady effect in such a release. The CFD model also enables ones to estimate the flammable mass in the case of impinging jets. For free jets, comparison between the CFD model, an integral approach and experimental data was proceed to ensure that all approaches are in accordance.

CFD was typically used, not only for jet dispersion modelling, but also to evaluate whether a surrounding fire could induce a tank burst, considering potential thermal barriers, based on the applied heat fluxes on the skin of the tank.