Numerical Analysis of the Initial Response to Hydrogen-vehicle Jet-flame Accidents

The hydrogen tank of a hydrogen vehicle is equipped with a thermally activated pressure-relief device, which releases hydrogen gas to prevent explosion above a certain temperature, thus avoiding jet flames. This study analyzed the risk of sudden jet-flame generation during response activities following hydrogen-vehicle accidents through numerical analysis. During the jet flame, heat fluxes of over 9.5 kW/m², which can cause second-degree burns to the driver’s seat and approximately 5 m behind the vehicle, were observed, and a zone of over 37.5 kW/m², which can cause catastrophic damage, was formed at the immediate area, including the lower part of the vehicle. At a distance of 0.5 m from the driver’s seat, a high heat flux of approximately 80 kW/m², which is similar to the test standard for the thermal-protection performance of fire-fighting clothing, was formed. Further analysis indicated that both rescue victims and first responders are at risk if jet flames are generated during rescue activities. The results of this analysis can be used to develop a safe accident-response strategy for hydrogen vehicles.