Consequence analysis of an accidental hydrogen release in a refuelling station

Widespread deployment and use of hydrogen in the transportation sector for both IC engines and fuel cell technologies can occur only if hydrogen safety issues have been addressed of hydrogen storage, transport and infrastructure. This paper analyses the consequences of an accidental hydrogen release that may occur in a hydrogen refuelling station. The re-fuelling station under consideration comply with the ISO/TS 20100:2008 for technical requirement, according to the Directive 2014/94/UE. The investigated scenarios are caused by a hose break during car and bus refuelling, at 70 and 35 MPa, respectively. The hose break event is assumed due to a person who drives away while connected to the dispenser. Both mitigated and non-mitigated conditions are considered. In the mitigated case a shut off valve is assumed to be activated 5 s after the start of release. In the non-mitigated case it is assumed that the shut off valve is not activated so that the release is continuously fed from the buffer tank located before the dispenser. To model the hydrogen release, a CFD code (Flacs by GexCon) was used to calculate the dispersion and mixing of hydrogen within the station. The hydrogen dispersion results were then used to calculate the corresponding pressure loads from hydrogen- air deflagrations in the station, or the resulting jet lengths and heat fluxes. It was found that overpressures created from hydrogen deflagration do not cause any effect to buildings, equipment’s and people in the station.