PHYSICS AND MODELLING OF UNDER-EXPANDED JETS AND HYDROGEN DISPERSION IN ATMOSPHERE

The broad use of hydrogen as an energy carrier to tackle the issue of climate change is unavoidable. The emerging hydrogen economy poses new problems to be solved to ensure a level of safety in hydrogen technologies and infrastructure comparable to that for today’s fossil fuels. The pressure of onboard hydrogen storage in early-market
vehicles already reaches extremely high value 700 bar. Such high storage pressures make accidental hydrogen release and dispersion a potentially hazardous scenario. An unscheduled release from high pressure hydrogen storage, e.g. through a pressure relief device (PRD), can create underexpanded sonic jets with dispersion of hydrogen
and a flammable envelope spreading over tens of meters. Safety or set-back distances for hydrogen refuelling stations and stationary applications require accident consequences analysis, performed by contemporary mathematical models and tools.