Hydrogen and fuel cell stationary applications: Key findings of modelling and experimental work in the HYPER project

This paper summarises the results of the research programme in the HYPER project(Installation Permitting Guidance for Hydrogen and Fuel Cells Stationary Applications) [1].The relevance of scientific findings to installation permitting guidelines (IPG) for smallstationary hydrogen and fuel cell systems is discussed. A key aim of the activities was togenerate new knowledge in the field of hydrogen safety, and, where possible, use this dataas a basis to support the recommendations in the IPG. The structure of the paper mirrorsthe HYPER research programme in that the work is described in terms of the followingrelevant scenarios: 1) high pressure releases, 2) small foreseeable releases, 3) catastrophicreleases, and 4) the effects of walls and barriers. Within each scenario the key objectives,activities and results are presented. The work on high pressure releases sought to provideinformation for informing safety distances for high pressure components and associatedfuel storage, activities on both ignited and unignited jets are reported. A study on smallforeseeable releases, which could potentially be controlled through natural or forcedventilation, is described. The aim of the study was to determine the ventilation requirementsin enclosures containing fuel cells, such that in the event of a foreseeable leak, theconcentration of hydrogen in air for zone 2 ATEX [2] is not exceeded. The hazard potentialof a possibly catastrophic hydrogen leakage inside a fuel cell cabinet was investigatedusing a generic fuel cell enclosure model. The rupture of the hydrogen feed line inside theenclosure was considered and both dispersion and combustion of the resulting hydrogeneairmixture were examined for a range of leak rates, and blockage ratios. Finally, thescenario on walls and barriers is discussed; a mitigation strategy to potentially reduce theexposure to jet flames is to incorporate barriers around hydrogen storage equipment.Conclusions of experimental and modelling work which aim to provide guidance onconfiguration and placement of these walls to minimise overall hazards are presented.