Hydrogen fuel cell (HFC) technology will first be commercialised for
market-ready applications such as backup power supply, portable power
generation and powering of materials handling vehicles. These
applications generally require, by nature or for security reasons, that
hydrogen systems be used indoors. Yet, existing regulations, codes and
standards (RCSs) are very incomplete regarding the practical
specification of safety requirements indoors.
Addressing the safe indoor use of HFC systems for early markets was
the main objective of the EU-funded project 'Pre-normative research on
safe indoor use of fuel cells and hydrogen systems' (HYINDOOR
The project sought to provide scientific and engineering knowledge for
specifying cost-effective means to control hazards, and to develop
state-of-the-art safety guidelines.
HYINDOOR addressed knowledge gaps regarding indoor hydrogen
accumulation, vented deflagration and under-ventilated jet fire. The
generated knowledge should be translated into safety guidelines,
including contemporary engineering tools supporting their
implementation. Recommendations should be formulated for advancements in
the EU and international RCS frameworks to support the safe
introduction of HFC in early markets.
Project partners sought to enhance understanding of hydrogen
dispersion and accumulation in confined spaces. Work focused on a
room-like enclosure of typically a few tens of cubic metres with natural
ventilation. Based on existing and new analytical and numerical models,
partners worked on identifying characteristic regimes of hydrogen
dispersion. Parameters such as the size of the venting area, the size of
the enclosure area and the leak flow rates were taken into account.
A number of experiments were conducted to study vented hydrogen–air
deflagrations and the interplay between hydrogen–air and enclosure
parameters with regard to overpressure effects. Another task was to
conduct experimental and numerical studies on hydrogen jet fire
dynamics. Focus was placed on parameters such as self-extinction,
re-ignition, radiation and flame length from external hydrogen jet
Possible safety strategies should be given in a guidelines document
with important rules for indoor hydrogen use in the configurations
addressed by HYINDOOR. Additional safety devices should be proposed when
sizing methods are not sufficient to respect the safety rules.