Designing an Inherently Safe H2 Infrastructure: Combining Analytical, Experimental, and Numerical Investigations to Optimize H2 Refuelling Stations Safety by Passive Mitigation

Natural ventilation is a well-known passive mitigation method to limit hydrogen build-up in confined spaces in case of accidental release [1-3]. In most cases, a basic design of H2 infrastructure is adopted and vents installed for natural ventilation are adjusted according to safety targets and constraints of the considered structure. With the growing H2 mobility market, the demand for H2 refueling infrastructure in our urban environment is on the rise. In order to meet both safety requirements and societal acceptance, the design of such infrastructure is becoming more important. In this study, a novel design concept is proposed for the hydrogen refueling station (HRS) by modifying physical structure while keeping safety consideration as the top priority of the concept. In this collaborative project between Air Liquide and the University of Delaware, an extensive evaluation was performed on new structures of the processing container and dispenser of HRS by integrating safety protocols via passive means. Through a SWOT analysis combined with the most relevant approaches including analytical engineering models, numerical simulations [4], and dedicated experimental trials an optimized design was obtained and its safety enhancement was fully evaluated. A small-scale processing container and an almost full-scale dispenser were built and tested to validate the design concepts by simulating accidental H2 release scenarios, and assessing the associated consequences in terms of accumulation and potential flammable volumes formation. A conical dispenser and a V-shaped roof-top processing container, which were easy to build and implement, were designed and tested for this proof-of-concept study. This unique methodology, from conception, fundamental analysis, investigation and validation through experimental design, execution, and evaluation, is fully described in this study.