Numerical investigation of the gas concentration field during accidental release in a one vent small enclosure: effect of vent configurations

The accumulation of a flammable cloud in an enclosure due to accidental leaks is one of the potential accident scenarios related to the indoor use of hydrogen and fuel cell technologies. Indoor accident configurations involves a wide range of scales, depending on the site and the type of hydrogen technology: a hydrogen dispenser in a warehouse (for hydrogen powered forklifts), a hydrogen powered vehicle in a garage, a fuel cell or hydrogen storage in a cabinet or in a section of a container (back-up power supply, portable power generation, etc.). Vents are an essential means to reduce the hydrogen concentration and the hydrogen flammable mass inside an enclosure when a leak occurs. In this context, the HyIndoor project [1] have addressed the issue of the safe indoor use of hydrogen and fuel cells systems for early markets applications (forklift refuelling and operation, back-up power supply, portable power generation). The project main aim has been to provide scientific and engineering knowledge for the specification of cost-effective means to control hazards specific to the use of hydrogen indoors or in confined space and developing state-of-the-art guidelines for European stakeholders [2]. The HyIndoor project has been co-funded by the Fuel Cell and Hydrogen Joint Undertaking (FCH JU) that is a public-private partnership whose public partner is the European Commission. Within the project an extensive campaign of experiments and CFD simulations has been undertaken to provide data and information to address the issue of the safe indoor use of fuel cell and hydrogen technologies. Experimental data were also used for the validation of CFD models as described in Giannissi et al. [3]. Following the validation, additional CFD calculations have been performed to investigate some of those configurations that could not be included in the experimental campaign due to the limited time and resources. The objective of this paper is to describe the CFD analysis of the effects of some relevant parameters on the capability of the vent of reducing the gas concentration and the amount of flammable mass in a small scale enclosure. The selected parameters are the vent thickness, the presence of a rain protection device, and the presence of a duct. To the authors’ knowledge, this is the first time that the effect of those specific parameters is investigated

MELIDEO Daniele;  BARALDI Daniele; 

2016-09-16

Spanish Hydrogen Association

JRC100667

http://www.whec2016.com/index.php,    https://publications.jrc.ec.europa.eu/repository/handle/JRC100667,