Influence of congestion on vented hydrogen deflagrations in 20-foot ISO containers: homogeneous fuel-air mixtures

This paper was presented at Twenty-Sixth International Colloquium on the Dynamics of Explosions and Reactive Systems (26 ICDERS) in Boston, 30 July – 4 August 2017.

Further progress in the field of hydrogen safety is a prerequisite for widespread acceptance and use of hydrogen as an energy carrier in society. Fires and explosions represent a significant hazard for hydrogen installations, and specific measures are generally required for reducing the risk to an acceptable level. It is common practice in industry to install electrolysers, refuelling stations, fuel cell backup systems and other equipment for hydrogen energy applications in containers or smaller enclosures, and explosion venting is a frequently used measure for reducing the consequences of hydrogen deflagrations in confined systems. Whereas most enclosures used for hydrogen applications in industry are inherently congested, the empirical correlations in international standards for design of venting devices, such as EN 14994 and NFPA 68, originate from explosion experiments performed with empty vessels. This situation motivated the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) call for proposal FCH-04.3-2014: ‘Pre-normative research on vented deflagrations in containers and enclosures for hydrogen energy applications’. In 2015, FCH JU granted funding to the project ‘Improving Hydrogen Safety for Energy Applications through pre-normative research on vented deflagrations’, or HySEA (www.hysea.eu). The HySEA project is scheduled to run from September 2015 to August 2018. The members of the HySEA consortium are Gexcon (coordinator), University of Warwick (UWAR), University of Pisa (UNIPI), Fike Europe B.v.b.a., Impetus Afea AS and Hefei University of Technology (HFUT).

The research activities in the project are organized in three work packages (WPs): engineering models and standards (WP1), experimental campaigns (WP2), and advanced modelling (WP3). The research activities in WP2 include two experimental studies: University of Pisa investigates hydrogen explosions in smaller enclosures and Gexcon conducts full-scale explosion experiments in 20-foot ISO containers. Each study consists of two separate campaigns: explosions in initially quiescent and homogeneous gas clouds, and explosions in initially turbulent and inhomogeneous clouds. In addition, Hefei University of Technology will conduct a series of experiments in 40-foot ISO containers. This paper presents results from the first part of the experimental campaign conducted by Gexcon, with homogeneous mixtures. The output from WP2 is important input to WP1, where the aim is to develop and validate engineering models suitable for standards, as well as to the work on computational fluid dynamics (CFD) and finite element (FE) methods in WP3.