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International audience; The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with high-momentum jet releases directed into congested geometries with subsequent ignition. The primary objective for the AIRRE project was to gain improved understanding of the effect that realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry. A secondary objective was to develop a methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or a medium level of congestion. For two of the tests, involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests and discusses the effect of the initial flow field generated by realistic releases - including turbulence, net flow and concentration gradients - on relevant explosion phenomena.

In the area of hydrogen safety, research facilities are essential for the experimental investigation of relevant phenomena, for testing devices and safety concepts, as well as for the generation of validation data for the various numerical codes and models. Within the framework of the European HySafe Network of Excellence (NoE), the 'Integration of Experimental Facilities (IEF)' activity has provided basic support for joint experimental work. Even beyond the funding period of the HySafe NoE in the 6th Framework Program, IEF represents a long-lasting effort for the sustainable integration of experimental research capacities and expertise of the partners from different research fields. In order to achieve a high standard in the quality of experimental data provided by the partners, emphasis was put on the know-how transfer between the partners. On the one hand, documentation on the experimental capacities was prepared and analyzed. On the other hand, a wiki-based communication platform was established, supported by biannual workshops covering topics ranging from measurement technologies to safety issues. Based on the partners' contributions, a working document was created on best practice including the joint experimental knowledge of all partners with regard to experimental set-ups and instrumentation. The paper gives an overview of the IEF partners and the network activities over the last five years. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

The paper presents an overview of the main achievements of the internal project InsHyde of the HySafe NoE. The scope of InsHyde was to investigate realistic small-medium indoor hydrogen leaks and provide recommendations for the safe use/storage of indoor hydrogen systems. Additionally, InsHyde served to integrate proposals from HySafe work packages and existing external research projects towards a common effort. Following a state of the art review, InsHyde activities expanded into experimental and simulation work. Dispersion experiments were performed using hydrogen and helium at the INERIS gallery facility to evaluate short and long term dispersion patterns in garage like settings. A new facility (GARAGE) was built at CEA and dispersion experiments were performed there using helium to evaluate hydrogen dispersion under highly controlled conditions. In parallel, combustion experiments were performed by FZK to evaluate the maximum amount of hydrogen that could be safely ignited indoors. The combustion experiments were extended later on by KI at their test site, by considering the ignition of larger amounts of hydrogen in obstructed environments outdoors. An evaluation of the performance of commercial hydrogen detectors as well as inter-lab calibration work was jointly performed by JRC, INERIS and BAM. Simulation work was as intensive as the experimental work with participation from most of the partners. It included pre-test simulations, validation of the available CFD codes against previously performed experiments with significant CFD code inter-comparisons, as well as CFD application to investigate specific realistic scenarios. Additionally an evaluation of permeation issues was performed by VOLVO, CEA, NCSRD and UU, by combining theoretical, computational and experimental approaches with the results being presented to key automotive regulations and standards groups. Finally, the InsHyde project concluded with a public document providing initial guidance on the use of hydrogen in confined spaces. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

International audience; The paper presents the results of the CFD inter-comparison exercise SBEP-V3, performed within the activity InsHyde, internal project of the HYSAFE network of excellence, in the framework of evaluating the capability of various CFD tools and modeling approaches in predicting the physical phenomena associated to the short and long term mixing and distribution of hydrogen releases in confined spaces. The experiment simulated was INERIS-TEST-6C, performed within the InsHyde project by INERIS, consisting of a 1 g/s vertical hydrogen release for 240 s from an orifice of 20 mm diameter into a rectangu ar room (garage) of dimensions 3.78x7.2x2.88 m in width, length and height respectively. Two small openings at the front and bottom side of the room assured constant pressure conditions. During the test hydrogen concentration time histories were measured at 12 positions in the room, for a period up to 5160 s after the end of release, covering both the release and the subsequent diffusion phases. The benchmark was organized in two phases. The first phase consisted of blind simulations performed prior to the execution of the tests. The second phase consisted of post-calculations performed after the tests were concluded and the experimental results made available. The participation in the benchmark was high: 12 different organizations (2 non-HYSAFE partners) 10 different CFD codes and 8 different turbulence models. Large variation in predicted results was found in the first phase of the benchmark, between the various modeling approaches. This was attributed mainly to differences in turbulence models and numerical accuracy options (time/space resolution and discretization schemes). During the second phase of the benchmark the variation between predicted results was reduced.

International audience; A method for determination of hazardous zones for hydrogen installations has been studied. This work has been carried out within the NoE HySafe. The method is based on the Italian Method outlined in Guide 31-30(2004), Guide 31-35(2001), Guide 31-35/A(2001), and Guide 31-35/A; V1(2003). Hazardous zones for a "generic hydrogen refuelling station"(HRS) are assessed, based on this method. The method is consistent with the EU directive 1999/92/EC "Safety and Health Protection of Workers potentially at risk from explosive atmospheres" which is the basis for determination of hazardous zones in Europe. This regulation is focused on protection of workers, and is relevant for hydrogen installations, such as hydrogen refuelling stations, repair shops and other stationary installations where some type of work operations will be involved. The method is also based on the IEC standard and European norm IEC/EN60079-10 "Electrical apparatus for explosive gas atmospheres. Part 10 Classification of hazardous areas". This is a widely acknowledged international standard/norm and it is accepted/approved by Fire and Safety Authorities in Europe and also internationally. Results from the HySafe work and other studies relevant for hydrogen and hydrogen installations have been included in the case study. Sensitivity studies have been carried out to examine the effect of varying equipment failure frequencies and leak sizes, as well as environmental condition (ventilation, obstacles, etc.). The discharge and gas dispersion calculations in the Italian Method are based on simple mathematical formulas. However, in this work also CFD (Computational Fluid Dynamics) and other simpler numerical tools have been used to quantitatively estimate the effect of ventilation and of different release locations on the size of the flammable gas cloud. Concentration limits for hydrogen to be used as basis for the extent of the hazardous zones in different situations are discussed.

This paper was presented at the Seventh International Conference of Hydrogen Safety (ICHS 2017) in Hamburg on 11-13 September 2017. The paper summarises the results from a blind-prediction study for models developed for estimating the consequences of vented hydrogen deflagrations. The work is part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA). The scenarios selected for the blind-prediction entailed vented explosions with homogeneous hydrogen-air mixtures in a 20-foot ISO container. The test program included two configurations and six experiments, i.e. three repeated tests for each scenario. The comparison between experimental results and model predictions reveals reasonable agreement for some of the models, and significant discrepancies for others. It is foreseen that the first blind-prediction study in the HySEA project will motivate developers to improve their models, and to update guidelines for users of the models. The paper is a deliverable from the project “Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations”, or HySEA (www.hysea.eu), which receives funding from the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) under grant agreement no. 671461. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and United Kingdom, Italy, Belgium and Norway.

International audience; In many areas European research has been largely fragmented. To support the required integration and to focus and coordinate related research efforts the European Commission created a new instrument, the Networks of Excellences (NoEs). The goal of the NoE HySafe has been to provide the basis to facilitate the safe introduction of hydrogen as an energy carrier by removing the safety related obstacles. The prioritisation of the HySafe internal project activities was based on a phenomena identification and ranking exercise (PIRT) and expert interviews. The identified research headlines were "Releases in (partially) confined areas", "Mitigation" and "Quantitative Risk Assessment". Along these headlines existing or planned research work was re-orientated and slightly modified, to build up three large internal research projects "InsHyde", "HyTunnel", and "HyQRA". In InsHyde realistic indoor hydrogen leaks and associated hazards have been investigated to provide recommendations for the safe use of indoor hydrogen systems including mitigation and detection means. The appropriateness of available regulations, codes and standards (RCS) has been assessed. Experimental and numerical work was conducted to benchmark simulation tools and to evaluate the related recommendations. HyTunnel contributed to the understanding of the nature of the hazards posed by hydrogen vehicles inside tunnels and its relative severity compared to other fuels. In HyQRA quantitative risk assessment strategies were applied to relevant scenarios in a hydrogen refuelling station and the performance was compared to derive also recommendations. The integration process was supported by common activities like a series of workshops and benchmarks related to experimental and numerical work. The networks research tools were categorised and published in online catalogues. Important integration success was provided by commonly setting up the International Conference on Hydrogen Safety, the first academic education related to hydrogen safety and the Hydrogen Safety Handbook. Finally, the network founded the International Association for Hydrogen Safety, which opens the future networking to all interested parties on an international level.