The growing number of hydrogen fillings stations and cars increases the need for accurate models to determine risk. The effect on hydrogen flame length was measured by varying the diameter of the spouting nozzle downstream from the chocked nozzle upstream. The results was compared with an existing model for flame length estimations. The experimental rig was setup with sensors that measured accurately temperature, mass flow, heat radiation and the pressure range from 0.1 to 11 MPa. The flame length was determined with an in-house developed image-processing tool, which analyzed a high-speed film of the each experiment. Results show that the nozzle geometry can cause a deviation as high as 50% compared to estimated flame lengths by the model if wrong assumptions are made. Discharge coefficients for different nozzles has been calculated and presented.

This paper describes a methodology for simulating the structural response of vented enclosures during hydrogen deflagrations. The paper also summarises experimental results for the structural response of 20-foot ISO (International Organization for Standardization) containers in a series of vented hydrogen deflagration experiments. The study is part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations(HySEA). The project is funded by the Fuel Cells and Hydrogen 2 Joint Undertaking under grant agreement No 671461. The HySEA project focuses on vented hydrogen deflagrations in containers and smaller enclosures with internal congestion representative of industrial applications. The structural response modelling involves one-way coupling of pressure loads taken either directly from experiments or from simulations with the computational fluid dynamics (CFD) tool FLACS to the non-linear finite element (FE) IMPETUS Afea Solver. The performance of the FE model is evaluated for a range of experiments from the HySEA project in both small-scale enclosures and 20-foot ISO containers. The paper investigates the sensitivity of results from the FE model to the specific properties of the geometry model. The performance of FLACS is evaluated for a selected set of experiments from the HySEA project. Furthermore, the paper discusses uncertainties associated with the combined modelling approach.

This paper presents results from experiments on gas explosions in inhomogeneous hydrogen-air mixtures. The experimental channel is 3 m with a cross section of 100 mm by 100 mm and a 0.25 mm ID nozzle for hydrogen release into the channel. The channel is open in one end. Spectral analysis of the pressure in the channel is used to determine dynamic load factors for SDOF structures. The explosion pressures in the channel will fluctuate with several frequencies or modes and a theoretical high DLF is seen when the pressure frequencies and eigen frequencies of the structure matches.

In Japan, 82 commercial Hydrogen Refueling Stations (HRSs) were constructed as of March 1, 2017, but few impact assessments have been reported on the surroundings at HRS. In addition, as HRSs become more widespread, the number of HRSs around narrow urban areas will also increase. Thus, the necessity of impact assessments on the surroundings of HRSs is expected to increase. In order to confirm that the influence from our HRS is not problematic to the surrounding residences, we conducted an impact assessment on the surroundings at HRS by using the actual HRS construction plan. Although safety is one of the objects of an impact assessment, in Japan, the safety of an HRS is guaranteed by observing the High Pressure Gas Safety Act, its Technical Standards, and other related regulations. On the other hand, if an accident such as a hydrogen leak or hydrogen fire occurs at an HRS, it becomes important to prevent secondary disasters and to minimize influence on the surroundings by means of an initial response by the operators of the HRS. Therefore, we have conducted training to improve the emergency response capability of the HRS operators and to prevent secondary disasters. In this paper, we describe the above mentioned information with regard to an impact assessment on the surroundings and for emergency response training

Thermal hazards from an under-expanded (900 bar) hydrogen jet fire have been numerically investigated. The simulation results have been compared with the flame length and radiative heat flux measured for the horizontal jet fire experiment conducted at INERIS. The release blowdown characteristics have been modelled using the volumetric source as an expanded implementation of the notional nozzleconcept. The CFD study employs the realizable k-ε model for turbulence and the Eddy Dissipation Concept for combustion. Radiation has been taken into account through the Discrete Ordinates (DO) model. The results demonstrated good agreement with the experimental flame length. Performance of the model shall be improved to reproduce the radiative properties dynamics during the first stage of the release (time < 10 s), whereas, during the remaining blowdown time, the simulated radiative heat flux at five sensors followed the trend observed in the experiment.

A hydrogen leak from a facility, which uses highly compressed hydrogen gas (714 bar, 800 K) during operation was studied. The investigated scenario involves supersonic hydrogen release from a 10 cm2 leak of the pressurized reservoir, turbulent hydrogen dispersion in the facility room, followed by an accidental ignition and burn-out of the resulting H2-air cloud. The objective is to investigate the maximum possible flame velocity and overpressure in the facility room in case of a worst-case ignition. The pressure loads are needed for the structural analysis of the building wall response. The first two phases, namely unsteady supersonic release and subsequent turbulent hydrogen dispersion are simulated with GASFLOW-MPI. This is a well validated parallel, all-speed CFD code which solves the compressible Navier-Stokes equations and can model a broad range of flow Mach numbers. Details of the shock structures are resolved for the under-expanded supersonic jet and the sonic-subsonic transition in the release. The turbulent dispersion phase is simulated by LES. The evolution of the highly transient burnable H2-air mixture in the room in terms of burnable mass, volume, and average H2-concentration is evaluated with special sub-routines. For five different points in time the maximum turbulent flame speed and resulting overpressures are computed, using four published turbulent burning velocity correlations. The largest turbulent flame speed and overpressure is predicted for an early ignition event resulting in 35–71 m/s, and 0.13–0.27 bar, respectively

Vented deflagration tests were conducted by UNIPI at B. Guerrini Laboratory during the experimental campaign for HySEA project. Experiments included homogeneous hydrogen-air mixture in a 10-18% vol. range of concentrations contained in an about 1 m3 enclosure, called SSE (Small Scale Enclosure). Displacement measurements of a test plate were taken in order to acquire useful data for the validation of FE model developed by IMPETUS Afea. In this paper experimental facility, displacement measurement system and FE model are briefly described, then comparison between experimental data and simulation results is discussed.

A concept of volume porosity together with model of moving walls were elaborated and implemented into the COM3D code. Additionally to that a support of real-time data exchange with finite-element code ABAQUS - © Dassault Systèmes provided possibility to perform simulations of the gas-dynamic simultaneously with geometrical adaptation of environmental conditions. Based on the data obtained in the KIT combustion experiments in narrow gaps [1], the authors performed a series of the simulation on the combustion in the corresponding conditions. Obtained numerical results demonstrated good agreement with the observed experimental data. These data were also compared with those obtained in the simulation without wall bending, where simulation showed considerably different combustion regime. Application of the developed technique allows to obtain results unreachable without accounting on wall displacements, which demonstrates massive over-estimation of the pressures observed during flame propagation

As the energy crisis and environment pollution growing severely, the hydrogen fuel motor vehicle has got more and more attention, many automobile companies and research institutions invest significant R&D resources to research and develop the hydrogen fuel vehicles. With the development of the hydrogen fuel cell vehicles and hydrogen fuel motor vehicles, the hydrogen had more to more extensive application. According to the categories of the hydrogen fuel vehicles, the characteristics of hydrogen fuel vehicle fire risk and accidents are analyzed in this paper. As for hydrogen fuel cell vehicles, the function of its key components such as the fuel cell, the high-pressure storage tank is presented firstly. Then, based on the low density, fast diffusion and flammable of hydrogen, the probable scenarios of accident such as fuel leak, jet flame are analyzed and the fire risk of the key components and the whole vehicle is evaluated. Finally, the development trend of the emergency warning system of hydrogen fuel cell vehicles is analyzed and some recommendations are proposed referring to the detection, pre-warning and control technologies used in the industrial sites. Aiming at the hydrogen car structure characteristics and the fire accident modes and accidents evolution rules, the emergency disposal technology system for hydrogen fuel motor vehicles is put forward.

The paper presents the outcomes of the HyResponse project i.e. the European Hydrogen Safety Training Programme for first responders. The threefold training is described: the content of the educational training is presented, the operational training platform and its mock-up real scale transport and hydrogen stationary installations are detailed, and the innovative virtual tools and training exercises are highlighted. The paper underlines the outcomes the three pilot sessions as well as the Emergency Response Guide available on the HyResponse’s public website. The next steps for widespread dissemination into the community are discussed.