Safety

The International Energy Agency’s Hydrogen Implementing Agreement (www.ieahia.org) initiated a collaborative task on hydrogen safety in 1994 and this has proved to an effective method of pooling expert knowledge to address the most significant problems associated with the barriers to the commercial adoption of hydrogen energy. Presently there are approximately 10 countries participating in the task and it has proven a valuable method of efficiently co Read More

The lay-out requirements developed for hydrogen systems operated in industrial environment are not suitable for the operating conditions specific to hydrogen refuelling stations (service pressure of up to 95 MPa facility for public use). A risk informed rationale has been developed to define and substantiate separation distance requirements in ISO 20100 Gaseous hydrogen – refuelling stations [1]. In this approach priority is given to preventing escalatio Read More

Hydrogen-air mixtures are flammable in a wide range of compositions and have a low ignition energy compared to gaseous hydrocarbons. Due to its low density high buoyancy and diffusivity the mixing is strongly enhanced which supports distribution into large volumes if accidentally released. Economically valuable discontinuous transportation over large distances is only expected using liquid hydrogen (LH2). Releases of LH2 at its low temperature (2 Read More

This paper gives a historical and technical overview of hydrogen storage vessels and details the specific issues and constraints of hydrogen energy uses. Hydrogen as an industrial gas is stored either as a compressed or as a refrigerated liquefied gas. Since the beginning of the last century hydrogen is stored in seamless steel cylinders. At the end of the 60s tubes also made of seamless steels were used; specific attention was paid to hydrogen embrittlem Read More

Efficient storage of hydrogen is crucial for the success of hydrogen energy markets (early markets as well as transportation market). Hydrogen can be stored either as a compressed gas a refrigerated liquefied gas a cryo-compressed gas or in hydrides. This paper gives an overview of hydrogen storage technologies and details the specific issues and constraints related to the materials behaviour in hydrogen and conditions representative of hydro Read More

Radiative heat fluxes from small to medium-scale hydrogen jet flames (<10 m) compare favorably to theoretical predictions provided the product species thermal emittance and optical flame thickness are corrected for. However recent heat flux measurements from two large-scale horizontally orientated hydrogen flames (17.4 and 45.9 m respectively) revealed that current methods underpredicted the flame radiant fraction by 40% or more. Newly Read More

Hydrogen leakage in a closed space is one of the causes of serious accidents because of its high detonability. Assuming the situation that hydrogen is accumulated in a closed space two-dimensional numerical simulation for hydrogen oxygen detonation which propagates in stratified fuel and oxidizer with concentration gradient is conducted by using detailed chemical reaction model. The concentration gradient between fuel and oxidizer is expresse Read More

The development of the temperature field in hydrogen tanks during the filling process has been investigated with Computational Fluid Dynamics (CFD). Measurements from experiments undertaken at the JRC GasTef facility have been used to develop and validate the CFD modelling strategy; by means of the CFD calculations the effect of the injector direction on the temperature distribution has been analysed. It has been found that the dynamics of the Read More

A possible consequence of pressurized hydrogen release is an under-expanded jet fire. Knowledge of the flame length radiative heat flux and fraction as well as the effects of variations in ground reflectance is important for safety assessment. The present study applies an open source CFD code FireFOAM to study the radiation characteristics of hydrogen and hydrogen/methane jet fires. For combustion the eddy dissipation concept for multi-component fuels Read More

This paper describes validation of the computational fluid dynamics tool FLACS-Hydrogen. The validation study focuses on concentration and pressure data from vented deflagration experiments performed in 20-foot shipping containers as part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA) funded by the Fuel Cells and Hydrogen 2 Joint Undertaking (FCH 2 JU). The paper Read More

The introduction of hydrogen into the UK natural gas main has been reviewed in terms of how materials within the gas distribution network may be affected by contact with up to 80% Natural Gas : 20 mol% hydrogen blend at up to 2 barg. A range of metallic polymeric and elastomeric materials in the gas distribution network (GDN) were assessed via a combination of literature review and targeted practical test programmes.The work considered:The Read More

The article discusses issues related to the operation of fuel cells stack fed with hydrogen at low temperature. The test object was a Toyota Mirai passenger car equipped with this type of powertrain. Tests were carried out in a thermoclimatic chamber at the Cracow University of Technology. They had an initial character and their aim was to evaluate the work of individual subassemblies of the propulsion system including the hydrogen supply system in ter Read More

Refueling infrastructure for use in gaseous hydrogen powered vehicles requires extensive manifolding for delivering the hydrogen from the stationary fuel storage at the refueling station to the vehicle as well as from the mobile storage on the vehicle to the fuel cell or combustion engine. Manifolds for gas handling often use welded construction (as opposed to compression fittings) to minimize gas leaks. Therefore it is important to understand the eff Read More

Hydrogen has potential applications that require larger-scale storage use and handling systems than currently are employed in emerging-market fuel cell applications. These potential applications include hydrogen generation and storage systems that would support electrical grid systems. There has been extensive work evaluating regulations codes and standards (RCS) for the emerging fuel cell market such as the infrastructure required to support f Read More

Explosion venting is a frequently used measure to mitigate the consequence of gas deflagrations in closed environments. Despite the effort to predict the vent area needed to achieved the protection through engineering formulas and CFD tools work has still to be done to reliably predict the outcome of a vented gas explosion. Most of available data derived from experimental campaigns performed in the past involved homogeneous conditions while especi Read More

This work presents a parametric study on the similitude between hydrogen and helium distribution when released in the air by a source located inside of a naturally ventilated enclosure with two vents. Several configurations were experimentally addressed in order to improve knowledge on dispersion. Parameters were chosen to mimic operating conditions of hydrogen energy systems. Thus the varying parameters of the study were mainly the s Read More

In industry handling hydrogen explosion presents a potential danger due to its effects on people and property. In the nuclear industry this explosion which is possible during severe accidents can challenge the reactor containment and it may lead to a release of radioactive materials into the environment. The Three Mile Island accident in the United States in 1979 and more recently the Fukushima accident in Japan have highlighted the importance of this Read More

Natural ventilation is an efficient and well-known way to mitigate a hydrogen build-up in the case of an accidental release in confined enclosures. However for some hydrogen energy applications natural ventilation is not possible or is not efficient enough to reach defined safety strategy. Thus mechanical or forced ventilation can be interesting means to avoid critical concentration of hydrogen considering degraded operation and associated potential hazardo Read More

Previous studies have shown that the two-layer model more accurately predicts hydrogen dispersion than the conventional notional nozzle models without significantly increasing the computational expense. However the model was only validated for predicting the concentration distribution and has not been adequately validated for predicting the velocity distributions. In the present study particle imaging velocimetry (PIV) was used to measure the velo Read More

The European Regulations on type-approval of hydrogen vehicles require thermally-activated pressure relief device (TPRD) to be installed on hydrogen onboard storage tanks to release its content in a fire event to prevent its catastrophic rupture. The aim of this study is to develop a model for design of an inherently safer system TPRD-storage tank. Parameters of tank materials and hydrogen external heat flux from the fire to the tank wall TPRD dia Read More

This paper examines the helium dispersion behaviour in a 16.6 m3 enclosure with a small opening in the floor and distributed leaks along the edges. Helium a simulant for hydrogen was injected near the center of the floor with an injection rate ranging from 2 to 50 standard liters per minute (Richardson number of 0.3–134) through an upward-facing nozzle. In a short-term transient the helium distribution predicted with the models of Baines & Turner (1969) a Read More

Tensile and fatigue tests were performed on an AA2198 aluminum alloy in the T851 condition in ambient air and liquid hydrogen (LH2). All fatigue tests were performed under load control at a frequency of 20 Hz and a stress ratio of R=0.1. The Gecks-Och-Function [1] was fitted on the measured cyclic lifetimes.The tensile strength in LH2 was measured to be 46 % higher compared to the value determined at ambient conditions and the fatigue limit was increa Read More

Purpose- To present an overview of the research and development carried out in a European funded framework 7 (FP7) project called SafeHPower for the implementation of neutron radiography to inspect fatigue cracks in vehicle and storage hydrogen fuel tanks. Project background– Hydrogen (H2) is the most promising replacement fuel for road transport due to its abundance efficiency low carbon footprint and the absence of harmful emissions. For the Read More

Liquid hydrogen (LH2) compared to compressed gaseous hydrogen offers advantages for large-scale transport and storage of hydrogen with higher densities. Although the gas industry has good experience with LH2 only little experience is available for the new applications of LH2 as an energy carrier. Therefore the European FCH JU funded project PRESLHY conducted pre-normative research for the safe use of cryogenic LH2 in non-industrial set Read More

Metastable austenitic stainless steels (ASSs) have excellent ductility but low strength so that their usage as load-bearing components is significantly limited. Rolling is an effective method of increasing strength whereas the effect of rolling temperature on microstructural evolution the hydrogen embrittlement (HE) sensitivity and fracture mechanisms is still unclear. In present study the effect of cold/warm rolling on detailed microstructural characteristics of 3 Read More