- Home
- A-Z Publications
- Publications
Publications
A Temperature Controlled Mechanical Test Facility to Ensure Safe Materials Performance in Hydrogen at 1000 Bar
Sep 2007
Publication
Increasingly car manufacturers are turning to high pressure hydrogen storage for on-board power applications. Many prototypes use costly materials and fabrication methods such as Type 316L austenitic stainless steel and processes such as TIG (GTA) welding. There is a need to move to less expensive options without compromising safety to assist in developing economic vehicles. It is important that the behaviour of new/modified materials and joints (including those fabricated by new technologies) is understood at anticipated service temperatures and hydrogen pressure as the consequences of poor material choice could be severe. The greatest detrimental effect of gaseous hydrogen on the mechanical properties of metallic materials is commonly observed under conditions of dynamic plastic strain. Under such conditions an atomically clean surface is produced where hydrogen molecules will dissociate and penetrate the material. Thus static load test methods with hydrogen charging are not reliable for engineering data generation. To meet the need for dynamically straining material in a pressurised hydrogen environment TWI has developed a facility to load specimens in a high pressure environment for tensile toughness and fatigue testing. The design of this has involved a number of innovative steps. This paper outlines the requirements and the design and construction issues that were encountered when installing a facility which can not only perform tests at up to 1000bar (100MPa) but also for temperatures between –150°C to +85°C.
Simulation of Flame Acceleration and DDT in H2-air Mixture with a Flux Limiter Centred Method
Sep 2005
Publication
Flame acceleration and deflagration to detonation transition (DDT) is simulated with a numerical code based on a flux limiter centred method for hyperbolic differential equations. The energy source term is calculated by a Riemann solver for the in homogeneous Euler equations for the turbulent combustion and a two-step reaction model for hydrogen-air. The transport equations are filtered for large eddy simulation (LES) and the sub filter turbulence is modelled by a transport equation for the the turbulent kinetic energy. The flame tracking is handled by the G-equation for turbulent flames. Numerical results are compared to pressure histories from physical experiments. These experiments are performed in a closed circular 4m long tube with inner diameter of 0.107m. The tube is filled with hydrogen-air mixture at 1atm which is at rest when ignited. The ignition is located at one end of the tube. The tube is fitted with an obstruction with circular opening 1m down the tube from the ignition point. The obstruction has a blockage ratio of 0.92 and a thickness of 0.01m. The obstruction creates high pressures in the ignition end of the tube and very high gas velocities in and behind the obstruction opening. The flame experiences a detonation to deflagration transition (DDT) in the super sonic jet created by the obstruction. Pressure build-up in the ignition end of the tube is simulated with some discrepancies. The DDT in the supersonic jet is simulated but the position of the DDT is strongly dependent on the simulated pressure in the ignition end.
Risk Assessment for Hydrogen Codes and Standards
Sep 2005
Publication
The development and promulgation of codes and standards are essential to establish a market-receptive environment for commercial hydrogen-based products and systems. The focus of the U.S. Department of Energy (DOE) is to conduct the research and development (R&D) needed to strengthen the scientific basis for technical requirements incorporated in national and international standards codes and regulations. In the U.S. the DOE and its industry partners have formed a Codes and Standards Tech Team (CSTT) to help guide the R&D. The CSTT has adopted an R&D Roadmap to achieve a substantial and verified database of the properties and behaviour of hydrogen and the performance characteristics of emerging hydrogen technology applications sufficient to enable the development of effective codes and standards for these applications. However to develop a more structured approach to the R&D described above the CSTT conducted a workshop on Risk Assessment for Hydrogen Codes and Standards in March 2005. The purpose of the workshop was to attain a consensus among invited experts on the protocols and data needed to address the development of risk-informed standards codes and regulations for hydrogen used as an energy carrier by consumers. Participants at the workshop identified and assessed requirements methodologies and applicability of risk assessment (RA) tools to develop a framework to conduct RA activities to address for example hydrogen fuel distribution delivery on-site storage and dispensing and hydrogen vehicle servicing and parking. The CSTT was particularly interested in obtaining the advice of RA experts and representatives of standards and model code developing organizations and industry on how data generated by R&D can be turned into information that is suitable for hydrogen codes and standards development. The paper reports on the results of the workshop and the RA activities that the DOE’s program on hydrogen safety codes and standards will undertake. These RA activities will help structure a comprehensive R&D effort that the DOE and its industry partners are undertaking to obtain the data and conduct the analysis and testing needed to establish a scientific and technical basis for hydrogen standards codes and regulations.
A Microstructure Informed and Mixed-mode Cohesive Zone Approach to Simulating Hydrogen Embrittlement
Mar 2022
Publication
Hydrogen induced failure under uniaxial tension is simulated in a duplex stainless steel considering microstructural feature of the material. There are three key ingredients in the modelling approach: image processing and finite element representation of the experimentally observed microstructure stress driven hydrogen diffusion and diffusion coupled cohesive zone modelling of fracture considering mixed failure mode. The microstructure used as basis for the modelling work is obtained from specimens cut in the transverse and longitudinal directions. It is found that the microstructure significantly influences hydrogen diffusion and fracture. The austenite phase is polygonal and randomly distributed in the transverse direction where a larger effective hydrogen diffusion coefficient and a lower hydrogen fracture resistance is found compared to the specimen in the longitudinal direction where the austenite phase is slender and laminated. This indicates that the proper design and control of the austenite phase help improve hydrogen resistance of duplex stainless steel. The strength of the interface in the shear direction is found to dominate the fracture mode and initiation site which reveals the importance of considering mixed failure mode and calibrating the hydrogen induced strength reduction in shear.
Safety Distances- Definition and Values
Sep 2005
Publication
In order to facilitate the introduction of a new technology as it is the utilization of hydrogen as an energy carrier development of safety codes and standards besides the conduction of demonstrative projects becomes a very important action to be realized. Useful tools of work could be the existing gaseous fuel codes (natural gas and propane) regulating the stationary and automotive applications. Some safety codes have been updated to include hydrogen but they have been based on criteria and/or data applicable for large industrial facilities making the realization of public hydrogen infrastructures prohibitive in terms of space. In order to solve the above mentioned problems others questions come out: how these safety distances have been defined? Which hazard events have been taken as reference for calculation? Is it possible to reduce the safety distances through an appropriate design of systems and components or through the predisposition of adequate mitigation measures? This paper presents an analysis of the definitions of “safety distances” and “hazardous locations” as well as a synoptic analysis of the different values in force in several States for hydrogen and natural gas. The above mentioned synoptic table will highlight the lacks and so some fields that need to be investigated in order to produce a suitable hydrogen standard.
Canadian Hydrogen Safety Program.
Sep 2005
Publication
This paper discusses the rationale structure and contents of the Canadian Hydrogen Safety Program developed by the Codes & Standards Working Group of the Canadian Transportation Fuel Cell Alliance consisting of representatives from industry academia government and regulators. The overall program objective is to facilitate acceptance of the products services and systems of the Canadian Hydrogen Industry by the Canadian Hydrogen Stakeholder Community to facilitate trade ensure fair insurance policies and rates ensure effective and efficient regulatory approval procedures and to ensure that the interests of the general public are accommodated. The Program consists of four projects including Comparative Quantitative Risk Assessment of Hydrogen and Compressed Natural Gas (CNG) Refuelling Stations; Computational Fluid Dynamics (CFD) Modelling Validation Calibration and Enhancement; Enhancement of Frequency and Probability Analysis and Consequence Analysis of Key Component Failures of Hydrogen Systems; and Fuel Cell Oxidant Outlet Hydrogen Sensor Project. The Program projects are tightly linked with the content of the IEA Task 19 Hydrogen Safety. The Program also includes extensive (destructive and non-destructive) testing of hydrogen components.
Evaluation of Metal Materials for Hydrogen Fuel Stations
Sep 2005
Publication
Under government funded project: "Development for Safe Utilization and Infrastructure of Hydrogen" entrusted by New Energy and Industrial Technology Development Organization (NEDO) special material testing equipment with heavy walled pressure vessel under 45MPa gaseous hydrogen is facilitated. Tensile properties strain controlled low-cycle and high-cycle fatigue and fatigue crack growth tests on CrMo steel (SCM435 (JIS G 4105)) which will be applied for the storage gas cylinders in Japanese hydrogen fuel stations are investigated. The results of the tensile tests under 45MPa ultra high purity hydrogen gas (O2<1ppm) at room temperature shows that there are no difference in yield and maximum tensile strength with those tested in air. However the reduced ductilities with brittle fracture surface were observed which indicates the occurrence of hydrogen environment embrittlement. It was also found by tensile tests that the embrittling origin is not only caused by machined traces on surface but also by the non-metallic inclusions dispersed on surface. Further discussions on surface treatment effects will be presented. In low cycle fatigue tests considerable reductions in cycles to failure in 45MPa ultra high purity hydrogen gas were observed. However there are tendencies that the effect of hydrogen environment embrittlement becomes not so significant as the plastic strain range decreases. It was demonstrated that there was no effect of hydrogen on fatigue limit and this implies that CrMo gas cylinders can be operated in limited fatigue safe condition. Another series of hydrogen test results temperature effect fatigue crack growth rate delayed fracture test using wedge opening loaded specimens and fatigue test of CrMo gas cylinders under repeated internal pressure with artificial crack will be presented.
Phenomena of Dispersion and Explosion of High Pressurized Hydrogen
Sep 2005
Publication
To make “Hydrogen vehicles and refuelling station systems” fit for public use research on hydrogen safety and designing mitigative measures are significant. For compact storage it is planned to store under high pressure (40MPa) at the refuelling stations so that the safety for the handling of high-pressurized hydrogen is essential. This paper describes the experimental investigation on the hypothetical dispersion and explosion of high-pressurized hydrogen gas which leaks through a large scale break in piping and blows down to atmosphere. At first we investigated time history of distribution of gas concentration in order to comprehend the behaviour of the dispersion of high-pressurized hydrogen gas before explosion experiments. The explosion experiments were carried out with changing the time of ignition after the start of dispersion. Hydrogen gas with the initial pressure of 40MPa was released through a nozzle of 10mm diameter. Through these experiments it was clarified that the explosion power depends not only on the concentration and volume of hydrogen/air pre-mixture but also on the turbulence characteristics before ignition. To clarify the explosion mechanism the numerical computer simulation about the same experimental conditions was performed. The initial conditions such as hydrogen distribution and turbulent characteristics were given by the results of the atmospheric diffusion simulation. By the verification of these experiments the results of CFD were fully improved.
Quantitative Risk Analysis Of Gaseous Hydrogen Storage Unit
Sep 2005
Publication
A quantitative risk analysis to a central pressurized storage tank for gaseous hydrogen has been performed to attend requirements of licensing procedures established by the State Environment Agency of São Paulo State Brazil. Gaseous hydrogen is used to feed the reactor to promote hydrogenation at the surfactant unit. HAZOP was the hazard identification technique selected. System components failures were defined by event and fault tree analysis. Quantitative risk analysis was complied to define the acceptability concepts on societal and individual risks required by the State Environmental Agency to approve the installation operation license. Acceptable levels to public society from the analysis were reached. Safety recommendations to the gaseous hydrogen central were proposed to assure minimization of risk to the near-by community operators environment and property.
Testing of Hydrogen Safety Sensors in Service Simulated Conditions
Sep 2005
Publication
Reliable and effective sensors for the accurate detection of hydrogen concentrations in air are essential for the safe operation of fuel cells hydrogen fuelled systems (e.g. vehicles) and hydrogen production distribution and storage facilities. The present paper describes the activity on-going at JRC for the establishment of a facility that can be used for testing and validating the performance of hydrogen sensors under a range of conditions representative of those to be encountered in service. Potential aspects to be investigated in relation to the sensors performances are the influence of temperature humidity and pressure (simulating variations in altitude) the sensitivity to target gas and the cross sensitivity to other gases/vapours the reaction and recovery time and the sensors’ lifetime. The facility set up at JRC for the execution of these tests is described including the program for its commissioning. The results of a preliminary test are presented and discussed as an example.
Innovative Passive Protection Systems For Hydrogen Production Plants
Sep 2005
Publication
As a part of a broader project on hydrogen production by reforming of methane in a membrane catalytic reactor this paper outlines the research activity performed at the University of Pisa Department of Chemical Engineering aimed at developing and testing composite panels that can operate as thermal protective shields against hydrogen jet fires. The shield design criterion that appears to give a more practical and convenient solution for the type of installation to be protected is the one that suggest to realize composite panels. Composite material are made of two elements fiber and matrix. In this study composite panels will be realized with basalt fabric as fiber and epoxy-phenolic resins as matrix. Therefore following the indications given by norms as UNI 9174 and ASTM E 1321-93 a test method has been studied to obtain temperature data from a specimen impinged by an hydrogen flame. Thanks to thermocouples applied on backside of the sample and an infrared video camera to realize thermal images of specimen surface impinged by flame this type of test try to characterize the behaviour of composite materials under the action of hydrogen flame simulating in a simple way the action of hydrogen jet fires.
Hydrogen Detection- Visualisation of Hydrogen Using Non Invasive Optical Schlieren Technique BOS
Sep 2005
Publication
The detection of hydrogen after its accidental release is not only important for research purposes but will be much more important under safety aspects for future applications when hydrogen should be a standard energy resource. At Fraunhofer ICT two principally different approaches were made: first the new optical background-oriented schlieren method (BOS) is used for the visualization of hydrogen distribution and mixing processes at a rate of up to 1000 frames per second. The results from experiments with small scale injection of hydrogen/air–mixtures into air flows and free jets of hydrogen and hydrogen/air–mixtures emerging from 1” hoses simulating exhaust pipes will be discussed and interpreted with support from selected high speed videos. Finally mixing zones and safety distances can be determined by this powerful method.
Methodology of CFD Safety Analysis for Large-Scale Industrial Structures
Sep 2005
Publication
The current work is devoted to problems connected with application of CFD tools for safety analysis of large-scale industrial structures. With the aim to preserve conservatism of overall process of multistage procedure of such analysis special efforts are required. A strategy which has to lead to obtaining of reliable results in CFD analysis is discussed. Different aspects of proposed strategy including: adequate choice of physical and numerical models procedure of validation simulations and problem of ‘under-resolved’ simulations are considered. For physical phenomena which could cause significant uncertainties in the course of scenario simulation an approach which complements CFD simulations by application of auxiliary criteria is presented. Physical basis and applicability of strong flame acceleration and detonation-to-deflagration transition criteria are discussed. In concluding part two examples of application of presented approach for nuclear power plant and workshop cell for hydrogen driven vehicles are presented.
Design of Catalytic Recombiners for Safe Removal of Hydrogen from Flammable Gas Mixtures
Sep 2007
Publication
Several today’s and future applications in energy technology bear the risk of the formation of flammable hydrogen/air mixtures either due to the direct use of hydrogen or due to hydrogen appearing as a by-product. If there’s the possibility of hydrogen being released accidentally into closed areas countermeasures have to be implemented in order to mitigate the threat of an explosion. In the field of nuclear safety passive auto-catalytic recombiners (PAR) are well-known devices for reducing the risk of a hydrogen detonation in a nuclear power plant in the course of a severe accident. Hydrogen and oxygen react on catalyst materials like platinum or palladium already far below conventional flammability limits. The most important concern with regard to the utilization of hydrogen recombiners is the adequate removal of the reaction heat. Already low hydrogen concentrations may increase the system temperature beyond the self-ignition limit of hydrogen/air mixtures and may lead to an unintended ignition on hot parts of the PAR.<br/>Starting from the nuclear application since several years IEF-6 and LRST perform joint research in the field of passive auto-catalytic recombiners including experimental studies modelling and development of new design concepts. Recently approaches on specifically designed catalysts and on passive cooling devices have been successfully tested. In a design study both approaches are combined in order to provide means for efficient and safe removal of hydrogen. The paper summarizes results achieved so far and possible designs for future applications.
Novel Safe Method Of Manufacturing Hydrogen Metallic Hydrides
Sep 2005
Publication
The present work proposes a novel safe method for obtaining metallic hydrides. The method is called SHS (Self-Propagating High temperature synthesis). A novel high pressure gas reactor governed by an electromechanical control device has been designed and built up in order to synthesise metallic hydrides. This system is provided with a control system that allows calculating the amount of gas coming into the reaction vessel at every stage of the process. The main feature of this method is that metallic hydrides can be safely synthesised using low gas reaction pressures. In order to validate the assessing system the main kinetic regularities of SHS in Ti-H2 system were studied. In addition phase analysis (by means of X ray diffraction) as well as chemical analysis have been performed.
Defining Hazardous Zones – Electrical Classification Distances
Sep 2005
Publication
This paper presents an analysis of computational fluid dynamic models of compressed hydrogen gas leaks into the air under different conditions to determine the volume of the hydrogen/air mixture and the extents of the lower flammable limit. The necessary hole size was calculated to determine a reasonably expected hydrogen leak rate from a valve or a fitting of 5 and 20 cfm under 400 bars resulting in a 0.1 and 0.2 mm effective diameter hole respectively. The results were compared to calculated hypothetical volumes from IEC 60079-10 for the same mass flowrate and in most cases the CFD results produced significantly smaller hydrogen/air volumes than the IEC standard. Prescriptive electrical classification distances in existing standards for hydrogen and compressed natural gas were examined but they do not consider storage pressure and there appears to be no scientific basis for the distance determination. A proposed table of electrical classification distances incorporating hydrogen storage volume and pressure was produced based on the hydrogen LFL extents from a 0.2 mm diameter hole and the requirements of existing standards. The PHOENICS CFD software package was used to solve the continuity momentum and concentration equations with the appropriate boundary conditions buoyancy model and turbulence models. Numerical results on hydrogen concentration predictions were obtained in the real industrial environment typical for a hydrogen refuelling or energy station.<br/><br/>
Effect of Carbon Dioxide, Argon and Hydrocarbon Fuels on the Stability of Hydrogen Jet Flames
Sep 2005
Publication
Experimental studies were carried out to examine the lift-off and blow-out stability of H2/CO2 H2/Ar H2/C3H8 and H2/CH4 jet flames. The experiments were carried out using a burner with a 2mm inner diameter. The flame structures were recorded by direct filming and also by a schlieren apparatus. The experiments showed that the four gases affected the lift-off and blow-out stability of the hydrogen differently. The experiments showed that propane addition to an initially attached flame always produced lifted flame and the flame was blown out at higher jet velocity. The blow-out velocity decreased as the increasing in propane concentration. Direct blow-off of hydrogen/propane was never observed. Methane addition resulted in a relatively stable flame comparing with the carbon dioxide and propane addition. Comparisons of the stability of H2/C3H8 H2/CH4 and H2/CO2 flames showed that H2/C3H8 produced the highest lift-off height. Propane is much more effective in lift-off and blow out hydrogen flames. The study carried out a chemical kinetic analysis of H2/CO2 H2/Ar H2/C3H8 and H2/CH4 flames for a comparison of effect of chemical kinetics on flame stability.
Characterization of Materials in Pressurized Hydrogen Under Cyclic Loading at Service Conditions in Hydrogen Powered Engines
Sep 2005
Publication
A new testing device for cyclic loading of specimens with a novel shape design is presented. The device was applied for investigations of fatigue of metallic specimens under pressurized hydrogen up to 300 bar at temperatures up to 200 °C. Main advantage of the specimen design is the very small amount of medium here hydrogen used for testing. This allows experiments with hazardous substances at lower safety level. Additionally no gasket for the load transmission is required. Woehler curves which show the influence of hydrogen on the fatigue behaviour of austenitic steel specimens at relevant service conditions in hydrogen powered engines are presented. Material and test conditions are in agreement with the cooperating industry.
Analysis of Buoyancy-driven Ventilation of Hydrogen from Buildings
Sep 2007
Publication
When hydrogen gas is used or stored within a building as with a hydrogen-powered vehicle parked in a residential garage any leakage of unignited H2 will mix with indoor air and may form a flammable mixture. One approach to safety engineering relies on buoyancy-driven passive ventilation of H2 from the building through vents to the outside. To discover relationships between design variables we combine two types of analysis: (1) a simplified 1-D steady-state analysis of buoyancy-driven ventilation and (2) CFD modelling using FLUENT 6.3. The simplified model yields a closed-form expression relating the H2 concentration to vent area height and discharge coefficient; leakage rate; and a stratification factor. The CFD modelling includes 3-D geometry; H2 cloud formation; diffusion momentum convection and thermal effects; and transient response. We modelled a typical residential two-car garage with 5 kg of H2 stored in a fuel tank; leakage rates of 5.9 to 82 L/min (tank discharge times of 12 hours to 1 week); a variety of vent sizes and heights; and both isothermal and nonisothermal conditions. This modelling indicates a range of the stratification factor needed to apply the simplified model for vent sizing as well as a more complete understanding of the dynamics of H2 movement within the building. A significant thermal effect occurs when outdoor temperature is higher than indoor temperature so that thermocirculation opposes the buoyancy-driven ventilation of H2. This circumstance leads to higher concentrations of H2 in the building relative to an isothermal case. In an unconditioned space such as a residential garage this effect depends on the thermal coupling of indoor air to outdoor air the ground (under a concrete slab floor) and an adjacent conditioned space in addition to temperatures. We use CFD modelling to explore the magnitude of this effect under rather extreme conditions.
An Inter-Comparison Exercise on the Capabilities of CFD Models to Predict the Short and Long Term Distribution and Mixing of Hydrogen in a Garage
Sep 2007
Publication
Alexandros G. Venetsanos,
E. Papanikolaou,
J. García,
Olav Roald Hansen,
Matthias Heitsch,
Asmund Huser,
Wilfried Jahn,
Jean-Marc Lacome,
Thomas Jordan,
H. S. Ledin,
Dmitry Makarov,
Prankul Middha,
Etienne Studer,
Andrei V. Tchouvelev,
Franck Verbecke,
M. M. Voort,
Andrzej Teodorczyk and
M. A. Delichatsios
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 modelling 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 rectangular 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 modelling 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.
Gaseous Hydrogen Refueling Stations: Selection Of Materials For High Pressure Hydrogen Fueling Connectors
Sep 2005
Publication
Design of hydrogen fueling components is critical for safety and reliability. Intensive usage of such components in urban public environment is expected in the near future. Any leakage of gas or failure of equipment will create potential hazards. Materials for such category of equipment must have specific mechanical characteristics including hardness (influence on the durability of the equipment and on the resistance to hydrogen) and be easy to machine. Air Liquide has developed a test program for qualifying equipment representing the present state of the art. Studies on the susceptibility of various steels to hydrogen embrittlement have been done. Test specimens were exposed to static and cyclic loads with hydrogen and an inert gas the inert gas representing a reference. Various tests are described here. As a result the importance of further development in the design and selection of appropriate materials for critical hydrogen components is required. Various options are presented and discussed.
Analysis of Jet Flames and Unignited Jets from Unintended Releases of Hydrogen
Sep 2007
Publication
A combined experimental and modeling program is being carried out at Sandia National Laboratories to characterize and predict the behavior of unintended hydrogen releases. In the case where the hydrogen leak remains unignited knowledge of the concentration field and flammability envelope is an issue of importance in determining consequence distances for the safe use of hydrogen. In the case where a high-pressure leak of hydrogen is ignited a classic turbulent jet flame forms. Knowledge of the flame length and thermal radiation heat flux distribution is important to safety. Depending on the effective diameter of the leak and the tank source pressure free jet flames can be extensive in length and pose significant radiation and impingement hazard resulting in consequence distances that are unacceptably large. One possible mitigation strategy to potentially reduce the exposure to jet flames is to incorporate barriers around hydrogen storage equipment. The reasoning is that walls will reduce the extent of unacceptable consequences due to jet releases resulting from accidents involving high-pressure equipment. While reducing the jet extent the walls may introduce other hazards if not configured properly. The goal of this work is to provide guidance on configuration and placement of these walls to minimize overall hazards using a quantitative risk assessment approach. Detailed Navier-Stokes calculations of jet flames and unignited jets are used to understand how hydrogen leaks and jet-flames interact with barriers. The effort is complemented by an experimental program that considers the interaction of jet flames and unignited jets with barriers.
Hydrogen Refueling Stations: Safe Filling Procedures
Sep 2005
Publication
Safety is a high priority for a hydrogen refueling station. Here we propose a method to safely refuel a vehicle at optimised speed of filling with minimum information about it. Actually we identify two major risks during a vehicle refuelling: over filling and overheating. These two risks depend on the temperature increase in the tank during refuelling. But the inside temperature is a difficult information to get from the station point of view. It assumes a temperature sensor in a representative place of the tank and an additional connection between the vehicle and the station for data exchange. The refuelling control may not depend on this parameter only. Therefore out objective was to effectively control the filling particularly to avoid the two identified risks independently of optional and safety redundant information from the vehicle. For that purpose we defined a maximum filling pressure which corresponds to the most severe following conditions: if the maximum temperature is reached in the tank or if the maximum capacity is reached in the tank. This maximum pressure depends on a few filling parameters which are easily available. The method and its practical applications are depicted.
Collaborative Activities On Hydrogen Safety under the International Energy Agency’s Hydrogen Implementing
Sep 2005
Publication
In October 2004 the International Energy Agency Hydrogen Implementing Agreement (www.ieahia.org) approved the initiation of a collaborative task on hydrogen safety. During the past twelve months a work plan has been established and several member countries have committed to participate. Because of the nature of the International Energy Agency which is an international agreement between governments it is hoped that such collaboration will complement other cooperative efforts to help build the technology base around which codes and standards can be developed. In this way the new task on hydrogen safety will further the IEA Hydrogen Agreement in fulfilling its mission to accelerate the commercial introduction of hydrogen energy. This paper describes the specific scope and work plan for the collaboration that has been developed to date.
An Intercomparison Exercise on the Capabilities of CFD Models to Predict Distribution and Mixing of H2 in a Closed Vessel.
Sep 2005
Publication
This paper presents a compilation and discussion of the results supplied by HySafe partners participating in the Standard Benchmark Exercise Problem (SBEP) V1 which is based on an experiment on hydrogen release mixing and distribution inside a vessel. Each partner has his own point of view of the problem and uses a different approach to the solution. The main characteristics of the models employed for the calculations are compared. The comparison between results together with the experimental data when available is made. Relative deviations of each model from the experimental values are also included. Explanations and interpretations of the results are presented together with some useful conclusions for future work.
Potential Models For Stand-Alone And Multi-Fuel Gaseous Hydrogen Refuelling Stations- Assessment Of Associated Risk
Sep 2005
Publication
Air pollution and traffic congestion are two of the major issues affecting public authorities policy makers and citizens not only in Italy and European Union but worldwide; this is nowadays witnessed by always more frequent limitations to the traffic in most of Italian cities for instance. Hydrogen use in automotive appears to offer a viable solution in medium-long term; this new perspective involves the need to carry out adequate infrastructures for distribution and refuelling and consequently the need to improve knowledge on hydrogen technologies from a safety point of view. In the present work possible different configurations for gaseous hydrogen refuelling station has been compared: “stand-alone” and “multi-fuel”. These two alternative scenarios has been taken into consideration each of one with specific hypotheses: “stand-alone” configuration based on the hypothesis of a potential model consisting of a hydrogen refuelling station composed by on-site hydrogen production via electrolysis a trailer of compressed gas for back-up compressor unit intermediate storage unit and dispenser. In this model it is assumed that no other refuelling equipment and/or dispenser of traditional fuel is present in the same site. “multi-fuel” configuration where it is assumed that the same components for hydrogen refuelling station are placed in the same site beside one or more refuelling equipment and/or dispenser of traditional fuel. Comparisons have been carried out from the point of view of specific risk assessment which have been conducted on both the two alternative scenarios.
Optimal Operation of a Microgrid with Hydrogen Storage Based on Deep Reinforcement Learning
Jan 2022
Publication
Microgrid with hydrogen storage is an effective way to integrate renewable energy and reduce carbon emissions. This paper proposes an optimal operation method for a microgrid with hydrogen storage. The electrolyzer efficiency characteristic model is established based on the linear interpolation method. The optimal operation model of microgrid is incorporated with the electrolyzer efficiency characteristic model. The sequential decision-making problem of the optimal operation of microgrid is solved by a deep deterministic policy gradient algorithm. Simulation results show that the proposed method can reduce about 5% of the operation cost of the microgrid compared with traditional algorithms and has a certain generalization capability.
CFD Modeling of Hydrogen Dispersion Experiments for SAE J2578 Test Methods Development
Sep 2007
Publication
This paper discusses the results of validation of Computational Fluid Dynamics (CFD) modelling of hydrogen releases and dispersion inside a metal container imitating a single car garage based on experimental results. The said experiments and modelling were conducted as part of activities to predict fuel cell vehicles discharge flammability and potential build-up of hydrogen for the development of test procedures for the Recommended Practice for General Fuel Cell Vehicle Safety SAE J2578. The experimental setup included 9 hydrogen detectors located in each corner and in the middle of the roof of the container and a fan to ensure uniform mixing of the released hydrogen. The PHOENICS CFD software package was used to solve the continuity momentum and concentration equations with the appropriate boundary conditions buoyancy effect and turbulence models. Obtained modelling results matched experimental data of a high-rate injection of hydrogen with fan-forced dispersion used to create near-uniform mixtures with a high degree of accuracy. This supports the conclusion that CFD modelling will be able to predict potential accumulation of hydrogen beyond the experimental conditions. CFD modelling of hydrogen concentrations has proven to be reliable effective and relatively inexpensive tool to evaluate the effects of hydrogen discharge from hydrogen powered vehicles or other hydrogen containing equipment.
Determination Of Hazardous Zones For A Generic Hydrogen Station – A Case Study
Sep 2007
Publication
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.
Safety Aspects of Land-Use Planning Scenarios for a Future Infrastructure with Hydrogen Re-Fuelling Stations
Sep 2005
Publication
Hydrogen is currently gaining much attention as a possible future substitute for oil in the transport sector. Hydrogen is not a primary energy source but can be produced from other sources of energy. A future hydrogen economy will need the establishment of new infrastructures for producing storing distributing dispensing and using hydrogen. Hydrogen can be produced in large-scale centralized facilities or in smaller scale on-site systems. Large-scale production requires distribution in pipelines or trucks. A major challenge is to plan the new infrastructures to approach an even safer society regarding safe use of hydrogen. The paper will on the basis of some scenarios for hydrogen deployment highlight and evaluate safety aspects related to future hydrogen economy infrastructures.
Evaluation of Safety Distances Related to Unconfined Hydrogen Explosions
Sep 2005
Publication
A simple approximate method for evaluation of blast effects and safety distances for unconfined hydrogen explosions is presented. The method includes models for flame speeds hydrogen distribution blast parameters and blast damage criteria. An example of the application of this methodology for hydrogen releases in three hypothetical obstructed areas with different levels of congestion is presented. The severity of the blast effect of unconfined hydrogen explosions is shown to depend strongly on the level of congestion for relatively small releases. Extremely large releases of hydrogen are predicted to be less sensitive to the congestion level.
HySafe European Network of Excellence on Hydrogen Safety
Sep 2005
Publication
Introduction and commercialisation of hydrogen as an energy carrier of the future make great demands on all aspects of safety. Safety is a critical issue for innovations as it influences the economic attractiveness and public acceptance of any new idea or product. However research and safety expertise related to hydrogen is quite fragmented in Europe. The vision of a significant increased use of hydrogen as an energy carrier in Europe could not go ahead without strengthening and merging this expertise. This was the reason for the European Commission to support the launch on the first of March 2004 of a so-called Network of Excellence (NoE) on hydrogen safety: HySafe.
Development of Hydrogen Sensors and Recombiners
Sep 2005
Publication
Hydrogen energy is very promising as it ensures a high efficiency and ecological cleanliness of energy conversion. The goal of the present work is to provide the analysis of hydrogen safety aspects and to prescribe methods of safety operation with hydrogen. The authors conducted a hazard analysis of hydrogen operation and storage in comparison with other fuels. Good ventilation is the main hydrogen operation requirement. Besides an effective way of protection against propagation of hazards (for instance leaks) is neutralization of dangerous hydrogen-air mixtures by a method of controlled catalytic combustion inside special devices so-called recombiners [1-3]. The basis of these devices is a high porosity cell material (HPCM) activated by platinum deposition. Apart from recombiners HPCM was also applied for development of hydrogen detectors intended for measurement and analysis of hydrogen concentration for hydrogen-driven transport and objects of hydrogen infrastructure (including vapor-air media at high pressure and temperatures). A system of hydrogen safety based on hydrogen detectors and hydrogen catalytic recombiners was developed. Experimental and theoretical studies of hydrogen combustion processes heat- and mass transfer and also gas flows in catalytic-activated HPCM allowed for a design optimization of recombiners and their location. Pilot hydrogen detectors and hydrogen catalytic recombiners were fabricated and their laboratory tests were successfully performed. Thus it was indicated that on condition of following the appropriate passive and active safety measures hydrogen is just as safe as the other fuels. This conclusion represents another incentive for a transition to the hydrogen energy.
Development of Tools for Risk Assessment and Risk Communication for Hydrogen Applications
Sep 2005
Publication
For decades risk assessment has been an important tool in risk management of activities in several industries world wide. It provides among others authorities and stakeholders with a sound basis for creating awareness about existing and potential hazards and risks and making decisions related to how they can prioritise and plan expenditures on risk reduction. The overall goal of the ongoing HySafe project is to contribute to the safe transition to a more sustainable development in Europe by facilitating the safe introduction of hydrogen technologies and applications. An essential element in this is the demonstration of safety: that all safety aspects related to production transportation and public use are controlled to avoid that introducing hydrogen as energy carrier should pose unacceptable risk to the society.<br/>History has proven that introducing risk analysis to new industries is beneficial e.g. in transportation and power production and distribution. However this will require existing methods and standards to be adapted to the specific applications. Furthermore when trying to quantify risk it is of utmost importance to have access to relevant accident and incident information. Such data may in many cases not be readily available and the utilisation of them will then require specific and long lasting data collection initiatives.<br/>In this paper we will present the work that has been undertaken in the HySafe project in developing methodologies and collecting data for risk management of hydrogen infrastructure. Focus is laid on the development of risk acceptance criteria and on the demonstration of safety and benefits to the public. A trustworthy demonstration of safety will have to be based on facts especially on facts widely known and emphasis will thus be put on the efforts taken to establish and operate a database containing hydrogen accident and incident information which can be utilised in risk assessment of hydrogen applications. A demonstration of safety will also have to include a demonstration of risk control measures and the paper will also present work carried out on safety distances and ignition source control.
Impact of Hydrogen Injection on Natural Gas Measurement
Dec 2021
Publication
Hydrogen is increasingly receiving a primary role as an energy vector in ensuring the achievement of the European decarbonization goals by 2050. In fact Hydrogen could be produced also by electrolysis of water using renewable sources such as photovoltaic and wind power being able to perform the energy storage function as well as through injection into natural gas infrastructures. However hydrogen injection directly impacts thermodynamic properties of the gas itself such as density calorific value Wobbe index sound speed etc. Consequently this practice leads to changes in metrological behavior especially in terms of volume and gas quality measurements. In this paper the authors present an overview on the impact of hydrogen injection in natural gas measurements. In particular the changes in thermodynamic properties of the gas mixtures with different H2 contents have been evaluated and the effects on the accuracy of volume conversion at standard conditions have been investigated both on the theoretical point of view and experimentally. To this end the authors present and discuss the effect of H2 injection in gas networks on static ultrasonic domestic gas meters both from a theoretical and an experimental point of view. Experimental tests demonstrated that ultrasonic gas meters are not significantly affected by H2 injection up to about 10%.
Hydrogen Transport Safety: Case of Compressed Gaseous Tube Trailer
Sep 2005
Publication
The following paper describes researches to evaluate the behaviour under various accidental conditions of systems of transport compressed hydrogen. Particularly have been considered gaseous tube trailer and the packages cylinders employed for the road transport which have an internal gas pressures up to 200 barg.<br/>Further to a verification of the actual safety conditions this analysis intends to propose a theme that in the next future if confirmed projects around the employment of hydrogen as possible source energetic alternative could become quite important. The general increase of the consumptions of hydrogen and the consequently probable increase of the transports of gaseous hydrogen in pressure they will make the problem of the safety of the gaseous tube trail particularly important. Gaseous tube trailers will also use as components of plant. for versatility easy availability' and inexpensiveness.<br/>The first part of the memory is related to the analysis of the accidents happened in the last year in Italy with compressed hydrogen transports and particularly an accurate study has been made on the behaviour of a gaseous tube trailer involved in fire following a motorway accident in March 2003. In the central part of the job has been done a safety analysis of the described events trying to make to also emerge the most critical elements towards the activities developed by the teams of help intervened.<br/>Finally in the last part you are been listed on the base of the picked data a series of proposals and indications of the possible structural and procedural changes that could be suggested with the purpose to guarantee more elevated safety levels.
A Reappraisal of Containment Safety Under Hydrogen Detonation
Sep 2005
Publication
The response of a typical steel-lined reinforced concrete nuclear reactor containment to postulated internal hydrogen detonations is investigated by detailed axisymetric non-linear dynamic finite element analysis. The wall pressure histories are calculated for hydrogen detonations using a technique that reproduces the sharp discontinuity at the shock front. The pressure results can be applied to geometrically similar vessels. The analysis indicates that the response is more sensitive to the point of initiation than to the strength of the detonation. Approximate solutions based on a pure impulse assumption where the containment is modelled as a single-degree-of freedom (SDOF) system may be seriously unconservative. This work becomes relevant because new nuclear reactors are foreseen as a primary of source of hydrogen supply.<br/><br/>
Guidelines for Fire Corps Standard Operating Procedures in the Event of Hydrogen Releases
Sep 2007
Publication
This paper presents a study on the Standard Operating Procedures (P.O.S.s) for the operation of the Fire Corps squads in the event of accidents with a hydrogen release fire or explosion. This study has been carried out by the Italian Working Group on the fire prevention safety issues as one of its main objectives. The Standard Operating Procedures proved to be a basic tool in order to improve the effectiveness of the Fire Corps rescue activity. The unique physical and chemical properties of the hydrogen its use without odorization and its almost invisible flame require a review of the already codified approaches to the rescue operations where conventional gases are involved. However this is only the first step; a Standard Operating Procedure puts together both the theoretical and practical experience achieved on the management of the rescue operations; therefore its arrangement is a cyclic process by nature always under continuous revision updating and improvement.
Simulator Development of Virtual Experience and Accident Scenarios of Hydrogen Stations for Safety
Sep 2007
Publication
Nowadays 4 type hydrogen stations have been demonstrated in Korea for preparing hydrogen economy. This simulator is consists of virtual experience modules and virtual accident scenarios of 4 type hydrogen stations. Virtual experience modules show the performance properties through a movie or a virtual reality technology. Also they provide an explanation of hydrogen station equipment and a guide for operators immediately after the accident. Virtual accident scenario modules show accident simulations based on modelling equations as 3D virtual reality. These modules could choose the sham accident for every kind of a station after categorizing all possible accidents in a station A Commercialized CFD program based on hydrogen dispersion model theory shows a movie of accident simulations. The result of a simulator has been developed as web applications. And will be applied to training materials and public relations for a user concerned about hydrogen stations.
Gas Build-up in a Domestic Property Following Releases of Methane/Hydrogen Mixtures
Sep 2007
Publication
The EC funded Naturalhy project is investigating the possibility of promoting the swift introduction of hydrogen as a fuel by mixing hydrogen with natural gas and transporting this mixture by means of the existing natural gas pipeline system to end-users. Hydrogen may then be extracted for use in hydrogen fuel cell applications or the mixture may be used directly in conventional gas-fired equipment. This means that domestic customers would receive a natural gas (methane)/hydrogen mixture delivered to the home. As the characteristics of hydrogen are different from natural gas there may be an increased risk to end-users in the event of an accidental release of gas from internal pipe work or appliances. Consequently part of the Naturalhy project is aimed at assessing the potential implications on the safety of the public which includes end-users in their homes. In order to understand the nature of any gas accumulation which may form and identify the controlling parameters a series of large scale experiments have been performed to study gas accumulations within a 3 m by 3 m by 2.3 m ventilated enclosure representing a domestic room. Gas was released vertically upwards at a pressure typical of that experienced in a domestic environment from hole sizes representative of leaks and breaks in pipe work. The released gas composition was varied and included methane and a range of methane/hydrogen mixtures containing up to 50% hydrogen. During the experiments gas concentrations throughout the enclosure and the external wind conditions were monitored with time. The experimental data is presented. Analysis of the data and predictions using a model developed to interpret the experimental data show that both buoyancy and wind driven ventilation are important.
Influence of Temperature on the Fatigue Strength of Compressed Hydrogen Tanks for Vehicles
Sep 2009
Publication
The influence of environmental temperatures on the fatigue strength of compressed-hydrogen tanks for vehicles was investigated. The fatigue strength of Type-3 tanks was found to decrease in a low temperature environment and increase in a high-temperature environment. The Type-3 tank has been subjected to autofrettage to improve fatigue strength. The investigation clarified that the effect of autofrettage changes according to the environmental temperature due to the difference between the coefficients of thermal expansion of carbon fiber reinforced plastic (CFRP) and aluminum alloy. This causes life strength to change with changes in temperature. These results indicate that the service life of the Type-3 tank is influenced by the environmental temperature. The Type-4 tank has a very long fatigue life and did not break after 45000 cycles in a room-temperature or low-temperature environment. In a high-temperature environment however the tank broke in fewer than 45000 cycles. The fatigue of CFRP was promoted in the high-temperature environment resulting in breakage of the tank.
Addressing Hydrogen Embrittlement of Metals in the Sae J2579 Fuel Cell Vehicle Tank Standard
Sep 2013
Publication
The SAE Technical Information Report (TIR) J2579 (Technical Information Report for Fuel Systems in Fuel Cell and Other Hydrogen Vehicles) has been created to address the safety performance of hydrogen storage and handling systems on vehicles. Safety qualification of the compressed hydrogen storage system is demonstrated through performance testing on prototype containment vessels. The two performance tests currently included in the SAE J2579 for evaluating unacceptable leakage and burst do not account for the potential effects of hydrogen embrittlement on structural integrity. This report describes efforts to address hydrogen embrittlement of structural metals in the framework of performance-based safety qualification. New safety qualification pathways that account for hydrogen embrittlement in the SAE J2579 include an additional pneumatic performance test using hydrogen gas or materials tests that demonstrate acceptable hydrogen embrittlement resistance of candidate structural metals.
Study of Hydrogen Diffusion and Deflagration in a Closed System
Sep 2007
Publication
A total of 12 ventilation experiments with various combinations of hydrogen release rates and ventilation speeds were performed in order to study how ventilation speed and release rate effect the hydrogen concentration in a closed system. The experiential facility was constructed out of steel plates and beams in the shape of a rectangular enclosure. The volume of the test facility was about 60m3. The front face of the enclosure was covered by a plastic film in order to allow visible and infrared cameras to capture images of the flame. The inlet and outlet vents were located on the lower front face and the upper backside panel respectively. Hydrogen gas was released toward the ceiling from the center of the floor. The hydrogen gas was released at constant rate in each test. The hydrogen release rate ranged from 0.002 m3/s to 0.02 m3/s. Ventilation speeds were 0.1 0.2 and 0.4 m3/s respectively. Ignition was attempted at the end of the hydrogen release by using multiple continuous spark ignition modules on the ceiling and next to the release point. Time evolution of hydrogen concentration was measured using evacuated sample bottles. Overpressure and impulse inside and outside the facility were also measured. The mixture was ignited by a spark ignition module mounted on the ceiling in eight of eleven tests. In the other three tests the mixture was ignited by spark ignition modules mounted next to the nozzle. Overpressures generated by the hydrogen deflagration in most of these tests were low and represented a small risk to people or property. The primary risk associated with the hydrogen deflagrations studied in these tests was from the fire. The maximum concentration is proportional to the ratio of the hydrogen release rate to the ventilation speed within the range of parameters tested. Therefore a required ventilation speed can be estimated from the assumed hydrogen leak rate within the experimental conditions described in this paper.
Hydrogen Related Risks Within a Private Garage: Concentration Measurements in a Realistic Full Scale Experimental Facility
Sep 2007
Publication
Next generation of hydrogen energy based vehicles is expected to come into widespread use in the near future. Various topics related to hydrogen including production storage and application of hydrogen as an energy carrier have become subjects of discussion in the framework of various European and International projects. Safety information is vital to support the successful introduction into mainstream and public acceptance of hydrogen as an energy carrier. One of such issues which is seeking major attention is related to hydrogen powered vehicles parked inside a confined area (such as in a private garage). It is of utmost importance to predict if uncontrolled release of hydrogen from a vehicle parked inside a confined area can create an explosive atmosphere. Subsequently how the preventive measures can be implied to control these explosive atmospheres if present inside a confined area? There is a little guidance currently developed for confined areas accommodating hydrogen fuelled vehicles. It is essential that mitigation measures for such conditions become established.<br/>Characterization of different scenarios those may arise in a real situation from hydrogen fuelled vehicle parked inside a garage and furthermore the investigation of an optimal ventilation rate for hydrogen risk mitigation are some of the main objectives described in the framework of the present study. This work is an effort to provide detail experimental information’s in view of establishing guidelines for hydrogen powered vehicles parked inside a private garage. The present work is developed in the framework of a European Network of Excellence HySafe and French project DRIVE. Present paper describes a purpose built realistic Garage test facility at CEA to study the dispersion of hydrogen leakage. The studied test cases evaluate the influence of injected volumes of hydrogen and the initial conditions at the leakage source on the dispersion and mixing characteristics inside the free volume of the unventilated garage. The mixing process and build-up of hydrogen concentration is measured for the duration of 24 hours. Due to safety reasons helium gas is used to simulate the hydrogen dispersion characteristics.
A Numerical Simulation on the Leakage Event of a High-Pressure Hydrogen Dispenser
Dec 2021
Publication
For the sake of the increasing demand of hydrogen fuel cell vehicles there are more concerns on the safety of hydrogen refueling stations. As one of the key pieces of equipment the hydrogen dispenser has drawn attention on this aspect since it involves massive manual operations and may be bothered by a high probability of failure. In this paper a numerical study is conducted to simulate the possible leakage events of the hydrogen dispenser based on a prototype in China whose working pressure is 70 MPa. The leakage accident is analyzed with respect to leakage sizes leak directions and the time to stop the leakage. It is found that due to the large mass flow rate under such high pressure the leak direction and the layout of the components inside the dispenser become insignificant and the ignitable clouds will form inside the dispenser in less than 1 s if there is a leakage of 1% size of the main tube. The ignitable clouds will form near the vent holes outside the dispenser which may dissipate quickly if the leakage is stopped. On the other hand the gas inside the dispenser will remain ignitable for a long time which asks for a design with no possible ignition source inside. The results can be useful in optimizing the design of the dispenser regarding the reaction time and sensitivity requirements of the leakage detector the size and amount of vent holes etc.
Quantification of the Uncertainty of the Peak Pressure Value in the Vented Deflagrations of Air-Hydrogen Mixtures
Sep 2007
Publication
In the problem of the protection by the consequences of an explosion is actual for many industrial application involving storage of gas like methane or hydrogen refuelling stations and so on. A simple and economic way to reduce the peak pressure associated to a deflagration is to supply to the confined environment an opportune surface substantially less resistant then the protected structure typically in stoichiometric conditions the peak pressure reduction is around the 8 bars for a generic hydrocarbon combustion in an adiabatic system lacking of whichever mitigation system. In general the problem is the forecast of the peak pressure value (PMAX) of the explosion. This problem is faced using CFD codes modelling the structure in which the explosion is located and setting the main parameters like concentration of the gas in the mixture the volume available the size of vent area and obstacles (if included) and so on. In this work the idea is to start from empirical data to train a Neural Network (NN) in order to find the correlation among the parameters regulating the phenomenon. Associated to this prediction a fuzzy model will provide to quantify the uncertainty of the predicted value.
Facilitating the Safest Possible Transition from Fossil to Hydrogen Fuels- Hydrogen Executive Leadership Panel
Sep 2005
Publication
In recent years federal and state safety authorities have worked to bring emergency planners and responders together with industry the scientific community and consumers to ensure high levels of safety with gas and liquid pipelines and more recently with liquefied natural gas terminals. The U.S. Department of Transportation (DOT) is the federal authority on the safe transportation of energy and the National Association of State Fire Marshals (NASFM) represents state-level safety authorities. Together they have produced firefighter safety training materials technical guidance and information for use in communities considering new energy infrastructure and conducted research to support these activities. In 2004 the DOT-NASFM partnership established the Hydrogen Executive Leadership Panel (HELP) to ensure a safe transition from fossil fuels to hydrogen fuel cells. HELP brings together senior policy-level experts from all sectors to understand and recommend mitigation strategies for the risks associated with the transportation and use of hydrogen in motor vehicles. The initial group includes experts from the United States Canada and Europe. HELP will be supported by an advisory committee of emergency planners and responders—individuals well-equipped to describe real-world scenarios of greatest concern—and by a second advisory committee of engineers and scientists who will help translate the real-world scenarios into useful technical solutions. By September 2005 HELP expects to define the initial real-world scenarios of greatest concern and bring together teams of experts to collaborate with automakers energy producers government authorities consumers and public safety officials. Much work lies ahead including creating guidance for hydrogen powered automobiles emergency response safety training establishing test methods to reflect real-world incident scenarios and modifying state and local building and fire codes. The HELP leadership will present its strategic plan and first report at the International Conference on Hydrogen Safety in September 2005.
Green Hydrogen Value Chain in the Sustainability for Port Operations: Case Study in the Region of Valparaiso, Chile
Dec 2021
Publication
The paper presents a complete value chain for the use of green hydrogen in a port facility. The main objective was to propose the sizing of the main components that make up green hydrogen to ensure the supply of 1 MWe in replacing the diesel generator. The energy demand required for the port was determined by establishing the leading small and large-scale conventional energyconsuming equipment. Hence 60 kgH2 was required to ensure the power supply. The total electrical energy to produce all the hydrogen was generated from photovoltaic solar energy considering threegeneration scenarios (minimum maximum and the annual average). In all cases the energy supply in the electrolyzer was 3.08 MWe. In addition the effect of generating in the port facility using a diesel generator and a fuel cell was compared. The cost of 1 kgH2 could be 4.09 times higher than the cost of 1 L of diesel meaning that the output kWh of each system is economically similar. In addition the value of electrical energy through a Power Purchase Agreement (PPA) was a maximum of 79.79 times the value of a liter of diesel. Finally the Levelized Cost of Energy (LCOE) was calculated for two conditions in which the MWe was obtained from the fuel cell without and with the photovoltaic solar plant.
Safety of Laboratories for New Hydrogen Techniques
Sep 2007
Publication
In this paper a case of hydrogen release in a typical research laboratory for the characterisation of hydrogen solid-state storage materials has been considered. The laboratory is equipped with various testing equipments for the assessment of hydrogen capacity in materials typically in the 1 to 200 bar pressure range and temperatures up to 500°C. Hydrogen is delivered at 200 bar by a 50 l gas bottle and a compressor located outside the laboratory. The safety measures directly related to hydrogen hazard consist in a distributed ventilation of the laboratory and air extraction fume hoods located on top of each instrument. Goal of this work is the modelling of hydrogen accidental release in a real laboratory case in order to provide a more fundamental basis for the laboratory safety design and assist the decision on the number and position of the safety sensors. The computational fluid dynamics code (CFD) ANSYS-CFX has been selected in order to perform the numerical investigations. Two basic accidental release scenarios have been assumed both at 200 bar: a major leak corresponding to a guillotine breaking of the hydrogen distribution line and a smaller leak typical for a not properly tight junction.
Overview of the New Combined Gasoline/Hydrogen Supply Station and Relevant Regulations in Japan
Sep 2007
Publication
When a hydrogen supply station is to be installed in Japan three fundamental laws must be taken into consideration: the High Pressure Gas Safety Law the Building Standards Law and the Fire Service Law. The High Pressure Gas Safety Law in particular regulates procedures for safety concerning hydrogen supply stations. This law came under review accompanying consideration of the potential utilization of fuel cell vehicles and hydrogen stations. At that time the Japan Petroleum Energy Center (JPEC) investigated safety technology for hydrogen supply stations and prepared a draft of the law. Since then a new combined gasoline/hydrogen supply station compliant with the revised law was established on December 2006. There are a large number of safety precautions incorporated into this station model which conform to the law. As a result of these modifications it was possible to reduce the safe setback distance. In this paper we present an overview of the new hydrogen supply station model the safety precautions and the regulations the station is based on.
No more items...