The temperature of the hydrogen cylinder needs to be carefully controlled during fueling process. The maximum temperature should be less than 85 according to the ISO draft code. If the fueling period is reduced, the maximum temperature should increase. In this study, temperature change of a Type IV cylinder was measured during the hydrogen fueling process up to 35 MPa. Fueling period was 3 to 5 minutes. Twelve thermocouples were installed to measure inside gas temperature and seven were attached on the outside of the cylinder. An infrared camera was also used for measuring temperature distribution of outside of cylinder. The maximum gas temperature was higher than 85? inside of the cylinder. Significant temperature difference between the upper and lower part of the vessel was observed view more
This study deals with the TNO Multi-Energy and Baker-Strehlow-Tang (BST) methods for estimating the positive overpressures and positive impulses resulting from hydrogen-air explosions. With these two methods, positive overpressure and positive impulse results depend greatly on the choice of the class number for the TNO Multi-Energy method or the Mach number for the BST methods. These two factors permit the user to read the reduced parameters of the blast wave from the appropriate monographs for each of these methods, i.e., positive overpressure and positive duration phase for the TNO Multi-Energy method, and positive overpressure and positive impulse for the BST methods. However, for the TNO Multi-Energy method, the determination of the class number is not objective because it is the view more
High pressure hydrogen leak is one of the top safety issues presently. This study elucidates the physics and mechanism of high pressure hydrogen jet ignition when the hydrogen suddenly spouts into the air. The experimental work was done elsewhere, while we did the numerical work on this high pressure hydrogen leak problem. The direct numerical simulation based on the compressible fluid dynamics considering viscous effect was carried out with the two-dimensional axisymmetric coordinate system. A detailed model of hydrogen reaction is applied and a narrow tube attached to a high pressure reservoir is assumed in the numerical simulation. The exit of the tube is opened in the atmosphere. When high pressure hydrogen is passing through the tube filled by atmospheric air, a strong shock wave view more
Transport by pipe is one the most usual way to carry liquid or gaseous energies from their extraction point until their final field sites. To limit explosion risk or escape, to avoid pollution problems and human risks, it is necessary to assess nocivity of defect promoting fracture. This need to know the mechanical properties of the pipes steels. Hydrogen is considered to day as a new energy vector, and its transport in one of the key problems to extension of its use. Within the European project NATURALHY, it has been proposed to transport a mixture of natural gas and hydrogen. 39 European partners have combined their efforts to assess the effects of hydrogen presence on the existing gas network. Key issues are durability of pipeline material, integrity management, safety aspects, life view more
The present article indicates the change of mechanical properties of X52 gas pipe steel in presence of hydrogen and its consequence on defect assessment particularly on notch like defects. The purpose of this work is to determine if the transport of a mixture of natural gas and hydrogen in the actual existing European natural gas pipe network can be done with a reasonable low failure risk (i.e. a probability of failure less than 10-6). To evaluate this risk, a deterministic defect assessment method has been established. This method is based on Failure Assessment Diagram and more precisely on a Modified Notch Failure Assessment Diagram (MNFAD) which has been proposed for this work. This MNFAD is coupled with the SINTAP failure curve and allows determining the safety factor associated view more
Determining the risk of accidental ignition of flammable mixtures is a topic of tremendous importance in industry and aviation safety. The concept of minimum ignition energy (MIE) has traditionally formed the basis for studying ignition hazards of fuels. In recent years, however, the viewpoint of ignition as a statistical phenomenon has formed the basis for studying ignition, as this approach appears to be more consistent with the inherent variability in engineering test data. We have developed a very low energy capacitive spark ignition system to produce short sparks with fixed lengths of 1 to 2 mm. The ignition system is used to perform spark ignition tests in lean hydrogen- oxygen-argon test mixtures over a range of spark energies. The test results are analyzed using statistical view more
Experiments with a hydrogen jet were performed at two different pressures, 96 psig (6.6 bars) and 237 psig (16.3 bars). The hydrogen leak was generated at two different hole sizes, 1/16 inch (1.6 mm) and 1/32 inch (0.79 mm). The flammable shape of the plume was characterised by numerous measurements of the hydrogen concentration inside of the jet. The effect of the nearby horizontal surface on the shape of the plume was measured and compared with results of CFD numerical simulations. The paper will present results and an interpretation on the nature of the plume shape.
In 2003 the US Department of Energy (DOE) initiated a project to coordinate the development of a national template of hydrogen codes and standards for both vehicular and stationary applications. The process consisted of an initial evaluation to determine where there were gaps in the existing hydrogen codes and standards and the codes and standards required to fill these gaps. These codes and standards were to be developed by several Standards Development Organizations (SDOs). This effort to develop codes and standards has progressed from a position in 2003 when there were relatively few codes and standards that directly addressed hydrogen technology applications to the position at the end of 2008 where requirements to permit hydrogen technologies have been implemented in primary view more
In socio-economics it is well known, that the success of an innovation process not only depends upon the technological innovation itself or the improvement of economic and institutional system boundaries, but also on the public acceptance of the innovation. The public acceptance can, as seen with genetic engineering for agriculture, be an obstacle for the development and introduction of a new and innovative idea. In respect to hydrogen technologies this means, that the investigation, compilation and communication of scientific risk assessments are not sufficient to enhance or generate public acceptance. Moreover, psychological, social and cultural aspects of risk perception have to be considered when introducing new technologies. Especially trust and familiarity play an important role view more
This paper describes a series of numerical simulations with release and ignition of hydrogen. The objective of this work was to re-investigate the accidental explosion in an ammonia plant which happened in Norway in 1985 with modern CFD tools. The severe hydrogen-air explosion led to two fatalities and complete destruction of the factory building where the explosion occurred. A case history of the accident was presented at the 1.st ICHS in Pisa, 2005.
The numerical simulations have been performed with FLACS, a commercial CFD simulation tool for gas dispersion and gas explosions. The code has in the recent years been validated in the area of hydrogen dispersion and explosions.
The factory building was 100 m long, 10 m wide and 7 m high. A blown-out gasket in a water pump view more
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