Numerical Investigation on the Self-Ignition Behavior of High Pressure Hydrogen Released from the Tube

This paper shows the numerical investigation on the self-ignition behavior of high pressure hydrogen released from the tube. The present study aims to clarify the effect of parameters on the behavior and duration of self-ignition outside the tube using two-dimensional axisymmetric numerical simulation with detailed chemistry. The parameters in this study are release pressure, tube diameter and tube length. The strength of the spherical shock wave to keep chemical reaction and expansion are important factors for self ignited hydrogen jet to be sustained outside the tube.

Effects of Oxidants on Hydrogen Spontaneous Ignition: Experiments and Modelling

Experiments were performed on the influence of oxidants (air, pure oxygen O2 and pure nitrous oxide N2O at atmospheric pressure) in the straight expansion tube after the burst disk on the hydrogen spontaneous ignition. The lowest pressure at which the spontaneous ignition is observed has been researched for a 4 mm diameter tube with a length of 10 cm for the two oxidant gases. The ignition phenomenon is observed with a high speed camera and the external overpressures are measured.

Effect of Rotation on Ignition Thresholds of Stoichiometric Hydrogen Mixtures

Successful transition to a hydrogen economy calls for a deep understanding of the risks associated with its widespread use. Accidental ignition of hydrogen by hot surfaces is one of such risks. In the present study, we investigated the effect that rotation has on the reported ignition thresholds by numerically determining the minimum surface temperature required to ignite stoichiometric hydrogen-air using a hot horizontal cylinder rotating at various angular velocities, ω.

Experimental Determination of Minimum Ignition Current (mic) for Hydrogen /Methane Mixtures for the Determination of the Explosion Group Corresponding to IEC 60079-20-1

Power to gas could get an important issue in future, permitting the valorisation of green electric excess energy by producing hydrogen, mixing it with natural gas (NG) and use the NG grid as temporary storage. NG grid stakeholders expect that blends up to 20% seem to be a realistic scenario. The knowledge of the explosion group for these hydrogen/NG (H2NG) mixtures is a necessary information for the choice of equipment and protective systems intended for the use in potentially explosive atmospheres of these mixtures.

Experiments on Flame Acceleration and DDT For Stoichiometric Hydrogen/Air Mixture in a Thin Layer Geometry

A series of experiments in a thin layer geometry performed at the HYKA test site of the KIT. The experiments on different combustion regimes for lean and stoichiometric H2/air mixtures were performed in a rectangular chamber with dimensions of 20 x 90 x h cm3 , where h is the thickness of the layer (h = 1, 2, 4, 6, 8, 10 mm). Three different layer geometries: (1) a smooth channel without obstructions; (2) the channel with a metal grid filled 25% of length and (3) a metal grid filled 100% of length.

PIV-Measurements of Reactant Flow in Hydrogen-Air Explosions

A study with PIV-measurements for gas explosion in hydrogen-air mixtures is presented in this paper. The present work is part of an ongoing research project. The experiments are performed with hydrogen-air mixture at atmospheric pressure and room temperature. The experimental rig is a square channel with 4.5 X 2.0 cm2 cross section, 30 cm long with a single cylindrical obstacle of blockage ratio 1/3. The equipment used for the PIV-measurements was a Firefly diode laser from Oxford lasers, Photron SA-Z high speed camera and a particle seeder producing 1 µm droplets of water.

Numerical Modelling of Flame Acceleration and Transition to Detonation in Hydrogen/Air Mixtures with Concentration Gradient

Hydrogen gas explosions in homogeneous reactive mixtures have been widely studied both experimentally and numerically. However, in practice, combustible mixtures are usually inhomogeneous and subject to both vertical and horizontal concentration gradients. There is still very limited understanding of the hydrogen explosion characteristics in such situations.

Hydrogen Combustion Experiments in a Vertical Semi-confined Channel

Experiments in an obstructed semi-confined vertical combustion channel with a height of 6 m (cross-section 0.4 × 0.4 m) inside a safety vessel of the hydrogen test center HYKA at the Karlsruhe Institute of Technology (KIT) are reported. In the work, homogeneous hydrogen-air-mixtures as well as mixtures with different well-defined H2-concentration gradients were ignited either at the top or at the bottom end of the channel.

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