Ettlingen, Germany
Ettlingen, Germany

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Sander M.,KIT ITEP | Brighenti F.,KIT ITEP | Gehring R.,KIT ITEP | Jordan T.,KIT IKET | And 6 more authors.
International Journal of Hydrogen Energy | Year: 2014

A new multi-functionality hybrid energy storage concept, LIQHYSMES, has been recently proposed. It combines the use of LIQuid HYdrogen (LH2) as the bulk energy carrier with much faster and efficient superconducting magnetic energy storage (SMES). The LIQHYSMES Storage Unit LSU integrates liquefaction and storage of H2 as well as the LH2-cooled SMES: A process for the intermediate storage of H2 in liquefied form is proposed, and alternative SMES designs are compared. The basic operational principle is simulated for a simple model case with two large LIQHYSMES storage plants supporting the transfer of renewable energy from one region of strong supply to a second one with a widely negative imbalance between supply and load. Losses of all plant components are analysed in terms of their relevance for the overall efficiency, and some cost issues are briefly addressed. A small first experimental demonstration is now underway and also briefly introduced. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Veser A.,Pro Science | Kuznetsov M.,Karlsruhe Institute of Technology | Fast G.,Karlsruhe Institute of Technology | Friedrich A.,Pro Science | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2011

Experiments on flame propagation regimes in a turbulent hydrogen jet with velocity and hydrogen concentration gradients have been performed. Horizontal stationary hydrogen jets released at normal and cryogenic temperatures of 290, 80 and 35 K with different nozzle diameters and mass flow rates have been investigated. Sampling probe method and laser PIV techniques have been used to evaluate the distribution of hydrogen concentration and flow velocity. High-speed photography combined with a Background Oriented Schlieren (BOS) system was used for the visual observation of the turbulent flame propagation. In order to investigate different flame propagation regimes the ignition position was changed along the jet axis. It was found that the flame propagates in both directions, up- and downstream of the jet flow if hydrogen concentration is >11%, whereas in case [H2] < 11%, the flame propagates only downstream. This means that at normal temperature the flame is able to accelerate effectively only if the expansion ratio σ of the H 2-air mixture is higher than a critical value σ (*) = 3.75 defined for a closed geometry. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Kuznetsov M.,Karlsruhe Institute of Technology | Friedrich A.,Pro Science | Stern G.,Pro Science | Kotchourko N.,Pro Science | And 2 more authors.
Journal of Loss Prevention in the Process Industries | Year: 2015

A series of medium-scale experiments on vented hydrogen deflagration was carried out at the KIT test side in a chamber of 1 × 1 × 1 m3 size with different vent areas. The experimental program was divided in three series: (1) uniform hydrogen-air mixtures; (2) stratified hydrogen-air mixtures within the enclosure; (3) a layer deflagration of uniform mixture. Different uniform hydrogen-air mixtures from 7 to 18% hydrogen were tested with variable vent areas 0.01-1.0 m2. One test was done for rich mixture with 50% H2. To vary a gradient of concentration, all the experiments with a stratified hydrogen-air mixtures had about 4%H2 at the bottom and 10 to 25% H2 at the top of the enclosure. Measurement system consisted of a set of pressure sensors and thermocouples inside and outside the enclosure. Four cameras combined with a schlieren system (BOS) for visual observation of combustion process through transparent sidewalls were used. Four experiments were selected as benchmark experiments to compare them with four times larger scale FM Global tests (Bauwens et al., 2011) and to provide experimental data for further CFD modelling. The nature of external explosion leading to the multiple pressure peak structure was investigated in details. Current work addresses knowledge gaps regarding indoor hydrogen accumulations and vented deflagrations. The experiments carried out within this work attend to contribute the data for improved criteria for hydrogen-air mixture and enclosure parameters to avoid unacceptable explosion overpressure. Based on theoretical analysis and current experimental data a further vent sizing technology for hydrogen deflagrations in confined spaces should be developed, taking into account the peculiarities of hydrogen-air mixture deflagrations in presence of obstacles, concentration gradients of hydrogen-air mixtures, dimensions of a layer of flammable cloud, vent inertia, etc. © 2015 Elsevier Ltd.

Kuznetsov M.,Karlsruhe Institute of Technology | Redlinger R.,Karlsruhe Institute of Technology | Breitung W.,Karlsruhe Institute of Technology | Grune J.,Pro Science | And 2 more authors.
Proceedings of the Combustion Institute | Year: 2011

Effects of elevated temperatures (up to 573 K) and pressures (up to 72 bar) on the laminar flame velocity of hydrogen-oxygen-steam mixtures were studied both experimentally and computationally. Stoichiometric hydrogen-oxygen mixtures diluted with steam up to 85% (mol.) have been tested in a spherical explosion chamber with an inner diameter of 25 cm using the pressure method and high speed shadow cinematography. The experimental data on the laminar burning velocity were compared with numerical calculations that used different H/O reaction mechanisms based on the Lutz, GRI-Mech 3.0, Li and Warnatz schemes. The calculations were performed with three codes: INSFLA, Cantera (for unstretched planar flames) and our own FP-code (based on the PREMIX code). Nonmonotonic pressure dependence and strong suppressing effect of steam dilution on laminar flame velocity was found both experimentally and numerically. The best consistency with the experimental measurements of the laminar flame velocity at elevated pressures and temperatures in presence of high steam concentrations was found for the Lutz H/O mechanism. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

Kim T.-S.,Korean University of Science and Technology | Kim T.-S.,Korea Atomic Energy Research Institute | Jeong S.H.,Korea Atomic Energy Research Institute | Chang D.-H.,Korea Atomic Energy Research Institute | And 8 more authors.
Current Applied Physics | Year: 2011

A prototype Long Pulse Ion Source (LPIS) was developed for the Neutral Beam Injection (NBI) system of the Korea Superconducting Tokamak Advanced Research (KSTAR) project. Beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) at KAERI. The second gap (the distance between the G2 grid and the G3 grid) of the accelerator was shortened from 9.0 mm to 7.0 mm and 6.0 mm as part of an effort to increase the ion beam current with low beam divergence. The performance improvement and the limitations of the LPIS with its shortened second gap are experimentally presented and discussed regarding the study of the beam characteristics. From these efforts to find the optimum beam parameters, design directions for the next accelerator are presented. © 2011 Elsevier B.V. All rights reserved.

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