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Ettlingen, Germany

Grune J.,Pro Science GmbH | Breitung W.,Simaps GmbH | Kuznetsov M.,Karlsruhe Institute of Technology | Yanez J.,Karlsruhe Institute of Technology | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2015

Abstract The paper presents the results of an experimental evaluation of the flammability limits and maximum pressure rise rate for multi-component (CO-H2)-O2-(H2O-CO2-N2)-mixtures at elevated temperatures of 170°C and 250°C at ambient pressure of 1 bar. A spherical explosion chamber with a volume of 8.2 dm3 was used for the experiments. A pressure method and a high-speed camera combined with a schlieren system for flame visualization were used in this work. Flammability limits and pressure rise rates are presented for multi-component mixtures with a steam concentration of 60% and a wide variation of fuel and oxidizer concentrations in which the H2 concentrations was limited to 3%. © 2015 Hydrogen Energy Publications, LLC.

Yanez J.,Karlsruhe Institute of Technology | Kuznetsov M.,Karlsruhe Institute of Technology | Grune J.,Pro Science GmbH
Combustion and Flame | Year: 2015

This work addresses the experimental investigation and analytical interpretation of a flame subject to acoustic-parametric instability exited by self-generated pressure pulses. The research presented herein was carried out with lean hydrogen-air mixtures during flame propagation in a smooth channel with an open end. It was found that very lean mixtures with hydrogen concentrations in air of less than 14% vol. H2 generate acoustic oscillations due to flame instabilities, which, in turn, significantly influence the propagation of the flame. Above a 14% vol. H2 concentration in the air, the flame becomes relatively stable with respect to self-generated acoustic perturbations. It was also found that an external polychromatic sound with a dominant frequency of 1000Hz inhibits the instabilities and results in a reduced flame propagation velocity. Numerical solutions of the Searby and Rochwerger analytical formulation for the acoustic-parametric instability were utilized in order to analyze the experiments and study the influence of different parameters on the existence of a spontaneous transition from the acoustic to the parametric instability. © 2015 The Combustion Institute.

Rudy W.,Warsaw University of Technology | Kuznetsov M.,Karlsruhe Institute of Technology | Porowski R.,Warsaw University of Technology | Teodorczyk A.,Warsaw University of Technology | And 2 more authors.
Proceedings of the Combustion Institute | Year: 2013

This work presents the results of the large scale experiments with detonation propagating in hydrogen-air mixtures in partially confined geometries. The main aim of the work was to find the critical conditions for detonation propagation in semi-confined geometries with uniform and non-uniform hydrogen-air mixtures. The experimental facility consisted of rectangular 9 × 3 × 0.6 m channel open from the bottom, acceleration section and test section, safety vessel, gas injection and data acquisition system. Sooted plates technique was used as a witness of the detonation. The rectangular channel was placed in a 100 m3 safety vessel. For uniform hydrogen-air mixtures experiments with four different channel heights h were performed: 8, 5, 3 and 2 cm. The critical hydrogen-air mixture height h for which the detonation may propagate in a layer is close to the 3 cm which corresponds to approximately three detonation cell sizes. For non-uniform hydrogen-air mixture with hydrogen concentration slope equal approximately -1.1%H2/cm the critical hydrogen concentration at the top of the layer is approximately equal 26% and the mean detonation layer height is close to the 8.5 cm corresponding to the hydrogen concentration at the bottom of the layer approximately equal 16-17%. © 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Grune J.,Pro Science GmbH | Sempert K.,Pro Science GmbH | Kuznetsov M.,Karlsruhe Institute of Technology | Jordan T.,Karlsruhe Institute of Technology
International Journal of Hydrogen Energy | Year: 2014

Spontaneous ignition processes due to high pressure hydrogen releases into air are known phenomena. The sudden expansion of pressurized hydrogen into a pipe, filled with ambient air, can lead to a spontaneous ignition with a jet fire. This paper presents results of an experimental investigation of the visible flame propagation and pressure measurements in 4 mm extension tubes of up to 1 m length attached to a bulk vessel by a rupture disc. Transparent glass tubes for visual observation and shock wave pressure sensors are used in this study. The effect of the extension tube length on the development of a stable jet fire after a spontaneous ignition is discussed. © 2014 Hydrogen Energy Publications, LLC. All rights reserved.

Grune J.,Pro Science GmbH | Sempert K.,Pro Science GmbH | Kuznetsov M.,Karlsruhe Institute of Technology | Jordan T.,Karlsruhe Institute of Technology
International Journal of Hydrogen Energy | Year: 2014

In order to simulate an accidental hydrogen release from the high pressure pipe system of a hydrogen facility a systematic study on the nature of transient hydrogen jets into air and their combustion behavior was performed at the KIT hydrogen test site HYKA. Horizontal unsteady hydrogen jets from a reservoir of 0.37 dm3 with initial pressures of up to 200 bar have been investigated. The hydrogen jets released via round nozzles 3, 4, and 10 mm were ignited with different ignition times and positions. The experiments provide new experimental data on pressure loads and heat releases resulting from the deflagration of hydrogen-air clouds formed by unsteady turbulent hydrogen jets released into a free environment. It is shown that the maximum pressure loads occur for ignition in a narrow position and time window. The possible hazard potential arising from an ignited free transient hydrogen jet is described. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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