Evaluation of barrier walls for mitigation of unintended releases of hydrogen

• Published in: International journal of hydrogen energy Vol. 35; no. 10; pp. 4758 - 4775
• Main Authors: Houf, W., Schefer, R., Evans, G., Merilo, E., Groethe, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2010; Elsevier
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Barrier walls; Barriers; Codes and standards; Deflection; Energy; Exact sciences and technology; Fuels; Hazards; Hydrogen; Hydrogen safety; Hydrogen storage; Ignition; Jet flames; Mathematical models; Walls; Hydrogen safety; Codes and standards; Barrier walls; Jet flames; Measurement; Hydrogen storage; Hydrogen; Ignition; Heat flow; Flame propagation; Modeling; Calculation; Hazard
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2010.02.086

Hydrogen jet flames resulting from ignition of unintended releases can be extensive in length and pose significant radiation and impingement hazards. Depending on the leak diameter and source pressure, the resulting consequence distances can be unacceptably large. One possible mitigation strategy to reduce exposure to jet flames is to incorporate barriers around hydrogen storage and delivery equipment. While reducing the extent of unacceptable consequences, the walls may introduce other hazards if not properly configured. An experimental and modeling program has been performed at Sandia National Laboratories to better characterize the effectiveness of barrier walls to reduce hazards. This paper describes the experimental and modeling program and presents results obtained for various barrier configurations. The experimental measurements include flame deflection using standard and infrared video and high-speed movies (500 fps) to study initial flame propagation from the ignition source. Measurements of the ignition overpressure, wall deflection, radiative heat flux, and wall and gas temperature were also made at strategic locations. The modeling effort includes three-dimensional calculations of jet flame deflection by the barriers, computations of the thermal radiation field around barriers, predicted overpressure from ignition, and the computation of the concentration field from deflected unignited hydrogen releases. The various barrier designs are evaluated in terms of their mitigation effectiveness for the associated hazards present. The results show that barrier walls are effective at deflecting jet flames in a desired direction and can help attenuate the effects of ignition overpressure and flame radiative heat flux.