Experimental Study of the Mitigation of Hydrogen-Air Explosions by Aqueous Foam

The development of hydrogen production technologies, as well as new uses, represents an opportunity both to accelerate the ecological transition and to create an industrial sector. However, the risks associated with the use of hydrogen must not be overlooked. The mitigation of a hydrogen explosion in an enclosure is partly based on prevention strategies such as detection and ventilation, but also on protection strategies such as explosion venting. However, in several situations, such as in highly constrained urban environments, the discharge of the explosion through blast walls could generate significant overpressure effects outside the containment which are unacceptable. Thus, having alternative mitigation solutions can make the effects of the explosion acceptable by reducing the flame speed and the overpressure loading, or suppressing the secondary explosion. The objective of this paper is to present the experimental study of the mitigation of hydrogen-air deflagration in a 4 m3 vented enclosure by injection of aqueous foam. After a description of the experimental set-up, the main experimental results are presented showing the influence of aqueous foam on flame propagation (Fig. 1). Different foam expansion ratios were investigated. An interpretation of the mitigating effect of foam on the explosion effects is proposed based on the work of Kichatov [5] and Zamashchikov [2].