Fire Safety Science Digital Archive

Hydrogen recombination on a catalytic surface or various configurations of catalytic elements has been investigated both experimentally and theoretically. The proposed H2-recombiners were collections of rods coated by Al2O3 film with catalytic platinum centers. The rod's surface was additionally coated by a porous teflon film, which prevents a contact of catalytic centers with liquid water but is penetrable for gases and steam. Operation characteristics of such H 2-recombiners in various regimes have been determined. The relationship between a rate of hydrogen recombination and temperature of the catalytic surface has been revealed. lt has been found that an availability of helium in a gaseous mixture causes a sufficient reduction of a hydrogen oxidation rate on the catalytic surface due to a decrease of temperature of the catalytic surface because of a high thermoconductivity coefficient for helium. A simple mathematical model of a hydrogen recombination on the catalytic surface has been proposed which describes the main peculiarities of this process. lt has been found that an allocation of catalytic rods into vertical metal tubes with internal diameter of 20 mm increases significantly an efficiency of each catalytic element by means of a formation of convective flows from the hot catalytic surface of the rod.