Effects of reactor core-simulant aerosols on hydrogen/air combustion

Three representative reactor core-simulant aerosols were dispersed, just before ignition, into combustible hydrogen-air mixtures contained in 5.1 and 0.18 m3 chambers. Oxidic aerosols (Al2O3, Fe2O3) produced only minor changes in the burns. A metallic aerosol (Fe) ignited along with the hydrogen, producing more complete combustion of the hydrogen and substantially increased overpressures and thermal effects compared to control experiments performed identically without the aerosols. We attempted to use the rule of Le Chatelier to correlate flammability limits in the iron aerosol-hydrogen-air system determined in both experimental chambers. We showed that the rule does not apply well to hybrid mixtures such as these. We also showed that results obtained in small-scale apparatus may be misleading for metallic aerosols, where the flame thicknesses (approx.1 m) may be larger than the vessel dimensions. We recommend that large-scale apparatus be used whenever possible when studying lean flammability limits of either aerosols alone or hybrid aerosol-gas mixtures. 3 refs., 2 figs