Effect of thermal properties on the fragmentation of spontaneous vapor explosions

This paper presents the mechanism of a spontaneous vapor explosion. The vapor film collapse and the subsequent fragmentation process are studied by considering both liquids properties. We propose a model that describes the fragmentation process in the spontaneous vapor explosion and examine the past experimental data using molten metal, as the hot liquid, and water, as the cold liquid. It is found that the mechanism of the vapor film collapse was affected by the hot liquid properties. It is also shown that the vapor explosion does not occur spontaneously if the surface tension and viscosity of the hot liquid are quite large. The fragmentation process depends on the mode of the vapor film collapse. The small-scale experiments were performed to investigate the cold liquid properties on the spontaneous vapor explosion. The results showed that surfactants increased the severity of spontaneous vapor explosions. The relation between quench temperature in a solid-liquid system and occurrence condition of spontaneous vapor explosions in a liquid-liquid system is also discussed. (author)