Evaporation, boiling and explosive breakup of heterogeneous droplet in a high-temperature gas

Experimental investigation of evaporation and boiling was carried out on fixed water droplet containing a single nontransparent solid inclusion and placed in gaseous environment at high-temperature (500-1100 K). We carried out experiments with water droplets (diameters 3-5 mm) containing graphite inclusions of different shapes (sphere, disk, cone, parallelepiped and polyhedron) with sizes between 2 and 4 mm. These droplets were in the hot flux on top of combustion of industrial ethanol. The behavior of the droplets was recorded by high-speed (up to 105 frames per second) video cameras “Phantom” and “TEMA Automotive” software. Conditions for intensive vaporization at solid/liquid interface inside droplets were determined. A phenomenon of explosive disintegration occurred when heating some of the heterogeneous droplets. Time of heating until an explosive disintegration and complete evaporation was recorded. Influence of gas temperature and inclusion sizes were measured.