Characteristics of the Child-Droplets Emerged by Micro-Explosion of the Heterogeneous Droplets Exposed to Conductive, Convective and Radiative Heating

A study provides for the experimental characteristics of the fragmentation process of the heterogeneous droplets during a strong heating. Among such characteristics are a number, a size, namely, mean, minimum and maximum one, and a total surface area of the child-droplets emerged. We consider three schemes of heating corresponding to convective, conductive and radiative heat transfer. Experiments are carried out using the suspension and emulsion droplets as well as the droplets of two immiscible fluids. The graphite particles are utilized as the solid admixtures to water; diesel is applied as a liquid combustible additive. The effect of heat transfer, concentrations and a type of the admixtures on the fragmentation characteristics is explored. Temperature ranges (100–650 °C) and heat fluxes (4–150 kW/m²) are chosen according to applications, namely, fuel technologies, contact heat exchangers, thermal treatment of liquids, fire extinguishing, etc. The findings are important to develop the technologies based on a secondary atomization of the droplets during overheating and boiling. The results of the conductive heating experiments define the optimum substrate temperatures ensuring an enhanced micro-explosion of the droplets of different composition. The radiative heating is characterized by a strong droplet breakup leading to a greater number of the child-droplets as compared to the conductive and convective one. The conclusions contain future ways of developing the study. [Figure not available: see fulltext.].