Radiation, thermal diffusion and kinetic effects in evaporation and combustion of large and moderate size fuel droplets

This paper analyzes quasi-steady combustion and evaporation of large and moderate size single fuel droplets in a quiescent atmosphere taking into account the kinetic effects, variable thermo-physical properties, thermal diffusion and radiation. An analytical solution is obtained for the heat and mass fluxes in the neighbourhood of the large burning droplets in the case of high reaction rates. The analytical formulae are derived for temperature and concentration distributions and heat and mass fluxes in the vicinity of the burning or evaporating droplet. The contribution of the various effects to the heat and mass fluxes is analyzed. It is shown that the effect of thermal diffusion is essential in the case of evaporation or combustion of fuel droplets with internal heat sources (i.e. when temperature at the surface of fuel droplet is higher than an ambient temperature) in a binary gas mixture with significant differences in molecular weights or diameters. Also it is shown that the effect of radiation is significant in case of evaporation and combustion of large droplets. The theoretical results are compared with the available experimental data.