On the Feasibility of Secondary Atomization of Small Slurry Droplets Exposed to Intense Thermal Radiation

Abstract

Feasibility of fragmentation of small slurry droplets in combustors caused by absorption of high-temperature thermal radiation is studied theoretically. The first model of explosive vaporization of the liquid assumes uniform radiant heating of the slurry droplet according to the computed absorption efficiency for black body radiation. The subsequent analysis of transient heat conduction inside the droplet provides estimates for threshold intensities of the radiation necessary for explosive evaporation at the hottest spot inside the droplet. The second model applies the extended effective medium theory together with Mie scattering theory in computations of absorption patterns of black body radiation inside the slurry droplet. The calculated absorption profiles are used subsequently in analysis of transient heat conduction and droplet swelling due to internal boiling. Explicit results of computations and predictions of secondary atomization are given for ultrafine coal-water slurry.