Some Aspects of Particle Agglomeration in Simulated Slurry Fuels

Abstract

Abstract A series of experiments and analyses with JP-10 slurries, prepared with inert particles ranging in size from 0.3 μm to 2 μm, have been performed to study the influence of particle size, mass loading and droplet diameter on particle agglomeration in a slurry fuel. Particle mass loadings of 20% and 50% in droplets ranging in size from 100 μm to 3000 μm were studied analytically. Inert SiC and Al2O3 particles were chosen to avoid the complexities associated with reacting solids. Similarly, slurries were prepared without any chemical additives which could decompose. The choice of non-stabilized slurry with inert particles was made in order to isolate the problem under study, and not to cloud the issue of particle agglomeration due to burning particles and secondary reactions involving chemical stabilizers. Scanning Electron Microscopic (SEM) studies of the residues from burning and also evaporating droplets suggest that instead of using the usual very small particles (1 μm or smaller), intermediate size particles (∼ 3 μm) should be used in preparing the slurries. Intermediate size particles are affected neither by any interacting forces nor by chemical cementation caused by fuel decomposition at the particle surface heated by flame radiation. Therefore, the intermediate size particles are expected to minimize particle agglomeration. Analysis corroborates the fact that fuel decomposition is negligible at the surface of small particles. Also the solid mass loading between 20% and 50% seems to have a very small effect on fuel decomposition at the particle surface. Because of increased mass and heat transfer rates in a flow field, analysis predicts a lower degree of fuel decomposition when droplets are exposed to flow.