Ii. Kantorovich et E. Barziv, ROLE OF THE PORE STRUCTURE IN THE FRAGMENTATION OF HIGHLY POROUS CHARPARTICLES, Combustion and flame, 113(4), 1998, pp. 532-541
Citations number
34
Categorie Soggetti
Thermodynamics,"Energy & Fuels","Engineering, Chemical
Fragmentation of highly porous particles burning in regime I under two
heating modes, uniform and nonuniform, is considered. Oxidation with
nonuniform heating is analogous to regime II, because it creates nonun
iform reactivity. A uniformly heated particle did not fragment, even f
or large extents of burning. The nonuniformly heated ones showed syste
matic local fragmentation. Analysis of a particle's behavior under the
two heating modes allowed one to substantiate that percolation fragme
ntation does not occur by a change in total porosity, but is due to ch
anges in the larger pores of the char (meso-and macro-). Calculations
were compared with experimental data from the literature and the follo
wing conclusions were drawn: (1) Fragmentation is determined by the po
rosity of the larger pores with diameters higher than the mean dimensi
on of a microcrystal within the microskeleton, (2) Shrinkage is determ
ined by the micromedium, or small pores. (3) For uniformly heated part
icles the porosity of the large pores barely changes during burning, w
hich accounts for nonfragmentation. (4) The reason for local fragmenta
tion under nonuniform oxidation is the increase in the local macroporo
sity, triggered by nonuniform shrinkage of the micromedium. (C) 1998 b
y The Combustion Institute.