Percolation Model for Simulation of Char Oxidation and Fragmentation Time-Histories
Chemical Engineering Science
A simulation model of char oxidation is introduced in which char particles are represented by randomly generated clusters of bonds on a lattice. Realizations are generated by means of a percolation algorithm. Bonds in contact with the ambience burn at a mean rate which depends on cluster size. By adjusting parameters governing this size dependence and the initial cluster size, simulated burning-rate time-histories are obtained which reproduce previously reported features of single-particle time-histories measured experimentally. The principal features are sharp increases in the burning rate, previously interpreted and here modeled as fragmentation events. Fragmentation is modeled as the separation of a cluster into disconnected pieces due to bond burnout. The agreement with experimental data lends support to this “percolative fragmentation” mechanism. The computations indicate the importance of the fragmentation process with regard to both its impact on the average burning time and its contribution to the production of fine particles.
"Percolation Model for Simulation of Char Oxidation and Fragmentation Time-Histories," A. R. Kerstein and B. F. Edwards, Chem. Engr. Sci., 42, 1629 (1987) .