Heterogeneous thermochemical decomposition of a semi-transparent particle under direct irradiation

摘要: Abstract Transient heat and mass transfer in a non-uniform emitting, absorbing anisotropically scattering medium inside semi-transparent, optically large chemically reacting particle directly exposed to an external source of high-flux radiation is analyzed numerically. Thermal decomposition calcium carbonate selected as the model chemical reaction. The unsteady energy equations are solved numerically using finite volume technique explicit Euler time-integration scheme. Radiative transport modeled Rosseland diffusion approximation Monte Carlo ray tracing method. Direct irradiation internal radiative highly favorable for heating reaction, decreasing total reaction time by factor 15, compared case with neglected analysis. In latter case, temperatures at center surface increase monotonically 1406 1417 K particle, 1428 1432 K non-reacting respectively, after 179 s—the particle. With included analysis, both from initial 300 1300 K less than 2 s, same rate until onset endothermic t =1.1 s. temperature increases further up 2000 K 12 s, when whole calcined. Weak dependence temperature, overall extent, on CaO grain size observed spite strong properties porous size.