Analytical modeling of combustion of a single iron particle burning in the gaseous oxidizing medium

Abstract

In the present study, a theoretical investigation is accomplished to model the combustion of a single iron particle by virtue of a novel thermophysical approach. It is assumed that a spherical iron particle falls freely in the gaseous medium and preheats and then burns heterogeneously on its external surface in this hot oxidizing environment and oxygen diffuses inward to the particle. A new physical parameter for thermal radiation is introduced. By solving the energy conservation equation for the iron particle, the temperature distribution of the iron particle during the preheating and combustion processes is calculated analytically. Also, by solving the oxygen mass conservation equation, the variation of oxygen concentration within the iron particle during the combustion stage is estimated. In the proposed model, the effect of thermal radiation and dynamic behavior of burning iron particle are considered. Because of high thermal conductivity and micro size of iron particle, the Biot number is negligibly small. The non-homogeneous partial differential equations of energy and mass species resulted from the modeling of combustion are solved by utilizing the method of separation of variables. The assumptions applied in the modeling are such that do not violate the actual combustion phenomenon. Also, the numerical solution of energy equation in the combustion stage is presented and compared with the obtained analytical solution. Also, the burnout time of iron particle is evaluated in this article. This investigation is one of the first performed efforts for analyzing and modeling of single iron particle combustion.