Modeling of Multiprocess Behavior for Feedstock-Mixed Porous Pellet: Heat and Mass Transfer, Chemical Reaction, and Phase Change

Insight into the complicated energy-mass transfer and hierarchical reaction in metallurgical industry is of particular value in improving productivity and reducing energy consumption. This work proposes a coupled multiphysical reaction-transport (c-MPRT) model that is based on the implicit finite difference method for the promising bisolid porous pellet to investigate its dynamic characteristics concerning heat transfer, chemical reaction, and phase change. This model successfully reveals a negative influence on the heat conduction from the outer layers to the inner layers of the pellet, due to the enormous heat absorption of the chemical reacting and physical melting process. Compared to the ex situ heat conduction, the in situ Joule heat plays a dominant role during the heating of the inner layers. Additionally, there appears to be a decline in the temperature in the inner layers of the pellet during the reaction process, corresponding to a decreasing reaction rate resulting from the insufficient energy input to the inner layers. The maximum decrement in the temperature and the reaction rate are 35 K and 7.86 mol/s, respectively. In contrast with the chemical reaction process, the fusion process costs less time because the latent heat is lower than the enthalpy of the chemical reaction. It was found that a critical time point at which the fusing region enlarges abruptly exists and is about 1230 s, while the entire multiprocess in the pellet consumed about 1477 s. This coupled multiphysical model contributes to revealing the reaction-transport details and is of great significance to the bisolid porous pellet.