Two-dimensional numerical simulations of the pneumatic drying in vertical pipes

Abstract

The Two-Fluid model has been used for modeling the flow of particulate materials through pneumatic dryer. The model was solved for a two-dimensional steady-state condition and considering axial and radial profiles for the flow variables. A two-stage drying process was implemented. In the first drying stage, heat transfer controls evaporation from the saturated outer surface of the particle to the surrounding gas. At the second stage, the particles were assumed to have a wet core and a dry outer crust; the evaporation process of the liquid from a particle assumed to be governed by diffusion through the particle crust and by convection into the gas medium. As evaporation proceeds, the wet core shrinks while the particle dries. Our developed model was applied to simulate drying process of wet sand in a pneumatic dryer. The numerical solutions were compared with the results of independent numerical and experimental investigations. These comparisons are quite encouraging.