Finite volume approach for solving multiphase flows in vertical pneumatic dryers

In the present study, a finite volume approach for solving two-dimensional, two-fluids flows with heat and mass transfer was developed for predicting 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. The numerical procedure includes discretization of calculation domain into torus-shaped final volumes, solving the gas phase conservation equations by a modified semi-implicit method for pressure-linked equations algorithm, and the conservation equations of particulate phase were solved by the explicit forward difference algorithm. The mass momentum and energy coupling between the phases were considered by principles of the Interphase slip algorithm. In order to validate the theoretical and the numerical models, the developed models were applied to simulate the drying process of wet PVC particles in a large-scale pneumatic dryer and to the drying process of wet sand in a laboratory-scale pneumatic dryer. The predictions of the numerical simulations were compared successfully with the results of independent numerical and experimental investigations. Following the models validation, the two-dimensional distributions of the flow characteristics were examined.