Numerical Simulation of Pneumatic Dryers Using Computational Fluid Dynamics

The hydrodynamic and drying mechanisms of a dilute-phase, gas solid flow have been predicted in a laboratory and a large-scale pneumatic dryer. A computational fluid dynamics (CFD) method based on the two-fluid multiphase flow model has been adopted. A control-volume based technique implemented in the FLUENT CFD package was applied along with the kinetic theory of granular flow (KTGF) to simulate the flow pattern and heat and mass transfer processes for wet PVC and sand particles by hot air. The mass-weighted averages of theoretical predictions for temperature and moisture content agree well with the experimental data for similar models. User-defined subroutines were added to extend FLUENT capability to account for mixture properties and to simulate the drying rate for surface moisture evaporation and moisture diffusion inside the particulate phase. The present model can be extended to simulate the drying of various temperature sensitive materials.