Numerical simulation of heat and mass transfer in pneumatic conveying dryer

Two-dimensional Eulerian-Lagrangian model is presented for heat and mass transfer in pneumatic conveying dryer. The model takes into account the particle-particle and particle-wall collisions, lift forces, particle rotation, turbulence modulation and turbulence dispersion (i.e., four-way coupling). The drying simulation is based on a two-stage drying model. Different correlations for heat transfer coefficient are tested and assessed in terms of their accuracy. The model is validated against the available experimental data and good agreement is obtained. The model predictions are compared to other models from literature and it produces better results than existing models. It is also found that the turbulence dispersion has greater effect on the model predictions than particle-particle collision. However, neglecting either particle-particle collision or turbulence dispersion results in a lower heat transfer and drying rates. (C) 2012 Elsevier Ltd. All rights reserved.