Numerical Simulation of Multiphase Transport Phenomena During Impinging Stream Drying of a Particulate Material

The objective of the present study was to employ an existing three-dimensional computational fluid dynamic model to investigate the multiphase transport phenomena in a coaxial impinging stream dryer. The continuous-phase equations were solved in the Eulerian frame, while the discrete-phase equations were solved in the Lagrangian frame. Two-way coupling between the continuous and dispersed phases was taken into account in the model. Standard k-epsilon and realizable k-epsilon turbulence models were compared in order to decide which model could better represent the turbulent behavior of the flow in the ISD, while the stochastic approach was used to treat the effect of turbulence on the particle motion. Simulated mean particle moisture content and air humidity ratio at the dryer outlet as well as the particle mean residence time were compared with the experimental data. The results indicated that the model could predict the experimental results within +/-10%, with the realizable turbulence model performing better than the standard model. The effects of various parameters including the inlet air velocity, inlet air temperature, material feed flow rate, and impinging distance on the transport and performance behavior of the dryer were then numerically investigated and discussed.