Influence of impeller geometry in a vertical mixer described by DEM simulation and the dispersion model

• Quantification of dispersive and convective particle motion using DEM.
• Experimental validation of DEM simulation.
• Determination of optimal operating conditions (balanced dispersion) in terms of the rotational speed.
• Influence of the impeller geometry on the dispersion and drift coefficients.

Using the Discrete Element Method, a vertical mixer is investigated with regard to its dispersive and convective mixing mechanisms. From the axial, radial, and tangential displacements, density distributions are derived to quantify dispersion and drift coefficients. Three different impellers are compared and it is observed that dispersion and drift coefficients are influenced by the geometry of impellers. Normalized dispersion coefficients as a function of rotational speed are compared to determine the conditions of balanced particle mobilities for the different impellers. In the case of balanced dispersion, particle mobilities are limited at the same rate. In addition, DEM simulations are compared with experimental studies on the basis of mixing efficiencies and particle trajectories.

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