Numerical investigation on the mixing mechanism in a cross-torus paddle mixer using the DEM-CFD method

Studies on powder mixing in industrial mixers are crucial for the improved criteria of mixing equipment design and optimization within various mixing unit operations. In the present study, a series of simulation for the powder mixing in an elaborately designed mixer, called a cross-torus paddle mixer, is conducted using the Advanced DEM-CFD method. The effects of various operational parameters on the mixing performance are analyzed and discussed in detail. Through these investigations, it is found that rotational speed, filling level, liquid viscosity, and paddle obliquity can significantly affect mixing performance. Owing to a much-enhanced convective motion of particles, a higher rotational speed exhibits a more efficient mixing process. Smaller number of particles inside the vessel shows the better mixing performance, which is attributed to an enhanced diffusive motion of particles. Decreasing the liquid viscosity or increasing the paddle obliquity can also result in a more efficient mixing in a diffusive dominant mode. By performing the simulation of mixing behavior in a mono-dispersed system, the present work provides significant evidence and novel insights to further understand the mixing mechanisms. [Display omitted] •Advanced DEM-CFD method is applied to investigate the mixing state in a cross-torus paddle mixer.•Various operational parameters can significantly affect the mixing performance.•Different mixing mechanisms can be identified using the probability distribution.