Influence of electrode geometry on transport and separation efficiency of powders using traveling wave field technique

In this paper, the separation processes of powders using a three-phase traveling wave field are studied, both theoretically and experimentally. The separation properties of the nonuniform traveling wave field was investigated by studying the amplitude of its spatial harmonics. Finite element software was used to model the spatial distribution of an electric field created by electrodes of different shapes. It was established that cylindrical, square, and stripe electrodes produce the most optimized field distribution. Based on the modeling results, several flatbed traveling wave panels with stripe and cylindrical electrodes were constructed and tested. The separation characteristics of the panels were assessed by examining the direction of transport of a two-powder mixture with different size distributions for AC frequencies up to 300 Hz. It was discovered that, for the majority of panels, successful powder separation could be achieved for two frequency bands. The position of the bands depended mainly on electrode geometry (i.e., pitch and width). In order to further understand transport phenomena in both separation bands, particle trajectories were examined using a CCD camera with telemicroscopic lenses interfaced with a computer controlled image grabbing system.