Modeling of tribo-electrification of a pneumatically conveyed powder in a squared duct using DEM-CFD

Dry separation technology is a sustainable alternative to conventional wet separation technology for production of food ingredients. This paper is concerned with the exploration of a new driving force for dry separation, i.e. triboelectrification. To investigate the possibilities of this driving force, we modified our in-house DEM-CFD code to model a learning system where powder is tribo-electrically charged by conveying it pneumatically through a squared tube. The charged particles will electrostatically interact with both other charged particles, as well as their induced charges on the conducting walls. We show that the amount of acquired charge depends on the electrostatic interaction between particles and walls and show the corresponding spatial distribution of the particles. They depend both highly on the (mean) charge of the particles. We observed a critical charge per particle after which particles charged rapidly to their saturation charge. This critical charge is delicate and lower than expected from first order derivations.