Numerical analysis of contact electrification using DEM-CFD

A successive condenser model was developed and implemented into a discrete element method (DEM) coupled with computational fluid dynamics (DEM-CFD) to analyse the charge transfer during powder processing. The numerical results for the contact electrification between a dielectric particle and a neutral conductive surface were in excellent agreement with experimental data reported in the literature. In a successive impact process, charge accumulation on a particle increases exponentially with the number of collisions and eventually reaches an equilibrium state. During these processes, larger particles gain higher steady state charge but the charge-to-mass ratio is smaller. In the case of gas fluidization, the electrostatic charge gradually accumulates on particles and eventually reaches an equilibrium state. Non-uniform charge distribution is generally induced. A higher superficial gas velocity results in a faster charge accumulation because more frequent collisions occur.