A particle tracking velocimetry method to measure size and charge distributions in tribocharged powder particles

Abstract

Simultaneous charge and size of tribocharged particles suspended in a gas stream are measured using image analysis. Under the action of a homogeneous electric field, drag, and electric forces are the main factors influencing particle trajectory, from which electric charge and polarity are derived. We could check that the system operates in a laminar gas regime inside the analysis cell since high flow turbulences would alter the particle “electrical” path, thus invalidating the measurement. Single component granular materials and binary mixtures are studied, all cases showing bipolar distributions and dependence on particle size. Mixture composition affects the overall charge polarity in the dispersed powder, and this effect can not solely be attributed to the weight proportion of the components. PTV is a powerful tool in techniques used for triboelectric dry separation of organic and inorganic products since their efficiency relies much on the charge to mass ratio.