Modeling the size distribution in a fluidized bed of nanopowder

Fluidization is a technique used to process large quantities of nanopowder with no solvent waste and a large gas–solid contact area. Nonetheless, nanoparticles in the gas phase form clusters, called agglomerates, due to the relatively large adhesion forces. The dynamics within the fluidized bed influence the mechanism of formation, and thus, the morphology of the agglomerates. There are many theoretical models to predict the average size of fluidized agglomerates; however, these estimates of the average lack information on the whole size range. Here, we predict the agglomerate size distribution within the fluidized bed by estimating the mode and width using a force balance model. The model was tested for titania (TiO2), alumina (Al2O3), and silica (SiO2) nanopowders, which were studied experimentally. An in-situ method was used to record the fluidized agglomerates for size analysis and model validation.