Saltation of pneumatically conveyed nanoparticles

Abstract

OF THE THESIS SALTATION OF PNEUMATICALLY CONVEYED NANOPARTICLES by Suleyman Kemal Betin Thesis Director: Prof. Jerry Shan The saltation velocity, the air velocity at which particles start to settle and form dunes and layers during their pneumatic transport, is experimentally studied for nanoparticle aerosol in a horizontal pipe. The nano-particles used are silica with primary particle size of 30nm and agglomerate size of 200-300nm and carbon black with average size of 45 nm. The nano-particle aerosol is characterized using DMA. The saltation of nano-particle aerosol is compared qualitatively with that of glass beads and quantitatively with the predicted values of Matsumoto correlation, which is verified for 47.5 μm glass beads. The saltation of nano-particle aerosols was different than that of 47.5 μm glass beads in terms of the form and the initial position of the particles that settle. The saltation Froude numbers predicted by Matsumoto are an order of magnitude higher than the experimental results for nano-particles and the discrepancy is explained by comparing the external forces acting on a particle through its interaction with another particle. The saltation of the silica nano-particles was different than that of carbon black nanoparticles: the saltation Froude number was essentially independent of mass loading ratio for nano-silica. The difference in the saltation behavior of two nano-particle aerosols is explained by particle charge measurements and control volume analysis.