Chemical Engineering Communications, Vol.199, No.3, 384-398, 2012
Effect of Variable Acoustic Field and Frequency on Gas-Solid Suspension of Fine Powder: A Review
Suspensions of fine particles in either Newtonian or non-Newtonian fluids are often encountered in the physical, engineering, and biological sciences. For example, the manufacture of particle-laden products such as reinforced composites, paints, paper, slurries, and cements involves the processing of particle suspensions. Fine particles become difficult to suspend due to interparticle attraction forces like ver der Waals, capillary, and cohesive forces, which are responsible for converting fine particles into aggregates. These aggregates prevent the particles from being suspended uniformly, hence external forces are essential to break these aggregates. External forces include magnetic fields, electrical fields, acoustic fields, and mechanical vibration, which are useful to break aggregates and suspend particle uniformly. This process is termed homogeneous fluidization. This article presents a comprehensive review of sound-assisted fluidized beds for group C, A, and B and binary materials. Furthermore, this review covers the effect of acoustic field intensity and frequency on minimum fluidization velocity and on bubbling.