Effects of acoustic fields on the dynamics of micron-sized particles in a fluidized bed

Abstract

The effect of external acoustic fields on hydrodynamic behavior of cohesive micron-sized particles in a pseudo-2D fluidized bed is studied using CFD-DEM simulations. The forces acting on a particle consist of the contact force and cohesive force between particles, the drag force by the surrounding fluid and the sound force by an acoustic field. A wide range of sound pressure levels and sound frequencies are investigated in terms of their effects on the pressure drop, bed expansion, distribution of particle velocity and concentration, as well as the sizes of bubbles and agglomerates. Comparing to the system without acoustic force, the application of acoustic field is found to induce the breakup of the formed agglomerates, and ultimately lead to a stable bubbling fluidization regime. A useful range of frequencies between 80 Hz to 100 Hz is found with a pressure level of 120 dB, resulting in most remarkable improvement of the process performance.