Experimental investigation of fluidized bed dynamics under resonant frequency of sound waves

Abstract

Sound-assisted fluidization has of late gained a significant research focus as a potential assisted fluidization technique for improving the hydrodynamics of solids that exhibit cohesive and non-homogeneous fluidization behavior. This study investigated the dynamics of a bed subjected to acoustic perturbations at different frequencies during the sound-assisted fluidization of a hydrophilic nanopowder with strong agglomeration behavior. The bed pressure transients were carefully monitored using sensitive pressure transducers in different sections of the bed over a wide range of velocities using ambient air as the fluidizing gas. Both fluidization and defluidization dynamics were investigated by varying the velocity in small steps using electronic mass flow controllers connected to a data acquisition system. In addition to the resonance frequency of 220 Hz, acoustic vibrations of 200 and 150 Hz frequency were also investigated to clearly delineate the effect of resonant frequency on the bed response. Our results clearly suggest that operation of sound-assisted fluidization at the resonant frequency greatly enhances its effectiveness.