Experimental and theoretical study of a micro-fluidized bed

Abstract

Large industrial scale fluidized beds (FBs) have been widely used because of their ability to greatly enhance mixing and both heat and mass transfer. This suggests that fluidized beds may offer a means of overcoming the poor mixing and transport characteristics of microfluidic devices where low Reynolds number flows prevail. We report experimental findings on liquid fluidization in microfluidic channels of 200-400 μm in size. Excellent fluidization is observed for various particles fluidized in ethanol where surface forces between the particles and the microfluidic channel are weak. In contrast, adhesion of the particles to the walls and subsequent de-fluidization is observed when water is used as the fluidizing medium. These findings demonstrate the importance of surface forces in micro-fluidized beds. We also find that conventional theories are able to explain the impact of surface forces on fluidization and, provided the effect of the walls on the particle packing and porosity is accounted for, the fluidization behavior. © 2013 AIP Publishing LLC.