Photoacoustic monitoring of sedimentation of micro-particles in low viscosity fluids

Abstract

In this work, the potential of photoacoustic technique in the study of the sedimentation process of particles in liquids is explored. Experiments were performed using zirconia particles of 50 and 100 μm in three different low viscosity liquids, water, citronella, and ethylene glycol. It is shown that the evolution of the PA signal depends not only on the kind of liquids used but also on the size of the particles. An effective thermal model is developed in order to study the process and to infer the evolution of the thermal conductivity of the sedimented layer when it behaves as thermally thin, or the thermal effusivity if it behaves as thermally thick. It is shown that based on these results, the time evolution of the volume fraction of particles, in the region in which the sediment is deposited, can be obtained. These results can be useful in establishing a methodology for the photoacoustic monitoring of the process of sedimentation in more complex systems. © 2013 AIP Publishing LLC.