Acoustic separation and fractionation of property-distributed particles from the gas phase

Abstract

Established particle fractionation techniques in gas driven processes typically are limited when facing small particles (dp < 10 µm). If the particles are also distributed in multiple of their property dimensions, fractionation becomes particularly difficult. Due to the low inertia of small particles, tailor-made fractionation and separation processes are required. The particle fractionation approach presented here utilizes a resonant acoustic field for multivariate fractionation of particles from the gas phase. The fractionation process exploits the differences in acoustic mobility of particles in a gaseous environment, which has been shown to be effective even for smaller particles. Particles with multi-dimensional distributed properties (as for instance size, shape, material, apparent density, …) can be selectively addressed and fractionated in this way. Numerical and experimental studies have been carried out for analysis of particle fractionation in a resonant ultrasonic field. The particle behaviour in acoustic waves is numerically derived and analysed. Computational fluid dynamics is used to simulate the acoustically driven gas phase behaviour and its impact on particles. In the intense resonant acoustic field secondary flow structures impact the fractionation process that will be analysed. Shadowgraphy and Schlieren experiments of the gas density variations in the acoustic field are used to validate the simulations.