Study on Heat Transfer and Flow Characteristic of an Acoustically Levitated Droplet

Abstract

Container-less processing using levitation technique could prevent heterogeneous nucleation and contamination from container wall. Acoustic levitation is expected to be used for analytical chemistry and manufacturing new materials. Thus, it is important to gather the knowledge about acoustically levitated droplet. The purpose of this study is to investigate the heat transfer and flow characteristic of an acoustically levitated droplet. The following results were obtained from experiments. Evaporation process of levitated droplet was observed. Surface temperature lowers after levitation and volume decreases while levitation. External flow was observed and differs by water and ethanol. Toroidal vortex near the aqueous solution of ethanol droplet interface was observed. By measuring temperature, temperature distribution near the droplet surface was found. Finally, heat transfer coefficient was estimated and it was higher than the existing experimental formula.