Experimental investigation of evaporation of multicomponent droplet by acoustic levitation

摘要

The purpose of our study is to understand the evaporation of an acoustically levitated multicomponent droplet and manipulate the evaporation process of the sample. In this paper, we present the experimental investigation on the evaporation process of pure and multicomponent droplets. The evaporation processes and the temporal evolution of the surface temperature of a droplet were measured by using the high speed camera and radiation thermometer, respectively. We used water, ethanol, methanol, hexane, acetone, pentane and binary liquid (25, 50 and 75wt% of ethanol, methanol and acetone solution) as test samples to clarify the effect of the saturated vapor pressure. For ethanol, methanol and acetone droplet evaporated with two different evaporation stage. It is indicated that the water vapor in the air was condensed during the evaporation process of the water-soluble droplet. Due to the condensation from the air, the experimental data did not agree with the theoretical prediction by d~2 law. Although the evaporation behavior in the first stage was consistent, the evaporation behavior in the second stage cannot be described by d~2 law. For binary droplets as the concentration increased by the evaporation, the transition time from the first to the second stage also increased by its preferential evaporation.