Thermal and fluid study in liquid droplet evaporation
Date of Issue2014
School of Mechanical and Aerospace Engineering
Droplet evaporation is related to many engineering applications and natural processes. The further understanding of the mechanism of evaporation will benefit the application. The statistical rate theory (SRT) approach has been applied to predict the thermodynamic properties for Deuterium Oxide (D2O). By comparing the prediction derived from SRT near the triple point with the published data, good agreements are found on saturation pressure, latent heat and specific heat at constant pressure. An experimental rig has been developed for evaporation of a pendant droplet at the steady state conditions. The evaporation conditions were managed to predict. Additionally, thermocapillary convection has been captured by using Particle Tracking Velocimetry method. Two recovery methods based on ray tracing algorithm have been developed to recover the measured velocity field of the droplet. A tilt-angle imaging method has been proved to be able to obtain the full flow field inside the droplet. By tilting the camera upwards between 10˚ and 20˚, about 95% of the full internal flow field of a pendant droplet, especially near the interface, can be recovered to the real positions for further analysis. A direct vector recovery method has been applied to recover the flow measurements of a pendant silicone oil droplet during evaporation. It is found that a higher temperature difference between the apex and the periphery would generate a high convection velocity, and a higher kinematic viscosity with a relative lower temperature variation would hinder the thermocapillary flow inside the droplet.