Influence of forced convection on sessile droplet evaporation

Abstract

Evaporation is a phase change process with potential for achieving large heat transfer rates under high air temperatures due to the latent heat of vaporization. Bioin-spired artificial perspiration systems can leverage the evaporation of sessile droplets to implement this effect for different cooling applications. In the case of human perspiration, droplet evaporation typically occurs under exposure to moving air, or forced convection. However, current approaches to understanding droplet evaporation primarily use a vapour-diffusion limited model. Experiments using an open-loop wind tunnel and computer-vision based control system were conducted to measure evaporation rates of continuously-fed sessile droplets under forced convection. Results demonstrated increases to the evaporation rate with the inclusion of forced convection and removal of the vapour-diffusion limit, but also shows evidence for a limit based on thermal behavior. Additional experiments also demonstrate boundary layer effects caused by adjacent droplets suppresses increases to the evaporation rates from forced convection.