Dropwise Condensation of Water Vapor Over Patterned Surfaces

Condensation of water vapor on a textured surface is encountered in water harvesting applications. Textured surfaces are required to be hydrophobic to encourage droplet formation and assist drainage. An alternative to chemical coatings is to create physically textured surfaces, for example, a distribution of sub-micron sized pillars over them, thus creating a pattern. Droplet shapes, coalescence, and condensation of water vapor over such patterned surfaces are of interest to the present study. Condensation rates in a dropwise condensation cycle from pure vapor and moist air are central to building an atmospheric water generator. The nature of investigation is experimental jointly with multi-scale simulation. Experiments will involve high speed imaging and stereomicroscopy to record drop movement, deformation, oscillations, coalescence, and gravitational release.  An important goal of this project was to improve the predictability of a complex interfacial phenomenon of drop movement over a patterned surface in an inherently three-dimensional setting via carefully conducted experiments juxtaposed against mesoscale simulation. Secondly, the understanding gained at the component scale of a patterned surface will be integrated with a large-scale dropwise condensation model to predict water production from pure vapor and a humid atmosphere.