Presentation Abstract

Title: Water-harvesting mesh surfaces
Presentation Time: Wednesday, Jun 13, 2012, 3:40 PM - 4:00 PM
Author Block: K. Park, S. S. Chhatre, A. Deng, R. E. Cohen, G. H. McKinley;
Massachusetts Institute of Technology, Cambridge, MA.
Category: Wetting
Abstract: Fog and dew represent a large, untapped source of potable water, especially in dry/arid climates. Various plants and animals use geometric as well as chemical features on their surfaces to harvest this precious resource. In this work, we investigate the influence of surface chemistry, heterogeneity and topographical details on the water harvesting ability of textured surfaces. We choose simple woven meshes as a canonical family of model textured surfaces due to the ability to systematically vary periodicity, porosity, mechanical robustness and ease of fabrication. We probe a set of meshes with (a) a directed stream of fog droplets to simulate a natural foggy/windy environment and (b) a static moist mass of air to replicate a humid early morning scenario. We study the influence of surface wettability, surface patterning, length scale of the mesh fibers, and relative openness of the mesh weave on the water harvesting ability of these model surfaces. Further, we investigate whether the surface reflectance and infrared emissivity of the water-harvesting surface has any efficacy in controlling condensation on these textured surfaces. We strive to develop and test design rules to understand and quantify the performance of such water harvesting surfaces so that they can be deployed for real-world applications.