Surface wettability of vertical harps for fog collection

Abstract

Surface wettability is an influential property and plays a pivotal role in fog harvesting. Two types of surfaces i.e., hydrophilic and hydrophobic are generally used for fog harvesting. A hydrophilic surface provides quick nucleation whereas a hydrophobic surface carries rapid transportation of water droplets. Animals and plants live in arid environment, control their surface wetting through their naturally grown surfaces in their biological structures. These patterns provide extremely high affinity of fog collection for these surfaces by reducing the friction and pinning force of water droplets sliding down towards storage. In this study, a comparison of hydrophilic and hydrophobic surfaces is carried out and the results are expressed in terms of wetting behavior. Hydrophilic and hydrophobic vertical harps are developed by plasma treated and silane treated monofilament polyesters respectively. Traditional raschel mesh is replaced with polyester monofilament-based prototype developed in this study. The reason to replace raschel mesh (standard fog collector element) with a harp design is to capture the maximal fog by avoiding clogging. It is revealed that fog collector element(FCE) treated with hydrophobic coating improve the collection rate, however, hydrophilic treatment shows adverse effects. In addition, we examined the contact angle hysteresis (CAH) of our prototypes to verify the wettability effect.