Engineered Surfaces for Dew Harvesting
thesisposted on 08.02.2018 by Sameera Khan
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
Structured surfaces have drawn considerable attention from both theoretical and experimental points of view due to their potential in enhancing the heat transfer coefficient by achieving desirable wetting properties, in many industrial applications such as thermal storage, water harvesting and power generations. Considering the water scarcity as one of the most challenging issue nowadays, here we apply a new technique for water harvesting through condensation phenomenon. This technique has the advantage of a) typically the source of the water for harvesting is external and comes from the nature such as sea or rain, but here a vapor stimulation process is applied to capture the vapors which have the potential to provide water by phase change process-condensation. b) using remarkable less input energy compared to the typical techniques of water harvesting. In the above mentioned application (water-harvesting), fast formation and subsequent removal of water droplets is critical for enhancing the efficiencies of their associated systems. Significant focus has been placed on the aspect of droplet removal from the surfaces, that has led to development of superhydrophobic surfaces with special textures on which droplets are self-removed after coalescence. Due to their inherent low surface energy, nucleation energy barrier is also high. In contrast to conventional superhydrophobic surfaces, here we show the surfaces can be engineered such that the simultaneous benefits of high nucleation rates and fast droplet removal can be obtained during the condensation process. The main objective of this work is to develop a fundamental understanding of impregnated oils in textured surfaces from theoretical and from experimental point of view, for enhanced condensation further leading to the application of dew harvesting.