A Study of Dew Harvesting and Freezing Performance of Non-Wetting Surfaces

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Virginia Tech


Non-wetting surfaces offer enhanced capabilities over bare metal substrates for condensation with or without phase change. This trait can be utilized to broaden strategies in combating water scarcity in water stressed areas. Slippery lubricant infused surfaces have the ability to shed water droplets with lower nucleation times, taking advantage of more of the limited amount of time available to collect dew and fog than traditional surfaces. However, existing studies focus on short durations with scant information available on the longer-term performance or durability of the materials in application environments. To address this knowledge gap, dew harvesting studies were conducted over a 96 hour period on a lubricant infused surface vis-à-vis regular surface of the same material. Three phases of performance are identified and discussed with regard to the water harvesting potential. The second part of the thesis addresses water condensation under conditions where freezing is a potential issue. Non-wetting surfaces have been shown to be a promising method of limiting the formation of ice from sessile droplets. This study explores the effect of surface roughness on the freeze time of sessile water droplets. Superhydrophobic and hydrophobic, lubricant infused, copper surfaces were created via electrodeposition and chemical etching in conjunction with chemical treatments to achieve non-wetting surfaces of varying surface textures. Freezing characteristics on the surfaces are studied experimentally and, for the first time, computationally, wherein the surface is described using a fractal surface topography. The effect of surface engineering on the freezing dynamics and comparison between the experimental and the computational studies are elucidated.



Superhydrophobic surface, Liquid infused surfaces, Dew harvesting, Dew condensation, Water collection, Freezing, Anti-icing, Numerical analysis