Capillary evaporation on micromembrane-enhanced microchannel wicks with atomic layer deposited silica

Due to the difficulty in depositing conformal coatings on high aspect ratio surfaces, capillary evaporation on superhydrophilic porous structures have not been well studied. In this work, superhydrophilic hybrid wick was fabricated by coating micromembrane-enhanced microchannels with 20 nm-thick silica (SiO2) using the atomic layer deposited (ALD) technique. Rapid ALD SiO2 coatings improve thin film evaporation of water on hybrid wicks by up to 56%. An appreciable enhancement of critical heat flux was not obtained in this study because of a compromise between the increased capillary pressure and viscous drag resulting from superhydrophilic ALD SiO2 coatings. (C) 2013 AIP Publishing LLC.