Dropwise condensation over superhydrophobic aluminium surfaces

Abstract

Superhydrophobic aluminum surfaces have been analyzed being a promising solution to promote dropwise condensation. Superhydrophobicity has been obtained on an aluminum substrate by etching it with two different reagents and by depositing a fluorosilane film over them to lower the surface energy. The samples are characterized by means of contact angle measurements and Scanning Electron Microscopy (SEM). Experimental tests of pure steam condensation have been carried out on the samples and DWC has been visualized. Images of the dropwise condensation have been captured with high speed camera and, furthermore, the phenomenon of the jumping droplets has been observed. A heat transfer coefficient higher than 50 kW m-2 K-1 has been measured over the samples.