Modeling of the evaporation rate of liquid droplets on anodized heated surfaces

Abstract

The present study investigates the sessile droplet evaporation and mass transfer characteristics on the anodized hole-patterned surfaces and proposes a theoretical model based on the experimental data. Polished aluminum specimens and oxalic acid are utilized to generate anodized surfaces with three cases by changing area fractions and hole diameter. The anodized hole surface contributes to enhancing surface wettability with higher capillary force inside the holes on the surface. The droplet evaporation rate increases with a reduction in the hole diameter. It is found that the previous models of the evaporation heat transfer rate on the bare surface do not fit well with the experimental results for the anodic oxidation surface. The solid-liquid-air interfacial equations involving the Gibbs energy are newly established for development of a new evaporation model that considers of the liquid displacement length. The results are validated against the previous results, showing that the new model has an error range of 6%. From the results, the smaller the hole diameter, or the deeper the hole depth, the capillary force increases, thereby widening the surface area of the droplet and promoting the evaporative heat transfer of the droplet.