Heat Transfer and Fouling Rate at Boiling on Superhydrophobic Surface with TiO2 Nanotube-Array Structure

Abstract

A superhydrophobic surface coating of a nanotubes array grown directly on a titanium substrate was prepared by using the method of electrochemical anodic oxidation under ultrasonic assistance and fluoroalkyl silane modification. Experimental investigations of nucleate pool boiling and fouling behaviors were carried out to assess the heat transfer enhancement and fouling inhibition on a superhydrophobic titanium-based nanoporous coating. The superhydrophilic titanium-based nanoporous surface and the bare titanium substrate surface were also investigated as contrasts. The results indicate that the heat transfer performance of the superhydrophobic titanium-based nanoporous coating is superior to the bare titanium substrate and the superhydrophilic titanium-based nanoporous surface due to higher density of nucleation sites in the range of low heat fluxes. Besides, the superhydrophobic nanoporous coating also has lower fouling resistance and better antifouling performance at pool boiling of CaCO₃ solution in comparison with bare and superhydrophilic surfaces.