Condensation heat transfer deterioration on superhydrophobic surface with dense nanostructures

Abstract Superhydrophobic surface with dense nanostructures was fabricated on copper substrate by template-assisted electrochemical deposition. During deposition process, bubbles generated and stayed at some regions to prevent the fabrication of nanostructure, yielding heterogeneous surface. To prepare homogeneous surface, the electrolyte composition and plating voltage are optimized. Repeated experiments of condensation heat transfer on superhydrophobic surface were performed. The heat transfer performance is deteriorated during experiments. Compared with hydrophilic and smooth surface, heat transfer coefficient on fresh superhydrophobic surface was improved by 154.3%, maximally. However, the heat transfer coefficient of superhydrophobic surface after repeated tests behaves only maximum 67.2% improvement. To explore the mechanism of heat transfer deterioration, SEM images and EDS elemental analysis were used. There is no obvious change of nanostructure after repeated experiments. However, the polymer attached on nanostructure to provide hydrophobicity is destroyed. This paper warns that the robustness of both nanostructure and polymer need to be considered to fabricate superhydrophobic surface with excellent condensation heat transfer performance.