Facile Fabrication of Three-Dimensional Micronano Hierarchical Architecture for Sustained and Efficient Dropwise Condensation.

Abstract

Condensation heat transfer is a phenomenon frequently observed in both everyday life and industrial settings, playing a crucial role in a variety of applications. Compared with filmwise condensation, dropwise condensation has attracted considerable interest due to its ability to effectively remove condensate from surfaces, thereby enhancing heat transfer efficiency. Nevertheless, the development of surfaces that can simultaneously facilitate rapid droplet nucleation and efficient droplet removal remains limited, presenting a significant challenge for optimizing heat transfer processes. In this study, we introduce a novel three-dimensional micronano hierarchically architectured surface (3D-MNHAS) designed to sustain dropwise condensation, alongside a straightforward fabrication technique. The 3D-MNHAS was fabricated in one step via ultrafine anodic scanning electrodeposition (UAS-ECD) on substrates masked with woven mesh. The resulting surface features regularly arranged microsized clusters embedded with micro- and nanoscale dendrites, complemented by a coarse base surface exhibiting micro/nano papillae between clusters, thereby providing an exceptionally large surface area. To promote rapid condensate drainage and maintain continuous condensation, the 3D-MNHAS was infused with a hydrophilic lubricant, forming a lubricant-infused structured surface (LISS). The lubricant film enables low contact-angle hysteresis and significantly diminishes droplet adhesion, facilitating rapid droplet coalescence and removal within the surface structures. Among LISS samples with varying structure densities, the optimally spaced 100-LISS exhibits superior condensation performance due to the optimal balance among droplet nucleation, coalescence, and removal. This sample achieved a condensate collection rate of 0.142 g cm^-2 h^-1 under atmospheric dropwise condensation, representing a 2.12-fold increase compared to a bare copper surface. Furthermore, heat transfer tests revealed that 100-LISS attained a high heat transfer coefficient of 7.67 kW·m^-2·K^-1, corresponding to 414% of that observed for bare copper. The innovative surface architecture combined with the facile fabrication method offers a promising approach for advancing high-efficiency, durable, dropwise condensation applications.