Details

Autor(en) / Beteiligte

• Chen, Xuemei
• Wu, Jun
• Ma, Ruiyuan
• Hua, Meng
• Koratkar, Nikhil
• Yao, Shuhuai
• Wang, Zuankai

Titel

Nanograssed Micropyramidal Architectures for Continuous Dropwise Condensation

Ist Teil von

• Advanced functional materials, 2011-12, Vol.21 (24), p.4617-4623

Ort / Verlag

Weinheim: WILEY-VCH Verlag

Erscheinungsjahr

2011

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• Engineering the dropwise condensation of water on surfaces is critical in a wide range of applications from thermal management (e.g. heat pipes, chip cooling etc.) to water harvesting technologies. Surfaces that enable both efficient droplet nucleation and droplet self‐removal (i.e. droplet departure) are essential to accomplish successful dropwise condensation. However it is extremely challenging to design such surfaces. This is because droplet nucleation requires a wettable surface while droplet departure necessitates a super‐hydrophobic surface. Here we report that these conflicting requirements can be satisfied using a hierarchical (multiscale) nanograssed micropyramid architecture that yield a gobal superhydrophobicity as well as locally wettable nucleation sites, allowing for ˜65% increase in the drop number density and ˜450% increase in the drop self‐removal volume as compared to a superhydrophobic surface with nanostructures alone. Further we find that synergistic co‐operation between the hierarchical structures contributes directly to a continuous process of nucleation, coalescence, departure, and re‐nucleation enabling sustained dropwise condensation over prolonged periods. Exploiting such multiscale coupling effects can open up novel and exciting vistas in surface engineering leading to optimal condensation surfaces for high performance electronics cooling and water condenser systems. A surface with nanograssed micropyramid arrays that allows for enhanced drop nucleation and departure simultaneously is successfully developed by harnessing the heterogeneous wetting and hierarchical roughness. The surface yields a global superhydrophobity as well as local smooth (wettable) patches. Synergistic co‐operation between the hierarchical structures contributes directly to a continuous process of nucleation, coalescence, departure, and re‐nucleation enabling sustained dropwise condensation over prolonged periods.