Enhancing Condensation Heat Transfer on Three-Dimensional Hybrid Surfaces

Abstract

In recent years, micro/nanostructured surfaces have been applied to enhance condensation heat transfer. However, condensation heat transfer is greatly deteriorated by the flooding phenomenon that occurs at high subcooling temperatures. Here, we propose a three-dimensional (3D) hybrid surface to enhance the condensation at high subcooling temperatures. The 3D hybrid surface consisted of superhydrophobic (SHB) Si nanowire (SiNW) arrays and hydrophilic microchannels. The microchannels could confine the liquid-film thickness, and the liquid bridges formed on the 3D hybrid surfaces could be self-removed. Both of these characteristics prevent the surfaces from flooding. In addition, liquid droplets formed in the SiNW regions were dragged into the microchannels, which also improved the heat transfer. The heat transfer coefficient on the 3D hybrid surface could be enhanced over a large subcooling range. More remarkably, a record high heat flux of 655 +/- 10 kW.m(-2) was obtained on the 3D hybrid surface.