Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Nano Lett. 2013 Jan 9;13(1):179-87. doi: 10.1021/nl303835d. Epub 2012 Dec 17.
When droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. If designed properly, these superhydrophobic nanostructured surfaces can not only allow for easy droplet removal at micrometric length scales during condensation but also promise to enhance heat transfer performance. However, the rationale for the design of an ideal nanostructured surface as well as heat transfer experiments demonstrating the advantage of this jumping behavior are lacking. Here, we show that silanized copper oxide surfaces created via a simple fabrication method can achieve highly efficient jumping-droplet condensation heat transfer. We experimentally demonstrated a 25% higher overall heat flux and 30% higher condensation heat transfer coefficient compared to state-of-the-art hydrophobic condensing surfaces at low supersaturations (<1.12). This work not only shows significant condensation heat transfer enhancement but also promises a low cost and scalable approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification. Furthermore, the results offer insights and an avenue to achieve high flux superhydrophobic condensation.
当液滴在超疏水纳米结构表面上聚结时，由于释放过多的表面能，由此产生的液滴可能会从表面弹起。如果设计得当，这些超疏水纳米结构表面不仅可以在微尺度凝结过程中轻松去除液滴，还可以提高传热性能。然而，理想纳米结构表面的设计原理以及证明这种弹起行为优势的传热实验仍然缺乏。在这里，我们展示了通过简单的制造方法制备的硅烷化氧化铜表面可以实现高效的弹跳起雾冷凝传热。我们的实验表明，与低过饱和度 (<1.12) 下的先进疏水性冷凝表面相比，总热通量提高了 25%，冷凝传热系数提高了 30%。这项工作不仅显示了显著的冷凝传热增强，而且还为大气水收集和除湿等应用提供了一种低成本、可扩展的方法来提高效率。此外，研究结果还提供了实现高通量超疏水冷凝的思路和途径。
