Jumping-Droplet-Enhanced Condensation on Scalable Superhydrophobic Nanostructured Surfaces

• Published in: Nano letters Vol. 13; no. 1; pp. 179 - 187
• Main Authors: Miljkovic, Nenad, Enright, Ryan, Nam, Youngsuk, Lopez, Ken, Dou, Nicholas, Sack, Jean, Wang, Evelyn N
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 09.01.2013
• Subjects: Atmospherics; Condensed matter: structure, mechanical and thermal properties; Condensing; COPPER OXIDE; Copper oxides; Droplets; Exact sciences and technology; Harvesting; Heat transfer; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; MICROSTRUCTURES; Nanostructure; OXIDES; Physics; State of the art; Surface energy; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Jumping droplets; nanostructure; superhydrophobic surface; condensation heat transfer; enhanced condensation; Manufacturing processes; Hydrophobic compound; Vapor condensation; Droplets; Nanostructures; Copper oxide; Surface energy; Heat transfer
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl303835d

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.