Biotemplated Nanostructured Surfaces for Enhanced Phase Change Heat Transfer

The fabrication and characterization of biotemplated nanostructured coatings based on the Tobacco mosaic virus for enhanced phase-change heat transfer is reported. A simple room temperature nanofabrication process, using the self-assembly and mineralization of the Tobacco mosaic virus (TMV), has been implemented to create superhydrophilic surfaces. Using this technique, a variety of structured surfaces have been fabricated and characterized showing enhanced surface wettability and heat transfer characteristics. High-speed images of droplet impact evaporation on flat and hierarchical samples have been recorded, showing increased wetting and evaporation for the nanostructured surfaces. The addition of nanostructures increases the heat transfer rate by more than a factor of three as compared to the flat surfaces, and hierarchical surfaces exhibit heat transfer rates more than an order of magnitude larger than flat non-structured surfaces. Additionally, an increase in Leidenfrost temperature of 100°C as compared to flat samples has been recorded. TMV nanostructures were also assembled onto the walls of heated minichannels, promoting continuous bubble detachment as well as reduced slug formation and instabilities during flow boiling. While bare minichannel exhibits nearly complete dry-out, the nanostructured channels maintain annular flow at similar loadings. This work demonstrates the feasibility of enhancing phase-change heat transfer using TMV structured coatings.