Sprayable, thin & robust carbon nanofiber composite for jumping dropwise condensation
This proposal focuses on providing a roadmap towards upscaling and commercialization of promising results obtained during the FET Innovation program HARMoNIC (grant No 801229). In particular, the coordinator partner (ETH Zurich) has developed a nanocomposite material to be coated on metallic steam condensers used in thermal power generation. The coating is composed of a mixture of polytetrafluoroethylene and carbon nanofibers and is superhydrophobic (i.e. minimal affinity to liquid water).  The optimal wettability of the coating ensures that condensed droplets, even smaller than 100 μm, coalesce and spontaneously jump off the surface. Additionally, the coating is very thin (~ 2 μm) so that it has minimal thermal resistance for heat transfer. As a result, it shows a 9-fold improvement in heat transfer coefficient compared to conventional steam condensers wherein the steam condenses as an undesirable continuous liquid film. Moreover, our coating is highly robust and is the first one to sustain coalescence induced droplet jumping behavior over extended time periods under accelerated aging conditions involving exposure to hot steam flow. This enhanced mode of condensation, if maintained long enough, can provide a new direction on how future industrial condensers will be designed. We expect that such thermodynamically efficient condensers will have an immense socio-economic impact by reducing the fossil fuel consumption of thermal power plants and minimizing the associated emission of greenhouse gases. With this proposal, we plan to set the foundation for the commercialization of this technology by accomplishing the next three major steps to be followed. These are: 1) further material optimization beyond the state-of-the-art demonstration, 2) scaling up of the fabrication procedure and implementation of the technology to industrial condensers, and 3) developing a business plan and setting up a spin-off company while attracting venture capital.