By Cameron Chai
A study by a research team from the Massachusetts Institute of Technology (MIT) has explained the mechanism behind the formation of water droplets during condensation and ways to design harvesting surfaces at the nanoscale to accelerate the formation of these droplets.
According to the team, these insights pave the way to develop a new class of high-efficiency desalination plants and power plants. The study findings were reported online in ACS Nano.
Nenad Miljkovic, one of the researchers, informed that the study of condensation mechanisms has re-emerged with advances in micro- and nano- patterning techniques that mould condensing surfaces to an unmatched degree.
The MIT research team compared different surface patterning techniques by integrating measurements of heat transfer and droplet growth rates into its computer models in order to determine which technique delivers the most efficient heat transfer. One method is to form a forest of microscopic pillars on the surface. In this method, droplets tend to be seated over the pillars, causing the surface to get wetted only locally instead of wetting the entire surface, which in turn reduces the area of contact and allows easier release.
However, the efficacy of the pillars vary with their nanoscale roughness, width-to-height ratios, spacing and exact sizes, according to the team. Miljkovic informed that the team demonstrated that its properly customized surfaces increased heat transfer by up to 71%. It is possible to enhance the value even further by exploring more differences in surface patterns, Miljkovic added.
The improved efficiency paves the way to increase the water production rate in desalination plants or even in future solar-power systems that depend on reducing the surface area of condenser or heat exchanger, and optimizing the surface area of solar collector or evaporator in order to improve the overall efficacy of the collection of solar energy. A similar system opens the door to enhance removal of heat in computer chips.
The research team’s next step is to use the findings from the computer modeling and droplet experiments to determine more-effective surface patterns and production methods to form droplets rapidly on an industrial scale at a lower cost, Miljkovic concluded.