MIT –Massachusetts Institute of Technology researchers have developed a completely passive, solar-powered way of combating ice buildup. Preventing the buildup, for instance on aircraft wings, usually requires energy-intensive heating systems or chemical sprays that are environmentally harmful. The new system offers another solution. It is remarkably simple, based on a three-layered material that can be applied or even sprayed onto the surfaces to be treated. It collects solar radiation, converts it to heat, and spreads that heat around so that the melting is not just confined to the areas exposed directly to the sunlight. Once applied, it requires no further action or power source. It can even do its de-icing work at night, using artificial lighting. A deeper insight is given in a paper published by associate professor of mechanical engineering Kripa Varanasi and postdocs Susmita Dash and Jolet de Ruiter in Sience Advances.
As they found out, it is not necessary to produce enough heat to melt the bulk of the ice that forms. All that’s needed is for the boundary layer, right where the ice meets the surface, to melt enough to create a thin layer of water. This makes the surface slippery enough, so any ice will just slide right off. The developed system consists of three layers: The top layer is an absorber, which traps incoming sunlight and converts it to heat. The second layer consists of aluminum as a spreader layer with a thickness of only 400 µm. It is heated by the absorber layer above it and efficiently spreads the heat to the entire surface. Finally, the bottom layer is simply foam insulation, to keep any of that heat from being wasted downward and keep it where it’s needed, at the surface. The three layers, all made of inexpensive commercially available material, are then bonded together, and can be bonded to the surface that needs to be protected. For some applications, the materials could instead be sprayed onto a surface, one layer at a time. The team carried out extensive tests, including real-world outdoor testing of the materials and detailed laboratory measurements, to prove the effectiveness of the system.