From airplane wings to overhead powerlines to the giant blades of wind turbines, a buildup of ice can cause problems ranging from impaired performance all the way to catastrophic failure. But preventing that buildup usually requires energy-intensive heating systems or chemical sprays that are environmentally harmful. Now, MIT researchers have developed a completely passive, solar-powered way of combating ice buildup.
The system 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. And, once applied, it requires no further action or power source. It can even do its de-icing work at night, using artificial lighting.
The new system is described today in the journal Science Advances, in a paper by MIT associate professor of mechanical engineering Kripa Varanasi and postdocs Susmita Dash and Jolet de Ruiter.
“Icing is a major problem for aircraft, for wind turbines, powerlines, offshore oil platforms, and many other places,” Varanasi says. “The conventional ways of getting around it are de-icing sprays or by heating, but those have issues.”
Inspired by the sun
The usual de-icing sprays for aircraft and other applications use ethylene glycol, a chemical that is environmentally unfriendly. Airlines don’t like to use active heating, both for cost and safety reasons. Varanasi and other researchers have investigated the use of superhydrophobic surfaces to prevent icing passively, but those coatings can be impaired by frost formation, which tends to fill the microscopic textures that give the surface its ice-shedding properties.
As an alternate line of inquiry, Varanasi and his team considered the energy given off by the sun. They wanted to see, he says, whether “there is a way to capture that heat and use it in a passive approach.” They found that there was.
It’s not necessary to produce enough heat to melt the bulk of the ice that forms, the team found. 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, which will make the surface slippery enough so any ice will just slide right off. This is what the team has achieved with the three-layered material they’ve developed.
Read more at Massachusetts Institute of Technology