MIT researchers make surfaces that are easier to cool under extreme heat. This finding could benefit power plants and electronics.
Japan’s Fukushima Nuclear Power plant was affected by Earthquake and Tsunami in 2011. Power Plant Engineers sprayed seawater on the reactors to cool them. But it didn’t work out. Because, water droplets couldn’t land on surfaces that hot. They instantly begin to evaporate, forming a thin layer of vapor and then bouncing along it — just as they would in a hot cooking pan.
Image Credit: MIT
Now, MIT researchers have come up with a way to cool hot surfaces more effectively by keeping droplets from bouncing. Their solution: Decorate the surface with tiny structures and then coat it with particles about 100 times smaller. Using that approach, they produced textured surfaces that could be heated to temperatures at least 100 degrees Celsius higher than smooth ones before droplets bounced.
Experiments confirmed their approach. When they sprayed water on their micro-nano surfaces at 400 C — the highest temperature their experimental setup could provide — the droplets quickly wet the surfaces and boiled. Interestingly, under the same conditions, the droplets did not wet the surfaces of samples with either the microscale posts or the nanoscale texture, but did wet the surfaces of samples with both.
In addition to nuclear safety systems, this work has important implications for systems such as steam generators, industrial boilers, fire suppression, and fuel-injected engines, as well as for processes such as spray cooling of hot metal. And, it can be used for electronics cooling too.
