How to Boil Water
❉ In breaking news, scientists have figured out how to boil water – at least 3 times more efficiently and producing twice as much steam. Before you shake your fist at “wasteful research spending”, this isn’t really about your whistling tea kettle!
❉ Phase change heat transfer processes (boiling, condensation) are a big part of everyday technology from water purification and HVAC units, power plants and cooling electronics. When water boils, a thin layer of steam can coat the heated surface, insulating it and drastically cutting down on the efficient transfer of heat to liquid. This can lead to surface burnout and a destructive condition known as critical heat flux. What is needed is a surface that discourages the vapor from sticking and wicks in water to quickly re-wet the heated surface. To create a superhydrophilic wicking surface, Drexel University scientist Matthew McCarthy turned to biotemplating with….viruses!
❉ The tobacco mosaic virus causes mottling of tobacco leaves, as its name implies, but is harmless to humans. It was the first virus ever to be discovered (in the late 1880’s) and is constructed simply of repeating units of a coat protein, wrapped around a single, helical strand of genetic material (RNA). A few tobacco plants can produce billions of virus particles, so it’s cheap to make. Dr. McCarthy tweaked the coat protein so it sticks to any engineered surface- from silicon to steel. After dunking the surface in a viral broth, nickel and palladium are added to grow a metallic grass.
❉ The viral tendrils work like a wicking surface, drawing down water to replace what’s boiled away. It’s the same idea behind thermal fabrics designed for athletes which draws moisture away from the body. They say a watched pot never boils. I’d volunteer to test a virally coated tea kettle, how about you?
Waterproofin’ with Hydrophobin: This old post shows how a fungal spore protein can do the opposite, creating a superhydrophobic surface that repels water but allows gases to exchange.
News Story and Short Video: http://drexel.edu/now/archive/2015/March/TMV-heat-transfer/
Ref: M.M. Rahman, E. Ölçeroğlu, and M. McCarthy, “The Role of Wickability on the Critical Heat Flux of Structured Superhydrophilic Surfaces”, Langmuir 2014, 30 (37), pp 11225–11234.