In summer not only sledge should be prepared for winter, but also roofs, which in Russia and other northern countries will definitely be covered with tons of snow and icicles. What shall we do to save our lives from icy threat?

Scientists from State Oceanographic Institute of Russian Hydrometeorologic Service develop technology for protecting roofs from freezing (ice crusts, snow and icicles). Roofs and icicles coexist for many years, and humanity has invented a variety of means for getting rid of snow formations – time has come to choose the best one.

Some suggest using deicing (anti-frost) coatings, but such coatings are rare guests on our roofs due to lack of recommendations for using them on various objects and under various climatic conditions. Russian researchers have made and installed an experimental construction, imitating fragment of a roof, outdoors. Tested coatings were applied between eaves trough and edge of the roof. In case weather didn’t allow icicles to appear, the roof was heated by means of heating elements from beneath and lights from above, thus simulating daytime thaw, necessary for ice formation. During first series of experiments scientists tested four deicing coatings. Roof, made of galvanized iron, was covered with Lavsan (polyester fiber) film with silicon coating, organosilicate mastic OS 56-22, and mix of organosilicate mastic OS 56-22 with special liquid “Turtle wax Clear Vue (Rain Repellent)”, made by Turtle Wax MFG.Ltd, Great Britain. Best deicing results were detected for silicon coating upon Lavsan film, which weakens binding of ice and roof, and killer icicles aren’t able to appear on this coating.

 

 

Together with the technique, described above, which can be called “passive”, researchers suggest one more “active” technology. In order to reduce or even prevent icing of a surface, scientists used vibrations of said surface. How a roof can vibrate? Scientists know how – by means of electric generator of elastic waves, which disturb surfaces, covered with ice or water. Roofs vibrated in both ways: transverse and longitudinal directions. Experiments showed that patterns of a frozen liquid borders were similar to wave propagation lines: the smaller vibration amplitude was, the thicker was frozen liquid layer. No ice was detected from vibration epicenter till critical shift line, which position depended on wave frequency.

“Active protection” turned out to make adhesion forces over 4 times less “sticky” – much better result than deicing coating showed. Set of preliminary experiments reveals that only several tens of Watts per one square meter are required for “active protection” of a city roof – considerably low power consumption, isn’t it?

Now researchers are busy with working out specific recommendations for distributing disturbance sources over the roof surface and for finding optimal mode of vibration. For this purpose scientists should solve the problem of wave propagation in a multiplayer medium. “Active” roof protection has patents of invention of Russian Federation.

Source: Russian Science News

Kizilova Anna