Leaf geometry inspires solution to prevent ice formation
Marie Donlon | March 12, 2020Source: Stephan HerbResearchers from Northwestern University have developed a method inspired by the geometry of leaves for preventing the formation of ice on surfaces.
Recognizing that the convex features of leaves tend to invite more frost formation than the concave features, the researchers discovered that modifying the texture of surfaces was key to reducing frost formation, by a reported 60% according to the study.
Surfaces rippled with peaks and valleys, like a leaf, discourage the build up of frost, according to researchers, because condensation is encouraged on the leaf’s peaks and suppressed in its valleys. The fraction of condensed water that collects in the valleys, reportedly evaporates, according to the research. As such, those components are virtually frost free when the temperature drops below freezing.
To achieve the ideal geometry of peaks and valleys on a surface to discourage frost formation, the team found that surfaces with millimeter-sized peaks and valleys with angles in the 40° to 60° range worked best. While frost still formed on surface peaks during testing when temperatures fell below freezing, it was defrosted using far less energy than was previously required to defrost a surface without peaks and valleys.
The finding, according to researchers, could one day mean reduced energy use associated with defrosting methods applied to refrigerators and freezers and it could potentially eliminate the formation of frost on airplane wings, which can delay and even cancel flights due to dangers such as drag that ice pose to airplanes.
Modifying the material design of a surface to prevent ice formation by including peaks and valleys is an environmentally friendly approach not available with similar solutions that employ chemicals, coatings and films to prevent ice build up.
The research appears in the journal Proceedings of the National Academy of Sciences.