A new scalable, robust surface prevents 100 percent of frost formation across flat areas. The initial trial demonstrated ‘frost proofing’ for one week. Remarkably, the surface structure innately prevents frost without heat or special coating.
The ability to reduce frost may increase energy efficiency in appliances, reduce drag on airplanes and have other useful applications.
How can frost be stopped from forming on a surface without imparting additional energy? To come up with the solution, researchers from Northwestern University were inspired by leaves, which do not form frost on their concave veins
The researchers discovered that by tweaking the texture of any surface and adding a thin layer of graphene oxide, they could prevent 100 percent of frost from forming on surfaces for one week or potentially even longer. This is 1,000 times longer than current, state-of-the-art anti-frosting surfaces.
Furthermore, the new scalable surface design is resistant to cracks, scratches and contamination. The goal was to fabricate a surface that was of a low cost and easy to implement. The resultant surface is scalable, durable and easily produced through 3D printing.
Going forwards, by incorporating the textured surface into infrastructure, companies and government agencies could potentially save billions of dollars per year in averted maintenance costs and energy inefficiencies.
On the concave regions (the veins), the researchers noted they tend to see much less frost. Investigations showed this to be down to the geometry — not the material. This led to experimental work and computation simulations, where it was shown that condensation is enhanced on the peaks and suppressed in the valleys of wavy surfaces.
The new study built upon earlier studies that discovered by adding millimeter-scale textures to a surface theoretically reduced frost formation by up to 80 percent. This is the part of the research inspired by leaves. The new surface comprises tiny bumps, with a peak-to-peak distance of 5 millimeters. Then a thin layer of graphene oxide, just 600 microns thick, coats the valleys between peaks.
The graphene oxide attracts water vapor and then confines water molecules within its structure. This means the graphene oxide layer acts like a container to prevent water vapor from freezing. When we combined graphene oxide with the macrotexture surface, it resisted frost for long times at high supersaturation. The hybrid surface becomes a stable, long-lasting, frost-free zone.
The research appears in the journal Science Advances, with the paper titled “Robust hybrid diffusion control for long-term scalable frost prevention.”
