Northwestern faculty to speak at TEDxChicago
August 19, 2024
Someday, people might finally say goodbye to defrosting the freezer or scraping frost off slippery surfaces. Northwestern University engineers have developed a new strategy that prevents frost formation before it begins.
In a new study, the researchers discovered that tweaking the texture of any surface and adding a thin layer of graphene oxide prevents 100% 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.
As an added bonus, the new scalable surface design also is resistant to cracks, scratches and contamination.
By incorporating the textured surface into infrastructure, the researchers imagine companies and government agencies could save billions of dollars per year in averted maintenance costs and energy inefficiencies.
The research was published today (Oct. 30) in the journal Science Advances.
“Unwanted frost accumulation is a major concern across industrial, residential and government sectors,” said Northwestern’s Kyoo-Chul Kenneth Park, who led the study. “For example, the 2021 power crisis in Texas cost $195 billion in damages, resulting directly from frost, ice and extreme cold conditions for more than 160 hours. Thus, it is critical to develop anti-frosting techniques, which are robust for long periods of time in extreme environmental conditions. It is also necessary to develop anti-frosting methods which are easy to fabricate and implement. We designed our hybrid anti-frosting technique with all of these needs in mind. It can prevent frosting for potentially weeks at a time and is scalable, durable and easily fabricated through 3D printing.”
Park is an assistant professor of mechanical engineering at Northwestern’s McCormick School of Engineering and a faculty affiliate of the Paula M. Trienens Institute for Sustainability and Energy and the International Institute for Nanotechnology.
Leaf-inspired discovery
The new study builds upon previous work from Park’s laboratory. In 2020, Park and his team discovered that adding millimeter-scale textures to a surface theoretically reduced frost formation by up to 80%. Published in the Proceedings of the National Academy of Sciences, the research was inspired by the rippling geometry of leaves.
“There is more frost formation on the convex regions of a leaf,” Park said at the time. “On the concave regions (the veins), we see much less frost. People have noticed this for several thousands of years. Remarkably, there was no explanation for how these patterns form. We found that it’s the geometry — not the material — that controls this.”
Through experimental work and computation simulations, Park and his collaborators found that condensation is enhanced on the peaks and suppressed in the valleys of wavy surfaces. The small amount of condensed water in the valleys then evaporates, resulting in a frost-free area.
Graphene-oxide trapping power
In the previous study, Park’s team developed a surface featuring millimeter-scale peaks and valleys with small angles in between. In the new study, Park’s team added graphene oxide on flat valleys, which reduced frost formation by 100% in those valleys. 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.
