10 December 2024
New research could improve de-icing technology
When water droplets freeze on cold surfaces, such as airplane wings or wind turbines, a complex internal flow occurs. Doctoral student Erik Fagerström at Luleå University of Technology has investigated in his thesis what drives this flow and how it can be controlled to reduce ice formation.
His research shows that both the material of the surface and the contact angle of the droplet against the surface significantly affect the direction and speed of the flow, which can lead to more efficient de-icing technology for several industries. Through experiments with metal plates cooled to sub-zero temperatures, Erik Fagerström analyzed how the contact angle of the droplets against the surface affects the internal flow and freezing time. The results show that droplets with a smaller contact angle – where the droplet is more spread out on the surface – have a stronger flow along the droplet's surface but lower in the middle. The contact angle also affects when the reversal of the flow direction occurs.
The Contact Angle and Freezing's Impact on the Internal Flow Direction
"Controlling the internal flow in droplets can be a factor in delaying ice formation. In droplets that did not freeze immediately, there was a delay in the reversal of the internal flow," says Erik Fagerström, doctoral student in fluid mechanics at Luleå University of Technology.
For materials with high thermal conductivity, such as copper, the highest speeds were noted along the droplet's midline.
"We saw that the choice of material affects the speed of the internal flow. Copper, with its high thermal conductivity, gave clear results with faster flows," says Erik Fagerström.
Erik Fagerström with the sweater he knitted to visualize the research.
Possible Applications in Medicine and Safety
In addition to anti-icing, the research also has potential applications in medicine, where the internal flow in droplets can be used to mix substances on a microscale or to sort particles to detect proteins more quickly.
Finally, Fagerström suggests that future research should investigate the effects of external factors such as wind and temperature to further optimize control over the flow in droplets.
"If we can understand the heat flows that affect the droplets, we can potentially create surfaces that actively counteract ice formation."
- Fluid mechanics
- Read more about Erik Fagerström's research
"The PhD student knitted a sweater to visualize the research"
Contact
Erik Fagerström
- Doctoral student
- 0920-493011
- erik.fagerstrom@associated.ltu.se
- Erik Fagerström
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