Enhancing Thermal Systems through Vibration-Assisted Droplet Transport on Metal Surfaces

Kirill Misiiuk

kirill.misiiuk@otago.ac.nz

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K. Misiiuk et al., Langmuir, 2022 DOI:10.1021/acs.langmuir.1c02518

All-metal wetting gradient (aluminium)

That’s also the strength of the gradient�

Or��How hard the droplet is pushed

Oh boy, here we go again…

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Flow Induced Vibration

Machinery Induced Vibration

Vibration as a Problem

YouTube: The Engineering Mindset

YouTube: Dynaflow Research Group

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Vibration as a Problem

Solution

“If you can’t beat them, lead them”

How a Droplet Harnessed Vibration

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“shaker”

Hydrophilic Surface�(Raw aluminium)

Experimental Setup

Vertical vibration

How a Droplet Harnessed Vibration

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Superhydrophobic Surface

Horizontal vibration

Vertical vibration

Wetting Gradient

How a Droplet Harnessed Vibration

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Superhydrophobic Surface

Wetting Gradient

Hydrophilic Surface�(Raw aluminium)

In black on the plot

In pink

In purple

Horizontal vibration

But the motion on gradients was up to 6-8 mm!

How a Droplet Harnessed Vibration

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Superhydrophobic Surface

Wetting Gradient

Hydrophilic Surface�(Raw aluminium)

In black on the plot

In pink

All other colours

Vertical vibration

The gradients beat the superhydrophobic surface and provide horizontal motion as well!

How a Droplet Harnessed Vibration

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And got Editor’s Pick!

Congratulations... Now what?

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HX

“Typically, 5 µL droplets do not drain even from vertical aluminium surfaces; however, if they can be removed through the introduction of these additional forces, the effect would be considerable. For example, using the latent heat of condensation for water at standard atmospheric pressure:

≈11.3 Joules per shed droplet

depending on how frequently these smaller droplets are removed from a surface, such energy savings could accumulate. On a heat exchanger, there may be hundreds—or even thousands—of droplets of this size. Therefore, the potential energy savings could reasonably reach the order of watts, or even tens of watts, depending on the shedding rate”

One of the reviewers started a good discussion

Test rig

Bigger shaker!

Special thanks to�OERC Seed Grant�for supporting this project!

Conclusions:

• Even low-level vibration could be utilised to enhance droplet shedding from HX surfaces;
• HPB surface reduce the threshold required to initiate the motion;
• Wetting gradients may reduce the threshold even more allowing in-plane motion of the droplet;
• The fundamental results show promising potential for further applications.

Kirill Misiiuk

kirill.misiiuk@otago.ac.nz

Enhancing Thermal Systems through Vibration-Assisted Droplet Transport on Metal Surfaces

Questions?

Kirill Misiiuk

kirill.misiiuk@otago.ac.nz

Let’s not, it’s almost 5 pm, we all want to go home…