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A novel thermal ground plane has been developed and experimental studies on thermal ground planes (TGPs) for thermal management have been carried out.
TGP used in this paper features a copper casing, circular micropillars, and oxidized nanostructure copper foam wick structure, with water as the working fluid. By studying the effect on thermal performance by the number of layers of porous wick structure of TGP, surface modification for a nanostructure-owning property of the copper wick structure and topper casing of different wettability. It is found that TGP with double layers of nanostructured copper foam wick structure and hydrophilic casing shows the best thermal performance among all the tested samples. A novel finding is that a double-layer wick structure with the same thickness owns a better thermal performance than a single-layer or quadruple-layer. Nanostructured wick structure also shows significant improvement from this project. Hydrophilic topper casing is superior to superhydrophobic/ superhydrophilic/ hydrophilic topper casing in axial heat transfer of the TGP.
Thermal management helps improve reliability and prevent premature failure and solve the barrier of energy-intensive electronics. Through the use of environmental-friendly materials, TGP improves energy efficiency for a sustainable digital world.
Traditional thermal management
Traditional heat pipes
Light emitting diodes (LEDs)
Flexible handy electronics
- Double-layer copper wick - works best in axial heat transfer compared to single/ quadruple-layer
- Oxidized nanostructured copper wick - improves water-carrying performance thus thermal performance
- Hydrophilic surface topper casing - works best compared to hydrophobic/ superhydrophilic/ superhydrophobic
Thermal ground plane (TGP) can improve thermal management of the heat-spots of electronics, by heat-spreading through convection.
Wettability surface modification - nanotechnology
- By chemical treatments, the flower-like nanostructure can be formed with different wettability properties
- With nanowires, water can be coated on the entire microscale fibre with a thin condensate layer with an adequate wicking length, increasing the number of nucleation sites and heat transfer area. The geometric parameters around the free meniscus surface increase the capillary pressure.
- By changing the surface wettability of the topper casing and copper wick, the axial thermal resistance has been investigated
Choice of materials
- Mainly copper and water
- Sustainable and recyclable
Effect of number of layers of wick
Double layer copper wick
- capillary effect while permeability
- evaporating meniscus develop both
on the top surface and inside the wick
Effect of oxidize nanostructure of wick
Wick with Oxidized nanostructure
- improve water-carrying capacity
- thin condensate layer
- reduce the chance of dryout
Effect of wettability of topper casing
Hydrophilic topper casing
- without clogging
- rejects water at an optimal rate
- Vapor core size: 6 cm * 2 cm * 0.677 mm
- Thermal resistance: 1.22 K/W at 19.9 W
- Heat source temperature: 65.7 °C at 19.9 Whttps://i.imgur.com/G61hXMP.png
The story behind this project
This project is my undergraduate final year design project (FYDP). Due to COVID-19, my co-op internship project was suspended midway and this FYDP is a substitute to satisfy my graduation requirement, without groupmates and I have got only half of the time as a normal FYDP project does. I would like to thank the support of my teaching assistant Yinchuang Yang and my supervisor Prof Huihe Qiu for guiding me through this cutting-edge technology, researching and achieving these remarkable breakthrough results. And more, I have won several regional awards from professional societies for this project.
As this project requires intensive laboratory techniques, for example, nanostructure forming process, degassing, soldering, etc. The TGP is extremely fragile and can be broken during the fabrication process. Moreover, due to limited experience from researchers worldwide in this nanotechnology, a lot of trial and error was required. I applied my engineering knowledge as a problem-solver and I hope to continue improving the world in the future.
(Some samples that are broken during the fabrication process)