Surface Engineering Approach to Simultaneously Boosting the Leidenfrost Point and Heat Dissipation Capability
- Zuankai WANG (Principal Investigator / Project Coordinator)Department of Mechanical Engineering
- David QUÉRÉ (Co-Investigator)
DescriptionEfficient thermal cooling is of fundamental interest and practical importance in numerous industrial applications, especially in extremely high temperature environments. Owing to many advantages such as high latent heat and easy operation, water droplet-based spray cooling has been widely explored. Despite extensive progress, achieving effective heat dissipation on high temperature surfaces remains challenging owing to the occurrence of a classical Leidenfrost phenomenon, characterized by the formation of a continuous, thermally insulating vapor layer that blocks effective heat transfer between liquid and hot surface. To overcome this bottleneck, much attention has been paid to the meticulous design and choice of structural and thermal properties of materials. To date, the highest Leidenfrost point is still less than 600℃, which is also achieved at the expense of heat transfer performances. Thus, it is important and pressing to develop novel strategies that can dramatically boost the Leidenfrost point and the heat dissipation capability simultaneously. In this project, we propose to design a novel three-dimensional hybrid surface that can fundamentally resolve the limitations encountered in conventional designs. Our approach leverages on the rational design of pillar arrays with high thermal conductivity (thermal bridge) embedded with inorganic porous membrane with extremely low thermal conductivity (thermal sponge), allowing the preferential pathways for a compete spreading of liquid and a timely departure of evaporating vapor and enabling the suppression of the onset of Leidenfrost phenomenon even at extremely high temperatures over 1000℃. Our preliminary work has shown that impacting droplets on the hybrid structure can exhibit a complete spreading and nucleate boiling in a broad temperature ranging from 100℃ to over 1000℃. In this project, we will first design, fabricate, and characterize the proposed hybrid surface. Then, to demonstrate the synergistic cooperation between the thermal bridge and the thermal sponge for achieving preferred functions, we will measure and compare Leidenfrost points and heat transfer performances of the hybrid surface and conventional samples. We will also develop theoretical models to advance our fundamental understanding and to guide the experimental optimization. As an extension from fundamental study to practical applications, we will develop facile processes for the manufacturing of large-scale samples. Finally, to demonstrate the generality of our concept, we will also fabricate flexible, hybrid structures that can be easily adapted to various substrates to serve as a thermal armor, endowing the efficient cooling of arbitrary surfaces and devices even in extreme high temperature environments.
|Effective start/end date||1/07/21 → …|