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Heat transfer suppression by suspended droplets on microstructured surfaces
- Source :
- Applied Physics Letters. 116:233703
- Publication Year :
- 2020
- Publisher :
- AIP Publishing, 2020.
-
Abstract
- Manipulating the degree of droplet contact with a surface significantly impacts applications involving drag reduction, corrosion inhibition, droplet transportation, and thermal management. Extensive studies have been conducted to study droplet wetting behavior on plain and micro/nanostructured surfaces, with a particular focus in the recent literature on heated surfaces, where evaporation beneath the droplet impacts the apparent wettability. In previous literature, the peak droplet lifetime and minimum heat transfer on heated surfaces were observed at the Leidenfrost point. In this study, however, we report the existence of two distinct peaks for droplet lifetime on heated surfaces structured with silicon micropillar arrays. Initially, droplets exhibit complete wetting at low surface temperatures, but as surface temperature increases, the wetting state transitions first to a contact non-wetting state (i.e., a Cassie–Baxter-like state) and then to the non-contact Leidenfrost state; two distinct local maxima in droplet lifetime are observed, one corresponding to each transition. The contact non-wetting transition temperature and Leidenfrost point increase with larger micropillar pitch and taller height, which we attribute primarily to the resulting lower effective thermal conductivity of the micropillar array beneath the droplets, in agreement with the analytical force-balance-based modeling. This study provides a comprehensive investigation of the effect of surface structuring on contact non-wetting and Leidenfrost phenomena and will serve as design guidelines in controlling the contact non-wetting and Leidenfrost temperatures for specific applications.
- Subjects :
- 010302 applied physics
Materials science
Physics and Astronomy (miscellaneous)
Silicon
Transition temperature
Evaporation
chemistry.chemical_element
02 engineering and technology
021001 nanoscience & nanotechnology
01 natural sciences
Leidenfrost effect
Physics::Fluid Dynamics
Thermal conductivity
chemistry
Drag
Chemical physics
0103 physical sciences
Heat transfer
Wetting
0210 nano-technology
Subjects
Details
- ISSN :
- 10773118 and 00036951
- Volume :
- 116
- Database :
- OpenAIRE
- Journal :
- Applied Physics Letters
- Accession number :
- edsair.doi...........708b7306e5f7cb1906e58f2f4877680e
- Full Text :
- https://doi.org/10.1063/5.0010510