Spatial Control of Heterogeneous Nucleation on the Superhydrophobic Nanowire Array

Condensation is a common phenomenon and is widely exploited in power generation and refrigeration devices. Although drop‐wise condensation offers high heat and mass transfer rates, it is extremely difficult to maintain and control. In this study, the ability to spatially control heterogeneous nuclea...

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Bibliographic Details
Published in:Advanced functional materials 2014-03, Vol.24 (9), p.1211-1217
Main Authors: Lo, Ching-Wen, Wang, Chi-Chuan, Lu, Ming-Chang
Format: Article
Language:English
Subjects:
Arrays
Condensing
Density
Droplets
heterogeneous nucleation
Nanostructure
Nanowires
Nucleation
Roughness
Si nanowire arrays
Silicon
spatial control
superhydrophobic surfaces
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Summary:Condensation is a common phenomenon and is widely exploited in power generation and refrigeration devices. Although drop‐wise condensation offers high heat and mass transfer rates, it is extremely difficult to maintain and control. In this study, the ability to spatially control heterogeneous nucleation on a superhydrophobic surface by manipulating the free energy barrier to nucleation through parameterizing regional roughness scale on the Si nanowire array‐coated surface is reported. Water vapor preferentially condenses on the designed microgrooves on the Si nanowire surface and continuous shedding of the drop‐wise condensate is observed on the surface. The nucleation site density can also be manipulated by tailoring the density of the microgroove on the surface. Moreover, the cycle time on the Si nanowire array with microgrooves is approximately ten times smaller than that on a plain Si surface. This suggests that potentially high heat and mass transfer rates can be achieved on the surface. The insight from this study has implications in enhancing energy efficiency in a wide range of thermal energy conversion systems. Spatial control of heterogeneous nucleation on superhydrophobic silicon nanowire array‐coated surfaces is achieved by manipulating free energy barriers to nucleation through parameterizing regional roughness scale on the surface. Water droplets with a large contact angle preferentially nucleate on the designed microgrooves on the Si nanowire surface, whereas nucleation sites on an ordinary surface are randomly distributed.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201301984