Spatial control of heterogeneous nucleation on the Superhydrophobic Nanowire Array

Ching Wen Lo, Chi-Chuan Wang, Ming-Chang Lu

Research output: Contribution to journalArticle

58 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)1211-1217
Number of pages7
JournalAdvanced Functional Materials
Volume24
Issue number9
DOIs
StatePublished - 5 Mar 2014

Keywords

  • heterogeneous nucleation
  • Si nanowire arrays
  • spatial control
  • superhydrophobic surfaces

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