Wettability-driven water condensation at the micron and submicron scale

Yutaka Yamada, Akira Kusaba, Tatsuya Ikuta, Takashi Nishiyama, Koji Takahashi, Yasuyuki Takata

Research output: Contribution to conferencePaperpeer-review

1 Citation (Scopus)


Water condensation on a graphite surface was investigated at the micron and submicron scale by environmental scanning electron microscopy. The graphite comprised a hydrophobic terrace and hydrophilic step edges, of which the nanoscale structure was precisely measured by atomic force microscopy prior to the condensation experiments. The condensed droplets were preferentially aligned parallel to the step edges with a step height of 1 nm. The droplets featured a diameter of 150-300 nm at intervals greater than 150 nm. Shorter droplet intervals were realized by narrower terraces and higher steps. The current findings extend beyond the nucleation theory, whereby the effect of adsorbed water molecules on hydrophilic step edges was considered. The contact angle (i.e., 10°) of the nucleated droplet at its initial stage (with diameter in the nanoscale) was determined from the extended theory, and was consistent with direct observation of slightly grown droplets. The growth mechanism of the submicrometer-sized droplets was also investigated; under this scale regime, the three-phase contact line does not recede during coalescence.

Original languageEnglish
Publication statusPublished - 2014
Externally publishedYes
Event15th International Heat Transfer Conference, IHTC 2014 - Kyoto, Japan
Duration: Aug 10 2014Aug 15 2014


Other15th International Heat Transfer Conference, IHTC 2014


  • Condensation
  • Environmental scanning electron microscopy
  • Graphite
  • Heat transfer enhancement
  • Hydrophobic-hydrophilic surface
  • Microscopic measurement

ASJC Scopus subject areas

  • Mechanical Engineering
  • Condensed Matter Physics


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