Persistent reduction of boiling incipience of ethanol on biphilic porous textured surfaces

Biao Shen, Takeshi Hamazaki, Kohei Kamiya, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata, Junji Nunomura, Akihiro Fukatsu, Yoichiro Betsuki

研究成果: ジャーナルへの寄稿学術誌査読

3 被引用数 (Scopus)

抄録

Boiling of highly wetting fluids is of great interest to thermal management of high-powered electronic devices, enhancement of which conventionally relies on functional modifications of surface shape and structure so as to promote bubble generation and growth. In this paper we attempt to combine the approach of porous texturing with a novel technique of surface wettability engineering to enhance saturated pool boiling of ethanol. Thin layers of microporous and nanoporous surface topographies were chemically deposited on an aluminum substrate by anodization in phosphoric acid and sulfuric acid, respectively. Boiling on the textured surfaces recorded over-twofold increases in terms of the heat transfer coefficient compared with that on a plain smooth surface, which can be attributed to a proliferation of active nucleation sites. The boiling incipience point on both porous surfaces, however, exhibited an interesting dependence on the initial wetting state of the surface. With the application of amphiphobic coatings of fluoropolymer modified with halloysite nanotubes, we managed to engender a biphilic (i.e., spatially alternating hydrophobicity and hydrophilicity) pattern on the porous-textured surfaces. The repeat control experiments on the hybrid surfaces showed an equally efficient mode of nucleate boiling, whose inception, by contrast, seemed to occur at consistently low superheats. The remarkable reduction (by more than 80%) of the minimum superheat at the boiling onset hints at an alternative nanobubble-related mechanism for heterogeneous bubble nucleation, which is notably less affected by incondensable gas, to the classic vapor-trapping-cavity model.

本文言語英語
論文番号103739
ジャーナルInternational Journal of Multiphase Flow
142
DOI
出版ステータス出版済み - 9月 2021

!!!All Science Journal Classification (ASJC) codes

  • 機械工学
  • 物理学および天文学(全般)
  • 流体および伝熱

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