Radiation induced surface activation on Leidenfrost and quenching phenomena

T. Takamasa*, T. Hazuku, K. Okamoto, K. Mishima, M. Furuya

*この研究の対応する著者

研究成果: Article査読

40 被引用数 (Scopus)

抄録

Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, zircaloy No. 4, SUS-304, and copper was improved significantly by the radiation induced surface activation (RISA) phenomenon. To delineate the effect of RISA on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by y-rays were investigated in this study. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co γ-ray irradiation.

本文言語English
ページ(範囲)267-274
ページ数8
ジャーナルExperimental Thermal and Fluid Science
29
3
DOI
出版ステータスPublished - 2005 3月 1
外部発表はい

ASJC Scopus subject areas

  • 化学工学(全般)
  • 原子力エネルギーおよび原子力工学
  • 航空宇宙工学
  • 機械工学
  • 流体および伝熱

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