2006 Fiscal Year Final Research Report Summary
Development of Practical TiO_2 Heat Transfer Surface by Advanced Coating Technique
| Project/Area Number |
17360097
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
TAKATA Yasuyuki Kyushu University, Faculty of Engineering, Professor, 大学院工学研究院, 教授 (70171444)
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| Co-Investigator(Kenkyū-buntansha) |
KOHNO Masamichi Kyushu University, Faculty of Engineering, Associate Professor, 大学院工学研究院, 助教授 (50311634)
KUBOTA Hiromi Kyushu University, Faculty of Engineering, Research Associate, 大学院工学研究院, 助手 (10117103)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Phase Change / Titanium Dioxide / Superhydrophilicity / Heat Transfer Enhancement / Heat Exchanger |
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| Research Abstract |
Titanium dioxide, one of photocatalysts, has been in spotlight since it has a strong oxidation power to harmful substances with the aid of UV light. In this research project, we tried to develop a practical TiO2 heat transfer surface by making use of flame coating technique. The four kinds of experiments have been performed and the results are summarized as follows.
1) In pool boiling, heat transfer coefficient and critical heat flux for hydrophilic surface become larger than those for normal surface.
2) In falling film evaporation, thin stable water film can be realized on the surface and resultant heat transfer coefficient increased by 40 times as the normal surface at its maximum case.
3) In immersion cooling, hot metal with hydrophilic coating is cooled down more rapidly than normal surface. The time required to cool down is tremendously shorten.
4) In water drop evaporation experiment, life time of water drop on superhydrophilic surface becomes much shorter than that on normal surface especially in lower temperature region. The wetting limit temperature increased for superhydrophilic surface.
Pool boiling experiment using flame coating surface was conducted. For comparison, experiments using sputtered and mirror surfaces were also tested and the following results were obtained.
a) Critical heat flux for flame coating increased by 1.5 times compared with the normal surface. However, heat transfer coefficient at higher heat flux decreased.
b) In higher heat flux region, heat transfer characteristic is much influenced by the thickness of coating layer.
We also conducted experiment of falling film evaporation using flame coating, sputtering and mirror surfaces and found the followings.
a) In lower temperature region, flame coating surface is the best among three surfaces.
b) In higher temperature region, thickness of coating layer and its structure influence the heat transfer characteristics.
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