| Project/Area Number |
06452181
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thermal engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KOBAYASHI Yasunori University of Tsukuba, Institute of Engineering Mechanics Professor, 構造工学系, 教授 (10132995)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 1995: ¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1994: ¥3,500,000 (Direct Cost: ¥3,500,000)
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| Keywords | Liquist Meniscus / Heat Pipe / Evaporative Heat Transfer / Macro-Region / Micro-Region / メニスカス / 蒸発しない薄膜 / 蒸発伝熱 / 溝形ヒートパイプ |
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| Research Abstract |
Major part of the second year (final year) is dedicated to conduct an experimental study of measuring non-evaporative film thickness of the working liquid at the meniscus edge contacting with the surrounding soild wall. The measured film thicknesses for different heating conditions are approximately in the range of 20 to 50 nanometers, which is about an order of magnitude larger than the calculated ones. However, by considering uncertainty of the value for accommodation coefficient used in the calculation, this discrepancy is not necessarily unexplainable. Dual-exposure laser holographic technique was introduced to obtain the film thickness pattern at the meniscus edge, but no clear photographs that will give quantitative information on film thickness have been available yet.
Improvement of the analytical model by changing the boundary conditions was also implemented, although the mainframe of the program was remained unchanged from the one developed in the previous year. Agreement between the calculated and measured heat transfer rates and the meniscus configurations seem to be good at least qualitatively. Through this study a significance role of the narrow meniscus-edge region on evaporative heat transfer rates was clarified, although further improvement of measuring technique as well as analytical modeling is required. It was also found that the axial-groove heat pipe used in the experiment was relatively insensitive to the direction of gravity due to its long fins.
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