| Project/Area Number |
08455103
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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 | University of Tokyo |
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Principal Investigator |
NISHIO Shigefumi University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (00111568)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAKASHI Ryo University of Tokyo, Institute of Industrial Science, Lecturer, 生産技術研究所, 講師 (80292754)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1997: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1996: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Heat Transport / Oscillation-Controlled Heat-Transport Tube / Dream Pipe / Heat Pipe / Micro Device / 熱輸送管 / 振動流 / 熱輸送限界 / マイクロシステム / ヒートシング |
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| Research Abstract |
The oscillation-controlled heat-transport device (OC-HTD) is suitable to develop the micro heat-transport devices. The type of OC-HTDs is the OC-HTD driven by an external oscillator (FDOC-HTD). In previous research, we have investigated the characteristics of FDOC-HTDs, but one of the remaining issues is their critical heat-transport rate (CHR) and the other is how to remove the external oscillator.
The most provable cause resulting in the CHR is the transition from laminar to turbulent oscillatory flow, and in this research the effects of the transition on the effective thermal conductivity of FDOC-HTD was experimentally investigated. The experimental results show that the transition does not result in a limitation of the effective thermal conductivity but produces an effective thermal conductivity higher than that predicted by the analysis assuming laminar oscillatory flow.
As for the issue removing the external oscillator, we focused on the meandering closed-loop heat-transport device (MCL-HTD) in which heating and cooling parts were connected with each other by a closed loop of tube meandering between them and operating liquid of a volume fraction was enclosed in the loop. Observation of fluid flow in the 10-turn MCL-HTD was conducted and it was found that a simple flow pattern appears at a high value of volume fraction of liquid. In such a condition, only two vapor plugs exist separately in adjacent turns, and one of them starts to grow when the other starts to shrink. When the latter plug disappears, a new vapor plug appears in the turn adjacent to the turn including the grown-up vapor plug. The vapor-plug propagation phenomena indicate that a kind of self-excited oscillation of liquid columns can be caused in MCL-HTDs if the number of turn is decreased.
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