| Project/Area Number |
16360428
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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 |
Aerospace engineering
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| Research Institution | High Energy Accelerator Research Organization (KEK) |
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Principal Investigator |
NAKAI Hirotaka High Energy Accelerator Research Organization (KEK), Accelerator Laboratory, Senior Assistant Professor, 加速器研究施設, 講師 (00188872)
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| Co-Investigator(Kenkyū-buntansha) |
KIMURA Nobuhiro High Energy Accelerator Research Organization (KEK), Cryogenics Science Center, Senior Assistant Professor, 超伝導低温工学センター, 講師 (10249899)
MAKIDA Yasuhiro High Energy Accelerator Research Organization (KEK), Institute of Particle and Nuclear Studies, Associate Professor, 素粒子原子核研究所, 助教授 (30199658)
NAGAI Hiroki Tohoku University, Graduate School of Engineering, Research Associate, 大学院工学研究科, 助手 (70360724)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥8,600,000 (Direct Cost: ¥8,600,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | Superfluid Helium / Superconducting Magnet / Space / Cooling Technology / Heat Transfer |
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| Research Abstract |
Boiling phenomena of superfluid helium have been visualized by employing a cryostat with optical windows on it and a high-speed camera, and variations of film boiling modes and heat transfer coefficients have been measured in wide ranges of pressure and temperature to unveil the thermal characteristics of superfluid helium for efficient cooling of superconducting magnets. It is concluded from the experimental results that the noisy film boiling, which is the unique boiling phenomenon of saturated superfluid helium, does not appear under the microgravity environment of space, even if almost the same amount of superfluid helium is located over the heater as that under the gravity. Because of rapid growing of vapor phase, "viscous fingering" phenomenon was observed, and higher thermal conduction may be obtained by the effect of mixed phases motion.
Loop heat pipes are suggested for the heat exhaust from cooling systems, since the loop heat pipes are light in weight, highly reliable, and can transfer large amount of heat. Their start-up and performance characteristics under microgravity are studied in cases of top-heating and bottom-heating. It is found out that when rather large heat was applied to the heat pipes, there was no difference in heat transfer capacity from the case when heat pipes are placed horizontally, and stable performance was observed once they had started up. Unstable performance had been sometimes observed when the heat load was small. This means the flow path of the vapor may be choked with the liquid at the outlet of the evaporator when start-up. Hence the initial distribution of the liquid may affect largely the start-up of heat pipes under the microgravity condition. The temperature control of the reservoir seems to be able to ensure the start-up of the heat pipes regardless of the initial distribution of the liquid.
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