| Project/Area Number |
12650193
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Tokyo Institute of Technology |
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Principal Investigator |
OKAMURA Tetsuji Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, Professor, 大学院・総合理工学研究科, 教授 (10194391)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2001: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Superfluid helium / Fountain effect / λ-transition / Porous material / Cooling channel / Superconducting magnet / λ転位 / 超伝道磁石 |
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| Research Abstract |
Heat transport characteristics of superfluid helium (He n) in channel segmented by different types of spacer having several holes have been investigated on the basis of both experiment and numerical analysis. The heat transport performance has been examined for the following spacers : (a) FRP spacer without any hole, (b) FRP spacer with several holes of 2 or 4 mm diameter, (c) porous spacer made of fine powder of sintered Al_2O_3, (d) porous spacer made of high density polyethylene (HDPE) which is more flexible than Al_2O_3. The average diameter of the porous is about 1μm. It is expected that helium flow is induced in the channel because of a fountain effect when the porous spacer is applied.
The λ-transition heat flux when we use the spacers having holes of diameter 2 mm and 4 mm is almost the same. This value is about 1.5 times larger than that in the case of using spacer without any hole. The λ-transition heat flux depends on the porosity of the spacer. A relatively high cooling performance can be realized when the porosity is only about 5%. These results lead to the understanding that the introduction of some holes in the spacer is a very effective way to suppress local temperature rise in the He II channel.
The λ-transition heat flux increases remarkably when the porous spacer is used instead of the FRP spacer with holes of 2 or 4 mm in diameter, because Hen flow is induced in the heated channel by a fountain effect. It is also found that the use of porous spacers between Hell channels is effective to suppress a steep temperature rise in the heated channel not only when the channel is filled with He II entirely but also when normal helium (He I ) is generated in the channel.
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