Unstable Operation and Erosion in Closed Two-Phase Thermosyphons
| Project/Area Number |
61550050
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | Tokyo Metropolitan Institute of Technology (1988)
Osaka Prefecture University (1986-1987) |
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Principal Investigator |
NEGISHI Kanji Tokyo Metropolitan Institute of Technology, 機械システム工学科, 教授 (60081262)
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| Project Period (FY) |
1986 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1986: ¥800,000 (Direct Cost: ¥800,000)
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| Keywords | Closed Two-Phase Thermosyphon / Heat Pipe / Unstable Operation / Evaporator / Condenser / Heat Transfer Coefficient / Erosion / 蒸気泡の崩壊 / 密閉二相熱サイフォン / 不安定作動 / 熱輸送特性 |
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| Research Abstract |
Closed two-phase thermosyphons are very excellent heat transter divices expanded heat pipe technology. However, it is posed recently as important problem awaiting solution that the heat transfer characteristics are disturbed by unstable phenomena and the life of thermosyphon is shortened due to the erosion with the unstable phenomena.
The present study has succeeded at first to explain the relations among the unstable operating condition, the generating mechanism and the kinds of unstable phenomena in the thermosyphons by many experiments employed copper tube thermosyphons and glass tube ones to visualize the behavior of the working fluid.
The temperature changes of evaporator, condenser and vapor during unstable period were obtained and the disturbance of heat transfer coefficient was found by a modelling analysis of the unstable working process in the thermosyphon. Especially, it became clear that the heat transfer coefficient changed largely at the early period of the unstable operation.
It was proved also that water thermosyphon had the most serious unstable phenomenon concerned with its life. It was confirmed that the erosion occurred on the container inner surface was induced by the collapse of small vapor bubbles in the working liquid. It is the cause that the collapse of vapor bubble generates a micro-jet and it strikes strongly the inner surface of the container. Moreover, the counterplans to the erosion are discussed in the final part of this report. The many problems connected with the erosion, however, are still left unsolved. They will be solved in the near future by the continual studies.
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Report
(4 results)
Research Products
(10 results)
