2021 Fiscal Year Final Research Report
Fundamental study on detection of local temperature anomalies in high-temperature superconducting transmission cables by application of phase transition
| Project/Area Number |
19K04340
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 21010:Power engineering-related
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
Takahata Kazuya 核融合科学研究所, ヘリカル研究部, 教授 (10216773)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 過熱液体 / 突沸現象 / 液体窒素 / 過熱限界 / クエンチ検出 / 超伝導機器 / 高温超伝導 / 圧力伝播 |
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| Outline of Final Research Achievements |
To promote the commercial use of high-temperature superconducting devices, the ability to detect temperature anomalies easily is important. In particular, a sudden local temperature increase due to a superconducting-to-normal transition can damage a device. In the present study, we propose a method to detect explosive boiling of superheated liquid nitrogen sealed in a long thin tube using a pressure gauge connected to the end of the tube. Experiments using a stainless-steel tube with an inner diameter of 1 mm and a maximum length of 50 m showed that the local temperature rise caused explosive boiling at a temperature slightly below the superheat limit of 110 K for liquid nitrogen; the results also showed that the rapid pressure increase was transmitted to the end of the tube at approximately the speed of sound (~830 m/s). The proposed method of placing a thin tube along high-temperature superconducting conductors can be used to easily detect a local temperature rise.
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| Free Research Field |
超伝導・低温工学
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| Academic Significance and Societal Importance of the Research Achievements |
超伝導送電ケーブルを含め，高温超伝導機器を普及させるためには，超伝導から常伝導への転移，いわゆるクエンチを確実に検出する必要がある。従来は電圧を測定する方法が主流であったが，電磁ノイズによる誤動作を避けられない。本研究で提案する突沸による圧力上昇を検出する方法では，電磁ノイズの影響を受けずクエンチによる局所温度上昇を確実に検出することができる。液体窒素の突沸現象は研究例が少なく，ステンレスの長尺細管内での実験は世界で初めてとなる。加熱条件によって突沸する温度が変化するなど，学術的に貴重な実験データが得られた。細管内での突沸現象は確実に起こることを実証し，超伝導機器への応用に期待が高まった。
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