| Project/Area Number |
17K06193
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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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| Research Field |
Thermal engineering
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| Research Institution | University of Fukui |
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Principal Investigator |
Nagai Niro 福井大学, 学術研究院工学系部門, 教授 (70251981)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2019: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
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| Keywords | 沸騰 / 固液接触 / 濡れ開始 / スプレー冷却 / MHF点 / 可視化 / 伝熱モデル |
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| Outline of Final Research Achievements |
During spray cooling of high temperature surface over boiling point, film boiling collapses by initiating localized and intermittent liquid-solid contacts on superheated surface, and rapid cooling begins. This criteria, i.e. wetting initiation condition was investigated by visual observation of localized and surface temperature measurements. As a result, localized liquid-solid contacts sisutations were successfully visualized during water spraying, which had not been so far realized due to experimental difficulties. Under spraying conditions of HFE-7100, which has lower boiling point, the above criteria had been grasped with several liquid flow densities. In addition, heat transfer modeling was conducted which can simulate simultaneously spontaneous nucleation process and unsteady heat conduction in solid and liquid layers.
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| Academic Significance and Societal Importance of the Research Achievements |
一般的に、沸点以上に過熱された高温面を液体で沸騰冷却する場合、固液接触の無い膜沸騰状態はいずれ局所的・間欠的に崩壊し、局所的な固液接触（濡れ）が発生し急冷が始まる。その発生条件（いわゆる濡れ開始条件）を汎用的に把握することは、鉄鋼業における製造プロセスの高度化、原発等の事故時安定性評価、超低温流体応用システムの起動安定性などに応用されるとともに、学術的な長年の課題解決を意味する。本研究では、液体沸騰冷却の内スプレー冷却条件下において、応用事例の多い水スプレー時の濡れ開始近傍の現象を直接観察することに成功し、また濡れ開始条件を検討するための伝熱モデルを構築することができた。
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