Developmental Mechanism of the Critical Heat Flux in Subcooled Flow Boiling - Research on the Vapor-Liquid Structure in the Near Wall Region

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06217
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Kyushu University
• Principal Investigator: Liu Wei 九州大学, 工学研究院, 准教授 (70446417)
• Co-Investigator(Kenkyū-buntansha): 小泉 安郎 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 原子力基礎工学研究センター, 嘱託 (20215156)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 限界熱流束 / 伝熱面配置角度 / 強制流動 / 正味蒸気発生点 / 気泡離脱直径 / 限界熱流束予測 / IVR

Outline of Final Research Achievements

To understand the mechanism of forced flow subcooled flow boiling CHF, a test loop and a test device were constructed. The test device has a square flow channel with a cross section of 8 × 8 mm. One of the channel surface is a heated surface of copper and the other three are made of glass to observe the flow inside the channel. The test piece setting angle can be adjusted freely from downward facing to vertical facing. We observed bubble departure behavior at the net vapor generation point, which is the starting point of the CHF phenomenon. Based on the detailed analyzing of the force balance on bubbles staying on the tube wall, a bubble departure diameter model that can account for the effect of the heating surface setting angle was proposed. The proposed bubble departure model was then incorporated into a CHF model. It has been confirmed that the forced flow subcooled boiling CHF under different arrangement angle conditions can be predicted accurately.

Free Research Field

伝熱流動

Academic Significance and Societal Importance of the Research Achievements

限界熱流束は水冷却原子炉を含む伝熱機器の除熱限界を定めるため、限界熱流束の発生メカニズムの解明及び限界熱流束の向上は伝熱機器出力の向上に直接つなぐ。エネルギー利用の観点からインパクトが大きい。また、本研究は伝熱面配置の角度の正味蒸気発生点への影響を明らかにするとともに、新たに伝熱面角度の効果をCHFモデルに取り入れた。これにより、伝熱面配置角度が変化する条件におけるCHFに対して機構論的な予測手法を開発し、シビアアクシデント時原子炉IVRの成立性の定量評価に貢献した。