Heat transfer of subcooled flow boiling and gas-liquid interface structure at boiling transition on boiling heat transfer enhancement surface

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06121
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Kobe University
• Principal Investigator: Asano Hitoshi 神戸大学, 工学研究科, 教授 (10260647)
• Co-Investigator(Kenkyū-buntansha): 村川 英樹 神戸大学, 工学研究科, 准教授 (40467668) ; 杉本 勝美 神戸大学, 先端融合研究環, 助教 (40420468)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 沸騰伝熱促進 / 気液二相流 / サブクール沸騰 / ボイド率 / 静電容量センサ / 限界熱流束 / 膜沸騰遷移 / 溶射被膜

Outline of Final Research Achievements

Boiling heat transfer enhancement and increase in the critical heat flux could be achieved simultaneously by thermal spray coated surface for forced convective subcooled boiling flow. Boiling heat transfer enhancement factor could be kept over the heat flux range up to the CHF. To clarify the gas-liquid interface structure in the boiling transition, two types of capacitance sensors for average and local void fraction near the heating surface had been dveloped. Obtained results for subcooled boiling flows are summarized as follows. High heat transfer enhancement could be obtained by surface boiling under the low heat flux condition. The difference in void fraction between smooth and coated surface was a little for the developed nucleate boiling. The void fraction at the boiling transition was higher for the coating than the smooth surface. These results show a method of flow control to improve the critical heat flux for the development of boiling heat transfer enhanced surface.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

データセンタやサーバーにおけるデータ処理量の増大，スーパーコンピュータに代表される電子機器の高性能化と安定動作に対応するためには，沸騰伝熱を利用した高性能冷却システムが必要不可欠であり，限界熱流束の向上が必須である．本研究では，高サブクール度の流れにおいて，限界熱流束増大と伝熱促進効果を両立できる伝熱面を製作した．
沸騰伝熱促進面での膜沸騰遷移における伝熱面近傍局所と流路断面平均ボイド率の情報は，バルクの液流制御による膜沸騰遷移の阻害，限界熱流束の増大につなげられると期待できる．