Study on ultra-low heat flux loop heat pipe based on understanding of a nucleate boiling phenomena in a porous medium

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14956
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 24010:Aerospace engineering-related
• Research Institution: Japan Aerospace EXploration Agency
• Principal Investigator: Odagiri Kimihide 国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 特任助教 (50866481)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 伝熱工学 / 多孔質体 / 核沸騰 / 気液二相流 / 低熱流束 / ループヒートパイプ

Outline of Final Research Achievements

The purposes of this study are (a) To clarify nucleate boiling phenomena and the effect of wettability control in a capillary porous medium, and (b) To establish a low heat flux loop heat pipe (LHP) technology that operates under heat flux conditions of 0.01 W/cm2 class. By using the microscale infrared/visible observation system and the microscale high-speed observation system, the nucleate boiling phenomena in a porous medium was observed. The effect of wettability of the heating plate on the heat transfer coefficient and the geometry of the porous media that enables high heat transfer performance under low heat flux conditions were clarified. Based on them, a low heat flux LHP was designed, fabricated, and tested. The operation at a heat flux of 0.02 W/cm2 which is extremely low heat flux conditions compared to conventional LHPs was successfully demonstrated.

Free Research Field

航空宇宙工学

Academic Significance and Societal Importance of the Research Achievements

蒸発器内部で生じる毛細管力駆動の多孔質熱流動現象は，LHP性能に大きく影響を与えるため，そのメカニズムを明らかにすることは重要である。特に知見の不足していた，濡れ性制御が熱伝達係数に与える影響，低熱流束条件での高熱伝達構造，気泡核生成過程について可視化によって理解を深めた点で，本研究成果は学術的意義がある。また高効率な低熱流束LHPの技術実証は，将来の宇宙科学・探査ミッションの熱設計自由度向上に資する。さらに本成果は宇宙機および地上用機器の熱制御技術に幅広く活用することが可能であり，社会的意義は大きい。