Investigation of the influence of microbubble and Marangoni flow on heat transfer efficiency in the microscale cooling devices

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H04904
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Fluid engineering
• Research Institution: Kyoto University
• Principal Investigator: Namura Kyoko 京都大学, 工学研究科, 助教 (20756803)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: マランゴニ対流 / 水冷 / マイクロバブル / 沸騰 / 金ナノ粒子薄膜 / 光熱変換

Outline of Final Research Achievements

We have investigated the microbubble generation and the flow around the bubble by using the photothermal property of a gold nanoisland film. By using our originally developed apparatus, we have succeeded in capturing the self-oscillation of a water vapor microbubble and have found that the oscillation is the critical factor of the rapid flow generation. Besides, we demonstrated the control of the direction of the flow around the bubble via the shape of the heating spot. Using this method, we successfully generated one-directional flow in a microchannel. Furthermore, using an alcohol-water mixture, the concentration gradient was induced using a temperature gradient, which generates a surface tension gradient and enhances the flow speed around the bubble.
These findings are useful for the development of microscale cooling devices.

Free Research Field

薄膜・表面・界面物性

Academic Significance and Societal Importance of the Research Achievements

宇宙空間に漂う機器類や高集積化する電子デバイス内での熱のマネジメントは急務となっている．特に小型のデバイスを冷却するためのマイクロメートルスケールの水冷技術の確立が求められている．本研究で得られた知見は，水冷の加熱壁面上に生成するマイクロバブルとその周辺に発生する対流を，積極的に制御する方法を与える．また，壁面近傍でのマイクロバブルの挙動解明は流体力学分野の発展につながる．今後は，排熱が自発的に熱を運び去るスマート冷却機構の開発につなげていきたい．