Elucidation of the heat transfer mechanism and applied research of sintered porous heat transfer tubes for achieving dramatic heat transfer

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03914
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: The University of Electro-Communications
• Principal Investigator: Enoki Koji 電気通信大学, 大学院情報理工学研究科, 准教授 (40719407)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 多孔質 / 焼結 / 伝熱 / 熱交換器 / 廃熱 / 排熱

Outline of Final Research Achievements

In experiments using dry air, a heat transfer tube sinter-bonded with a porous material made of metal fibers shows an approximately 1000-fold improvement in heat transfer rate. The porosity of the porous body is about 80%, with an internal diameter of the tube around 20mm and a filling length of 25mm. When the inlet temperature of the dry air in the heat transfer tube is maintained at 315°C and the outside of the tube is cooled with a coolant at 15°C to achieve boiling cooling, the dry air is cooled to 15°C, achieving a temperature difference of 300°C over a 25mm filling length. While it is difficult to measure the temperature and flow velocity distribution within the porous body in experimental studies, successful replication has been achieved through numerical simulation. This has allowed for a preliminary elucidation of the heat transfer mechanism based on information that could not be obtained experimentally.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

空気など密度の低い流体の熱伝達率は，密度の高い液体などの流体と比較すると劣る．そのため，現在使用されずに捨てられている工場廃熱などの300℃以下の熱エネルギーは，大規模な熱交換器を使用しなければ有効利用できないという社会的な問題がある．この問題を科学技術で解決することは，脱炭素社会を構築する上で非常に意義のある研究である．
今回の研究成果は，これまでコストパフォーマンスの面から捨てられていた熱エネルギーを省スペースで回収する可能性を示した．また，粘度の低い液体でも同様の効果が確認されていることから，廃熱回収だけでなく，高効率な熱交換器としても利用できると考えられる．