New developments from extreme cooling to innovative hydrogen production based on the analogy between boiling and water electrolysis.

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K20976
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
• Research Institution: Kyushu University
• Principal Investigator: Mori Shoji 九州大学, 工学研究院, 教授 (10377088)
• Project Period (FY): 2020-07-30 – 2023-03-31
• Keywords: 毛管力 / 水電解 / 多孔質体 / 限界熱流束

Outline of Final Research Achievements

Based on the similarity between boiling and water splitting, this study focused on whether the critical current density (CCD), which is the upper operational limit of water electrolysis, can be improved by means of improving the heat transfer coefficient and critical heat flux (CHF). It has been known that boiling CHF can be improved by using a porous honeycomb plate (HPP) due to two effects: capillary forces and gas-liquid path separation. In this study, a cooling method using HPPs, which successfully improved CHF, was applied to alkaline water electrolysis. As a result, CCD was successfully improved by about 1.3 times (CCD: 6.6 A/cm2) compared with no capillary force (CCD: 5.1 A/cm2) for the first time.

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Free Research Field

熱流体工学

Academic Significance and Societal Importance of the Research Achievements

これまで沸騰研究は70年以上の歴史があり、かなりの知識が蓄積されている。そのような背景下において、沸騰と水分解の類似性に基づきCCDを向上できたと言うことは、これまでの沸騰の知識が水電解の高性能化に活用できる可能性を示す大きな第一歩となったことは意義があると考えている。また、本構想は、水電解に限らず化学反応など気体と液体が関わる、特に気体発生が律速となってしまうような状況となる幅広い分野に応用できる可能性があり、学術的価値もあると考えている。