Ohmura, Ryo

写真a

Affiliation

Faculty of Science and Technology, Department of Mechanical Engineering (Yagami)

Position

Professor
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Career 【 Display / hide 】

  • 1999.04
    -
    2000.03

    JSPS Research Fellow (DC1)

  • 2000.04
    -
    2002.03

    JSPS Research Fellow (PD)

  • 2002.04
    -
    2006.03

    Research Scientist, AIST

  • 2006.04
    -
    Present

    Assistant Professor

  • 2009.04
    -
    Present

    慶應義塾大学准教授

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Academic Background 【 Display / hide 】

  • 1996.03

    Keio University, Faculty of Science and Technology, Dapartment of Mechanical Engineering

    University, Graduated

  • 2000.03

    Keio University, －, 機械工学専攻

    Graduate School, Completed, Doctoral course

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Academic Degrees 【 Display / hide 】

  • Ph. D., Keio University, Coursework, 2000.03

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Research Areas 【 Display / hide 】

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Thermal engineering (Thermal Engineering)

  • Nanotechnology/Materials / Fundamental physical chemistry (Physical Chemistry)

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Research Keywords 【 Display / hide 】

  • Energy

  • Clathrate Hydrates

  • Physical Chemistry

  • Environment

  • Crystal Growth

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Research Themes 【 Display / hide 】

  • Physical Chemistry in Clathrate Hydrate Forming Systems, 

    1996
    -
    Present

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Papers 【 Display / hide 】

  • Synthesis and evaluation of green phase change materials for efficient air conditioning by tetrabutylphosphonium phosphate ionic semiclathrate hydrate

    Iwai T., Miyamoto T., Kurokawa N., Hotta A., Ohmura R.

    Journal of Energy Storage (Journal of Energy Storage)  52 2022.08

    　View Summary

    A tetrabutylammonium bromide (TBAB) hydrate is the only ionic semiclathrate hydrate that has been commercialized as a medium for efficient thermal energy storage targeting general air conditioning. However, TBAB is an environmental pollutant, while liquid water and ice that have been widely used as conventional media, also have difficulty in increasing the thermal energy storage density as well as the coefficient of performance (COP) of a refrigerator to form solid. In this study, a tetrabutylphosphonium phosphate ((TBP)3PO4) hydrate was proposed as an alternative green medium. The dissociation heat and the phase equilibrium temperature, which were both crucial factors to evaluate the thermal energy storage density, and COP was experimentally determined. It was found that the maximum dissociation heat was 154.1 ± 2.0 kJ・kg−1 at the mass fraction of 0.309. The highest phase equilibrium temperature was 10.0 °C at the mass fractions of 0.290, 0.299, and 0.309. The thermal energy storage density of (TBP)3PO4 hydrates was 3.7 times larger than that of water. (TBP)3PO4 hydrates increased the COP of a refrigerator to form solid by 42% as compared with ice, indicating the potential size-reduction of conventional devices with the decrease in the power consumption of a refrigerator. The effective balance between environmental protection and the system performance through (TBP)3PO4 hydrates was also discussed.

  • Pinacol hydrate as a novel thermal energy storage medium for electric vehicles

    Kiyokawa H., Kondo Y., Koyama R., Kurokawa N., Atsushi H., Alavi S., Ota I., Ohmura R.

    Journal of Energy Storage (Journal of Energy Storage)  51 2022.07

    　View Summary

    Movement towards the gradual replacement of gasoline combustion vehicles to electrical vehicles is occurring on a global scale. Heat management of lithium-ion batteries (LIB) is necessary for long-term operation and safety of the power sources of electrical vehicles. This research suggests pinacol hydrate as a phase change material (PCM) for use as an alternative cooling media for LIB. The pinacol hydrate crystallizes under atmospheric pressure and temperatures around 45 °C, which are compatible with LIB operating conditions. Its dissociation enthalpy can control the excessive heating of the battery. The equilibrium phase transition temperature of pinacol hydrate was reported about a decade ago, but its thermal storage capacity has not been reported yet and updated quantitative measurements are required. Hence, in this study the equilibrium temperatures and dissociation enthalpies are experimentally measured for pinacol aqueous solutions prepared with mass fractions between 0.40 and 0.85. The maximum thermal storage capacity is measured by differential scanning calorimetry to be 301.9 kJ/kg for mass fraction of 0.50 which is compatible with operating conditions of up to 45.6 °C. A minimization of reservoir tank mass by 35% of that needed for conventional technologies may be possible by using pinacol hydrate.

  • Investigation of crystal growth of CO<inf>2</inf> hydrate in aqueous fructose solution for the potential application in carbonated solid foods

    Shigehara S., Ohmura R.

    Food Chemistry (Food Chemistry)  371 2022.03

    ISSN  03088146

    　View Summary

    CO2 hydrate is applicable to solid carbonated foods. The hydrate crystal morphology, which represents the crystal size and shape, is an important characteristic that changes the texture of foods. We report an observational study of the crystal growth of CO2 hydrate in aqueous fructose solution. The difference between the phase equilibrium temperature and the experimental temperature, ΔTsub, is applied as an index of the driving force. Experiments were performed at ΔTsub range of 0.9 K to 5.4 K. At all ΔTsub, initial crystal formed at the gas-solution interface and grew along the interface. After covering the interface, the crystals grew in the liquid phase The individual crystals were identified as polyhedral with facets (ΔTsub = 0.9 K), skeletal crystals (ΔTsub = 2.0 K) and dendrites (ΔTsub = 3.0 K and 5.4 K). Based on these results, the potential effect of gas hydrate morphology on texture of foods has been discussed.

  • Synthesis and thermophysical property evaluation of ionic semiclathrate hydrate formed with tetrabutylphosphonium glycine as a chilling temperature phase change material

    Miyamoto T., Kurokawa N., Ota I., Hotta A., Ohmura R.

    Journal of Energy Storage (Journal of Energy Storage)  45 2022.01

    　View Summary

    Ionic semiclathrate hydrate, which is formed under atmospheric pressure with sustainably safe properties, has a potential for solid-liquid phase change materials(PCMs). In this study, the thermophysical property of tetrabutylphosphonium glycine(TBPGly) hydrate containing no halogen guest compound, glycine (aminoacetic acid), was investigated to evaluate the availability as an eco-efficient thermal energy storage medium. The phase equilibrium temperature was obtained through visual observation method. The heat flow rate curve behavior and dissociation heat were measured via differential scanning calorimetry(DSC). In the dissociation process, a single hydrate dissociation peak emerged, indicating TBPGly hydrate has one type of crystallographic structure. The concentration dependency of the TBPGly aqueous solution on the equilibrium temperature and the dissociation heat was confirmed. The highest equilibrium temperature of 5.8 °C was confirmed at the fraction range wTBPGly =0.368 or xTBPGly =0.0306, and the largest dissociation heat was 177.7 kJ·kg−1 at the fraction range wTBPGly =0.377or xTBPGly =0.0318. The estimated hydration number in the congruent composition was found to be in 31.2 to 32.5. In addition, based on the measured physical property, the optimum operating temperature and volume fraction of TBPGly hydrate was evaluated to determine the concentration for the practical cooling system. These data revealed TBPGly hydrate is available as a solid or slurry PCM under the operating temperature range 2 °C to 5.8 °C. The experimental data as well as the illustrative calculations contribute to accelerate the expansion in the application range, and provide the prospect in selecting the suitable composition toward the actual hydrate-based cooling system.

  • Investigation of the thermodynamic properties of hydrates as cooling phase change materials for their implementation in electric vehicles

    Kiyokawa H., Miyamoto T., Takeya S., Ota I., Iwai T., Hotta A., Ohmura R.

    New Journal of Chemistry (New Journal of Chemistry)   2022

    ISSN  11440546

    　View Summary

    Electric vehicles (EVs) play key roles in realizing a sustainable society. Lithium-ion batteries (LIBs) implemented in EVs deteriorate due to significant temperature changes. To maintain LIBs in an appropriate temperature range, a competitive thermal energy storage (TES) medium is needed. Phase change materials (PCMs) that can utilize their latent heat have great potential. In this study, we focused on piperazine hexahydrate as a promising candidate for a PCM and investigated its thermodynamic properties that are essential for practical design. The equilibrium temperature and dissociation enthalpy were determined in the mass fraction range of 0.250 to 0.550. The results showed that piperazine hexahydrate had a maximum equilibrium temperature of 42.9 °C and a maximum dissociation enthalpy of 250.0 ± 3.7 kJ kg−1 at a mass fraction of 0.443, which is the congruent point of piperazine hexahydrate. Piperazine hexahydrate can be utilized as a PCM in the temperature range of 34.4 °C to 42.9 °C. By utilizing piperazine hexahydrate instead of a conventional water-cooling system, the volume of the TES tank may be reduced by 31% approximately. The crystal system of the piperazine hexahydrate prepared in the present study was determined to be pseudomonoclinic by powder X-ray diffraction (PXRD) measurements, which is the same as that reported in the literature.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Presentations 【 Display / hide 】

  • 二酸化炭素分離に適したクラスレートハイドレートの探索と物性測定

    Ohmura Ryo

    化学工学会第46回秋季大会, 

    2014.09
    , 

    Oral presentation (invited, special), 公益社団法人 化学工学会

  • Crystallographic structure and thermodynamic stability of clathrate hydrates formed with halogen-containing guests

    Ryo Ohmura

    2012 "Natural Gas Hydrate Systems" Gordon Research Conference (Ventura, CA) , 

    2012.03
    , 

    Oral presentation (invited, special)

  • Crystal growth of clathrate hydrates in hydrophobic-guest fluid + liquid-water systems

    Ohmura Ryo

    ACS 241st National Meeting (Anaheim, CA, USA) , 

    2011.03
    , 

    Oral presentation (invited, special), American Chemical Society

  • Understanding thermodynamics of clathrate hydrates toward energy/environment technology innovations

    Ohmura Ryo

    21st IUPAC International Conference on Chemical Thermodynamics Conference (ICCT-2010) (Tsukuba) , 

    2010.08
    , 

    Oral presentation (invited, special), IUPAC

  • Combustion Characteristics of Methane Hydrate in a Laminar Boundary Layer

    Yuki Nakmura, Ryoji Katsuki, Takeshi Yokomori, Ryo Ohmura, Toshihisa Ueda, Masahiro Takahashi, Toru Iwasaki and Kazuo Uchida

    6th International Conference on Gas Hydrates (ICGH 2008) (Vancouver) , 

    2008.07
    , 

    Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • 海水と炭酸ガスの炭酸塩晶析反応に関する基礎研究

    2007.07
    -
    2008.03

    受託研究費, Commissioned ｒesearch, No Setting

  • クラスレート水和物の結晶モルフォロジー多様性の解明

    2007.04
    -
    2008.03

    Grant-in-Aid for Scientific Research, Research grant, No Setting

  • シクロペンタンハイドレートの生成特性の解明

    2006.10
    -
    2007.03

    東京電力株式会社, 共同研究費, Joint research, No Setting

  • クラスレート水和物の結晶構造多様性を利用した省エネルギー天然ガス貯蔵・輸送技術に関する研究

    2005.10
    -
    2006.09

    NEDO, -, Research grant, No Setting

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Intellectual Property Rights, etc. 【 Display / hide 】

  • 構造Hクラスレート水和物の生成方法

    Date announced： 特開2003-3181   

    Patent, Single

  • 気体の分離剤及び気体を分離濃縮するための方法と装置

    Date announced： 特開2003-138281   

    Patent, Single

  • 不凍タンパク質を用いた包接化合物の生成制御法

    Date announced： 特開2005-89353   

    Patent, Single

  • トレハロースを用いた包接化合物の生成制御法

    Date announced： 特開2005-89331   

    Patent, Single

  • 新規構造H水和物

    Date announced： 特願2004-355852   

    Patent, Joint

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Awards 【 Display / hide 】

  • 日本機械学会奨励賞（研究）

    大村　亮, 2004.04, 日本機械学会, クラスレートハイドレートに関する熱工学的研究

  • 日本機械学会奨励賞（研究）

    Ohmura Ryo, 2004.04, クラスレートハイドレートに関する熱工学的研究

    Type of Award： Award from Japanese society, conference, symposium, etc.

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Courses Taught 【 Display / hide 】

  • THERMAL ENGINEERING

    2024

  • PHYSICAL CHEMISTRY OF MOLECULAR CRYSTALS

    2024

  • INTRODUCTION TO THERMODYNAMICS

    2024

  • INTRODUCTION TO INTERDISCIPLINARY SCIENCE AND TECHNOLOGY

    2024

  • INDEPENDENT STUDY ON SCIENCE FOR OPEN AND ENVIRONMENTAL SYSTEMS

    2024

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Social Activities 【 Display / hide 】

  • ガスハイドレート産業創出イノベーション

    2006.09
    -
    Present

    　View Summary

    産業技術総合研究所が主催する研究会の会員．産総研，民間企業，大学から会員を集め，ハイドレート利用技術の事業化へ向けた取り組みを進める．

  • 天然ガスハイドレート製造利用システム実証特別委員会

    2006.08
    -
    2008.03

    　View Summary

    上記委員会はNEDOから三井造船（株）と中国電力（株）への委託事業におけるプロジェクトリーダーの諮問機関という位置づけ

  • NEDO平成17年度「天然ガスハイドレート技術の国内市場への適用可能性調査」検討委員会

    2005.04
    -
    2005.07

    　View Summary

    NEDOから（財）エネルギー総合工学研究所への委託研究の検討委員会委員

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Memberships in Academic Societies 【 Display / hide 】

  • 日本機械学会, 

    2011.04
    -
    Present

  • 日本機械学会　メカライフ編集委員会, 

    2007.04
    -
    2008.03

  • 日本機械学会熱工学部門 広報委員, 

    2005.04
    -
    2006.03
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Committee Experiences 【 Display / hide 】

  • 2011.04
    -
    Present

    Committee Member, 日本機械学会

  • 2007.04
    -
    2008.03

    Committee Member, 日本機械学会　メカライフ編集委員会

  • 2006.09
    -
    Present

    Member, ガスハイドレート産業創出イノベーション

    　View Remarks

    産業技術総合研究所が主催する研究会の会員．産総研，民間企業，大学から会員を集め，ハイドレート利用技術の事業化へ向けた取り組みを進める．

  • 2006.08
    -
    2008.03

    Committee Member, 天然ガスハイドレート製造利用システム実証特別委員会

    　View Remarks

    上記委員会はNEDOから三井造船（株）と中国電力（株）への委託事業におけるプロジェクトリーダーの諮問機関という位置づけ

  • 2005.04
    -
    2006.03

    Committee Member, 日本機械学会熱工学部門 広報委員

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