Yasuda Keita

写真a

Title

Associate Professor

Researcher Number(JSPS Kakenhi)

60760163

Date of Birth

1984

Laboratory Address

1 Senbaru,Nishihara,Okinawa

Mail Address

E-mail address

Laboratory Phone number

+81-98-895-8613
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Current Affiliation Organization 【 display / non-display 】

  • Duty   University of the Ryukyus   Faculty of Engineering   School of Engineering_Energy and Environment Program   Associate Professor  

  • Charge of Lecture   University of the Ryukyus   Graduate School of Engineering and Science   Thermal and Fluid Engineering   Associate Professor  

  • Charge of Lecture   University of the Ryukyus   Graduate School of Engineering and Science   Material,Structural and Energy Engineering   Associate Professor  

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University 【 display / non-display 】

  • 2003.04
    -
    2007.03

    Keio University   Faculty of Science and Engineering   Department of Mechanical Engineering   Graduated

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Graduate School 【 display / non-display 】

  • 2007.04
    -
    2009.03

    Keio University  Graduate School, Division of Science and Engineering  School of Science for Open and Environmental Systems  Master's Course  Completed

  • 2009.04
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    2015.03

    Keio University  Graduate School, Division of Science and Engineering  School of Science for Open and Environmental Systems  Doctor's Course  Completed

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Academic degree 【 display / non-display 】

  • Keio University -  Ph.D. in Engineering

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External Career 【 display / non-display 】

  • 2009.04
    -
    2010.03

     

  • 2010.04
    -
    2012.03

     

  • 2010.05
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    2010.10

    Visiting Scholar in Colorado School of Mines  

  • 2015.04
    -
    2017.03

    University of the Ryukyus, Faculty of Engineering, Department of Mechanical Systems Engineering, Instructor  

  • 2017.04
    -
    2022.05

    University of the Ryukyus, Faculty of Engineering, School of Engineering, Energy and Environment Program, Instructor  

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Research Interests 【 display / non-display 】

  • Physical Chemistry and Engineering of Clathrate Hydrates

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Research Areas 【 display / non-display 】

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

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Thesis 【 display / non-display 】

  • 氷点下温度域におけるクラスレートハイドレートの相平衡条件と結晶構造

    2015.03

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Published Papers 【 display / non-display 】

  • Mist cooling lithium–ion battery thermal management system for hybrid electric vehicles

    Aoto Teranishi, Takuma Kurogi, Izuru Senaha, Shoichi Matsuda, Keita Yasuda

    Applied Energy ( Elservier )  364   123214   2024.06 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    Battery Thermal Management System (BTSM) is essential for maintaining optimal operation conditions for hybrid electric vehicles (HEVs) and electric vehicles (EVs). This study aimed to propose an innovative impinging jet cooling BTMS for HEVs using mist cooling. The dilute mist completely evaporated to avoid the risk of external circuit failure or corrosion that could result from surface wetting. Impinging experiments were performed under the conditions where inflow air temperature, Ta,in, was 21.2 ◦C ≤ Ta,in ≤ 31.0 ◦C and initial humidity, φ, was 50.9 %RH ≤ φ ≤ 96.0 %RH. It was found that the target plate was cooled down by up to 0.8 K without surface wetting by adding 5.5 mg/s water mist to the air. Numerical analyses were performed under conditions ranging from 21.2 ◦C ≤ Ta,in ≤ 31.0 ◦C and 0.0 %RH ≤ φ ≤ 100.0 %RH. The results and discussion highlight the importance of the critical initial humidity, φcritical: the complete evaporative threshold. Deviation between the experimental and numerical results at a fixed inflow air temperature, Δφ, was 1.9 %RH ≤ Δφ ≤ 3.0 %RH. Δφ was within the range of measurement uncertainty U(φ) = 4.0 %RH. Thus, the experimental and numerical results were consistent within the experimental measurement uncertainty. As a result, φcritical tends to be high in the case of high inflow temperature. The mist cooling is a viable way of BTMS for HEVs without surface wetting due to its large cooling capacity that results in a 7.4 K cooling effect in a hot environment.

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  • Phase equilibrium conditions in carbon dioxide + cyclopentane double clathrate hydrate forming system coexisting with sodium chloride aqueous solution

    Kouki Mekaru, Takuto Miyagi, Ayaka Mishima, Isami Uehara, Ryo Ohmura, Keita Yasuda

    The Journal of Chemical Thermodynamics ( Elservier )  189   107185   2024.02 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    The four-phase equilibrium conditions were measured in carbon dioxide + cyclopentane double clathrate hydrate forming systems coexisting with either sodium chloride aqueous solution or pure water as a technological basis for developing seawater desalination technology utilizing clathrate hydrate formation and decomposition. The equilibrated phases included sodium chloride aqueous solution or pure water, carbon dioxide + cyclopentane double clathrate hydrate, liquid cyclopentane, and carbon dioxide gas. The experiments were performed using the batch isochoric procedure. Three different concentrations of sodium chloride in the aqueous solution were tested: 0.035, 0.070, or 0.105 in mass fraction. Pressures ranged from 0.385 MPa to 2.488 MPa. The results were compared with the equilibrium conditions for carbon dioxide and cyclopentane simple clathrate hydrate forming systems. The comparison revealed that the double clathrate hydrate is more thermodynamically stable than the simple clathrate hydrates, under a given sodium chloride concentration in the aqueous solution.

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  • Renewed Measurements of Carbon Dioxide Hydrate Phase Equilibrium

    Haruki Ito, Akari Gibo, Sayaka Shiraishi, Keita Yasuda, Ryo Ohmura

    International Journal of Thermophysics ( Springer )  44   128   2023.08 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    This paper investigates the phase equilibrium conditions in the carbon dioxide hydrate forming system. Carbon dioxide hydrate can be utilized for carbon capture, salt manufacture, carbonated solid foods and tritium water concentration, so the phase equilibrium conditions have been substantially reported so far. However, the data from previous studies were inconsistent with each other, such as there is a difference of 1.0 K in the phase equilibrium temperature at 2 MPa. In this study, the newly three-phase (water rich liquid + hydrate + guest rich vapor) equilibrium conditions in the carbon dioxide hydrate forming system were measured at twenty different temperature conditions within the range of (271.9-282.7) K in the two different laboratories. The six pairs of the three-phase equilibrium condition data measured under equivalent pressure conditions were consistent within mutual uncertainties. The internal consistency of the data measured in this study was evaluated by the Clausius-Clapeyron equation. The data measured in this study existed within the uncertainty range of the data from several previous studies.

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  • Zero Emissions, Low-Energy Water Production System Using Clathrate Hydrate: Engineering Design and Techno-Economic Assessment

    Meku Maruyama, Shigeo Tomura, Keita Yasuda, Ryo Ohmura

    Journal of Cleaner Production ( Elsevier )  383   135425   2023.01 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    Seawater desalination via the crystallization using clathrate hydrate is a promising technology for displacing conventional desalination processes, yet the technology immaturity and poor cost performance are the issues to be resolved. In this study, conceptual designs of hydrate-based dual functional plant (desalination and salt production) utilizing the eutectic crystallization of hydrate and NaCl dihydrate have been presented on an industrial scale with the capacity of 24 m3/day. The conceptual design proposed in this study focuses on detailed and executive aspects, including the size of individual reactors, the selection of pumps, and the setting of operating temperature and pressure conditions. The process designs help meet these present demands on hydrate-based desalination and conform to the global standards of minimizing energy requirement and the disposal of environmental pollutants. Hydrate-based plant was designed as a novel Zero Liquid Discharge (ZLD) process to produce potable water and salt simultaneously, with the recovery ratio of pure water from seawater achieving 95%. The design-based cost estimation showed that the annual operating cost is estimated US$2.29/m3 for cyclopentane-hydrate-based plant and US$3.64/m3 for CO2-hydrate-based plant. The results suggest that the hydrate-based plants will bring gross profit comparable to the reported ZLD plants; that is, the gross profit will achieve US$20 per 1 m3 of water production. In addition to these two improvements over the existing plants, the hydrate-based process designs also exhibit favorable energy requirement compared to the eutectic system of ice. This design-based study may contribute to the promotion of additional construction of hydrate-based process unit to the existing reverse osmosis plant or even the new construction of hydrate-based desalination plant worldwide.

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  • Phase Equilibrium Conditions in Cyclopentane Hydrate Forming Systems Coexisting with Sodium Chloride Aqueous Solution under Atmospheric Pressure and Vacuum Condition

    Keitatsu Kamochi, Ayushman Tripathi, Masanao Taoka, Ryo Ohmura, Keita Yasuda

    The Journal of Chemical Thermodynamics ( Elsevier )  175   106886   2022.12 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

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    The equilibrium condition measurements were performed in the cyclopentane clathrate hydrate forming systems coexisting with sodium chloride as a technological basis for the development of seawater desalination technology using clathrate hydrates. The experiments were performed in the system under vacuum condition in addition to the system under atmospheric pressure. The equilibrium conditions in the system under the vacuum condition are essential to accurately construct the phase diagram in the cyclopentane clathrate hydrate forming system without the effects of the surrounding air. The equilibrated phases were sodium chloride aqueous solution + cyclopentane clathrate hydrate + liquid cyclopentane + vapor cyclopentane in the system under the vacuum condition. The concentration of sodium chloride investigated in this study, wNaCl, was 0 ≤ wNaCl ≤ 0.210 in mass fraction. The equilibrium temperature in both systems decreased with increasing wNaCl. The equilibrium temperature at a fixed concentration of sodium chloride under the vacuum condition was lower than that under the atmospheric pressure. It was attributed to the compression by the atmospheric pressure in addition to the incorporation of molecules constituting the atmospheric air.

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Other Papers 【 display / non-display 】

  • Phase Equilibrium Conditions in Cyclopentane Clathrate Hydrate Forming Systems Coexisting with Sodium Chloride Aqueous Solutions

    Toshikazu Sasaki, Keitatsu Kamochi, Ayushman Tripathi, Masanao Taoka, Ryo Ohmura, Keita Yasuda

    The 12th International Conference on Separation Science and Technology     109   2023.11  [Refereed]

     

  • Relative Density of Carbon Dioxide Clathrate Hydrate and Sodium Chloride Aqueous Solution: Implications for Desalination Processes

    Shun Tsunekawa, Akari Gibo, Toshiyuki Tanaka, Sayaka Shiraishi, Ryo Ohmura, Keita Yasuda

    The 12th International Conference on Separation Science and Technology     109   2023.11  [Refereed]

     

  • Eutectic Conditions of Carbon Dioxide Clathrate Hydrate and Sodium Chloride Dihydrate for Desalination and Salt Production

    Hideya Suzuki, Akari Gibo, Seiya Nakao, Ryo Ohmura, Keita Yasuda

    The 12th International Conference on Separation Science and Technology     109   2023.11  [Refereed]

     

  • Laboratory Experiments Utilizing Clathrate Hydrates as Educational Materials

    Keita Yasuda, Izuru Senaha

    10th International Conference on Gas Hydrates     109   2023.07  [Refereed]

     

  • Precipitation of Calcium Sulfate Dihydrate during Clathrate-Hydrate-Based Seawater Desalination/Salt Manufacturing Process

    Mion Orita, Yuta Agatsuma, Koki Mekaru, Yukari Sukegawa, Rinnosuke Tamaki, Ryo Ohmura, Keita Yasuda

    10th International Conference on Gas Hydrates     110   2023.07  [Refereed]

     

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SDGs 【 display / non-display 】

  • クラスレートハイドレートの物理化学とエンジニアリング

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