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

Current Affiliation Organization 【 display / non-display

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

University 【 display / non-display

  • 2003.04
    -
    2007.03

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

Graduate School 【 display / non-display

  • 2007.04
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    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

Academic degree 【 display / non-display

  • Keio University -  Ph.D. in Engineering

External Career 【 display / non-display

  • 2009.04
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    2010.03

     

  • 2010.04
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    2012.03

     

  • 2010.05
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    2010.10

    Visiting Scholar in Colorado School of Mines  

  • 2015.04
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    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

Research Areas 【 display / non-display

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

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

Published Papers 【 display / non-display

  • 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)

     View Summary

    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.

  • 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)

     View Summary

    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.

  • Development of Dual Functional Methodology for Seawater Desalination and Salt Manufacture by Carbon Dioxide Hydrate Formation

    Akari Gibo, Seiya Nakao, Sayaka Shiraishi, Satoshi Takeya, Shigeo Tomura, Ryo Ohmura, Keita Yasuda

    Desalination ( Elsevier )  539   115937   2022.10 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Clathrate-hydrate-based seawater desalination is a novel technology that is performed by reaction between seawater and guest compounds to obtain fresh water. This study proposed a dual functional methodology for seawater desalination and salt manufacture by using carbon dioxide clathrate hydrate. In this methodology, the clathrate hydrate formation continues until the concentration of electrolytes in unreacted brine reaches the saturated solubility for the salt precipitation. The visual observation of the clathrate hydrate formation and the salt precipitation coupled with the analysis utilizing the powder X-ray diffraction (PXRD) technique was implemented to demonstrate the methodology. The carbon dioxide clathrate hydrate formation was first performed with sodium chloride aqueous solution. The carbon dioxide clathrate hydrate crystals floated on high salinity water. This experiment was followed by the occurrence of the sodium chloride dihydrate precipitation upon the carbon dioxide clathrate hydrate formation. The formed compounds, carbon dioxide clathrate hydrate and sodium chloride dihydrate, were identified by PXRD analysis. The mass fraction of the compounds was also determined by PXRD.

  • Visual Observation of Tetra-n-butylammonium Bromide Ionic Semiclathrate Hydrate Formation: A Laboratory Experiment

    Keita Yasuda

    Journal of Chemical Education ( American Chemical Society )  98   3587 - 3592   2021.11 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    A laboratory experiment was performed using tetra-n-butylammonium bromide (TBAB) ionic semiclathrate hydrate, a crystalline compound. Ionic semiclathrate hydrates have unique properties, and hence, novel technologies utilizing the ionic semiclathrate hydrates have been proposed to date. Thus, students could learn fundamentals of functional materials through ionic semiclathrate hydrates from chemical and engineering points of view. In the experiment, formation of the TBAB hydrate was observed at fixed temperature and under atmospheric pressure by using TBAB aqueous solutions having TBAB mass fractions of wTBAB = 0.10, 0.20, 0.30, 0.40, and 0.50. There are no serious safety hazards. In addition, the experiment can be performed using inexpensive equipment and materials. The amount of the formed TBAB hydrate and its crystal morphology depended on the concentration of the aqueous solution. The students needed to submit a laboratory report describing fundamentals of the ionic semiclathrate hydrates, a relationship between equilibrium conditions and the amount of the formed TBAB hydrate, and an adequate crystal morphology of the TBAB hydrate crystals as a thermal storage material. Most students understood the experiment well, and the average score of the reports was approximately 80%.

  • Simultaneous Crystallization of Cyclopentane Hydrate and Sodium Chloride for Desalination and Salt Manufacture

    Mikihiro Tanaka, Keita Tsugane, Daiki Suga, Shigeo Tomura, Ryo Ohmura, Keita Yasuda

    ACS Sustainable Chemistry & Engineering ( American Chemical Society )  9   9078 - 9084   2021.07 [ Peer Review Accepted ]

    Type of publication: Research paper (scientific journal)

     View Summary

    Simultaneous crystallization of cyclopentane hydrate and sodium chloride dihydrate was implemented to demonstrate a dual-functional system for hydrate-based seawater desalination and salt manufacture that could be performed with zero emission. A sodium chloride aqueous solution having an initial mass fraction of sodium chloride of 0.235 or 0.264 was used for the experiments as an alternative to seawater. When using the aqueous solution having a sodium chloride concentration of 0.264 in mass fraction, the precipitation of polyhedral sodium chloride dihydrate crystals was first observed, followed by the formation of particulate cyclopentane hydrate crystals. In contrast, when using the aqueous solution having a sodium chloride concentration of 0.235 in mass fraction, the formation of particulate cyclopentane hydrate was first observed and then the particulate sodium chloride dihydrate precipitated. The formed cyclopentane hydrate and the precipitated sodium chloride dihydrate were separated by the remaining sodium chloride aqueous solution due to the density difference even after the agitation of the system. The eutectic temperature and concentration were determined to be 259.75 K and 0.238 in mass fraction of sodium chloride, respectively.

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Other Papers 【 display / non-display

  • A Study on Heat Transfer Characteristics by Impinging Jet with in a Few Amounts of Mist

    Seydou Nourou Diop, Izuru Senaha, Keita Yasuda, Shoichi Matsuda

    The Ninth JSME-KSME Thermal and Fluids Engineering Conference     2018.10  [Refereed]

     

  • Phase Equilibrium Condition Measurements in Carbon Dioxide Hydrate Forming System Coexisting with Sodium Chloride Aqueous Solutions

    Rihito Nakane, Eito Gima, Ryo Ohmura, Izuru Senaha, Keita Yasuda

    4th International Congress on Water, Waste and Energy Management     2018.07  [Refereed]

     

  • Quadruple Point Determination in Carbon Dioxide Hydrate Forming System

    Yuki Nema, Ryo Ohmura, Izuru Senaha, Keita Yasuda

    The 11th Asian Thermophysical Properties Conference     2016.10  [Refereed]

     

  • Designing Clathrate Hydrate Materials for Hydrogen Storage

    Keita Yasuda, Martin Braniff, E. Dendy Sloan, Carolyn A. Koh, Amadeu K. Sum, Ryo Ohmura, Hiroaki Sakamoto

    7th International Conference on Gas Hydrates     2011.07  [Refereed]

     

  • Characterization of Alcohol + Methane Hydrate Using Raman Spectroscopy and X-Ray Diffraction

    Keita Yasuda, Ryo Ohmura, Amadeu K. Sum

    7th International Conference on Gas Hydrates     2011.07  [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