2021/06/24 更新

写真a

ゴウコン ノブユキ
郷右近 展之
GOKON Nobuyuki
所属
教育研究院 自然科学系 生産デザイン工学系列 准教授
工学部 工学科 准教授
職名
准教授
外部リンク

学位

  • 博士(工学) ( 2000年3月   東京工業大学 )

  • 修士(工学) ( 1997年3月   東京工業大学 )

研究キーワード

  • Medical Organism Engineering and Material Science of Organism. Inorganic compounds. Metallic materials in general

  • Metal oxide for use in solar thermochemical heat storage

  • Metallic alloy for use in solar latent heat storage

  • Thermochemical two-step CO2 splitting

  • 水素エネルギー生産

  • エネルギー変換

  • 高温太陽集光熱

  • バイオマスのソーラーガス化

  • 高温化学蓄熱

  • 高温潜熱蓄熱

  • 触媒材料

  • ナノ粒子

  • 金属物性学

  • 無機材料化学

研究分野

  • ナノテク・材料 / 無機材料、物性

  • ナノテク・材料 / 金属材料物性

  • ライフサイエンス / 生体材料学

  • ものづくり技術(機械・電気電子・化学工学) / 触媒プロセス、資源化学プロセス

  • ナノテク・材料 / エネルギー化学

  • エネルギー / 地球資源工学、エネルギー学

  • ナノテク・材料 / 金属生産、資源生産

  • ライフサイエンス / 生体医工学

▶ 全件表示

経歴

  • 新潟大学   工学部 工学科   准教授

    2019年2月 - 現在

  • 新潟大学   研究推進機構   准教授

    2017年4月 - 2019年1月

  • 新潟大学   研究推進機構 超域学術院   准教授

    2011年4月 - 2017年3月

  • 新潟大学   超域研究機構   准教授

    2009年4月 - 2011年3月

  • 新潟大学   自然科学研究科 材料生産システム専攻   助教

    2007年4月 - 2009年3月

  • 新潟大学   自然科学研究科   助手

    2005年4月 - 2007年3月

▶ 全件表示

学歴

  • 東京工業大学   総合理工学研究科   材料物理科学専攻

    1997年4月 - 2000年3月

      詳細を見る

    国名: 日本国

    researchmap

  • 東京工業大学   総合理工学研究科   材料科学専攻

    1995年4月 - 1997年3月

      詳細を見る

    国名: 日本国

    researchmap

  • 茨城大学   工学部   物質工学科

    1991年4月 - 1995年3月

      詳細を見る

    国名: 日本国

    researchmap

所属学協会

  • 日本化学会

    2000年4月 - 現在

      詳細を見る

  • 日本エネルギー学会 新エネルギー・水素部会

      詳細を見る

  • アメリカ機械学会 太陽エネルギー部会

      詳細を見る

  • 日本太陽エネルギー学会 太陽熱部会

      詳細を見る

  • 粉体粉末冶金協会

    2000年4月 - 2003年3月

      詳細を見る

  • 日本金属学会

    1996年4月 - 2010年3月

      詳細を見る

▶ 全件表示

委員歴

  • 欧州科学財団   研究プロポーザル審査官  

    2021年4月 - 現在   

      詳細を見る

    団体区分:その他

    researchmap

  • 日本エネルギー学会 新エネルギー・水素部会   副部会長  

    2019年4月 - 現在   

      詳細を見る

    団体区分:学協会

    researchmap

  • 文部科学省 科学技術・学術政策研究所 科学技術予測センター   NISTEP専門調査員  

    2017年 - 現在   

      詳細を見る

    団体区分:政府

    researchmap

  • 日本太陽エネルギー学会   太陽エネルギー部会  

    2017年 - 現在   

      詳細を見る

    団体区分:学協会

    researchmap

  • 日本エネルギー学会   新エネルギー・水素部会 庶務幹事委員  

    2017年 - 2019年3月   

      詳細を見る

    団体区分:学協会

    researchmap

  • IEA SolarPACES国際会議   Scientific Committee  

    2014年 - 現在   

      詳細を見る

    団体区分:学協会

    researchmap

  • 日本エネルギー学会   新エネルギー部会 編集委員  

    2011年 - 2017年   

      詳細を見る

    団体区分:学協会

    researchmap

  • 新潟大学化学教育協議会   幹事委員  

    2010年 - 2011年   

      詳細を見る

    団体区分:その他

    researchmap

  • 日本エネルギー学会   新エネルギー部会 幹事委員  

    2009年 - 2017年   

      詳細を見る

    団体区分:学協会

    researchmap

  • 日本エネルギー学会   学会大会実行委員  

    2009年 - 2011年   

      詳細を見る

    団体区分:学協会

    researchmap

  • 日本化学会関東支部   新潟地方大会 大会実行委員  

    2009年   

      詳細を見る

    団体区分:学協会

    researchmap

▶ 全件表示

 

論文

  • Phase change material of copper-germanium alloy as solar latent heat storage at high temperatures 招待 査読

    Nobuyuki Gokon, Chew Shun Jie, Yuya Nakano, Shogo Okazaki, Tatsuya Kodama, Tsuyoshi Hatamachi, Selvan Bellan

    Frontiers in Energy Research, section Solar Energy9   696213-1 - 696213-19   2021年6月

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Thermal charge/discharge performance of iron–germanium alloys as phase change materials for solar latent heat storage at high temperatures 査読

    Nobuyuki Gokon, Chew Shun Jie, Yuya Nakano, Tatsuya Kodama, Selvan Bellan, Hyun seok Cho

    Journal of Energy Storage30   101420-1 - 101420-18   2020年3月

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Thermochemical two-step water splitting cycle using perovskite oxides based on LaSrMnO3 redox system for solar H2 production 査読

    Nobuyuki Gokon, Kazuki Hara, Yuta Sugiyama, Selvan Bellan, Tatsuya Kodama, Cho Hyun-seok

    Thermochimica Acta680   178374-1 - 178374-13   2019年10月

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Heat transfer and particulate flow analysis of a 30 kW directly irradiated solar fluidized bed reactor for thermochemical cycling 査読

    Selvan Bellan, Tatsuya Kodama, Koji Matsubara, Nobuyuki Gokon, Hyun Seok Cho, Kousuke Inoue

    Chemical Engineering Science203   511 - 525   2019年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Thermochemical behavior of perovskite oxides based on LaxSr1-x(Mn, Fe, Co)O3-δ and BaySr1-yCoO3-δ redox system for thermochemical energy storage at high temperatures 査読

    Nobuyuki Gokon, Takehiro Yawata, Selvan Bellan, Tatsuya Kodama, Hyun-Seok Cho

    Energy171   971 - 980   2019年3月

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Development of a 5kWth internally circulating fluidized bed reactor containing quartz sand for continuously-fed coal-coke gasification and a beam-down solar concentrating system 査読

    Nobuyuki Gokon, Satoshi Kumaki, Yosuke Miyaguchi, Selvan Bellan, Tatsuya Kodam, Hyunseok Cho

    Energy166   1 - 16   2019年

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Numerical and experimental study on granular flow and heat transfer characteristics of directly-irradiated fluidized bed reactor for solar gasification 査読

    Selvan Bellan, Nobuyuki Gokon, Koji Matsubara, Hyun Seok Cho, Tatsuya Kodama

    International journal of hydrogen energy43 ( 34 ) 1 - 15   2018年8月

  • A CFD-DEM study of hydrodynamics with heat transfer in a gas-solid fluidized bed reactor for solar thermal applications 査読

    Selvan Bellan, Koji Matsubara, Hyun Seok Cho, Nobuyuki Gokon, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER116   377 - 392   2018年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The particles flow and heat transfer characteristics of a high temperature solar thermochemical fluidized bed reactor have been studied for solar beam-down concentrating systems. A numerical model has been developed by the combined approach of computational fluid dynamics (CFD) and discrete element method (DEM) collisional model since it is an effective approach for studying the gas-solid flow. The discrete ordinate model has been used to solve the radiation heat transfer. An experimental visualization of particles circulation pattern and mixing of two-tower fluidized bed system has been presented. A good agreement has been found between the experimental measurements and numerical predictions. The effect of gas superficial velocity, bed mass and inlet gas temperature on the flow pattern and temperature characteristics of the bed have been investigated. The results showed that the maximum and average temperature of the bed, depends on the top layer position and focal point of the concentrated radiation, decreased when increasing the total mass of the bed. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijheatmasstransfer.2017.09.015

    Web of Science

    researchmap

  • Heat transfer analysis of 5kWth circulating fluidized bed reactor for solar gasification using concentrated Xe light radiation 査読

    Selvan Bellan, Nobuyuki Gokon, Koji Matsubara, Hyun Seok Cho, Tatsuya Kodama

    Energy160   245 - 256   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Fe-doped Mn2O3/Mn3O4 redox material for thermochemical energy storage at high-temperatures 査読

    Nobuyuki Gokon, Aoi Nishizawa, Takehiro Yawata, Hyun-seok Cho, Selvan Bellan, Tatsuya Kodama

    SolarPACES 2018, Casabranca, Morocco, October 2-5, 2018   2018年

     詳細を見る

    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Heat transfer and fluid flow analysis of a fluidized bed reactor for beam-down optics 査読

    Selvan Bellan, Tatsuya Kodama, Koji Matsubara, Nobuyuki Gokon, Hyun Seok Cho

    SolarPACES 2018, Casabranca, Morocco, October 2-5, 2018   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Particles Fluidized Bed Receiver/Reactor with a Beam-Down Solar Concentrating Optics: First Performance Test on Two-Step Water Splitting with Ceria Using a Miyazaki Solar Concentrating System 査読

    Tatsuya Kodama, Nobuyuki Gokon, Hunseok Cho, Selvan Bellan

    SolarPACES 2018, Casabranca, Morocco, October 2-5, 2018   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Reactivity of Mn-Doped Ceria for a Thermochemical Two-Step Water-splitting cycle at low temperature 査読

    Enzo Shida, Kiko Naito, Tsuyoshi Hatamachi, Selvan Bellan, Cho Hyun-Seok, Nobuyuki Gokon, Tatsuya Kodama

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical test of quartz window type fluidized bed solar reactor by 30 kW sun simulator 査読

    Kosuke Inoue, Kazuya Senuma, Tsuyoshi Hatamachi, Hyun Seok Cho, Selvan Bellen, Nobuyuki Gokon, Tatsuya Kodama

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Research on thermal charge / discharge cyclic performance of new thermal storage materials for solar thermal power generation 査読

    Asato Shirai, Mami Kaneko, Selvan Bellan, Hyun Seok Cho, Tsuyoshi Hatamachi, Nobuyuki Gokon, Tatsuya Kodama

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Solar gasification of coals by a windowed fluidized bed reactor with beam-down optics 査読

    Shimpei Takagi, T. Hatamachi, S.Vellan, C. Hyunseok, N. Gokon, T. Kodama

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical tewo-step water-splitting cyclew of the CeO2/MPSZ ractive foam device by the high temperature solar furnace 査読

    Issei Tsuruma, Manami Ymada, Hun-Seok Cho, Nobuyuki Gokon, Tatsuya Kodama

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Study on the reactivity of perovskite oxides in thermochemical storage cycle 査読

    Takehiro Yawata, Tsuyoshi Hatamachi, Vellan Selvan, Hunseok Cho, Tatsuya Kodama, Nobuyuki Gokon

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Development of Thermochemical Two-Step Water Splitting Cycle of the CeO2/M-CeO2 Foam Device by the 3 kW Sun-simulator 査読

    Hyun-Seok Cho, Issei Tsuruma, Manami Yamada, Tatsuya Kodama, Nobuyuki Gokon

    The 6th International Symposium on Fusion Technology, Niigata University, Niigata, Japan, January 26-28, 2018.   2018年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Buoyancy-opposed volumetric solar receiver with beam-down optics irradiation 査読

    Mitsuho Nakakura, Koji Matsubara, Hyun-Seok Cho, Tatsuya Kodama, Nobuyuki Gokon, Selvan Bellan, Kazuo Yoshida

    Energy141   2337 - 2350   2017年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier Ltd  

    This paper describes a volumetric solar receiver that is vertically integrated with beam-down optics for condensed light irradiation. The heat-transfer performance of a silicon carbide honeycomb receiver was investigated using a 30-kWth solar simulator and numerical simulation. The experiments achieved an air temperature of 840 K at the receiver outlet by varying the operational parameters. Numerical simulations were performed for a vertical honeycomb block with beam-down irradiation and a horizontal honeycomb block with tower-type irradiation to elucidate the effects of buoyancy. Three blocks with different sizes were simulated for a variety of operational parameters. When the block was oriented vertically, the flow and temperature fields remained nearly symmetric in and near the receiver. In contrast, when it was oriented horizontally, the flow and temperature became asymmetric, with the hot spot moving toward the receiver's side wall and the stream in the receiver being reversed. The vertical orientation's robustness to buoyancy effects prevented any reduction in the receiver efficiency or outlet temperature and suppressed the thermal leakage.

    DOI: 10.1016/j.energy.2017.11.147

    Scopus

    researchmap

  • Particle reactors for solar thermochemical processes 査読

    Tatsuya Kodama, Selvan Bellan, Nobuyuki Gokon, Hyun Seok Cho

    SOLAR ENERGY156   113 - 132   2017年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Utilization of solar thermal power for high temperature fuel production has the potential to significantly reduce the fossil fuel dependence of our current economy. Over the past two decades, remarkable progress has been made in the development of solar driven thermochemical reactors for the production of hydrogen and syngas as they are promising energy carriers for transportation, domestic and industrial applications. However, there are solar peculiarities in comparison to conventional thermochemical processes high thermal flux density and frequent thermal transients because of the fluctuating insolation-, and conventional industrial thermochemical reactors are generally not suitable for solar driven reactors. Therefore, solar-specific modifications of reactor design are necessary to realize efficient solar driven thermochemical processes. In solar thermochemical reactors, the methods for solar-heating particulate solid feedstock to high temperatures can be broadly classified as solar "directly" and "indirectly" absorbing reactors. On solar thermochemical processes involving reacting solid particles at high temperatures, such as "solar two-step water splitting with metal oxides" and "solar gasification", various types of solar directly and indirectly absorbing particle reactors have been developed. In this review, recent development of solar particle reactors for the above solar thermochemical processes is described. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2017.05.084

    Web of Science

    researchmap

  • CFD-DEM investigation of particles circulation pattern of two-tower fluidized bed reactor for beam-down solar concentrating system 査読

    Selvan Bellan, Koji Matsubara, Cho Hyun Cheok, Nobuyuki Gokon, Tatsuya Kodama

    POWDER TECHNOLOGY319   228 - 237   2017年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    In this study, a numerical model has been developed by the combined approach of computational fluid dynamics (CFD) and discrete element method (DEM) collisional model to study the particle-fluid flow of the fluidized bed reactor for solar beam-down concentrating system. The contact forces between the particles have been calculated by the spring-dashpot model, based on the soft-sphere method. An experimental visualization of particles circulation pattern and mixing of two-tower fluidized bed system has been presented. A good agreement has been found between the experimental measurements and numerical predictions. To investigate the influence of fluid flow rate and particle size on the flow pattern of the reactor, simulations have been performed for various conditions. The results indicate that the large size particles induce three-dimensional effects as they are accumulated at the central axis region. The average bed height of the left tower increased by 23.4% when increasing the flow rate about 70%. (C) 2017 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.powtec.2017.06.060

    Web of Science

    researchmap

  • CFD-DEM Investigation on Flow and Temperature Distribution of Ceria Particles in a Beam-Down Fluidized Bed Reactor 査読

    Selvan Bellan, Koji Matsubara, Hyun Seok Cho, Nobuyuki Gokon, Tatsuya Kodama

    SolarPACES 2017, Santiago, Chili, September 26-29, 2017   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • THERMOCHEMICAL TWO-STEP WATER-SPLITTING USING PEROVSKITE OXIDE FOR SOLAR HYDROGEN PRODUCTION 査読

    Yuta Sugiyama, Nobuyuki Gokon, Hyun-Seok Cho, Selvan Bellan, Tsuyoshi Hatamachi, Tatsuya Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • HYDROGEN PRODUCTIVITY AND REPEATABILITY FOR THERMOCHEMICAL TWO-STEP WATER-SPLITTING CYCLE USING MN-DOPED CERIUM OXIDES 査読

    Kiko Naito, Nobuyuki Gokon, Hyun-Seok Cho, Selvan Bellan, Tsuyoshi Hatamachi, Tatsuya Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • SOLAR RECEIVER/REACTOR OF FLUIDIZED BED WITH MIYAZAKI BEAM-DOWN SOLAR CONCENTRATING SYSTEM 査読

    Kazuya Senuma, Nobuyuki Gokon, Hyun-Seok Cho, Selvan Bellan, Tsuyoshi Hatamachi, Tatsuya Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Investigation of reaction temperature of cerium oxide in two-step carbon dioxide splitting cycles 査読

    Kazuya Senuma, Nobuyuki Gokon, Hyun-Seok Cho, Selvan Bellan, Tsuyoshi Hatamachi, Tatsuya Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • HEAT TRANSFER ANALYSIS OF AN OVAL CERAMIC CONTAINER ENCAPSULATED BY PHASE CHANGE MATERIAL FOR THERMAL ENERGY STORAGE SYSTEM 査読

    Selvan Bellan, Shunichi Tazawa, Tomohiro Nakamata, Cho Hyun Cheok, Nobuyuki Gokon, Koji Matsubara, Tatsuya Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • NUMERICAL SIMULATION OF VOLUMETRIC AIR RECEIVER FOR BEAM DOWN REFLECTOR 査読

    M. Nakakura, K. Matsubara, S. Kawagoe, S. Bellan, H. S. Cho, N. Gokon, T. Kodama

    Asian Conference on thermal sciences 2017, ICC JEJU, JEJU ISLAND, KOREA, March 26-30, 2017.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Melting process of PCM in ceramic capsule for solar thermal storage 査読

    Selvan Bellan, Shunichi Tazawa, Koji Matsubara, Cho Hyun Seok, Nobuyuki Gokon, Tatsuya Kodama

    SOLARIS Conference 27 - 28 Jul 2017, London, UK.   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Heat Transfer Analysis of Fluidized Bed Particle Receiver for High-Temperature Solar Concentration 査読

    Koji Matsubara, Atsushi Sakurai, Takahiro Suzuki, Selvan Bellan, Nobuyuki Gokon, Cho Hyun-Seok, Tatsuya Kodama

    SOLARIS Conference 27 - 28 Jul 2017, London, UK   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Discrete ordinates simulation of volumetric solar receiver with beam-down irradiation and its verification using big sun simulator 査読

    Mitsuho Nakakura, Koji Matsubara, Yuki Aoki, Selvan Bellan, Cho Hyun-Seok, Nobuyuki Gokon, Tatsuya Kodama

    SOLARIS Conference 27 - 28 Jul 2017, London, UK   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Preliminary Tests of Batch Type Fluidized Bed Reactor for Development of Continuously-Feeding Fluidized Bed Reactor - an Elevated Temperature and Gasification Processes ? 査読

    Nobuyuki Gokon, Shinpei Takagi, Hyun-seok Cho, Selvan Bellan, Tatsuya Kodama

    SolarPACES 2017, Santiago, Chili, September 26-29, 2017   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermal Storage/Discharge Performances of Cu-Si Alloy for Solar Thermochemical Process 査読

    Nobuyuki Gokon, Tomoya Yamaguchi, Hyun-seok Cho, Selvan Bellan, Tsuyoshi Hatamachi, Tatsuya Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2016)1850   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    The present authors (Niigata University, Japan) have developed a tubular reactor system using novel "double-walled" reactor/receiver tubes with carbonate molten-salt thermal storage as a phase change material (PCM) for solar reforming of natural gas and with Al-Si alloy thermal storage as a PCM for solar air receiver to produce high-temperature air. For both of the cases, the high heat capacity and large latent heat (heat of solidification) of the PCM phase circumvents the rapid temperature change of the reactor/receiver tubes at high temperatures under variable and uncontinuous characteristics of solar radiation. In this study, we examined cyclic properties of thermal storage/discharge for Cu-Si alloy in air stream in order to evaluate a potentiality of Cu-Si alloy as a PCM thermal storage material. Temperature-increasing performances of Cu-Si alloy are measured during thermal storage (or heat-charge) mode and during cooling (or heat-discharge) mode. A oxidation state of the Cu-Si alloy after the cyclic reaction was evaluated by using electron probe micro analyzer (EPMA).

    DOI: 10.1063/1.4984465

    Web of Science

    researchmap

  • Numerical Analysis of Fluid Flow and Heat Transfer During Melting Inside a Cylindrical Container for Thermal Energy Storage System 査読

    Selvan Bellan, Cho Hyun Cheok, Nobuyuki Gokon, Koji Matsubara, Tatsuya Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2016)1850   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solidliquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part.

    DOI: 10.1063/1.4984427

    Web of Science

    researchmap

  • Particles Fluidized Bed Receiver/Reactor Tests with Quartz Sand Particles Using a 100-kW(th) Beam-Down Solar Concentrating System at Miyazaki 査読

    Tatsuya Kodama, Nobuyuki Gokon, Hyun Seok Cho, Koji Matsubara, Hiroshi Kaneko, Kazuya Senuma, Sumie Itoh, Shin-nosuke Yokota

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2016)1850   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A window-type, solar fluidized bed receiver with quartz sand particles was tested by a 100-kWth novel beam-down solar concentrating system at Miyazaki, Japan. A compound parabolic concentrator (CPC) was placed above the quartz window of the receiver to increase the concentration of the solar fluxes from the beam-down solar concentrating system. The solar tests were performed in the middle of December, 2015. The central bed temperature of the receiver was reached around 960-1100 degrees C. It was found that only 20 Ndm(3)/min of air flow rate was enough to create the uniform fluidization of the particles at the given temperature range. It was predicted that if the central bed temperature could have been higher than 1100 degrees C if solar receiver test had conducted in other seasons than winter. The next solar campaign of the receiver test will be carried out in October, 2016.

    DOI: 10.1063/1.4984469

    Web of Science

    researchmap

  • Development and Experimental Study for Hydrogen Production from the Thermochemical Two-step Water Splitting Cycles with a CeO2 Coated New Foam Device Design Using Solar Furnace System 査読

    Hyun Seok Cho, Tatsuya Kodama, Nobuyuki Gokon, Jong Kyu Kim, Sang Nam Lee, Yong Heack Kang

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS (SOLARPACES 2016)1850   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A solar reactor containing a CeO2-coated reactive foam device for producing hydrogen via a thermochemical two-step water splitting cycle was proposed and experimentally tested. Modeling of the optical properties of the 40 kW(th) KIER (Korea Institute of Energy Research) solar furnace was performed to design and prepare the optimized foam matrix shape and the new solar reactor. Solar demonstration of the solar reactor was accomplished in the KIER 40 kW(th) solar furnace and hydrogen was produced successfully during the water decomposition step. The conical shape foam device was suggested and tested the temperature gradients and hydrogen productivity. Finally, five cyclic test was conducted with the conical shape CeO2-coated foam device, the total hydrogen production was 1394.32 Ncm(3) during the five cycles and the average hydrogen production per cycle was 278.86 Ncm(3).

    DOI: 10.1063/1.4984460

    Web of Science

    researchmap

  • Cyclic thermal storage/discharge performances of a hypereutectic Cu-Si alloy under vacuum for solar thermochemical process 査読

    Nobuyuki Gokon, Tomoya Yamaguchi, Tatsuya Kodama

    ENERGY113   1099 - 1108   2016年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A copper-silicon alloy (Cu-Si alloy) was examined and evaluated as a phase-change material (PCM) for thermal energy storage applications such as load shaving and peak load shifting when coupled to a solar thermochemical reactor, reformer, or gasifier for the production of solar fuel. The Cu-Si alloy was selected as a high-temperature PCM thermal storage medium alternative to molten carbonate salts, and the compatibility of this alloy with a graphite-carbon encapsulation material was experimentally examined. The cyclic thermal storage/discharge properties of the Cu-Si alloy as a latent-heat energy storage material were studied with respect to thermal cycles. A thermal stability test was performed on Cu-20 wt% Si, Cu-25 wt% Si, and Cu-30 wt% Si alloys placed in a graphite container under vacuum. The performances of the Cu-Si alloys with increasing and decreasing temperature were measured during the thermal storage (heat-charge) and cooling (heat-discharge) modes, respectively. The elemental distribution of each Cu-Si alloy after the cyclic reaction was evaluated using an electron probe microanalyzer (EPMA). The heat storage capacities before and after the cyclic reaction were evaluated using differential scanning calorimetry (DSC) and were compared to the thermal storage properties of the molten carbonate salt. (C) 2016 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.energy.2016.07.005

    Web of Science

    researchmap

  • Cyclic thermal storage/discharge performances of hypereutectic alloy for solar latent heat storage 査読

    Tomoya Yamaguchi, Nobuyuki Takahashi, Tsuyoshi Hatamachi, Hyun-Seok Cho, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2016, Harbin Institute of Technology, Harbin, China, January 19-21, 2016.   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Particles Fluidized Bed Receiver/Reactor with a Beam-Down Solar Concentrating Optics: 30-kW(th) Performance Test Using a Big Sun-Simulator 査読

    Tatsuya Kodama, Nobuyuki Gokon, Hyun Seok Cho, Koji Matsubara, Tetsuro Etori, Akane Takeuchi, Shin-nosuke Yokota, Sumie Ito

    SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS1734   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A novel concept of particles fluidized bed receiver/reactor with a beam-down solar concentrating optics was performed using a 30-kW(th) window type receiver by a big sun-simulator. A fluidized bed of quartz sand particles was created by passing air from the bottom distributor of the receiver, and about 30 kW(th) of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directly irradiated on the top of the fluidized bed in the receiver through a quartz window. The particle bed temperature at the center position of the fluidized bed went up to a temperature range from 1050 to 1200 degrees C by the visible light irradiation with the average heat flux of about 950 kW/m(2), depending on the air flow rate. The output air temperature from the receiver reached 1000 - 1060 degrees C.

    DOI: 10.1063/1.4949206

    Web of Science

    researchmap

  • Particles Fluidized Bed Receiver/Reactor with a Beam-Down Solar Concentrating Optics: 30-kW(th) Performance Test Using a Big Sun-Simulator 査読

    Tatsuya Kodama, Nobuyuki Gokon, Hyun Seok Cho, Koji Matsubara, Tetsuro Etori, Akane Takeuchi, Shin-nosuke Yokota, Sumie Ito

    SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS1734   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A novel concept of particles fluidized bed receiver/reactor with a beam-down solar concentrating optics was performed using a 30-kW(th) window type receiver by a big sun-simulator. A fluidized bed of quartz sand particles was created by passing air from the bottom distributor of the receiver, and about 30 kW(th) of high flux visible light from 19 xenon-arc lamps of the sun-simulator was directly irradiated on the top of the fluidized bed in the receiver through a quartz window. The particle bed temperature at the center position of the fluidized bed went up to a temperature range from 1050 to 1200 degrees C by the visible light irradiation with the average heat flux of about 950 kW/m(2), depending on the air flow rate. The output air temperature from the receiver reached 1000 - 1060 degrees C.

    DOI: 10.1063/1.4949206

    Web of Science

    researchmap

  • Experimental Demonstration and Numerical Model of a Point Concentration Solar Receiver Evaluation System Using a 30 kWth Sun Simulator 査読

    M. Nakakura, M. Ohtake, K. Matsubara, K. Yoshida, H. S. Cho, T. Kodama, N. Gokon

    SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS1734   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    In 2014, Niigata University and the Institute of Applied Energy developed a point-concentration receiver-evaluation system using a silicon carbide (SiC) honeycomb and a three-dimensional simulation method. The system includes several improvements over its forerunner, including the ability to increase/decrease the power-on aperture (POA), air-mass flow-rate (AMF) and the height of the focal surface. This paper will focus on the results of tests using an improved receiver evaluation system, at a focal height of 1600 mm. Maximum outlet air temperature reached as high as 800 K, but exerted no untoward effects on the system. Also, receiver efficiency rated between 45 % and 70 %, according to POA. A numerical, 3D method of analysis was created at the same time, in order to analyze temperature and flow-distribution, in detail. This simulation, based on the dual-cell approach, reproduced the thermal non-equilibrium between the solid and fluid domain of the receiver material. The most interesting feature of this simulation, is that, because it includes upper and lower computational domains, it can be used to analyze the influence of both inward-and outward-flowing receiver materials.

    DOI: 10.1063/1.4949078

    Web of Science

    researchmap

  • Synthesis of CeO2 particles by spray dryer method for solar hydrogen production 査読

    Sumie Ito, Shiori Abe, Tsuyoshi Hatamachi, Cho Hyunseok, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2016, Harbin Institute of Technology, Harbin, China, January 19-21, 2016.   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Cold Test with a Benchtop Set-up for Fluidized Bed Reactor Using Quartz Sand to Simulate Gasification of Coal Cokes by Concentrated Solar Radiation 査読

    Nobuyuki Gokon, Tomoaki Tanabe, Tadaaki Shimizu, Tatsuya Kodama

    SOLARPACES 2015: INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS1734   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    The impacts of internal circulation of a mixture of coal-coke particles and quartz sand on the fluidization state in a fluidized bed reactor are investigated by a cold test with a benchtop set-up in order to design 10-30 kWth scale prototype windowed fluidized-bed reactor. Firstly, a basic relationship between pressure loss of inlet gas and gas velocity was experimentally examined using quartz sand with different particle sizes by a small-scale quartz tube with a distributor at ambient pressure and temperature. Based on the results, an appropriate particle range of quartz sand and layer height/layer diameter ratio (L/D ratio) was determined for a design of the fluidized bed reactor. Secondly, a windowed reactor mock-up was designed and fabricated for solar coke gasification using quartz sand as a bed material. The pressure loss between the inlet and outlet gases was examined, and descending cokes and sand particles on the sidewall of the reactor was observed in the reactor mock-up. The moving velocity and distance of descending particles/sands from the top to bottom of fluidized bed were measured by the visual observation of the colored tracer particles on outside wall of the reactor.

    DOI: 10.1063/1.4949204

    Web of Science

    researchmap

  • Oxygen and hydrogen productivities and repeatable reactivity of 30-mol%-Fe-, Co-, Ni-, Mn-doped CeO2?δ for thermochemical two-step water-splitting cycle 査読

    Nobuyuki Gokon, Toshinori Suda, Tatsuya Kodama

    Energy90   1280 - 1289   2015年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.energy.2015.06.085

    Web of Science

    researchmap

  • Thermochemical reactivity of 5-15 mol% Fe, Co, Ni, Mn-doped cerium oxides in two-step water-splitting cycle for solar hydrogen production 査読

    Nobuyuki Gokon, Toshinori Suda, Tatsuya Kodama

    THERMOCHIMICA ACTA617 ( 10 ) 179 - 190   2015年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The thermochemical two-step water-splitting cycle using transition element-doped cerium oxide (M CeO2-delta; M=Fe, Co, Ni, Mn) powders was studied for hydrogen production from water. The oxygen/hydrogen productivity and repeatability of M CeO2-delta materials with M doping contents in the 5-15 mol% range were examined using a thermal reduction (TR) temperature of 1500 degrees C and water decomposition (WD) temperatures in the 800-1150 degrees C range. The temperature, steam partial pressure, and steam flow rate in the WD step had an impact on the hydrogen productivity and production rate. 5 mol% Fe- and Co-doped CeO2-delta enhances hydrogen productivity by up to 25% on average compared to undoped CeO2, and shows stable repeatability of stoichiometric oxygen and hydrogen production for the cyclic thermochemical two-step water-splitting reaction. In addition, 5 mol% Mn-doped CeO2-delta, 10 and 15 mol% Fe- and Mn-doped CeO2-delta show near stoichiometric reactivities. (C) 2015 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tca.2015.08.036

    Web of Science

    researchmap

  • Improved operation of solar reactor for two-step water-splitting H-2 production by ceria-coated ceramic foam device 査読

    H. S. Cho, N. Gokon, T. Kodama, Y. H. Kang, H. J. Lee

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY40 ( 1 ) 114 - 124   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The joint international project between Niigata University (Japan) and the Korea Institute of Energy Research, KIER (Korea) on "Solar Demonstration of Water-Splitting Reactor using Ceramic Foam Device" has two goals. (1) Develop a solar reactor using reactive cerium oxide foam devices for high-temperature two-step thermochemical water-splitting cycle. (2) Test its performance under various operational methods using a 40 kW(th) solar furnace driven by natural solar energy. The reactive CeO2/MPSZ (MgO partially stabilized zirconia) foam device for two-step water-splitting was developed and prepared by Niigata University/Japan; it involves coating an inert zirconia foam matrix with reactive CeO2. In this paper, highly reactive CeO2 particles were used the redox material in CeO2/MPSZ foam devices to investigate the use of solar energy for hydrogen production. The solar-driven thermochemical two-step water-splitting cycle was demonstrated using the 40 kWth KIER solar furnace in Korea combined with the CeO2/MPSZ foam device. At the center of the foam device, temperatures were 1500 degrees C-1600 degrees C during the thermal reduction step and 600 degrees C-1100 degrees C during the subsequent water decomposition step. Hydrogen was successfully produced from the CeO2/MPSZ foam device, and profiles for hydrogen production and CeO2 conversion indicated definitely improved operations compared to earlier studies. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2014.10.084

    Web of Science

    researchmap

  • Steam gasification of coal cokes by internally circulating fluidized-bed reactor by concentrated Xe-light radiation for solar syngas production 査読

    Nobuyuki Gokon, Takuya Izawa, Tatsuya Kodama

    ENERGY79   264 - 272   2015年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A laboratory-scale prototype windowed reactor using a fluidized bed of coal coke particles was tested for thermochemical gasification using concentrated Xe light radiation as an energy source. The fluidized-bed reactor, designed to be combined with a solar reflective tower or beam-down optics, is evaluated for steam gasification of coal coke according to gasification performance: CO, H-2, and CO2 production rates; carbon conversion; light-to-chemical efficiency. Internal circulation of coal coke particles inside the reactor increases gasification performance, which is further enhanced by higher steam partial pressure of the inlet gas. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.energy.2014.11.012

    Web of Science

    researchmap

  • Laboratory experiment and simulation of higherature fluidized bed air receiver for concentrated solar power generation 査読

    Koji Matsubara, Yuki Kazuma, Atsushi Sakurai, Tatsuya Kodama, Nobuyuki Gokon, Hyun-Seok Cho, Kazuo Yoshida, Yoshinori Nagase

    Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy94 ( 11 ) 1323 - 1329   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Japan Institute of Energy  

    This study proposes a t wo-tower t ype fluidized receiver for receiving concentrated s olar light at high temperatures is proposed. This fluidized receiver is coupled with the Miyazaki beam-down reflector system. The visualization and the numerical simulation was made for the laboratory model to show the fluid-dynamics and the heat transport as well as to elaborate the existing demonstration model. The experimental visualization of the cold model demonstrated that in each tower, the particles are moved by the aerated organized flow. The numerical simulation was made using the thermal input cited from the 5.0kWth sun simulator. The numerical simulation demonstrated that the inner particles are heated above 950 °C after 3.0 minutes of the aeration start time. The increase in temperature is caused by the intrusion of the heated particles from the high-pressure side tower to the low-pressure side tower. It is thus suggested that collective circulation occurs between high- and low-pressure side towers and this can be utilized for a direct thermal storage system.

    DOI: 10.3775/jie.94.1323

    Scopus

    researchmap

  • Cyclic properties of thermal storage/discharge for Al-Si alloy in vacuum for solar thermochemical fuel production 査読

    N. Gokon, S. Nakamura, T. Yamaguchi, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1759 - 1769   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thermal energy storage using phase-change materials (PCM) can be utilized for load shaving or peak load shifting when coupled to a solar thermochemical reactor, reformer, or gasifier for the production of solar fuel. The PCM is embedded in packages or used in bulk in these storage systems, and therefore the compatibility of the encapsulation materials and the selection of the PCM are key factors for ensuring the long operational life of the system. Various kinds of molten fluoride, chloride and carbonate salts, and mixed molten salt, which function at high temperatures of over 500 degrees C, are known to cause corrosion or thermal degradation. It is therefore worth studying new high-temperature PCM thermal storage alternatives to these molten salts for use in solar thermochemical processes. In this study, the focus was on aluminum-silicon alloy (Al-Si alloy) as a high-temperature PCM thermal storage medium, and the compatibility of this alloy with graphite-carbon encapsulation material was experimentally examined. The cyclic properties of thermal storage/discharge for Al-Si alloy as a latent-heat energy storage material was studied with respect to various thermal cycles. A thermal stability test was performed for the Al-20wt% Si, Al-25wt% Si, Al-30wt% Si, and Al-35wt% Si alloys placed in the graphite container in vacuum. The temperature increasing and cooling performances of the Al-Si alloy were measured during the thermal storage (heat-charge) mode and during the cooling (heat-discharge) mode. The oxidation level of the Al-Si alloy after the cyclic reaction (20 cycles) was evaluated using an electron probe microanalyzer (EPMA). (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.145

    Web of Science

    researchmap

  • Cyclic properties of thermal storage/discharge for Al-Si alloy in vacuum for solar thermochemical fuel production 査読

    N. Gokon, S. Nakamura, T. Yamaguchi, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1759 - 1769   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thermal energy storage using phase-change materials (PCM) can be utilized for load shaving or peak load shifting when coupled to a solar thermochemical reactor, reformer, or gasifier for the production of solar fuel. The PCM is embedded in packages or used in bulk in these storage systems, and therefore the compatibility of the encapsulation materials and the selection of the PCM are key factors for ensuring the long operational life of the system. Various kinds of molten fluoride, chloride and carbonate salts, and mixed molten salt, which function at high temperatures of over 500 degrees C, are known to cause corrosion or thermal degradation. It is therefore worth studying new high-temperature PCM thermal storage alternatives to these molten salts for use in solar thermochemical processes. In this study, the focus was on aluminum-silicon alloy (Al-Si alloy) as a high-temperature PCM thermal storage medium, and the compatibility of this alloy with graphite-carbon encapsulation material was experimentally examined. The cyclic properties of thermal storage/discharge for Al-Si alloy as a latent-heat energy storage material was studied with respect to various thermal cycles. A thermal stability test was performed for the Al-20wt% Si, Al-25wt% Si, Al-30wt% Si, and Al-35wt% Si alloys placed in the graphite container in vacuum. The temperature increasing and cooling performances of the Al-Si alloy were measured during the thermal storage (heat-charge) mode and during the cooling (heat-discharge) mode. The oxidation level of the Al-Si alloy after the cyclic reaction (20 cycles) was evaluated using an electron probe microanalyzer (EPMA). (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.145

    Web of Science

    researchmap

  • Flowability control of bed materials in a fluidized bed reactor for solar thermochemical process 査読

    T. Etori, N. Gokon, A. Takeuchi, T. Miki, M. Yokota, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1741 - 1749   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Hydrogen production by solar thermochemical process uses concentrated solar radiation as its energy source. Various thermochemical processes operating at technically manageable temperatures which are a solar thermochemical two-step water splitting and solar gasification of carbonaceous material have been extensively studied and demonstrated by researchers around the world. These processes are capable of converting high-temperature heat from concentrated solar radiation into clean hydrogen from water. In this study, in order to control a flowability (fluidization state) of bed materials in a fluidized bed reactor for thermochemical processes (two-step water splitting cycle and gasification of coal coke), firstly, a basic relationship between pressure drop of inlet gas and gas flow rate was experimentally examined using bed materials with different particle sizes by a small-scale quartz reactor at ambient pressure and temperature. Secondly, the CeO2 particles having the size determined by above-described flowability test were tested using a windowed fluidized bed reactor prototype. The fluidized bed of CeO2 particles was exposed to a concentrated Xe light by sun-simulator with an input power of about 5 kWth for the T-R step in order to release oxygen. The production rate and productivity of oxygen and the reactivity of CeO2 particles were examined in this paper. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.143

    Web of Science

    researchmap

  • Flowability control of bed materials in a fluidized bed reactor for solar thermochemical process 査読

    T. Etori, N. Gokon, A. Takeuchi, T. Miki, M. Yokota, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1741 - 1749   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Hydrogen production by solar thermochemical process uses concentrated solar radiation as its energy source. Various thermochemical processes operating at technically manageable temperatures which are a solar thermochemical two-step water splitting and solar gasification of carbonaceous material have been extensively studied and demonstrated by researchers around the world. These processes are capable of converting high-temperature heat from concentrated solar radiation into clean hydrogen from water. In this study, in order to control a flowability (fluidization state) of bed materials in a fluidized bed reactor for thermochemical processes (two-step water splitting cycle and gasification of coal coke), firstly, a basic relationship between pressure drop of inlet gas and gas flow rate was experimentally examined using bed materials with different particle sizes by a small-scale quartz reactor at ambient pressure and temperature. Secondly, the CeO2 particles having the size determined by above-described flowability test were tested using a windowed fluidized bed reactor prototype. The fluidized bed of CeO2 particles was exposed to a concentrated Xe light by sun-simulator with an input power of about 5 kWth for the T-R step in order to release oxygen. The production rate and productivity of oxygen and the reactivity of CeO2 particles were examined in this paper. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.143

    Web of Science

    researchmap

  • Internally-circulating fluidized bed reactor using thermal storage material for solar coal coke gasification 査読

    T. Abe, N. Gokon, T. Izawa, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1722 - 1730   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    A windowed reactor prototype of internally-circulating fluidized bed is tested and demonstrated at laboratory scale for steam gasification of coal coke irradiated directly by concentrated Xe light from a 3-kWth sun simulator. The bed material is composed of particle mixture of coal coke and quartz sand. A coal coke of the bed material works as a carbonous feedstock, while quartz sand functions as a thermal storage/transfer medium inside the reactor. The fluidized bed reactor, having a transparent window due to incoming radiation of concentrated solar beam on the ceiling of the reactor, is designed to be combined with a solar reflective tower or beam-down optics. A potential of quartz sand in the internally-circulating fluidized bed reactor is evaluated for steam gasification of coal coke by gasification performance (CO, H-2 and CO2 production rates, carbon conversion, and lightto- chemical efficiency). The gasification performances for use of the particle mixture in the reactor are compared with that for use of coal coke particle. The fluidized bed of a particle mixture including coal coke and quartz sand was gasified at lower temperature with a higher rate in comparison to that of a coal coke. Furthermore, a use of smaller and lighter coal coke particles were easily converted to gaseous species due to larger surface area as well as the gasification rates. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.140

    Web of Science

    researchmap

  • Internally-circulating fluidized bed reactor using thermal storage material for solar coal coke gasification 査読

    T. Abe, N. Gokon, T. Izawa, T. Kodama

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   1722 - 1730   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    A windowed reactor prototype of internally-circulating fluidized bed is tested and demonstrated at laboratory scale for steam gasification of coal coke irradiated directly by concentrated Xe light from a 3-kWth sun simulator. The bed material is composed of particle mixture of coal coke and quartz sand. A coal coke of the bed material works as a carbonous feedstock, while quartz sand functions as a thermal storage/transfer medium inside the reactor. The fluidized bed reactor, having a transparent window due to incoming radiation of concentrated solar beam on the ceiling of the reactor, is designed to be combined with a solar reflective tower or beam-down optics. A potential of quartz sand in the internally-circulating fluidized bed reactor is evaluated for steam gasification of coal coke by gasification performance (CO, H-2 and CO2 production rates, carbon conversion, and lightto- chemical efficiency). The gasification performances for use of the particle mixture in the reactor are compared with that for use of coal coke particle. The fluidized bed of a particle mixture including coal coke and quartz sand was gasified at lower temperature with a higher rate in comparison to that of a coal coke. Furthermore, a use of smaller and lighter coal coke particles were easily converted to gaseous species due to larger surface area as well as the gasification rates. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.140

    Web of Science

    researchmap

  • Simulation of flux distributions on the foam absorber with solar reactor for thermo-chemical two-step water splitting H-2 production cycle by the 45 kW(th) KIER solar furnace 査読

    H. S. Cho, N. Gokon, T. Kodama, Y. H. Kang, J. K. Kim

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   790 - 801   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The flux distributions on the device in the solar reactor with the solar furnace were studied. This study aims to understand of characters of concentrated sun rays through KIER solar furnace and design of device shape for uniform heat distribution on the device surface. For the calculation of heat flux on the device with the KIER solar furnace, the optical modeling program Soltrace was used. At first, the KIER 45 kW(th) solar furnace and flat disk type device shape was simulated for understand of past experimental results. And then 3 cylinder shape device model and 1 conical shape device model was suggested and the heat flux intensity on the device was calculated. Finally, 5 models which is including flat disk type device shape, 3 cylinder shape, and 1 conical shape device models was calculated and compared. The results show that the concentrated sun rays from dish and heat flux intensity are has a directional characteristic concentrated to normal direction than perpendicular direction. The results will be applied to next solar demonstrations which are design of new solar reactor and new device shape. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.088

    Web of Science

    researchmap

  • Simulation of flux distributions on the foam absorber with solar reactor for thermo-chemical two-step water splitting H-2 production cycle by the 45 kW(th) KIER solar furnace 査読

    H. S. Cho, N. Gokon, T. Kodama, Y. H. Kang, J. K. Kim

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   790 - 801   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The flux distributions on the device in the solar reactor with the solar furnace were studied. This study aims to understand of characters of concentrated sun rays through KIER solar furnace and design of device shape for uniform heat distribution on the device surface. For the calculation of heat flux on the device with the KIER solar furnace, the optical modeling program Soltrace was used. At first, the KIER 45 kW(th) solar furnace and flat disk type device shape was simulated for understand of past experimental results. And then 3 cylinder shape device model and 1 conical shape device model was suggested and the heat flux intensity on the device was calculated. Finally, 5 models which is including flat disk type device shape, 3 cylinder shape, and 1 conical shape device models was calculated and compared. The results show that the concentrated sun rays from dish and heat flux intensity are has a directional characteristic concentrated to normal direction than perpendicular direction. The results will be applied to next solar demonstrations which are design of new solar reactor and new device shape. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.088

    Web of Science

    researchmap

  • Development of a receiver evaluation system using 30 kWth point concentration solar simulator 査読

    M. Nakakura, M. Ohtake, K. Matsubara, K. Yoshida, H. S. Cho, T. Kodama, N. Gokon

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   497 - 505   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The point-concentration receiver evaluation system was developed using the world class 30 kWth light source of 19 arc xenon lamps. The system comprises of a receiver unit, heat exchanger, blower, chiller and light source. Precise measurement of the thermal power absorbed by air was performed by the enthalpy rise of the coolant water and that of the exhausted air. The experimental test was performed using silicon carbide honeycomb in order to achieve a high air temperature of 560 degrees C. The efficiency of the receiver, based on the power of the aperture, was 40% to 80%. A three-dimensional simulation based on the dual cell approach was made to reveal detailed information of the flow and temperature fields. This successfully reproduced the thermal nonequilibrium between the solid and fluid parts of the receiver. The air exit temperature and efficiency of the numerical simulation were consistent with that determined experimentally. Air was suctioned from the broad space above the receiver top surface. The adopted simulation model with the free stream was confirmed to be essential for evaluating an open loop receiver. (C) 2015 Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.058

    Web of Science

    researchmap

  • Development of a receiver evaluation system using 30 kWth point concentration solar simulator 査読

    M. Nakakura, M. Ohtake, K. Matsubara, K. Yoshida, H. S. Cho, T. Kodama, N. Gokon

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   497 - 505   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The point-concentration receiver evaluation system was developed using the world class 30 kWth light source of 19 arc xenon lamps. The system comprises of a receiver unit, heat exchanger, blower, chiller and light source. Precise measurement of the thermal power absorbed by air was performed by the enthalpy rise of the coolant water and that of the exhausted air. The experimental test was performed using silicon carbide honeycomb in order to achieve a high air temperature of 560 degrees C. The efficiency of the receiver, based on the power of the aperture, was 40% to 80%. A three-dimensional simulation based on the dual cell approach was made to reveal detailed information of the flow and temperature fields. This successfully reproduced the thermal nonequilibrium between the solid and fluid parts of the receiver. The air exit temperature and efficiency of the numerical simulation were consistent with that determined experimentally. Air was suctioned from the broad space above the receiver top surface. The adopted simulation model with the free stream was confirmed to be essential for evaluating an open loop receiver. (C) 2015 Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.058

    Web of Science

    researchmap

  • Numerical modeling of a two-tower type fluidized receiver for high temperature solar concentration by a beam-down reflector system 査読

    K. Matsubara, H. Sakai, Y. Kazuma, A. Sakurai, T. Kodama, N. Gokon, H. S. Cho, K. Yoshida

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   487 - 496   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    This study describes the flow and thermal field of a two-tower fluidized receiver, aimed to be incorporated into a beam-down reflector system. An experimental visualization and numerical simulation were made to accumulate phenomenological knowledge, in order to complete the design of a demonstration model. Visualization of the cold particle bed with no irradiation revealed that global circulation occurs between the two towers by the aeration with different line velocities. The numerical simulation revealed that this global circulation enhances the transport of sensible heat from the irradiated layer in the high pressure tower to the low pressure tower. The global circulation in the two-tower fluidized receiver has the potential to be extended for use in a thermal receiver and direct storage system. Unexpectedly, local circulations occur on the high and low pressure sides, and are stronger than the global circulation. These local circulations contribute to the thermal mixing in each tower. The bottom distributor on the low pressure side can cause an uprising flow which leads to the local circulation. The design of the distributor is suggested to be elaborated based on these findings. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.057

    Web of Science

    researchmap

  • Cold model experiments on fluidization behavior of mixture of quartz sand and coal cokes for solar gasification 査読

    Nobuyuki Gokon, Tomoaki Tanabe, Tadaaki Shimizu, Tatsuya Kodama

    SolarPACES 2015, Cape Town, South Africa, October 13-16, 2015.   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Numerical modeling of a two-tower type fluidized receiver for high temperature solar concentration by a beam-down reflector system 査読

    K. Matsubara, H. Sakai, Y. Kazuma, A. Sakurai, T. Kodama, N. Gokon, H. S. Cho, K. Yoshida

    INTERNATIONAL CONFERENCE ON CONCENTRATING SOLAR POWER AND CHEMICAL ENERGY SYSTEMS, SOLARPACES 201469   487 - 496   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    This study describes the flow and thermal field of a two-tower fluidized receiver, aimed to be incorporated into a beam-down reflector system. An experimental visualization and numerical simulation were made to accumulate phenomenological knowledge, in order to complete the design of a demonstration model. Visualization of the cold particle bed with no irradiation revealed that global circulation occurs between the two towers by the aeration with different line velocities. The numerical simulation revealed that this global circulation enhances the transport of sensible heat from the irradiated layer in the high pressure tower to the low pressure tower. The global circulation in the two-tower fluidized receiver has the potential to be extended for use in a thermal receiver and direct storage system. Unexpectedly, local circulations occur on the high and low pressure sides, and are stronger than the global circulation. These local circulations contribute to the thermal mixing in each tower. The bottom distributor on the low pressure side can cause an uprising flow which leads to the local circulation. The design of the distributor is suggested to be elaborated based on these findings. (C) 2015 The Authors. Published by Elsevier Ltd.

    DOI: 10.1016/j.egypro.2015.03.057

    Web of Science

    researchmap

  • Cold testings of a windowed fluidized bed reactor using quartz sand for solar gasification of coke 査読

    N. Gokon, T. Tanabe, H. S. Cho, T. Hatamachi, T. Kodama

    ISES Solar World Congress 2015, Conference Proceedings   799 - 805   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:International Solar Energy Society  

    A windowed fluidized bed reactor prototype was studied and developed for solar thermochemical gasification of coal cokes with steam and CO2. The windowed fluidized bed reactor is assumed to be combined with a newly developed beam-down optics. Recently, quartz sand was employed as a chemically-inert bed material for the fluidized bed and worked as a thermal transfer/storage medium inside the reactor for coke gasification under direct light irradiation. In order to design a laboratory-scale prototype windowed fluidized-bed containing of quartz sand and coke particles, the reactor model of fluidized bed was made from a transparent acrylic resin to allow us to observe a fluidizing particle through the sidewall of the reactor body
    a branching tube is equipped with the sidewall of the reactor to continuously supply coal-coke particles from a screw feeder. In the present study, in order to evaluate fluidization performance of coal-cokes, the pressure loss between the inlet and outlet gases was examined, and descending coal-coke particles on the sidewall of the reactor was observed in the reactor model. The moving velocity and distance of descending particles from the top to bottom of fluidized bed were measured by the visual observation of the tracer particles on outside wall of reactor model.

    DOI: 10.18086/swc.2015.04.24

    Scopus

    researchmap

  • Redox and fluidization performances of Co3O4/CoO for solar Thermochemical energy storage 査読

    N. Gokon, S. Yokota, H. S. Cho, T. Hatamachi, T. Kodama

    ISES Solar World Congress 2015, Conference Proceedings   806 - 815   2015年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:International Solar Energy Society  

    Thermochemical energy storage using redox pair of Co3O4/CoO powders was studied for thermal energy storage (TES) using concentrated solar radiation as the energy source. Reversible chemical reactions (reduction - oxidation redox cycles) of oxides under air atmosphere are used to storage significant thermal energy via the enthalpies of the chemical reactions at high-temperature. A promising concept for solar TES is proposed using fluidized bed with Co3O4/CoO redox pair. In the present study, the effects of particles size of Co3O4/CoO powders on thermochemical storage performances are investigated in order to explore the potential of the material for fluidized-particle bed reactor. The Co3O4 powders with particle sizes of 100-200, 200-300, 300-500 and 500-700 μm were used to test redox performances by thermo-gravimetric analysis. A flowability (fluidization state) of Co3O4 powders in a fluidized bed reactor for thermochemical energy storage is also examined in this study. A basic relationship between pressure drop of inlet gas and gas flow rate was experimentally examined using bed materials with different particle sizes by a small-scale quartz reactor at ambient pressure and temperature.

    DOI: 10.18086/swc.2015.04.25

    Scopus

    researchmap

  • Steam gasification of coal cokes in an internally circulating fluidized bed of thermal storage material for solar thermochemical processes 査読

    Nobuyuki Gokon, Takuya Izawa, Takehiko Abe, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY39 ( 21 ) 11082 - 11093   2014年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A laboratory-scale prototype windowed internally circulating fluidized-bed reactor made of quartz sand and coal coke particles was investigated for steam gasification using concentrated Xe-light radiation as the energy source. The quartz sand was used as a chemically inert bed material for the fluidized bed, while the coal coke particles functioned as the reacting particles for the endothermic gasification reaction. The advantages of using quartz sand as the bed material for the directly irradiated gasification reactor are as follows: (1) The bed height is maintained at a constant level during the gasification. (2) The quartz sand functions as a thermal transfer/storage medium inside the reactor. The gasification performances such as the production rates of CO, H-2, and CO2; carbon conversion; and light-to-chemical energy conversion were evaluated for the fluidized-bed reactor with a thermal transfer/storage medium (quartz sand). The effects of using the bed material (quartz sand) on the gasification performance are described in this paper. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2014.05.124

    Web of Science

    researchmap

  • Steam reforming of methane using double-walled reformer tubes containing high-temperature thermal storage Na2CO3/MgO composites for solar fuel production 査読

    Nobuyuki Gokon, Shohei Nakamura, Tsuyoshi Hatamachi, Tatsuya Kodama

    ENERGY68   773 - 782   2014年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Double-walled reactor tubes containing thermal storage materials based on the molten carbonate salts-100 wt% Na2CO3 molten salt, 90 wt% Na2CO3/10 wt% MgO and 80 wt% Na2CO3/20 wt% MgO composite materials were studied for the performances of the reactor during the heat charging mode, while those of methane reforming with steam during heat discharging mode for solar steam reforming. The variations in the temperatures of the catalyst and storage material, methane conversion, duration of reforming for obtaining high levels of methane conversion (> 90%), higher heating value (HHV) power of reformed gas and efficiency of the reactor tubes were evaluated for the double-walled reactor tubes and a single-wall reactor tube without the thermal storage. The results for the heat charging mode indicated that the composite thermal storage could successfully store the heat transferred from the exterior wall of the reactor in comparison to the pure molten-salt. The double-walled reactor tubes with the 90 wt% Na2CO3/10 wt% MgO composite material was the most desirable for steam reforming of methane to realize large HHV amounts of reformed gas and higher efficiencies during heat-discharging mode. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.energy.2014.01.107

    Web of Science

    researchmap

  • Kinetics of thermal reduction step of thermochemical two-step water splitting using CeO2 particles: Master-plot method for analyzing non-isothermal experiments 査読

    T. Ishida, N. Gokon, T. Hatamachi, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1970 - 1979   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thermochemical two-step water splitting cycle by concentrated solar heat has been studied as an energy conversion of solar energy into hydrogen energy. The thermochemical two-step water splitting cycle using metal oxide redox pair was composed of thermal reduction (T-R) step of metal oxide at higher temperature to release oxygen and, subsequent water decomposition (W-D) step of the reduced metal oxide with steam at lower temperature to produce hydrogen. Recently, cerium oxide (CeO2) is concerned as a redox pair of the thermochemical cycle for highly reactivity and cyclicity at high temperature. In this study, we focused a kinetic analysis of thermochemical two-step water splitting using cerium oxide. Various theoretical reaction models for thermal reduction (T-R) step of CeO2 particles are examined, and the appropriate reaction model for experimental results of thermogravimetric analysis was found by Master plot method. Finally, the reaction rate equation of thermal reduction is estimated. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.209

    Web of Science

    researchmap

  • Solar flux distribution of new beam-down solar concentrating system at Miyazaki for solar thermochemical processes 査読

    Shunta Tokunaga, Naoya Watanabe, Kei Omori, Tatsuya Kodama, Nobuyuki Gokon, Shoji Koikari, KazuoYoshida, Yoshinori Nagase, Katsushige Nakamura

    International Symposium on Fusion Tech 2013 at Korea, Seoul, Korea, January 15-17, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Solar Hydrogen Production Via Thermochemical Two-Step Water Splitting Cycle Using CeO?/MPSZ Ceramic Foam device by KIER Solar Furnace 査読

    Takuya Myojin, Shintaro Kawakami, Hyun Seok Cho, Nobuyuki Gokon, Tatsuya Kodama, Yong Heack Kang, Sang Nam Lee, Khwan Kyo Chai, Hwan Ki Yoon, Hyun Jim Lee

    International Symposium on Fusion Tech 2013 at Korea, Seoul, Korea, January 15-17, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Development of Solar Fluidized Bed Reactor For Hydrogen Production Via Thermochemical Two‐Step Water Splitting 査読

    Naoya Watanabe, Shunta Tokunaga, Kei Omori, Tsuyoshi Hatamachi, Nobuyuki Gokon, Tatsuya Kodama

    Grand Renewable Energy 2014 International Conference and Exhibition together with international solar energy society asia pacific conference 2014 and the 2nd asia wave and tidal energy conference, Tokyo Big Sight, Tokyo, Japan, July 27-August 1, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical Gasification of Coal Cokes Using Fluidized Bed Reactor for Solar−Hybrid Fuel Production 査読

    Nobuyuki Gokon, Takehiko Abe, Takuya Izawa, Chiaki Kogure, Tatsuya Kodama

    Grand Renewable Energy 2014 International Conference and Exhibition together with international solar energy society asia pacific conference 2014 and the 2nd asia wave and tidal energy conference, Tokyo Big Sight, Tokyo, Japan, July 27-August 1, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • CPC performances with a novel 100-kW beam-down solar concentrating system at Miyazaki for demonstration of thermochemical water-splitting reactors 査読

    Tatsuya Kodama, Nobuyuki Gokon, Koji Matsubara, Kazuo Yoshida, Souji Koikari, Hiroshi Kaneko, Katsusige Nakamura

    SolarPACES 2014, Beijing, China, September 16-19, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • DEVELOPMENT OF METAL-DOPED CERIA AIMED AT LOWER TEMPERATURE OF THERMAL REDUCTION STEP OF THERMOCHEMICAL TWO-STEP WATER-SPLITTING CYCLE FOR SOLAR HYDROGEN PRODUCTION 査読

    Toshinori Suda, Nobuyuki Gokon, Tatsuya Kodama

    AFORE 2014, Yeosu, Korea, November 17-20, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • FLUIDIZED BED REACTOR FOR SOLAR THERMOCHEMICAL TWO-STEP WATER-SPLITTING CYCLE 査読

    Akane Takeuchi, Tetsuro Etori, Shinosuke Yokota, Sumie Ito, Nobuyuki Gokon, Tatsuya Kodama

    AFORE 2014, Yeosu, Korea, November 17-20, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • SOLAR THERMOCHEMICAL TWO-STEP WATER-SPLITTING USING CEO2 COATED FOAM DEVICE FOR HYDROGEN PRODUCTION 査読

    Satoshi Tsuchida, Hyun Seok Cho, Shintaro Kawakami, Takuya Myojin, Nobuyuki Gokon, Tatsuya Kodama

    AFORE 2014, Yeosu, Korea, November 17-20, 2014.   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical two-step water splitting cycle using Ni-ferrite and CeO2 coated ceramic foam devices by concentrated Xe-light radiation 査読

    S. Kawakami, T. Myojin, H. -S. Cho, T. Hatamachi, N. Gokon, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1980 - 1989   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Nickel ferrite (NiFe2O4) and pure cerium oxide (CeO2) supported on monoclinic zirconia (NiFe2O4/m-ZrO2) are proposed as promising redox materials for the production of hydrogen from water via a thermochemical two-step water splitting cycle. Ceramic foam devices coated with NiFe2O4/m-ZrO2 or pure CeO2 particles are prepared as a receiver/reactor operating a thermochemical water splitting cycle to produce hydrogen. The foam devices are examined in a directly irradiated receiver/reactor by a sun simulator on a laboratory scale. The purpose of this study is to examine the evolution of oxygen and hydrogen during the cyclization reaction different thermal-reduction (T-R) temperatures of 1450 and 1550 degrees C, and to compare the reproducible and stoichiometric oxygen/hydrogen production for both foam devices through a repeatable two-step reaction. In this study, a zirconia ceramic foam was used as a matrix for the reacting materials of NiFe2O4/m-ZrO2 or CeO2 particles. The zirconia ceramic foam has a diameter of 60 mm, a thickness of 15 mm, and a porosity of 10 cpi (cell number per linear inch). The loading amounts of reacting materials are 5 wt% for NiFe2O4/m-ZrO2 and 40 wt% for CeO2 particles. A concentrated Xe-beam is radiated to the foam device in a N-2 stream for the T-R step and in a N-2/steam gas mixture for the subsequent water-decomposition (W-D) step. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.210

    Web of Science

    researchmap

  • Thermochemical two-step water splitting cycle using Ni-ferrite and CeO2 coated ceramic foam devices by concentrated Xe-light radiation 査読

    S. Kawakami, T. Myojin, H. -S. Cho, T. Hatamachi, N. Gokon, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1980 - 1989   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Nickel ferrite (NiFe2O4) and pure cerium oxide (CeO2) supported on monoclinic zirconia (NiFe2O4/m-ZrO2) are proposed as promising redox materials for the production of hydrogen from water via a thermochemical two-step water splitting cycle. Ceramic foam devices coated with NiFe2O4/m-ZrO2 or pure CeO2 particles are prepared as a receiver/reactor operating a thermochemical water splitting cycle to produce hydrogen. The foam devices are examined in a directly irradiated receiver/reactor by a sun simulator on a laboratory scale. The purpose of this study is to examine the evolution of oxygen and hydrogen during the cyclization reaction different thermal-reduction (T-R) temperatures of 1450 and 1550 degrees C, and to compare the reproducible and stoichiometric oxygen/hydrogen production for both foam devices through a repeatable two-step reaction. In this study, a zirconia ceramic foam was used as a matrix for the reacting materials of NiFe2O4/m-ZrO2 or CeO2 particles. The zirconia ceramic foam has a diameter of 60 mm, a thickness of 15 mm, and a porosity of 10 cpi (cell number per linear inch). The loading amounts of reacting materials are 5 wt% for NiFe2O4/m-ZrO2 and 40 wt% for CeO2 particles. A concentrated Xe-beam is radiated to the foam device in a N-2 stream for the T-R step and in a N-2/steam gas mixture for the subsequent water-decomposition (W-D) step. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.210

    Web of Science

    researchmap

  • Flux measurement of a new beam-down solar concentrating system in Miyazaki for demonstration of thermochemical water splitting reactors 査読

    T. Kodama, N. Gokon, K. Matsubara, K. Yoshida, S. Koikari, Y. Nagase, K. Nakamura

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1990 - 1998   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    A two-step thermochemical water splitting cycle using nonstoichiometric cerium oxide is a promising solar thermochemical hydrogen production process. One of the present authors has developed new solar reactors using "internally circulating fluidized beds" with cerium oxide particles for the high-temperature cycle. These solar reactors need to be combined with a beam-down solar concentrating system. Niigata University, University of Miyazaki, and Mitaka Kohki Co. Ltd. recently started an R&D joint project to demonstrate the up-scaled fluidized bed reactors with solar. A new type of 100 kW(th) beam-down solar concentrating system was built in August, 2012 at the campus of University of Miyazaki. This paper describes the first results of solar flux measurements on the new Miyazaki beam-down system for demonstration of thermochemical water splitting reactors. The fluxes of concentrated solar radiation at the focus point were measured by moving an array of thirteen Gardon gauges. The solar power in an area of 130 x 130 cm in the focal spot was larger than 90 kWth during three hours of daytime radiation, exceeding 110 kW(th) around noon on October 12, 2012. A new CPC specific to this new beam-down system was designed and fabricated to concentrate the solar fluxes into a 44 cm diameter circle of the solar reactor aperture. The solar demonstration of the reactors will start at the Miyazaki beam-down system from October 2013. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.211

    Web of Science

    researchmap

  • Flux measurement of a new beam-down solar concentrating system in Miyazaki for demonstration of thermochemical water splitting reactors 査読

    T. Kodama, N. Gokon, K. Matsubara, K. Yoshida, S. Koikari, Y. Nagase, K. Nakamura

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1990 - 1998   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    A two-step thermochemical water splitting cycle using nonstoichiometric cerium oxide is a promising solar thermochemical hydrogen production process. One of the present authors has developed new solar reactors using "internally circulating fluidized beds" with cerium oxide particles for the high-temperature cycle. These solar reactors need to be combined with a beam-down solar concentrating system. Niigata University, University of Miyazaki, and Mitaka Kohki Co. Ltd. recently started an R&D joint project to demonstrate the up-scaled fluidized bed reactors with solar. A new type of 100 kW(th) beam-down solar concentrating system was built in August, 2012 at the campus of University of Miyazaki. This paper describes the first results of solar flux measurements on the new Miyazaki beam-down system for demonstration of thermochemical water splitting reactors. The fluxes of concentrated solar radiation at the focus point were measured by moving an array of thirteen Gardon gauges. The solar power in an area of 130 x 130 cm in the focal spot was larger than 90 kWth during three hours of daytime radiation, exceeding 110 kW(th) around noon on October 12, 2012. A new CPC specific to this new beam-down system was designed and fabricated to concentrate the solar fluxes into a 44 cm diameter circle of the solar reactor aperture. The solar demonstration of the reactors will start at the Miyazaki beam-down system from October 2013. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.211

    Web of Science

    researchmap

  • Solar demonstration of thermochemical two-step water splitting cycle using CeO2/MPSZ ceramic foam device by 45kW(th) KIER solar furnace 査読

    H. S. Cho, T. Myojin, S. Kawakami, N. Gokon, T. Kodama, Y. H. Kang, S. N. Lee, K. K. Chai, H. K. Yoon, H. J. Lee

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1922 - 1931   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The joint international project of Niigata University (Japan) - Korea Institute of Energy Research, KIER (Korea) on the "Solar demonstration of Water-Splitting Reactor using Ceramic Foam Device" aims to develop a novel-type of solar reactor with reactive cerium oxide foam devices for high-temperature two-step thermochemical water splitting cycle, and to demonstrate its performances on sun with a 45-kW(th) solar furnace. The reactive CeO2 foam device for the two-step water splitting is proposed and prepared by Niigata University, Japan, and involves coating inert zirconia foam with reactive CeO2. The project includes the development of reactive foam devices, the new design and the fabrication of solar reactor with the reactive foam devices, and finally the solar demonstration on the KIER's 45-kW(th) solar furnace in Korea. In this paper, highly-active CeO2 particles were used as a redox material for preparing CeO2 foam devices. A ceramic foam disk made of MgO partially-stabilized Zirconia (MPSZ) was used as a ceramic matrix that was coated with the CeO2 particles. Solar thermochemical two-step water splitting was demonstrated with solar furnace in Korea system using the prepared CeO2-coated MPSZ (CeO2/MPSZ) foam devices. The prepared CeO2/MPSZ foam device has a diameter of 15 and 20cm and thickness of 2.5 cm, the loading of CeO2 was set to approximately 20 wt%.
    Then, the temperatures of the foam device at a center position were 1400-1600 degrees C for the T-R step, and 900-1100 degrees C for the subsequent W-D step. Hydrogen was successfully produced from the CeO2-MPSZ foam by a solar thermochemical two-step water-splitting, and the rate of hydrogen production and CeO2 conversion using 15 cm CeO2/MPSZ foam device were 215.6 mL/min and 3.67%, at 1st cycle. We also performed continuous testing for 20 cm diameter of the CeO2-MPSZ device, the rate of hydrogen production and CeO2 conversion were 443 ml/min and 3.27%, 1st cycle. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.204

    Web of Science

    researchmap

  • Solar demonstration of thermochemical two-step water splitting cycle using CeO2/MPSZ ceramic foam device by 45kW(th) KIER solar furnace 査読

    H. S. Cho, T. Myojin, S. Kawakami, N. Gokon, T. Kodama, Y. H. Kang, S. N. Lee, K. K. Chai, H. K. Yoon, H. J. Lee

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1922 - 1931   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The joint international project of Niigata University (Japan) - Korea Institute of Energy Research, KIER (Korea) on the "Solar demonstration of Water-Splitting Reactor using Ceramic Foam Device" aims to develop a novel-type of solar reactor with reactive cerium oxide foam devices for high-temperature two-step thermochemical water splitting cycle, and to demonstrate its performances on sun with a 45-kW(th) solar furnace. The reactive CeO2 foam device for the two-step water splitting is proposed and prepared by Niigata University, Japan, and involves coating inert zirconia foam with reactive CeO2. The project includes the development of reactive foam devices, the new design and the fabrication of solar reactor with the reactive foam devices, and finally the solar demonstration on the KIER's 45-kW(th) solar furnace in Korea. In this paper, highly-active CeO2 particles were used as a redox material for preparing CeO2 foam devices. A ceramic foam disk made of MgO partially-stabilized Zirconia (MPSZ) was used as a ceramic matrix that was coated with the CeO2 particles. Solar thermochemical two-step water splitting was demonstrated with solar furnace in Korea system using the prepared CeO2-coated MPSZ (CeO2/MPSZ) foam devices. The prepared CeO2/MPSZ foam device has a diameter of 15 and 20cm and thickness of 2.5 cm, the loading of CeO2 was set to approximately 20 wt%.
    Then, the temperatures of the foam device at a center position were 1400-1600 degrees C for the T-R step, and 900-1100 degrees C for the subsequent W-D step. Hydrogen was successfully produced from the CeO2-MPSZ foam by a solar thermochemical two-step water-splitting, and the rate of hydrogen production and CeO2 conversion using 15 cm CeO2/MPSZ foam device were 215.6 mL/min and 3.67%, at 1st cycle. We also performed continuous testing for 20 cm diameter of the CeO2-MPSZ device, the rate of hydrogen production and CeO2 conversion were 443 ml/min and 3.27%, 1st cycle. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.204

    Web of Science

    researchmap

  • Solar demonstration of thermochemical two-step water splitting cycle using CeO2/MPSZ ceramic foam device by 45kW(th) KIER solar furnace 査読

    H. S. Cho, T. Myojin, S. Kawakami, N. Gokon, T. Kodama, Y. H. Kang, S. N. Lee, K. K. Chai, H. K. Yoon, H. J. Lee

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1922 - 1931   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    The joint international project of Niigata University (Japan) - Korea Institute of Energy Research, KIER (Korea) on the "Solar demonstration of Water-Splitting Reactor using Ceramic Foam Device" aims to develop a novel-type of solar reactor with reactive cerium oxide foam devices for high-temperature two-step thermochemical water splitting cycle, and to demonstrate its performances on sun with a 45-kW(th) solar furnace. The reactive CeO2 foam device for the two-step water splitting is proposed and prepared by Niigata University, Japan, and involves coating inert zirconia foam with reactive CeO2. The project includes the development of reactive foam devices, the new design and the fabrication of solar reactor with the reactive foam devices, and finally the solar demonstration on the KIER's 45-kW(th) solar furnace in Korea. In this paper, highly-active CeO2 particles were used as a redox material for preparing CeO2 foam devices. A ceramic foam disk made of MgO partially-stabilized Zirconia (MPSZ) was used as a ceramic matrix that was coated with the CeO2 particles. Solar thermochemical two-step water splitting was demonstrated with solar furnace in Korea system using the prepared CeO2-coated MPSZ (CeO2/MPSZ) foam devices. The prepared CeO2/MPSZ foam device has a diameter of 15 and 20cm and thickness of 2.5 cm, the loading of CeO2 was set to approximately 20 wt%.
    Then, the temperatures of the foam device at a center position were 1400-1600 degrees C for the T-R step, and 900-1100 degrees C for the subsequent W-D step. Hydrogen was successfully produced from the CeO2-MPSZ foam by a solar thermochemical two-step water-splitting, and the rate of hydrogen production and CeO2 conversion using 15 cm CeO2/MPSZ foam device were 215.6 mL/min and 3.67%, at 1st cycle. We also performed continuous testing for 20 cm diameter of the CeO2-MPSZ device, the rate of hydrogen production and CeO2 conversion were 443 ml/min and 3.27%, 1st cycle. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.204

    Web of Science

    researchmap

  • High-temperature fluidized receiver for concentrated solar radiation by a beam-down reflector system 査読

    K. Matsubara, Y. Kazuma, A. Sakurai, S. Suzuki, L. Soon-Jae, T. Kodama, N. Gokon, C. Hyun Seok, K. Yoshida

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   447 - 456   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    This study proposes a novel fluidized receiver for absorbing concentrated solar light at high temperatures. Previously, a tubular receiver and a volumetric receiver were developed to make high-temperature air for a solar gas turbine system. The aim was to combine these elements with a tower reflector; however, it was challenging to install these heavy receivers on the top of the tower. Currently, a fluidized receiver prototype is tested by a 3 kWh solar simulator in preparation for a field test at the Miyazaki beam-down reflector system. The fluid dynamics of the prototype receiver is numerically investigated. The currently treated receiver is an inner-circulating fluidized bed spouted by concentric gas streams with high and low velocities in the center and outer annulus, respectively. The draft tube is submerged in the particles to organize particle circulation. Concentrated light irradiates the particles through a quartz window at the top of the receiver container. Such a fluidized bed was first adopted by Kodama et al. for thermochemical reactions; however, it is currently pursued for its potential as a high-temperature receiver aimed at concentrated solar power generation. Experiments of the prototype receiver (inner diameter = 45 mm) demonstrated that the inner particles are heated to a temperature greater than 900 degrees C and that an increase of the central gas velocity removes the excess temperature near the particle bed surface. A numerical computation suggests that the large-scale circulation of particles leads to the activation of thermal mixing. The currently proposed receiver is thus expected to attenuate re-radiation losses likely to occur in a conventional volumetric porous receiver. The scale-up of the receiver is being considered by the numerical computation for a field test in the Miyazaki 100 kWh beam-down reflector system. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

    DOI: 10.1016/j.egypro.2014.03.048

    Web of Science

    researchmap

  • High-temperature fluidized receiver for concentrated solar radiation by a beam-down reflector system 査読

    K. Matsubara, Y. Kazuma, A. Sakurai, S. Suzuki, L. Soon-Jae, T. Kodama, N. Gokon, C. Hyun Seok, K. Yoshida

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   447 - 456   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    This study proposes a novel fluidized receiver for absorbing concentrated solar light at high temperatures. Previously, a tubular receiver and a volumetric receiver were developed to make high-temperature air for a solar gas turbine system. The aim was to combine these elements with a tower reflector; however, it was challenging to install these heavy receivers on the top of the tower. Currently, a fluidized receiver prototype is tested by a 3 kWh solar simulator in preparation for a field test at the Miyazaki beam-down reflector system. The fluid dynamics of the prototype receiver is numerically investigated. The currently treated receiver is an inner-circulating fluidized bed spouted by concentric gas streams with high and low velocities in the center and outer annulus, respectively. The draft tube is submerged in the particles to organize particle circulation. Concentrated light irradiates the particles through a quartz window at the top of the receiver container. Such a fluidized bed was first adopted by Kodama et al. for thermochemical reactions; however, it is currently pursued for its potential as a high-temperature receiver aimed at concentrated solar power generation. Experiments of the prototype receiver (inner diameter = 45 mm) demonstrated that the inner particles are heated to a temperature greater than 900 degrees C and that an increase of the central gas velocity removes the excess temperature near the particle bed surface. A numerical computation suggests that the large-scale circulation of particles leads to the activation of thermal mixing. The currently proposed receiver is thus expected to attenuate re-radiation losses likely to occur in a conventional volumetric porous receiver. The scale-up of the receiver is being considered by the numerical computation for a field test in the Miyazaki 100 kWh beam-down reflector system. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

    DOI: 10.1016/j.egypro.2014.03.048

    Web of Science

    researchmap

  • Carbonate molten-salt absorber/reformer: heating and steam reforming performance of reactor tubes 査読

    N. Gokon, S. Nakamura, K. Matsubara, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1940 - 1949   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Steam reforming of methane is a candidate process for converting concentrated high-temperature solar heat to chemical fuels because it is a high-temperature, highly endothermic process. We developed a tubular reformer system using novel double-walled reactor tubes with molten-salt thermal storage for solar reforming to produce hydrogen or synthetic gas (CO + H-2) from a gas mixture of methane and steam using concentrated solar radiation as an energy source. The high heat capacity and large latent heat (heat of solidification) of the molten salt circumvents rapid temperature changes in the reactor tubes at high temperatures under fluctuating insolation. In this paper, we focused on under intermittent heating-cooling mode, the steam reforming performance of double-walled reactor tubes with Na2CO3/MgO composite thermal storage in comparison to pure Na2CO3 thermal storage. A heating mode using an electric furnace simulates reactor startup in the morning and reheating of the reactor by concentrated solar radiation after brief periods of cloud passage. The intermittent heating-cooling mode simulates fluctuating incident solar radiation during cyclic short-term cloud passage. The temperature variations of the catalyst and storage material, methane conversion, and higher heating value power of the reformed gas were examined for the double-walled reactor tubes and a single-wall (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.206

    Web of Science

    researchmap

  • Carbonate molten-salt absorber/reformer: heating and steam reforming performance of reactor tubes 査読

    N. Gokon, S. Nakamura, K. Matsubara, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1940 - 1949   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Steam reforming of methane is a candidate process for converting concentrated high-temperature solar heat to chemical fuels because it is a high-temperature, highly endothermic process. We developed a tubular reformer system using novel double-walled reactor tubes with molten-salt thermal storage for solar reforming to produce hydrogen or synthetic gas (CO + H-2) from a gas mixture of methane and steam using concentrated solar radiation as an energy source. The high heat capacity and large latent heat (heat of solidification) of the molten salt circumvents rapid temperature changes in the reactor tubes at high temperatures under fluctuating insolation. In this paper, we focused on under intermittent heating-cooling mode, the steam reforming performance of double-walled reactor tubes with Na2CO3/MgO composite thermal storage in comparison to pure Na2CO3 thermal storage. A heating mode using an electric furnace simulates reactor startup in the morning and reheating of the reactor by concentrated solar radiation after brief periods of cloud passage. The intermittent heating-cooling mode simulates fluctuating incident solar radiation during cyclic short-term cloud passage. The temperature variations of the catalyst and storage material, methane conversion, and higher heating value power of the reformed gas were examined for the double-walled reactor tubes and a single-wall (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.206

    Web of Science

    researchmap

  • Kinetics of thermal reduction step of thermochemical two-step water splitting using CeO2 particles: Master-plot method for analyzing non-isothermal experiments 査読

    T. Ishida, N. Gokon, T. Hatamachi, T. Kodama

    PROCEEDINGS OF THE SOLARPACES 2013 INTERNATIONAL CONFERENCE49   1970 - 1979   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE BV  

    Thermochemical two-step water splitting cycle by concentrated solar heat has been studied as an energy conversion of solar energy into hydrogen energy. The thermochemical two-step water splitting cycle using metal oxide redox pair was composed of thermal reduction (T-R) step of metal oxide at higher temperature to release oxygen and, subsequent water decomposition (W-D) step of the reduced metal oxide with steam at lower temperature to produce hydrogen. Recently, cerium oxide (CeO2) is concerned as a redox pair of the thermochemical cycle for highly reactivity and cyclicity at high temperature. In this study, we focused a kinetic analysis of thermochemical two-step water splitting using cerium oxide. Various theoretical reaction models for thermal reduction (T-R) step of CeO2 particles are examined, and the appropriate reaction model for experimental results of thermogravimetric analysis was found by Master plot method. Finally, the reaction rate equation of thermal reduction is estimated. (C) 2013 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

    DOI: 10.1016/j.egypro.2014.03.209

    Web of Science

    researchmap

  • Comparative study of activity of cerium oxide at thermal reduction temperatures of 1300-1550 degrees C for solar thermochemical two-step water-splitting cycle 査読

    Nobuyuki Gokon, Sachi Sagawa, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY38 ( 34 ) 14402 - 14414   2013年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Thermochemical two-step water-splitting using CeO2 (cerium oxide) particles was studied to examine oxygen and hydrogen productivity and repeatability at thermal reduction (T-R) temperatures of 1300-1550 degrees C and water decomposition (W-D) temperatures of 400-1000 degrees C for the production of hydrogen from water using concentrated solar radiation as the energy source. The temperature dependency of oxygen and hydrogen productivity and the cyclic repeatability of CeO2 are reported in this paper. The characteristic features of CeO2 particles in the thermochemical two-step water-splitting cycle are compared with the well-known highly active reactive mediums of zirconia-supported Ni-ferrites (NiFe2O4/m-ZrO2 and NiFe2O4/c-YSZ) and unsupported NiFe2O4. Copyright (C) 2013, Hydrogen En ergy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2013.08.108

    Web of Science

    researchmap

  • Oxygen-releasing step of nickel ferrite based on Rietveld analysis for thermochemical two-step water-splitting 査読

    Nobuyuki Gokon, Ken Kondo, Tsuyoshi Hatamachi, Mineo Sato, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY38 ( 12 ) 4935 - 4944   2013年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    We investigated the thermal reduction (T-R) of NiFe2O4, either supported by m-ZrO2 or unsupported, as the oxygen-releasing step of a solar thermochemical water splitting cycle based on a ferrite/wustite redox system, by performing the Rietveld analysis using powder X-ray diffraction. The solid materials obtained after the T-R step at 1300-1400 degrees C were subjected to Rietveld analysis. The amounts and chemical compositions of the wustite phase produced by the T-R step and the remaining ferrite phase were identified quantitatively. Chemical reaction formulas for the different T-R temperatures were determined from the results. Consistency for the chemical reactions of the thermal reduction was discussed and evaluated comparing the O2 amounts predicted by the chemical reaction formulas and measured experimentally by mass spectrometry. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2013.02.014

    Web of Science

    researchmap

  • CO2 gasification of coal cokes using internally circulating fluidized bed reactor by concentrated Xe-light irradiation for solar gasification 査読

    Nobuyuki Gokon, Ryuta Ono, Tsuyoshi Hatamachi, Li Liuyun, Hee-Joon Kim, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY37 ( 17 ) 12128 - 12137   2012年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    For the solar thermochemical gasification of coal coke to produce CO + H-2 synthetic gas using concentrated solar radiation, a windowed reactor prototype is tested and demonstrated at laboratory scale for CO2 gasification of coal coke using concentrated Xe light from a 3-kW(th) sun simulator. The reactor was designed to be combined with a solar reflective tower or beam-down optics. The results for gasification performance (CO production rate, carbon conversion, and light-to-chemical efficiency) are shown for various CO2 flow rates and ratios. A kinetics analysis based on homogeneous and shrinking core models and the temperature distributions of the prototype particle bed are compared with those for a conventional fluidized bed reactor tested under the same Xe light irradiation and CO2 flow-rate conditions. The effectiveness and potential impacts of internally circulating fluidized bed reactors for enhancing gasification performance levels and inducing consistently higher bed temperatures are discussed in this paper. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2012.05.133

    Web of Science

    researchmap

  • Heat Transfer characteristics of internally circulating fluidized bed solar reactor 査読

    Atsushi Sakurai, So Sakuma, Gokon Nobuyuki, Koji Matsubara, Kodama Tatsuya

    SolarPACES 2012, Marrakech, Morocco, September 11-14, 2012.   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • The basic study about reforming biomass-tar using catalysts for solar energy biomass gasfication 査読

    Liuyun Li, Gokon Nobuyuki, Kodama Tatsuya, Tadaaki Shimizu, Hee Joon Kim

    SolarPACES 2012, Marrakech, Morocco, September 11-14, 2012.   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • COMPARISON STUDIES OF REACTIVITY ON NICKEL-FERRITE AND CERIUM-OXIDE REDOX MATERIALS FOR TWO-STEP THERMOCHEMICAL WATER SPLITTING BELOW 1400 degrees C 査読

    Tatsuya Kodama, Nobuki Imaizumi, Nobuyuki Gokon, Tsuyoshi Hatamachi, Daiki Aoyagi, Ken Kondo

    PROCEEDINGS OF THE ASME 5TH INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY 2011, PTS A-C   1617 - 1623   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    A two-step thermochemical water splitting cycle using a redox system of non-volatile metal oxide is one of the promising processes for converting concentrated solar high-temperature heat into clean hydrogen in sun-belt regions. In the 1st step of the cycle or the thermal reduction step, metal oxide is thermally reduced to release oxygen molecules in an inert gas atmosphere at a higher temperature above 1400 degrees C. In the second step or the water-decomposition step at a lower temperature, the thermally-reduced metal oxide reacts with steam to produce hydrogen. As the reactive redox metal oxide materials to be capable of working below 1400 degrees C, nickel-doped iron oxides or Ni-ferrites supported on zirconia, and non-stoichiometric cerium oxides are the promising working materials. In the present work, a series of the nickel-ferrite redox materials of monoclinic-zirconia-supported, cubicYSZ(yttrium-stabilized zirconia)-supported, and non-supported Ni-ferries and non-stoichiometric cerium oxide were compared on reactivity for two-step thermochemical water splitting cycle. The monoclinic-zirconia-supported Ni-ferrite produced the most quantity of hydrogen in the repeated cycles when the thermal reduction step was performed for 30 mm at 1400 degrees C and the water decomposition step for 60 min at 1000 degrees C.

    Web of Science

    researchmap

  • Steam gasification of coal cokes using fluidized bed reactor for solar thermochemical conversion 査読

    Nobuyuki Gokon, Ryuta Ono, Kei Omori, Tsuyoshi Hatamachi, Li Liuyun, Hee Joon Kim, Tatsuya Kodama

    SolarPACES 2012, Marrakech, Morocco, September 11-14, 2012.   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Two-step switching test of water-splitting process using internally-circulating fluidized bed reactor 査読

    Kei Omori, Nobuyuki Gokon, Tsuyoshi Hatamachi, Tatsuya Kodama

    SolarPACES 2012, Marrakech, Morocco, September 11-14, 2012.   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Solar Demonstration Project on a Novel Fluidized Bed Reactor for “Single-processed” Thermochemical Water-splitting Cycle with a Beam-Down Concentrating System at Miyazaki 査読

    Tatsuya Kodama, Nobuyuki Gokon, Kei Omori, Yoshinori Nagase, Katsushige Nakamura

    SolarPACES 2012, Marrakech, Morocco, September 11-14, 2012.   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • A Study of Themal Design for the Development of High-efficiency Fluidized Bed Solar Reactor

    So Sakuma, Atsushi Sakurai, Kyohei Ogino, Seung-Jae Lee, Koji Matsubara, Nobuyuki Gokon, Tatsuya Kodama

    Proceedings of the 8th international conference on flow dynamics   562 - 563   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Numerical Visualization of Radiative Heat Flux of Dispersed Particles Irradiated by Solar Light

    S. Sakuma, A. Sakurai, K. Matsubara, N. Gokon, T. Kodama

    Proceedings of the 11th Asian Symposium on Visualization (ASV11)   ASV11-po-33   2011年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical two-step water splitting by internally circulating fluidized bed of NiFe2O4 particles: Successive reaction of thermal-reduction and water-decomposition steps 査読

    Nobuyuki Gokon, Tetsuro Mataga, Nobuyuki Kondo, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY36 ( 8 ) 4757 - 4767   2011年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Thermochemical two-step water splitting using a redox system of iron-based oxides or ferrites is a promising process for producing hydrogen without CO2 emission by the use of high-temperature solar heat as an energy source and water as a chemical source. In this study, thermochemical hydrogen production by two-step water splitting was demonstrated on a laboratory scale by using a single reactor of an internally circulating fluidized bed. This involved the successive reactions of thermal-reduction (T-R) and water-decomposition (W-D). The internally circulating fluidized bed was exposed to simulated solar light from Xe lamps with an input power of 2.4-2.6 kW(th) for the T-R step and 1.6-1.7 kW(th) for the subsequent W-D step. The feed gas was switched from an inert gas (N-2) in the T-R step to a gas mixture of N-2 and steam in the W-D step. NiFe2O4/m-ZrO2 and unsupported NiFe2O4 particles were tested as a fluidized bed of reacting particles, and the production rate and productivity of hydrogen and the reactivity of reacting particles were examined. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2011.01.076

    Web of Science

    researchmap

  • Ferrite/zirconia-coated foam device prepared by spin coating for solar demonstration of thermochemical water-splitting 査読

    Nobuyuki Gokon, Tatsuya Kodama, Nobuki Imaizumi, Jun Umeda, Taebeom Seo

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY36 ( 3 ) 2014 - 2028   2011年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A Ferrite/zirconia foam device in which reticulated ceramic foam was coated with zirconia-supported Fe(3)O(4) or NiFe(2)O(4) as a reactive material was prepared by a spin-coating method. The spin-coating method can shorten the preparation period and reduce the coating process as compared to the previous wash-coating method. The foam devices were examined for hydrogen productivity and cyclic reactivity in thermochemical two-step water-splitting. The reactivity of these foam devices were studied for the thermal reduction of ferrite on a laboratory scale using a sun simulator to simulate concentrated solar radiation, while the thermally reduced foam devices were reacted with steam in another quartz reactor under homogeneous heating in an infrared furnace. The most reactive foam device, NiFe(2)O(4)/m-ZrO(2)/MPSZ, was tested for successive two-step water-splitting in a windowed single reactor using solar-simulated Xe-beam irradiation with a power input of 0.4-0.7 kW(th). The production of hydrogen continued successfully in the 20 cycles that were demonstrated using the NiFe(2)O(4)/m-ZrO(2)/MPSZ foam device. The NiFe(2)O(4)/m-ZrO(2)/MPSZ foam device produced hydrogen at a rate of 1.1-4.6 cm(3) per gram of device through 20 cycles and reached a maximum ferrite conversion of 60%. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2010.11.034

    Web of Science

    researchmap

  • Kinetics of methane reforming over Ru/gamma-Al2O3-catalyzed metallic foam at 650-900 degrees C for solar receiver-absorbers 査読

    Nobuyuki Gokon, Yuhei Yamawaki, Daisuke Nakazawa, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY36 ( 1 ) 203 - 215   2011年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The kinetics of methane reforming over Ru/gamma-Al2O3-catalyzed high porosity Ni-Cr-Al foam were examined at temperatures of 650-900 degrees C in a quartz tubular reactor using an electric furnace. The kinetic data were analyzed by four different types of kinetic models based on the basic, Eley-Rideal, Langmuir-Hinshelwood, and stepwise mechanisms. Validation of the kinetic models was carried out by calculating the determination coefficient r(2) between the predicted and the experimental results for each model. The absolute average deviation percentage (AAD%) between the predicted and the experimental results was also estimated for each model. The kinetic model based on the reversible stepwise mechanism provided the best prediction of the experimental reforming rates with an AAD value of 6% in the range 650-850 degrees C. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2010.09.042

    Web of Science

    researchmap

  • Water-Splitting Foam Device Reactor for Solar Thermochemical Hydrogen Production 査読

    Naoki Sato, Nobuki Imaizumi, Masanori Sugisaki, Tsuyoshi Hatamachi, Seo Taebeom, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2011 at Dalian, Dalian, China, December 15-17, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • HIGH-TEMPERATURE SOLAR THERMOCHEMICAL HYDROGEN PRODUCTION 査読

    Tatsuya Kodama, Tetsuro Mataga, Kei Oomori, Tsuyoshi Hatamachi, Nobuyuki Gokon

    International Symposium on Fusion Tech 2011 at Dalian, Dalian, China, December 15-17, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • 3kWth Internally circulating fluidized bed reactor for solar gasification of coal cokes 査読

    Nobuyuki Gokon, Ryuta Ono, Tsuyoshi Hatamachi, Li Liuyun, Hee Joon Kim, Atsushi Sakurai, Koji Matsubara, Tatsuya Kodama

    SolarPACES 2011, Granada, Spain, 20-23 September, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Continuous hydrogen production by an internally-curcurating fluidized particle bed reactor for thermochemical water splitting 査読

    Tatsuya Kodama, Tetsuro Mataga, Nobuki Imaizumi, Tsuyoshi Hatamachi, Nobuyuki Gokon

    SolarPACES 2011, Granada, Spain, 20-23 September, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Activity test of a ferrite foam device reactor for solar thermochemical two-step water-splitting 査読

    Nobuki Imaizumi, Naoki Sato, Tsuyoshi Hatamachi, Taebeom Seo, Nobuyuki Gokon, Tatsuya Kodama

    SolarPACES 2011, Granada, Spain, 20-23 September, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • FUNDAMENTAL STUDY OF RADIATIVE TRANSFER ANALYSIS OF INTERNALLY CIRCULATING FLUIDIZED BED SOLAR REACTOR 査読

    Atsushi Sakurai, So Sakuma, Nobuyuki Gokon, Koji Matsubara, Tatsuya Kodama

    SolarPACES 2011, Granada, Spain, 20-23 September, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Solar Thermochemical Two Step Water-Splitting by Beam Down Solar Concentrating System 査読

    Kei Omori, Tetsuro Mataga, Megumi Saito, Tsuyoshi Hatamachi, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2011 at Dalian, Dalian, China, December 15-17, 2011.   2011年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Coal Coke Gasification in a Windowed Solar Chemical Reactor for Beam-Down Optics 査読

    Tatsuya Kodama, Nobuyuki Gokon, Shu-ich Enomoto, Shouta Itoh, Tsuyoshi Hatamachi

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME132 ( 4 ) 041004-6 - 041004-6   2010年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME-AMER SOC MECHANICAL ENG  

    Solar thermochemical processes, such as solar gasification of coal, require the development of a high temperature solar reactor operating at temperatures above 1000 degrees C. Direct solar energy absorption by reacting coal particles provides efficient heat transfer directly to the reaction site. In this work, a windowed reactor prototype designed for the beam-down optics was constructed at a laboratory scale and demonstrated for CO(2) gasification of coal coke using concentrated visible light from a sun-simulator as the source of energy. Peak conversion of light energy to chemical fuel ( CO) of 14% was obtained by irradiating a fluidized bed of 500-710 mu m coal coke size fraction with a power input of about 1 kW and a CO(2) flow-rate of 6.5 dm(3) min(-1) at normal conditions. [DOI: 10.1115/1.4002081]

    DOI: 10.1115/1.4002081

    Web of Science

    researchmap

  • Comparative study of the activity of nickel ferrites for solar hydrogen production by two-step thermochemical cycles 査読

    Fernando Fresno, Tomoaki Yoshida, Nobuyuki Gokon, Rocio Fernandez-Saavedra, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY35 ( 16 ) 8503 - 8510   2010年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    In this work, we compare the activity of unsupported and monoclinic zirconia supported nickel ferrites, calcined at two different temperatures, for solar hydrogen production by two-step water-splitting thermochemical cycles at low thermal reduction temperature. Commercial nickel ferrite, both as-received and calcined in the laboratory, as well as laboratory made supported NiFe(2)O(4), are employed for this purpose. The samples leading to higher hydrogen yields, averaged over three cycles, are those calcined at 700 degrees C in each group (supported and unsupported) of materials. The comparison of the two groups shows that higher chemical yields are obtained with the supported ferrites due to better utilisation of the active material. Therefore, the highest activity is obtained with ZrO(2)-supported NiFe(2)O(4) calcined at 700 degrees C. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2010.05.032

    Web of Science

    researchmap

  • Ni/MgO-Al2O3 and Ni-Mg-O catalyzed SiC foam absorbers for high temperature solar reforming of methane 査読

    Nobuyuki Gokon, Yuhei Yamawaki, Daisuke Nakazawa, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY35 ( 14 ) 7441 - 7453   2010年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Ni catalyst supported on MgO-Al2O3 (Ni/MgO-Al2O3) prepared from hydrotalcite, and Ni-Mg-O catalyst are studied in regard to their activity in the CO2 reforming of methane at high temperatures in order to develop a catalytically activated foam receiver absorber for use in solar reforming. First, the activity of their powder catalysts is examined. Ni/MgO-Al2O3 powder catalyst exhibits a remarkable degree of high activity and thermal stability as compared with Ni-Mg-O powder catalyst. Secondly, a new type of catalytically activated ceramic foam absorber - Ni/MgO-Al2O3/SiC - and Ni-Mg-O catalyzed SiC foam absorber are prepared and their activity is evaluated using a laboratory-scale receiver reactor with a transparent quartz window and a sun-simulator. The present Ni-based catalytic absorbers are more cost effective than conventional Rh/gamma-Al2O3 catalyzed alumina and SiC foam absorbers and the alternative Ru/gamma-Al2O3 catalyzed SiC foam absorbers. Ni/MgO-Al2O3 catalyzed SiC foam absorber, in particular, exhibits superior reforming performance that provides results comparable to that of Rh/gamma-Al2O3 catalyzed alumina foam absorber under a high flux condition or at high temperatures above 1000 degrees C. Ni/MgO-Al2O3 catalyzed SiC foam absorber will be desirable for use in solar receiver reactor systems to convert concentrated high solar fluxes to chemical fuels via endothermic natural-gas reforming at high temperatures. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2010.04.040

    Web of Science

    researchmap

  • Internally Circulating Fluidized Bed Reactor Using m-ZrO2 Supported NiFe2O4 Particles for Thermochemical Two-Step Water Splitting 査読

    Nobuyuki Gokon, Hiroki Yamamoto, Nobuyuki Kondo, Tatsuya Kodama

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME132 ( 2 ) 021102-1 - 021102-10   2010年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME  

    A windowed internally circulating fluidized bed reactor was tested using m-ZrO2-supported NiFe2O4 (NiFe2O4/m-ZrO2) particles as redox material for thermochemical two-step water splitting to produce hydrogen from water. The internally circulating fluidized bed of NiFe2O4/m-ZrO2 particles is directly heated by solar-simulated Xe light irradiation through a transparent quartz window mounted on top of the reactor. A sun simulator with three Xe lamps at laboratory scale has been newly installed in our laboratory for testing the fluidized bed reactor. The input power of incident Xe light can be scaled up to 2.6 kW(th). Temperature distributions within the fluidized bed are measured under concentrated Xe light irradiation with an input power of 2.6 kW(th). Hydrogen productivity and reactivity for the fluidized bed of NiFe2O4/m-ZrO2 particles are examined using two different reactors under the N-2 flow rate and flow ratio, which yield a higher bed temperature. The feasibility of successive two-step water splitting using the fluidized bed reactor is examined by switching from N-2 gas flow in the thermal reduction step to a steam/N-2 gas mixture in the water decomposition step. It is confirmed that hydrogen production takes place in the single fluidized bed reactor by successive two-step water splitting. [DOI: 10.1115/1.4001154]

    DOI: 10.1115/1.4001154

    Web of Science

    researchmap

  • Two-Step Thermochemical Cycles for High-Temperature Solar Hydrogen Production 査読

    Tatsuya Kodama, Nobuyuki Gokon

    Advances in Science and Technology72   119 - 128   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • MOLTEN-SALT TUBULAR ABSORBER/REFORMER (MoSTAR) PROJECT: REFORMING PERFORMANCE OF REACTOR TUBES DURING INTERMITTENT HEATING 査読

    Nobuyuki Gokon, Tatsuya Kodama, Shingo Yamashita, Tsuyoshi Hatamachi, Taebeom Seo

    ES2010: PROCEEDINGS OF ASME 4TH INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY, VOL 2   105 - 113   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    Reforming performances for the double-walled reactor tubes with Na2CO3/MgO composite thermal storage was examined by an intermittent heating The intermittent heating of the reactor tubes is composed of the heat-discharge (or cooling) mode and the subsequent heating mode. The heat-discharging mode simulates a fluctuating Insolation for cloud passages The heating mode simulates a heating of reactor due to concentrated solar radiation by using an electric furnace. The internal tube of the reactor was packed with the 2wt%Ru/Al2O3 catalyst balls while the thermal storage materials were filled in the annular region of the reactor tubes The reactor was heated up to 920 degrees C in the cylindrical electric furnace and the CH4/CO2 mixture was fed into the internal catalyst tube at gas hourly space velocity (GHSV) of 12500 h(-1).
    Through the cooling mode and the subsequent heating mode, temperature variations of reactor tubes, catalyst and composite material, H-2/CO ratio variations of effluent gas from the reactor, higher heating value (HHV) power of reformed gas were respectively examined for the double-walled reactor tubes and a single-wall reactor tube without the thermal storage.

    DOI: 10.1115/ES2010-90114

    Web of Science

    researchmap

  • Molten-salt tubular absorber/reformer (MoSTAR) project: NaCl/MgO composite thermal storage for double-walled reactor tubes 査読

    Nobuyuki Gokon, Shingo Yamashita, Shogo Takahashi, Tatsuya Kodama, Taebeom Seo

    SolarPACES2010, Perpinan, France, September 21-25 2010.   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • 5kWth-solar demonstration of a ferrite foam device reactor for thermochemical two-step water-splitting 査読

    Tatsuya Kodama, Taebeom Seo, Nobuyuki Gokon, Ju Han Lee, Sang Joon Oh, Koichi Sakai, Nobuki Imaizumi

    SolarPACES2010, Perpinan, France, September 21-25 2010.   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project: The Thermal Storage Media of Na2CO3-MgO Composite Materials 査読

    Tatsuya Kodama, Nobuyuki Gokon, Shin-ichi Inuta, Shingo Yamashita, Taebeom Seo

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME131 ( 4 ) 041013-1 - 041013-8   2009年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME  

    The molten-salt tubular absorber/reformer (MoSTAR) project aims to develop a novel type of "double-walled" tubular absorber/reformer with molten-salt thermal storage at high temperature for use in solar natural-gas reforming and solar air receiver, and to demonstrate its performances on the sun with a 5 kW(t) dish-type solar concentrator. The new concept of double-walled reactor tubes is proposed for use in a solar reformer by Niigata University, Japan, and involves packing a molten/ceramic composite material in the annular region between the internal catalyst tube and the exterior solar absorber wall. This solar tubular absorber concept may be also applied to solar air receiver for solar thermal power generation. The MoSTAR project includes the development of molten-salt thermal storage media, the new design and the fabrication of absorber/reformer with the double-walled absorber tubes, and finally the solar demonstration on the 5 kW(t) dish concentrator of Inha University in Korea. In this paper, thermal storage media of the series of Na2CO3-MgO composite materials were tested in a double-walled reformer tube with a thermal storage capacity of about 0.3 kWh. The chemical reaction performances for dry reforming of methane during cooling or heat-discharge mode of the reactor tube were investigated using an electric furnace. The experimental results obtained under feed gas mixture of CH4/CO2=1:3 at a residence time of 0.3 s and at 1 atm showed that the single reactor tube with 90 wt % Na2CO3/10 wt % MgO composite material successfully maintained a high methane conversion above 90% with about 0.9 kW reforming scale based on high heating value during 45 min of the heat-discharge mode. The chemical reaction performances of the reactor tube were investigated also for the solar-simulating operation mode. The application of the new reactor tubes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.

    DOI: 10.1115/1.3197840

    Web of Science

    researchmap

  • Double-walled reformer tubes using high-temperature thermal storage of molten-salt/MgO composite for solar cavity-type reformer 査読

    Nobuyuki Gokon, Shin-ichi Inuta, Shingo Yamashita, Tsuyoshi Hatamachi, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY34 ( 17 ) 7143 - 7154   2009年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Composite materials with alkali carbonate and magnesia have been examined for high-temperature thermal storage in solar tubular reformers. The concept of a double-walled reactor tube involves packing a molten-salt/ceramic composite material into the annular region between internal catalyst tube and exterior solar-absorber wall. In this paper, the shape and interior structure of the reactor tube are newly designed for use in solar cavity-type reformers using straight reactor tubes. Na2CO3, K2CO3, and Li2CO3 composite materials with magnesia were tested as thermal storage media for CO2 reforming of methane during cooling mode of the reactor tube at a laboratory scale. The efficiency of Na2CO3/MgO composite with various MgO contents was also estimated. Composite materials of Na2CO3 80-90 wt% and MgO 20-10 wt% were successfully delayed the cooling of the catalyst bed and sustained methane conversion at >90%. A solar cavity-type reformer consisting of multiple straight reactor tubes is expected to enable stable operation of the solar reforming process under fluctuating solar insolation during cloud passage. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2009.06.047

    Web of Science

    researchmap

  • Thermochemical two-step water splitting cycles by monoclinic ZrO2-supported NiFe2O4 and Fe3O4 powders and ceramic foam devices 査読

    Nobuyuki Gokon, Hiroko Murayama, Ayumi Nagasaki, Tatsuya Kodama

    SOLAR ENERGY83 ( 4 ) 527 - 537   2009年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A thermochemical two-step water splitting cycle is examined for NiFe2O4 and Fe3O4 supported on monoclinic ZrO2 (NiFe2O4/m-ZrO2 and Fe3O4/m-ZrO2) in order to produce hydrogen from water at a high-temperature. The evolution of oxygen and hydrogen by m-ZrO2-supported ferrite powders was studied, and reproducible and stoichiometric oxygen/hydrogen productions were demonstrated through a repeatable two-step reaction. Subsequently, a ceramic foam device coated with NiFe2O4/m-ZrO2 powder was made and examined as a water splitting device by the direct irradiation of concentrated Xe-light in order to simulate solar radiation. The reaction mechanism of the two-step water splitting cycle is associated with the redox transition of ferrite/wustite on the surface of m-ZrO2. A hydrogen/oxygen ratio for these redox powder systems exhibited good reproducibility of approximately two throughout the repeated cycles. The foam device loaded NiFe2O4/m-ZrO2 powder was also successful with respect to hydrogen production through 10 repeated cycles. A ferrite conversion of 24-76% was obtained over an irradiation period of 30 min. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2008.10.003

    Web of Science

    researchmap

  • New Solar Water-Splitting Reactor With Ferrite Particles in an Internally Circulating Fluidized Bed 査読

    Nobuyuki Gokon, Shingo Takahashi, Hiroki Yamamoto, Tatsuya Kodama

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME131 ( 1 )   2009年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME-AMER SOC MECHANICAL ENG  

    The thermal reduction of metal oxides as part of a thermochemical two-step water-splitting cycle requires the development of a high-temperature solar reactor operating at 1000-1500 degrees C. Direct solar energy absorption by metal-oxide particles provides direct efficient heat transfer to the reaction site. This paper describes the experimental results of a windowed small reactor using an internally circulating fluidized bed of reacting metal-oxide particles under direct solar-simulated Xe-beam irradiation. Concentrated Xe-beam irradiation directly heats the internally circulating fluidized bed of metal-oxide particles. NiFe(2)O(4)/m-ZrO(2) (Ni-ferrite on zirconia support) particles are loaded as the working redox material and are thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally reduced sample is oxidized back to Ni-ferrite with steam at 1000 degrees C. The conversion efficiency of ferrite reached 44% (+/- 1.0%), which was achieved using the reactor at 1 kW of incident Xe lamp power. The effects of preheating temperature and NiFe(2)O(4)/m-ZrO(2) particle size on the performance of the reactor for thermal reduction using an internally circulating fluidized bed were evaluated.

    DOI: 10.1115/1.3027511

    Web of Science

    researchmap

  • Monoclinic zirconia-supported Fe3O4 for the two-step water-splitting thermochemical cycle at high thermal reduction temperatures of 1400-1600 degrees C 査読

    Nobuyuki Gokon, Hiroko Murayama, Jun Umeda, Tsuyoshi Hatamachi, Tatsuya Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY34 ( 3 ) 1208 - 1217   2009年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Two-step thermochemical water-splitting using monoclinic ZrO2-supported Fe3O4 (Fe3O4/m-ZrO2) for hydrogen production was examined at high thermal reduction temperatures of 1400-1600 degrees C. After thermal reduction of Fe3O4/m-ZrO2, the reduced sample was quenched in liquid nitrogen, and was subsequently subjected to the water-decomposition step at 1000 degrees C. Quenching of the solid sample was conducted for analysis of the chemical reactions, such as phase transitions, occurring at high-temperature. The hydrogen productivity of Fe3O4 on a m-ZrO2 support and the conversion of Fe3O4 to FeO were significantly enhanced with higher thermal reduction temperatures. The Fe3O4-to-FeO conversion reached 60% when the Fe3O4/m-ZrO2 was thermally reduced at 1600 degrees C. The phase transition of m-ZrO2 support to tetragonal ZrO2 (t-ZrO2) did not occur during the thermal reduction at 1400-1500 degrees C, but it did proceed slightly at 1600 degrees C. Fe ions from Fe3O4 did not enter the ZrO2 lattice during high-temperature thermal reduction. Thus, the Fe3O4 loaded on a m-ZrO2 support can continuously contribute as a Fe3O4-FeO redox reactant for thermochemical water-splitting at high-temperatures of 1400-1600 degrees C. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2008.12.007

    Web of Science

    researchmap

  • Kinetics of CO2 reforming of methane by catalytically activated metallic foam absorber for solar receiver-reactors 査読

    Nobuyuki Gokon, Yusuke Osawa, Daisuke Nakazawa, Tatsuya Kodma

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY34 ( 4 ) 1787 - 1800   2009年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Ni-Cr-Al metallic foam absorber with high porosity was catalytically activated using a Ru/gamma-Al2O3 catalyst, and was subsequently tested with respect to CO2 reforming of methane in a small-scale volumetric receiver-reactor by using a sun-simulator. A chemical storage efficiency of 37% was obtained for a mean light flux of 325 kW m(-2). Furthermore, the activity and the stability of the metallic foam absorber were compared with those of a SiC foam absorber activated with the same Ru/gamma-Al2O3 catalyst for 50 h of light irradiation, and it was found that the metallic foam absorber has superior catalytic stability in comparison to the SiC form absorber. In addition, unlike ceramic foams such as SiC, metallic foams feature superior plasticity, which prevents the emergence of cracks caused by mechanical or thermal shock.
    The kinetics of CO2 reforming of methane over Ru/gamma-Al2O3/metallic foams was also examined for temperatures of 600-750 degrees C using a quartz tube reactor and an electric furnace. The experiments were performed by varying the methane/CO2 ratios of 0.3-3.0. Moreover, the kinetic data were fitted to four different types of kinetic models, namely the Langmuir-Hinshelwood, Basic, Eley-Rideal, and Stepwise mechanisms. The kinetic model which provided the best prediction of the experimental reforming rates was the Langmuir-Hinshelwood mechanism for temperatures of 600-700 degrees C. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2008.12.018

    Web of Science

    researchmap

  • CO2 reforming of CH4 using molten salt/MgO composite thermal storages for solar hydrogen production 査読

    Nobuyuki Gokon, Shin-ichi Inuta, Shingo Yamashita, Tsuyoshi Hatamachi, Tatsuya Kodama

    International Symposium on Fusion Tech 2009 at Incheon, Incheon, Korea, January 13-15, 2009   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • KINETICS OF CO(2) REFORMING OF METHANE BY CATALYTICALLY ACTIVATED METALLIC FOAM ABSORBER FOR SOLAR RECEIVER-REACTORS 査読

    Nobuyuki Gokon, Yusuke Osawa, Daisuke Nakazawa, Tsuyoshi Hatarnachi, Tatsuya Kodama

    ES2008: PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY, VOL 234 ( 4 ) 371 - 383   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    Ni-Cr-Al alloy foam absorber with high porosity was catalytically activated using a Ru/gamma-Al(2)O(3) catalyst, and was subsequently tested with respect to CO(2) reforming of methane in a small-scale volumetric receiver-reactor by using a sun simulator. A chemical storage efficiency of about 40% was obtained for a mean light flux of 325 kW m(-2). Furthermore, the activity and the stability of the metallic foam absorber were compared with those of a SiC foam absorber activated with the same Ru/gamma-Al(2)O(3) catalyst for 50 h of light irradiation, and it was found that the metallic foam absorber has superior catalytic stability in comparison to the SiC form absorber. In addition, unlike ceramic foams such as SiC, metallic foams feature superior plasticity, which prevents the emergence of cracks caused by mechanical or thermal shock.
    The kinetics of CO(2) reforming of methane over metallic foam absorbers were also examined for temperatures of 600-750 degrees C using a quartz tube reactor and an electric furnace. The experiments were performed by varying the methane/CO(2) ratios of 0.5-2.3. Moreover, the kinetic data were fitted to four different types of kinetic models, namely the Langmuir-Hinshelwood, Basic, Eley-Rideal, and Stepwise mechanisms. The kinetic model which provided the best prediction of the experimental reforming rates was the Langmuir-Hinshelwood mechanism.

    DOI: 10.1016/j.ijhydene.2008.12.018

    Web of Science

    researchmap

  • Thermochemical Two-Step Water Splitting by Zirconia-Supported Ferrites and Its foam Device for Solar Demonstration 査読

    Tatsuya Kodama, Nobuyuki Gokon, Juyn Umeda, Kouchi Sakai, Taebeom Seo

    SolarPACES2009, Berlin, Germany, September 15-18 2009.   2009年

     詳細を見る

    記述言語:英語  

    researchmap

  • Reactive ferrite-coated ceramic foam device for a solar thermochemical hydrogen production 査読

    Ayumi Nagasaki, Tsuyoshi Hatamachi, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2009 at Incheon, Incheon, Korea, January 13-15, 2009   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Solar thermochemical hydrogen production research in Inha and Niigata Universities collaboration 査読

    Tatsuya Kodama, Nobuyuki Gokon, Ayumi Nagasaki, Taebeom Seo

    International Symposium on Fusion Tech 2009 at Incheon, Incheon, Korea, January 13-15, 2009   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Ferrite-loaded ceramic foam devices prepared by spin-coating method for a Solar Two-Step thermochemical cycle 査読

    Nobuyuki Gokon, Tatsuya Kodama, Ayumi Nagasaki, Ko-ichi Sakai, Tsuyoshi Hatamachi

    ASME 2009 3rd International Conference of Energy Sustainability (ES2009), San Francisco, California, USA, July 19-23, 2009   439 - 449   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.1115/ES2009-90172

    Web of Science

    researchmap

  • MOLTEN-SALT TUBULAR ABSORBER/REFORMER (MoSTAR) PROJECT: METAL-PLATE-BRIDGED DOUBLE TUBE REACTOR 査読

    Tatsuya Kodama, Nobuyuki Gokon, Shin-ichi Inuta, Shin-go Yamashita, Tsuyoshi Hatamachi, Taebeom Seo

    ES2009: PROCEEDINGS OF THE ASME 3RD INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY, VOL 2   451 - 457   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    The Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project, which is jointly conducted by Niigata University, Japan, and Inha University, Korea, aims to develop a novel-type of "double-walled" tubular absorbers/reformers with molten-salt thermal storage at high temperature for use in solar natural-gas reforming and solar air receiver, and to demonstrate their performances on sun with a 5-kW, dish-type solar concentrator. The new concept of "double-walled" reactor tubes was proposed for use in a solar reformer by Niigata University, Japan, and involves packing a molten salt in the annular region between the internal catalyst tube and the exterior solar absorber tube of the double reactor tube. In this work, "metal-plate-bridged" double reactor tubes are newly proposed for use in a solar reformer. Two different sized reactor tubes are constructed, and tested on chemical reaction performance for dry reforming of methane during cooling or heat-discharge mode of the reactor tube using an electric furnace. The experimental results obtained under feed gas mixture of CH(4)/CO(2) = 1:3 at a residence time of 0.36 s and at 1 atm showed that the double reactor tube with the heat storage medium Na(2)CO(3) in the annular region successfully sustained a high methane conversion above 90% with about 0.7-kW output power of the reformed gas based on HHV for 40 min of the heat-discharge mode. The application of the new reactor tubes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.

    DOI: 10.1115/ES2009-90230

    Web of Science

    researchmap

  • Internally circulating fluidized bed reactor with NiFe2O4 particles for thermochemical water-splitting 査読

    Nobuyuki Gokon, Nobuyuki Kondo, Tetsuro Mataga, Tatsuya Kodama

    SolarPACES2009, Berlin, Germany, September 15-18 2009.   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • KINETICS OF CO(2) REFORMING OF METHANE BY CATALYTICALLY ACTIVATED METALLIC FOAM ABSORBER FOR SOLAR RECEIVER-REACTORS 査読

    Nobuyuki Gokon, Yusuke Osawa, Daisuke Nakazawa, Tsuyoshi Hatarnachi, Tatsuya Kodama

    ES2008: PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY, VOL 2   371 - 383   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    Ni-Cr-Al alloy foam absorber with high porosity was catalytically activated using a Ru/gamma-Al(2)O(3) catalyst, and was subsequently tested with respect to CO(2) reforming of methane in a small-scale volumetric receiver-reactor by using a sun simulator. A chemical storage efficiency of about 40% was obtained for a mean light flux of 325 kW m(-2). Furthermore, the activity and the stability of the metallic foam absorber were compared with those of a SiC foam absorber activated with the same Ru/gamma-Al(2)O(3) catalyst for 50 h of light irradiation, and it was found that the metallic foam absorber has superior catalytic stability in comparison to the SiC form absorber. In addition, unlike ceramic foams such as SiC, metallic foams feature superior plasticity, which prevents the emergence of cracks caused by mechanical or thermal shock.
    The kinetics of CO(2) reforming of methane over metallic foam absorbers were also examined for temperatures of 600-750 degrees C using a quartz tube reactor and an electric furnace. The experiments were performed by varying the methane/CO(2) ratios of 0.5-2.3. Moreover, the kinetic data were fitted to four different types of kinetic models, namely the Langmuir-Hinshelwood, Basic, Eley-Rideal, and Stepwise mechanisms. The kinetic model which provided the best prediction of the experimental reforming rates was the Langmuir-Hinshelwood mechanism.

    Web of Science

    researchmap

  • REACTIVITY OF IRON-CONTAINING YSZ FOR A TWO-STEP THERMOCHEMICAL WATER SPLITTING USING THERMAL REDUCTION TEMPERATURES OF 1400-1500 degrees C 査読

    Tatsuya Kodama, Eiji Hiraiwa, Nobuyuki Gokon

    ES2008: PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON ENERGY SUSTAINABILITY, VOL 2   361 - 369   2009年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    A thermochemical two-step water splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting solar energy into clean hydrogen in sunbelt regions. Fe3O4 supported on YSZ (Yttrium-Stabilized Zirconia) or Fe3O4/YSZ is a promising working material for the two-step water splitting cycle. In the water splitting cycle, an iron-containing YSZ or Fe2+-YSZ is formed by a high-temperature reaction between Fe3O4 and YSZ support at 1400 degrees C in an inert atmosphere. The Fe2+-YSZ reacts with steam and generate hydrogen at 1000 degrees C, to form Fe3+-YSZ that is re-activated by a thermal reduction ill a;separate step at 1400 degrees C under an inert atmosphere. In the present work, the thermal reduction was performed in a higher temperature range of 1400-1500 degrees C while the hydrolysis reaction was carried Out at 1000 degrees C. It was confirmed by XRD analysis that the cyclic redox reactions Occurred based on the same reaction mechanism when using a thermal reduction temperature between 1400 and 1500 degrees C. The conversions of Fe3O4 to Fe2+-YSZ were 20, 26 and 47% when the thermal reduction temperature were 1400, 1450, and 1500 degrees C respectively, indicating that the x values in the formed Fe2+-YSZ or Fex2+YyZr1-yO2-y/2+x, were 0.08, 0.11, and 0.19 respectively, where y = 0.15. The conversions of Fe2+-YSZ to Fe3+-YSZ ill the hydrolysis reaction (at 1000 degrees C), however, decreased from 90% to 60% when the thermal reduction temperature increased from 1400 to 1500 degrees C. As the results, the hydrogen production reactivity of Fe3O4 supported on YSZ increased from 5.6 x 10(-4) to 7.5 x 10(-4) g per gram of Fe3O4/YSZ for one cycle on the cycle average by elevated thermal reduction temperature from 1400 to 1500 degrees C.

    Web of Science

    researchmap

  • Occurrence of Faceting for [110] Symmetric Tilt Boundaries in Cu Doped with Bi 査読

    Nobuyuki Gokon, Masanori Kajihara

    MATERIALS TRANSACTIONS49 ( 11 ) 2584 - 2590   2008年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:JAPAN INST METALS  

    The faceting of the grain boundary in the binary Cu-Bi system was experimentally observed by transmission electron microscopy (TEM). For the observation, Cu bicrystals with Sigma 33, Sigma 9 and Sigma 11[110] symmetric tilt boundaries were doped with Bi at 1173 K for 120 h, and then homogenized at 1173 K for 48 h. followed by furnace cooling or water quenching. The misorientation angle between the [001] directions of the two single-crystals is 20.1 degrees, 39.9 degrees and 50.5 degrees for the Sigma 33, Sigma 9 and Sigma 11 boundaries, respectively. According to the TEM observation, the grain boundary is faceted markedly in the bicrystal with furnace cooling but barely in that with water quenching. Thus, the faceting takes place during furnace cooling but not during homogenization. The faceting was analyzed quantitatively on the basis of the inclination angle dependence of the boundary energy in Cu. The analysis yields that the contribution of the torque term to the faceting is important. Comparing the boundary diffusivities of Bi and Cu in Cu, we may expect that the mobility is much greater for the grain boundary with Bi than for that without Bi. As a result, the faceting during furnace cooling takes place considerably for the grain boundary with Bi but scarcely for that without Bi. [doi: 10.2320/matertrans.MRA2008062]

    DOI: 10.2320/matertrans.MRA2008062

    Web of Science

    researchmap

  • Thermochemical two-step water-splitting for hydrogen production using Fe-YSZ particles and a ceramic foam device 査読

    Nobuyuki Gokon, Tomoki Hasegawa, Shingo Takahashi, Tatsuya Kodama

    ENERGY33 ( 9 ) 1407 - 1416   2008年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Fe3O4 supported on cubic yttria-stabilized zirconia (Fe3O4/C-YSZ) is proposed as a promising redox material for the production of hydrogen from water via a thermochemical two-step water-splitting cycle. In this study, the evolution of oxygen and hydrogen during the cyclic reaction was examined using Fe3O4/C-YSZ particles in order to demonstrate reproducible and stoichometric oxygen/hydrogen production through a repeatable two-step reaction. Subsequently, a ceramic foam device coated with Fe3O4 and c-YSZ particles was prepared and examined as a thermochemical water-splitting device in a directly irradiated receiver/reactor hydrogen production system. The Fe3O4/C-YSZ system formed a Fe-containing YSZ (Fe-YSZ) by high-temperature reaction between Fe3O4 and the c-YSZ support at 1400 degrees C in an inert atmosphere. The reaction mechanism of the two-step water-splitting cycle is associated with the redox transition of Fe2+-Fe3+ ions in the c-YSZ lattice. The Fe-YSZ particles exhibit good reproducibility for reaction with a hydrogen/oxygen ratio of approximately 2.0 throughout repeated cycles. The foam device coated with Fe-YSZ particles was also successful for continual hydrogen production through 32 repeated cycles. A 20-27% ferrite conversion was obtained using 10.5 wt% Fe3O4 loading over an irradiation period of 60 min. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.energy.2008.04.011

    Web of Science

    researchmap

  • Fracture behavior of Σ9 [110] asymmetric tilt boundaries in Cu doped with Bi 査読

    N. Gokon, S. Ohyama, M. Kajihara

    Material Science and Engineering A488 ( 1-2 ) 252 - 259   2008年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.msea.2007.11.015

    Web of Science

    researchmap

  • Development of novel magnetic nano-carriers for high-performance affinity purification 査読

    Kosuke Nishio, Yuka Masaike, Morihito Ikeda, Hiroki Narimatsu, Nobuyuki Gokon, Shingo Tsubouchi, Mamoru Hatakeyama, Satoshi Sakamoto, Naohiro Hanyu, Adarsh Sandhu, Haruma Kawaguchi, Masanori Abe, Hiroshi Handa

    COLLOIDS AND SURFACES B-BIOINTERFACES64 ( 2 ) 162 - 169   2008年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We developed novel magnetic nano-carriers around 180 mn in diameter for affinity purification. Prepared magnetic nano-carriers possessed uniform core/shell/shell nano-structure composed of 40 nm magnetite particles/poly(styrene-co-glycidyl methacrylate (GMA))/polyGMA, which was constructed by admicellar polymerization. By utilizing relatively large 40 nm magnetite particles with large magnetization, the magnetic nanocarriers could show good response to permanent magnet. Thanks to uniform polymer shell with high physical/chemical stability, the magnetic nano-carriers could disperse in a wide range of organic solvent without disruption of core/shell structure and could immobilize various kinds of drugs. We examined affinity purification using our prepared magnetic nano-carriers with anti-cancer agent methotrexate (MTX) as ligand. Our magnetic nano-carriers showed higher performance compared to commercially available magnetic beads in terms of purification efficiency of target including extent of non-specific binding protein. (c) 2008 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2008.01.013

    Web of Science

    researchmap

  • Thermochemical two-step water-splitting reactor with internally circulating fluidized bed for thermal reduction of ferrite particles 査読

    N. Gokon, S. Takahashi, H. Yamamoto, T. Kodama

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY33 ( 9 ) 2189 - 2199   2008年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A thermochemical two-step water-splitting cycle using a redox system of iron-based oxides or ferrites was examined on hydrogen productivity and reactivity of ferrite in order to convert solar energy into hydrogen in sunbelt regions. In the present paper, a new concept is proposed for a windowed thermochemical water-splitting reactor, using an internally circulating fluidized bed of NiFe2O4/m-ZrO2 particles, and thermal reduction of the bed is demonstrated on a laboratory scale by using a solar-simulating Xe-beam irradiation. The concept is that concentrated solar radiation passes through the transparent window and directly heats the internally circulating fluidized bed. The fluidized bed reactor enabled the NiFe2O4/M-ZrO2 sample to remain in powder form without sintering and agglomerating during direct Xe-beam irradiation over 30 min. Approximately 45% of the NiFe2O4 was converted to the reduced phase by the solar-simulated high-flux beam, and was then completely reoxidized with steam at 1000 degrees C to generate hydrogen. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.ijhydene.2008.02.044

    Web of Science

    researchmap

  • Experimental determination of boundary energies of Sigma 9 [110] asymmetric tilt boundaries in Cu 査読

    N. Gokon, A. Kajihara

    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING477 ( 1-2 ) 121 - 128   2008年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE SA  

    A silica particle observation (SPO) method was used in order to determine experimentally the boundary energies of Sigma 9 [110] asymmetric tilt boundaries with a misorientation angle of theta = 38.9 degrees in Cu for various inclination angles between phi = 0 degrees and 90 degrees. The SPO method has no drawbacks which are inevitable in boundary grooving and tri-junction methods. The boundary energy takes the maximum value at phi = 0 degrees but the minimum value at phi = 65 degrees. The minimum value is 65% of the maximum value. The inclination angle dependence of the boundary energy was utilized to evaluate quantitatively the possibility of faceting and dissociation for the boundary. According to the evaluation, the faceting into the {112} {552} and {552} {112} boundaries is possible for the {778} {110}, {554} {17, 17, 4} and {221} {221} boundaries. Furthermore, the dissociation into the Sigma 3 {111} {111} and {112} {112} twin boundaries is feasible for the {111} {115}, {447} {001} and {778} {110} boundaries. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.msea.2007.05.029

    Web of Science

    researchmap

  • Application of an internally circulating fluidized bed for windowed solar chemical reactor with direct irradiation of reacting particles 査読

    Tatsuya Kodama, Syu-ichi Enomoto, Tsuyoshi Hatamachi, Nobuyuki Gokon

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME130 ( 1 ) 014504-1 - 014504-4   2008年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME  

    Solar thermochemical processes require the development of a high-temperature solar reactor operating at 1000-1500 degrees C, such as solar gasification of coal and the thermal reduction of metal oxides as part of a two-step water splitting cycle. Here, we propose to apply "an internally circulating fluidized bed" for a windowed solar chemical reactor in which reacting particles are directly illuminated. The prototype reactor was constructed in a laboratory scale and demonstrated on CO2 gasification of coal coke using solar-simulated, concentrated visible light from a sun simulator as the energy source. About 12% of the maximum chemical storage efficiency was obtained by the solar-simulated gasification of the coke.

    DOI: 10.1115/1.2807213

    Web of Science

    researchmap

  • Iron-containing yttria-stabilized zirconia system for two-step thermochemical water splitting 査読

    Nobuyuki Gokon, Takayuki Minno, Yumiko Nakamuro, Tatsuya Kodama

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME130 ( 1 ) 011018-1 - 011018-6   2008年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME  

    An iron-containing yttria-stabilized zirconia (YSZ) or Fe-YSZ was found to be a promising working redox material for the thermochemical two-step water-splitting cycle. The Fe-YSZ was formed by a high-temperature reaction between YSZ doped with more than 8 mol % Y2O3 and Fe3O4 supported on the YSZ at 1400 degrees C in an inert atmosphere. The formed Fe-YSZ reacted with steam to generate hydrogen at 1000 degrees C. The oxidized Fe-YSZ was reactivated by a thermal reduction at 1400 degrees C in an inert atmosphere. The alternative O-2 and H-2 generations in the repeated two-step reactions and the X-ray diffraction and chemical analysis studies on the solid materials indicated that the two-step water splitting was associated with a redox transition between Fe2+-Fe3+ ions in the cubic YSZ lattice.

    DOI: 10.1115/1.2807197

    Web of Science

    researchmap

  • Coal Coke gasification in a windowed solar chemical reactor for beam-down optics 査読

    Tatsuya Kodama, Shu-ich Enomoto, Shouta Itoh, Tsuyoshi Hatamachi, Nobuyuki Gokon

    14th Biennial CSP SolarPACES Symposium, LasVegas, Nevada, USA, March 4-7, 2008   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochemical two-step water splitting by ZrO2-supported NixFe3-xO4 for solar hydrogen production 査読

    T. Kodama, N. Gokon, R. Yamamoto

    SOLAR ENERGY82 ( 1 ) 73 - 79   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A thermochemical two-step water-splitting cycle using a redox metal oxide was examined for Ni(II) ferrites or NixFe3-xO4 (0 <= x <= 1) for the purpose of converting solar high-temperature heat to hydrogen. The Ni(II) ferrite was decomposed to Ni-doped wustite (NiyFe1-yO) at 1400 degrees C under an inert atmosphere in the first thermal-reduction step of the cycle; it was then reoxidized with steam to generate hydrogen at 1000 degrees C in the second water-decomposition step. Although nondoped Fe3O4 powders formed a nonporous, dense mass of iron oxide by the fusion of FeO and its subsequent solidification after the thermal-reduction step, Ni(II)-ferrite powders were converted into a porous, soft mass after the step. This was probably because Ni doping in the FeO phase raised the melting point of wustite above 1400 degrees C. Supporting the Ni(II) ferrites on m-ZrO2 (monoclinic zirconia) alleviated the high-temperature sintering of iron oxide; as a result, the supported ferrites exhibited greater reactivity and assisted the repeatability of the cyclic water splitting process as compared to the unsupported ferrites. The reactivity increased with the doping value x, and was maximum at x = 1.0 in the NixFe3-xO4/m-ZrO2 system. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2007.03.005

    Web of Science

    researchmap

  • High-temperature carbonate/MgO composite materials as thermal storage media for double-walled solar reformer tubes 査読

    N. Gokon, D. Nakano, S. Inuta, T. Kodama

    SOLAR ENERGY82 ( 12 ) 1145 - 1153   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The composite materials of molten alkali-carbonate/MgO-ceramics are examined as thermal storage media in a tubular reformer using a double-walled reactor tube of a laboratory scale. The concept of a double-walled reformer tube is proposed as a solar tubular reformer and involves packing a molten salt/ceramic composite material in the annular region between the internal catalyst tube and the exterior solar absorber wall. The composite materials of Na(2)CO(3), K(2)CO(3), and Li(2)CO(3) with magnesia are tested as thermal storage media. The reforming performances of the composite materials are tested in the cooling mode of the double-walled reactor tube. The experimental result obtained under feed gas mixture of CH(4)/CO(2) = 1:3 at 1 atm shows that the use of 80 wt%Na(2)CO(3)/20 wt%MgO composite material successfully delayed the cooling time of the catalyst bed by 5-19 min in comparison to the case without a composite material. In addition, the Li(2)CO(3)/MgO and Na(2)CO(3)/MgO composite materials relatively revealed good performances: they prolonged the cooling time by over 10 min in the gas hourly space velocity (GHSV) range of 5000-12,500 h(-1). The application of the reactor tubes to solar tubular reformers is expected to realize stable operation of the solar reforming process under fluctuating insolation during cloud passage. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2008.05.011

    Web of Science

    researchmap

  • Two-Step Water Splitting By Fe3O4 on Monoclinic Zirconia Support Using Thermal Reduction Temperatures of 1400-1600?C 査読

    Nobuyuki Gokon, Hiroko Murayama, Eiji Hiraiwa, Jun Umeda, Tsuyoshi Hatamachi, Tatsuya Kodama

    14th Biennial CSP SolarPACES Symposium, LasVegas, Nevada, USA, March 4-7, 2008   2008年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Thermochernical cycles for high-temperature solar hydrogen production 査読

    Tatsuya Kodama, Nobuyuki Gokon

    CHEMICAL REVIEWS107 ( 10 ) 4048 - 4077   2007年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    DOI: 10.1021/cr050188a

    Web of Science

    researchmap

  • Preparation of size-controlled (30-100 nm) magnetite nanoparticles for biomedical applications 査読

    K. Nishio, M. Ikeda, N. Gokon, S. Tsubouchi, H. Narimatsu, Y. Mochizuki, S. Sakamoto, A. Sandhu, M. Abe, H. Handa

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS310 ( 2 ) 2408 - 2410   2007年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Size-controlled magnetite nanoparticles (MNPs) with several dozen nanometers ( nm) were synthesized for biomedical applications. Nanoparticles of single-phase magnetite, as revealed by X-ray analyses and magnetic measurements, were prepared by oxidizing ferrous hydroxide (Fe(OH)(2)) with a weak oxidant NaNO3 in an N-2-deaerated aqueous NaOH solution ( pH = 12-13) at various temperatures below 37 degrees C. As the synthesis temperature increases from 4 to 37 degrees C, the MNPs are decreased in size (d) from 102 +/- 5.6 to 31.7 +/- 4.9 nm and widened in size distribution, Delta d/d increases from 5.5% to 15%. Prepared without using any surfactant, the MNPs are advantageous for immobilizing functional molecules stably on the surfaces for biomedical applications. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jmmm.2006.10.795

    Web of Science

    researchmap

  • Identification of a chemical substructure that is immobilized to ferrite nanoparticles (FP) 査読

    Kosuke Nishio, Nobuyuki Gokon, Makoto Hasegawa, Yuji Ogura, Morihito Ikeda, Hiroki Narimatsu, Masaru Tada, Yuki Yamaguchi, Satoshi Sakamoto, Masanori Abe, Hiroshi Handa

    COLLOIDS AND SURFACES B-BIOINTERFACES54 ( 2 ) 249 - 253   2007年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Despite the wide utility of ferrite nanoparticles (FP), a methodology to conjugate heterologous molecules to FP is still limited and characterization of small molecule-conjugated FP is not well known. Here, we describe what kinds of proteins and amino acids are selectively immobilized onto FP when FP is synthesized in the presence of these molecules. Two-dimentional gel electrophoresis (2D SDS-PAGE) showed that proteins with low pl value were selectively bound to FP. Quantitative analyses using HPLC suggested that L-aspartic acid (Asp) and L-cysteine (Cys) were bound to FP selectively among natural amino acids examined. Additional analysis of compounds-conjugated FP revealed that selective binding of Asp to FP was attributed with its molecular structure. It was found that the substructure of amino acid-bound to FP specifically was composed of a defined chelation of two carboxyl groups separated by two carbon atoms as deduced from FT-IR measurement. Thus, we concluded that molecules possessing two carboxyl groups separated by two carbons were bound to FP spontaneously and selectively, which might enable the attachment of free functional groups onto the FP surface if their molecules have functional groups other than carboxyl groups. The resulting complex might be applicable as a chemical tag to immobilize various molecules onto FP. (C) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.colsurfb.2006.10.039

    Web of Science

    researchmap

  • Thermochemical Two-Step Water-Splitting Cycle by ZrO2-supported Fe3O4 for Solar Hydrogen Production 査読

    Hiroko Murayama, Shingo Takahashi, Nobuyuki Gokon, Tatsuya Kodama

    The 4th International Symposium on Advanced Materials in Asia-Pacific Rim, Niigata, Niigata, Japan, July 13-15 2007   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • A two-step water splitting with ferrite particles and its new reactor concept using an internally circulating fludized-bed 査読

    Nobuyuki Gokon, Takayuki Mizuno, Shingo Takahashi, Tatsuya Kodama

    Proceedings of the ASME International Solar Energy Conference   205 - 214   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    A thermochemical two-step water splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting and storing solar energy into a fuel in sunbelt regions. The ZrO2-supported ferrite (or the ferrite/ZrO2) powders exhibit superior performances on activity and repeatability of the cyclic reactions when compared to conventional unsupported ferrites. In the first step at 1400 degrees C under an inert atmosphere, ferrite on ZrO2 support is thermally decomposed to the reduced phase of wustite that is oxidized back to ferrite on ZrO2 with steam in a separate second step at 1000 degrees C. In this paper, a number of ZrO2-supporetd ferrites, Mn-, Mg-, Co-, Ni- and Co-Mn-ferrites, are examined on activity. The NiFe2O4/ZrO2 powder was found to have a greatest activity between them. This paper also describes a new concept of a windowed solar chemical reactor using an internally circulating fluidized bed of ferrite/ZrO2 particles. In this concept, concentrated solar radiation passes downwards through the transparent window and directly heats the internally circulating fluidized bed. The exploratory experimental studies on this reactor concept are carried out in a laboratory scale for the thermal decomposition of NiFe2O4/ZrO2 particle bed as part of two-step water splitting cycle.

    Web of Science

    researchmap

  • Solar tubular reformer with molten-salt thermal storage - Design modification of the reactor tube and testing 査読

    Tatsuya Kodama, Tsuyoshi Hatamachi, Daisuke Nakano, Youhei Igarashi, Nobuyuki Gokon

    Proceedings of the ASME International Solar Energy Conference   197 - 204   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    For thermal storage in solar tubular reformers, high-temperature composite materials with alkali carbonate and magnesia have been examined. The new concept of "double-walled reactor tube" was previously proposed to use in solar tubular reformers, which involves storing the molten-salt/ceramic composite material in the annular regions between an internal catalyst tube and the exterior solar absorber wall. The shape and structure of the reactor tube can be modified to match with design of a solar tubular reformer. In this paper, the interior structure of the reactor tube has been modified for use in cavity-type reformers using straight reactor tubes. The Na2CO3, K2CO3 and Li2CO3 composite materials with magnesia were prepared, and tested on heat-discharge mode performances for CO2 reforming of methane in the modified reactor tube of a laboratory scale.

    DOI: 10.1115/ISEC2006-99062

    Web of Science

    researchmap

  • Solar Thermochemical Water-Splitting Reactor Using Internally-Fluidized Beds of Ferrite Particles, 査読

    Nobuyuki Gokon, Shingo Takahashi, Hiroki Yamamoto, Tatsuya Kodama

    International Symposium on Fusion Tech 2006-2007 at Niigata, Niigata, Japan, 17-19 January, 2007.   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Reactive Ferrite Devices for Solar Thermochemical Water Splitting 査読

    Tatsuya Kodama, Nobuyuki Gokon

    International Symposium on Fusion Tech 2006-2007 at Niigata, Niigata, Japan, 17-19 January, 2007.   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • New solar water-splitting reactor with ferrite particles in an internally circulating fluidized bed 査読

    Nobuyuki Gokon, Shingo Takahashi, Hiroki Yamamoto, Tatsuya Kodama

    PROCEEDINGS OF THE ENERGY SUSTAINABILITY CONFERENCE 2007131   831 - 839   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    The thermal reduction of metal oxides as part of a thermochemical two-step water splitting cycle requires the development of a high temperature solar reactor operating at 1000-15000 degrees C. Direct solar energy absorption by metal-oxide particles provides efficient heat transfer directly to the reaction site. This paper describes experimental results of a windowed thermochemical water-splitting reactor using an internally circulating fluidized bed of the reacting metal-oxide particles under direct solar irradiation. The reactor has a transparent quartz window on the top as aperture. The concentrated solar radiation passes downward through the window and directly heats the internally circulating fluidized bed of metal-oxide particles. Therefore, this reactor needs to be combined with a solar tower or beam down optics.
    NiFe2O4/M-ZrO2 (Ni-ferrite supported on zirconia) particles is loaded as the working redox material in the laboratory scale reactors, and thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally-reduced sample is oxidized back to Ni-ferrite with steam at 1000 degrees C. As the results, the conversion of ferrite reached about 44% of maximum value in the reactor by 1 kW of incident solar power. The effects of preheating temperature and particle size of NiFe2O4/m-ZrO2 were tested for thermal reduction of internally circulating fluidized bed in this paper.

    DOI: 10.1115/1.3027511

    Web of Science

    researchmap

  • Iron-containing YSZ for the Thermochemical Water-Splitting and its Water-Splitting Device 査読

    Tomoki Hasegawa, Yumiko Nakamuro, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2006-2007 at Niigata, Niigata, Japan, 17-19 January, 2007.   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Catalyst Properties and its Thermal Resistance of Foam Matrix for Methane Reforming under Concentrated Solar Radiation 査読

    Takehiro Shimoyama, Yuusuke Oosawa, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2006-2007 at Niigata, Niigata, Japan, 17-19 January, 2007.   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Carbonate/Magnesia Composites for Thermal Storage in Solar Tubular Reformers 査読

    Daisuke Nakano, Shinichi Inuta, Youhei Igarashi, Tsuyoshi Hatamachi, Nobuyuki Gokon, Tatsuya Kodama

    International Symposium on Fusion Tech 2006-2007 at Niigata, Niigata, Japan, 17-19 January, 2007.   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Double-Walled Tubular Reactor with Molten Salt Thermal Storage for Solar Reforming of Methane 査読

    Shin-ichi Inuta, Daisuke Nakano, Yoshinori Hara, Nobuyuki Gokon, Tatsuya Kodama

    The 4th International Symposium on Advanced Materials in Asia-Pacific Rim, Niigata, Niigata, Japan, July 13-15 2007   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Reactive Fe-YSZ coated foam devices for solar two-step water splitting 査読

    Tatsuya Kodama, Tomoki Hasegawa, Ayumi Nagasaki, Nobuyuki Gokon

    PROCEEDINGS OF THE ENERGY SUSTAINABILITY CONFERENCE 2007131 ( 2 ) 821 - 829   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    A thermochemical two-step water splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting solar energy into clean hydrogen in sunbelt regions. An iron-containing YSZ (Yttrium-Stabilized Zirconia) or Fe-YSZ is a promising working redox material for the two-step water splitting cycle. The Fe2+-YSZ is formed by a high-temperature reaction between YSZ, and Fe3O4 supported on the YSZ at 1400 degrees C in an inert atmosphere. The Fe2+-YSZ reacts with steam and generate hydrogen at 1000-1100 degrees C, to form Fe3+-YSZ that is re-activated by a thermal reduction in a separate step at temperatures above 1400 degrees C under an inert atmosphere. In the present work, a ceramic foam coated with the Fe-YSZ particles is examined as the thermochemical water splitting device for use in a solar-directly-irradiated receiver/reactor system. The Fe-YSZ particles were coated on an Mg-partially-stabilized zirconia foam disk and the foam device was tested on the two-step water splitting cycle being performed alternately at temperatures between 1100 and 1400 degrees C. The foam device was irradiated by concentrated visible light from a sun-simulator at the peak flux density of 1000 kW/m(2) and the average flux density of 470 kW/m(2) in a N-2 gas stream, and then, was reacted with steam at 1100 degrees C while heating by an infrared furnace. Hydrogen successfully continued to be produced in the repeated cycles.

    DOI: 10.1115/1.3090819

    Web of Science

    researchmap

  • Reactive Fe-YSZ coated foam devices for solar two-step water splitting 査読

    Tatsuya Kodama, Tomoki Hasegawa, Ayumi Nagasaki, Nobuyuki Gokon

    PROCEEDINGS OF THE ENERGY SUSTAINABILITY CONFERENCE 2007   821 - 829   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    A thermochemical two-step water splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting solar energy into clean hydrogen in sunbelt regions. An iron-containing YSZ (Yttrium-Stabilized Zirconia) or Fe-YSZ is a promising working redox material for the two-step water splitting cycle. The Fe2+-YSZ is formed by a high-temperature reaction between YSZ, and Fe3O4 supported on the YSZ at 1400 degrees C in an inert atmosphere. The Fe2+-YSZ reacts with steam and generate hydrogen at 1000-1100 degrees C, to form Fe3+-YSZ that is re-activated by a thermal reduction in a separate step at temperatures above 1400 degrees C under an inert atmosphere. In the present work, a ceramic foam coated with the Fe-YSZ particles is examined as the thermochemical water splitting device for use in a solar-directly-irradiated receiver/reactor system. The Fe-YSZ particles were coated on an Mg-partially-stabilized zirconia foam disk and the foam device was tested on the two-step water splitting cycle being performed alternately at temperatures between 1100 and 1400 degrees C. The foam device was irradiated by concentrated visible light from a sun-simulator at the peak flux density of 1000 kW/m(2) and the average flux density of 470 kW/m(2) in a N-2 gas stream, and then, was reacted with steam at 1100 degrees C while heating by an infrared furnace. Hydrogen successfully continued to be produced in the repeated cycles.

    Web of Science

    researchmap

  • New solar water-splitting reactor with ferrite particles in an internally circulating fluidized bed 査読

    Nobuyuki Gokon, Shingo Takahashi, Hiroki Yamamoto, Tatsuya Kodama

    PROCEEDINGS OF THE ENERGY SUSTAINABILITY CONFERENCE 2007   831 - 839   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    The thermal reduction of metal oxides as part of a thermochemical two-step water splitting cycle requires the development of a high temperature solar reactor operating at 1000-15000 degrees C. Direct solar energy absorption by metal-oxide particles provides efficient heat transfer directly to the reaction site. This paper describes experimental results of a windowed thermochemical water-splitting reactor using an internally circulating fluidized bed of the reacting metal-oxide particles under direct solar irradiation. The reactor has a transparent quartz window on the top as aperture. The concentrated solar radiation passes downward through the window and directly heats the internally circulating fluidized bed of metal-oxide particles. Therefore, this reactor needs to be combined with a solar tower or beam down optics.
    NiFe2O4/M-ZrO2 (Ni-ferrite supported on zirconia) particles is loaded as the working redox material in the laboratory scale reactors, and thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally-reduced sample is oxidized back to Ni-ferrite with steam at 1000 degrees C. As the results, the conversion of ferrite reached about 44% of maximum value in the reactor by 1 kW of incident solar power. The effects of preheating temperature and particle size of NiFe2O4/m-ZrO2 were tested for thermal reduction of internally circulating fluidized bed in this paper.

    Web of Science

    researchmap

  • A Thermochemical Two-Step Water-Splitting Cycle with Magnetite-coated Ceramic Foam Device 査読

    Ayumi Nagasaki, Koichi Sakai, Nobuyuki Gokon, Tatsuya Kodama

    The 4th International Symposium on Advanced Materials in Asia-Pacific Rim, Niigata, Niigata, Japan, July 13-15 2007   2007年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Ru/Ni-Mg-O catalyzed SiC-foam absorber for solar reforming receiver-reactor 査読

    Tatsuya Kodama, Takuya Moriyama, Takehiro Shimoyama, Nobuyuki Gokon, Hidemasa Andou, Nobuhiro Satou

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME128 ( 3 ) 318 - 325   2006年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME  

    High-temperature solar reforming of methane with CO2 is investigated using a directly solar-irradiated absorber subjected to a solar mean flux level above 400 kW m(-2) (the peak flux of about 700 kW m(-2)). The new type of catalytically activated ceramic foam absorber-a Ru/Ni-Mg-O catalyzed SiC-foam absorber-was prepared, and its activity was tested in a laboratory-scale volumetric receiver-reactor with a transparent (quartz) window by using a sun-simulator Compared to conventional Rh/Al2O3 catalyzed SiC-foam absorber, this new catalytic absorber is more cost effective and is found to exhibit a superior reaction performance at the high solar flux or at high temperatures, especially above 950 degrees C. This new absorber will be applied in solar receiver-reactor systems for converting concentrated high solar fluxes to chemical fuels via endothermic natural-gas reforming at high temperatures.

    DOI: 10.1115/1.2210497

    Web of Science

    researchmap

  • Direct detection of redox reactions of sulfur-containing compounds on ferrite nanoparticle (FP) surface 査読

    Kosuke Nishio, Nobuyuki Gokon, Shingo Tsubouchi, Morihito Ikeda, Hiroki Narimatsu, Satoshi Sakamoto, Yasuo Izumi, Masanori Abe, Hiroshi Handa

    CHEMISTRY LETTERS35 ( 8 ) 974 - 975   2006年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    Direct observation of sulfur sites for sulfur-containing compounds (cysteine and its oxidative derivatives) on ferrite nanoparticles (FP) was performed by X-ray adsorption near edge structure (XANES) measurements. XANES spectra of cysteine derivatives conjugated with FP indicated that redox reactions occurred on the FP surface. Cysteine was completely oxidized to cystine and cysteinesulfinic acid and cysteic acid were partially reduced. These studies revealed that the FP surface should possess both an oxidation and reduction reactive center for sulfur-containing functional groups.

    DOI: 10.1246/cl.2006.974

    Web of Science

    researchmap

  • Double-walled reactor tube with molten salt thermal storage for solar tubular reformers 査読

    T Hatamachi, T Kodama, Y Isobe, D Nakano, N Gokon

    JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME128 ( 2 ) 134 - 138   2006年5月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ASME-AMER SOC MECHANICAL ENG  

    This paper proposes a novel-type of "double-walled" reactor tube with molten-salt thermal storage at high temperatures for use in solar tubular reformers. The prototype reactor tube is demonstrated on the heat-discharge and chemical reaction performances during cooling mode of the reactor tube at laboratory scale. The Na2CO3 composite material with MgO ceramics was filled into the outer annulus of the double-walled reactor tube while the Ru-based catalyst particles were filled into the inner tube. The heat discharge form the molten Na2CO3 circumvented the rapid temperature change of the catalyst bed, which resulted in the alleviation of decrease in chemical conversion during cooling mode of the reactor tube. The application of the new reactor tribes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.

    DOI: 10.1115/1.2183803

    Web of Science

    researchmap

  • Novel Synthetic Clays for Cation Exchange 査読

    T. Kodama, N. Gokon, S. Komarneni

    Advance in Science and Technology45   209 - 217   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Ru/Ni-Mg-O catalyzed SiC-foam absorber for solar reforming receiver-reactor 査読

    Tatsuya Kodama, Takuya Moriyama, Takehiro Shimoyama, Nobuyuki Gokon

    Solar Engineering 2005   697 - 705   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    High-temperature solar reforming of methane with CO2 is investigated using a directly solar-irradiated 2 absorber subjected to a solar mean flux level above 400 kWm(-2) (the peak flux of about 700 kWm(-2)). The new type of catalytically-activated ceramic foam absorber - an Ru/Ni-Mg-O catalyzed SiC foam absorber - was prepared and its activity was tested in a laboratory-scale volumetric receiver-reactor with a transparent (quartz) window by using a sun-simulator. Compared to conventional Rh/Al2O3 catalyzed SiC foam absorber, this new catalytic absorber is more cost-effective and is found to exhibit a superior reaction performance at the high solar flux or at high temperatures, especially above 950 degrees C. This new absorber will be applied in solar receiver-reactor systems for converting concentrated high solar fluxes to chemical fuels via endothermic natural-gas reforming at the high temperatures.

    Web of Science

    researchmap

  • Iron-containing YSZ (Yttrium-Stabilized Zirconia) system for a two-step thermochemical water splitting 査読

    N. Gokon, T. Mizuno, Y. Nakamuro, T. Kodama

    13th International Symposium on Concentrated Solar Power and Chemical Energy Technologies, Seville Spain, June 20-23, 2006.   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • A new solar chemical reactor with an internally circulating fluidized bed for direct irradiation of reacting particles 査読

    T. Kodama, S. Enomoto, T. Hatamachi, N. Gokon

    13th International Symposium on Concentrated Solar Power and Chemical Energy Technologies, Seville Spain, June 20-23, 2006.   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Double-walled reactor tube with molten salt thermal storage for solar tubular reformers 査読

    T. Hatamachi, T. Kodama, Y. Isobe, D. Nakano, N. Goukon

    Solar Engineering 2005   691 - 695   2006年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER SOC MECHANICAL ENGINEERS  

    This paper proposes a novel type of "double-walled" reactor tube with molten-salt thermal storage at high temperatures for use in solar tubular reformers. The prototype reactor tube is demonstrated on the heat-discharge and chemical reaction performances during cooling mode of the reactor tube at laboratory scale. The Na2CO3 composite material with MgO ceramics was filled into the outer annulus of the double-walled reactor tube while the Ru-based catalyst particles were filled into the inner tube. The heat discharge form the molten Na2CO3 circumvented the rapid temperature change of the catalyst bed, which resulted in the alleviation of decrease in chemical conversion during cooling mode of the reactor tube. The application of the new reactor tubes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.

    Web of Science

    researchmap

  • Solar thermochemical process for hydrogen production using ferrites 査読

    H Kaneko, N Gokon, N Hasegawa, Y Tamaura

    ENERGY30 ( 11-12 ) 2171 - 2178   2005年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    A two-step water splitting process using the ZnFe2O4/Zn/Fe3O4 reaction system was proposed for H-2 generation utilizing concentrated solar heat. The mixture of Zn and Fe3O4 was heated to 873 K in flowing steam with an Ar carrier gas, and the H2 gas was generated at 93.4% of the theoretical yield for the reaction of 3Zn+2Fe(3)O(4)+ 4H(2)O=3ZnFe(2)O(4)+4H(2) (H-2 generation step). The XRD and Mossbauer spectroscopy showed that the Zn-submitted ferrite (ZnxFe3-xO4; 0.2 <= x <= 1) (main solid product) and ZnO (minor) were formed in the solid products after the H-2 generation reaction. The ZnFe2O4 product, which was formed after the H-2 generation step during the two-step water splitting process with the ZnFe2O4/Zn/Fe3O4 system, could be decomposed into Zn (and ZnO) and Fe3O4 by the Xe beam irradiation at 1900 K after 3 min with a 67.8% yield for the reaction of 3ZnFe(2)O(4) = 3Zn + 2Fe(3)O(4) + 2O(2) (O-2 releasing step = solar thermal step). (c) 2004 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.energy.2004.08.020

    Web of Science

    researchmap

  • Novel Medical Ferrite Nanobeads with Bioactive Molecules Immobilized Strongly onto the Surfaces 査読

    Masanori Abe, Nobuhiro Matsushita, Masaru Tada, Nobuyuki Gokon, Kosuke Nishio, Hiroshi Handa

    Material Research Society Symposium, San francisco, U.S.A., March 28-April 1, 2005.   2005年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Polymer coating of ferrite nanoparticles by using “connecter” chemical compounds” 査読

    Shingo Tsubouchi, Kosuke Nishio, Morihito Ikeda, Hiroki Narimatsu, Mamoru Hatakeyama, Nobuyuki Gokon, Hiroshi Handa

    International Conference on Ferrite, San francisco, U.S.A. August 23-27, 2004.   449 - 454   2005年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    Web of Science

    researchmap

  • Solar hydrogen generation with H2O/ZnO/MnFe2O4 system 査読

    M Inoue, N Hasegawa, R Uehara, N Gokon, H Kaneko, Y Tamaura

    SOLAR ENERGY76 ( 1-3 ) 309 - 315   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The hydrogen generation reaction in the H2O/ZnO/MnFe2O4 system was studied to clarify the possibility of whether this reaction system can be used for the two-step water splitting to convert concentrated solar heat to chemical energy of H-2. At 1273 K, the mixture of ZnO and MnFe2O4 reacted with water to generate H-2 gas in 60% yield. X-ray diffractometry and chemical analysis showed that 48 mol% of Mn-II (divalent manganese ion) in the A-site of MnFe2O4 was substituted with Zn-II (divalent zinc ion) and that chemical formula of the solid product was estimated to be (Zn0.58Mn0.42Mn0.39Fe1.61O4)-Mn-II-Fe-III (Mn-III : trivalent manganese ion). Its lattice constant was smaller than that of the MnFe2O4 (one of the two starting materials). From the chemical composition, the reaction mechanism of the H-2 generation with this system was discussed. Since the Mn ions in the product solid after the H-2 generation reaction are oxidized to Mn3+, which can readily release the O2- ions as O-2 gas around 1300 K, the two-step of H-2 generation and O-2 releasing seem to be cyclic. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2003.08.033

    Web of Science

    researchmap

  • Synthesis of monodisperse ferrite nanoparticles coated with polyacrilic acid (PAA) 査読

    K. Nishio, M. Hasegawa, M. Ikeda, H. Narimatsu, Y. Hase, Y. Ogura, N. Gokon, S. Tsubouchi, M. Hatakeyama, M. Abe, H. Handa

    Transactions of the Materials Research Society of Japan29 ( 4 ) 1659 - 1662   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Decomposition of Zn-ferrite for O-2 generation by concentrated solar radiation 査読

    H Kaneko, T Kodama, N Gokon, Y Tamaura, K Lovegrove, A Luzzi

    SOLAR ENERGY76 ( 1-3 ) 317 - 322   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The O-2 generation step in two-step water splitting with Zn-ferrite/Zn, Fe3O4 system was studied with a stainless steel reactor having a window of quartz glass plate (Sandwich Reactor) using the 15 kW solar dish concentrator in Australian National University. The reactant flat layer with a small thickness in the Sandwich Reactor was assumed to simulate the flow section of the particle cloud reactor. The temperature of the sample attained 1750 K in a few minutes by concentrated solar radiation, and 40% molar of the Zn-ferrite was decomposed into Fe3O4 to produce Zn0.4Fe2.6O4, which is the solid solution between ZnFe2O4 and Fe3O4. The laboratory experiment with the Xe beam irradiation showed that the Zn-ferrite decomposition reaction proceeds according to (3)/2ZnFe2O4 = (3)/Zn-2 + Fe3O4 + O-2. In the solar furnace experiment, the metal Zn vapor produced according to this equation seems to be deposited on the surface of the inner wall of the reactor, or it seems to recombine with the released O-2, converting to ZnO under the condition without quenching system in the present experimental setup. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2003.08.034

    Web of Science

    researchmap

  • Decomposition of Zn-ferrite for O-2 generation by concentrated solar radiation 査読

    H Kaneko, T Kodama, N Gokon, Y Tamaura, K Lovegrove, A Luzzi

    SOLAR ENERGY76 ( 1-3 ) 317 - 322   2004年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The O-2 generation step in two-step water splitting with Zn-ferrite/Zn, Fe3O4 system was studied with a stainless steel reactor having a window of quartz glass plate (Sandwich Reactor) using the 15 kW solar dish concentrator in Australian National University. The reactant flat layer with a small thickness in the Sandwich Reactor was assumed to simulate the flow section of the particle cloud reactor. The temperature of the sample attained 1750 K in a few minutes by concentrated solar radiation, and 40% molar of the Zn-ferrite was decomposed into Fe3O4 to produce Zn0.4Fe2.6O4, which is the solid solution between ZnFe2O4 and Fe3O4. The laboratory experiment with the Xe beam irradiation showed that the Zn-ferrite decomposition reaction proceeds according to (3)/2ZnFe2O4 = (3)/Zn-2 + Fe3O4 + O-2. In the solar furnace experiment, the metal Zn vapor produced according to this equation seems to be deposited on the surface of the inner wall of the reactor, or it seems to recombine with the released O-2, converting to ZnO under the condition without quenching system in the present experimental setup. (C) 2003 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.solener.2003.08.034

    Web of Science

    researchmap

  • Photocatalytic effect of ZnO on carbon gasification with CO2 for high temperature solar thermochemistry 査読

    N Gokon, N Hasegawa, H Kaneko, H Aoki, Y Tamaura, M Kitamura

    SOLAR ENERGY MATERIALS AND SOLAR CELLS80 ( 3 ) 335 - 341   2003年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A photocatalytic effect of ZnO on carbon gasification with CO2 was studied using a concentrated Xe beam to enhance the gasification rate in solar/chemical energy conversion process. The sample, activated carbon impregnated with ZnO (5 wt%), was heated at 873 K by a Xe beam irradiation with UV (< 400 nm). The gasification rate at 873 K increased 2 folds in comparison with the Xe irradiation without UV, but, the difference of the rate of CO evolution decreased with the increasing temperature from 873 to 1073 K. The carbothermal reduction of ZnO (ZnO + C --> Zn + CO) proceeded at above 950 K, which was demonstrated by XRD analysis and thermodynamic calculation. These results indicate that the photocatalytic effect of ZnO with the UV irradiation enhance the gasification rate of carbon at low temperature (873 K). (C) 2003 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.solmat.2003.08.016

    Web of Science

    researchmap

  • A high magnetic field effect on the M(II)-substituted magnetite formation (M = Ni, Mn, Co) in the wet process 査読

    N Gokon, N Hasegawa, H Kaneko, T Ohara, Y Tamaura

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS256 ( 1-3 ) 293 - 300   2003年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The M(II)-substituted magnetite (M = Ni, Co and Mn) formation in the wet process in a high magnetic field from 0 to 8 T generated by a superconducting magnet has been studied at the iron ion concentration of 1500 mg/l and the Fe(II)/ Fe(III) mole ratios (R-f) of 1/2 and 2/1. The particle size of the M(II)-substituted magnetite was about 12 nm at R-f and T about 7 nm at R-f The Ni(II) content of the Ni(II)-substituted magnetite at R-f = 2 was lower than that at R-f=1/2 . In 2 T 2 the Ni(II)-substituted magnetite, the lattice parameter increases with an increase in the magnetic field from 0 to 8 T, indicating that high magnetic fields enhance the formation of the Ni(II)-substituted magnetite (solubility enhancement of Ni(II) to magnetite). Also, the lattice parameter of the Co (II)- substituted magnetite decreased with the increasing magnetic field, however, an increase in the lattice parameter was not found in the Mn(II)-substituted magnetite. The presence of large amounts of vacancies was found in the Ni(II)-substituted magnetite formed in high magnetic fields by XRD and atomic absorption analysis. This result is supported by the experimental result in which the magnetite formed in a high magnetic field tends to adsorb Ni(II) in a high magnetic field, and results in the higher incorporation of Ni(II) into the spinel structure. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(02)00582-6

    Web of Science

    researchmap

  • Synthesis of monodisperse ferrite nanoparticles coated with polyacrilic acid (PAA) 査読

    K. Nishio, M. Hasegawa, M. Ikeda, H. Narimatsu, Y. Hase, Y. Ogura, N. Gokon, M. Abe, H. Handa

    Material Research Society Japan, Yokohama, Japan, 11?13 October 2003.   2003年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Reaction mechanism of H-2 generation for H2O/Zn/Fe3O4 system 査読

    H Kaneko, N Kojima, N Hasegawa, M Inoue, R Uehara, N Gokon, Y Tamaura, T Sano

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY27 ( 10 ) 1023 - 1028   2002年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Several ideas on the reaction mechanism of H2O/Zn/Fe3O4 water splitting system were considered from the aspect of Zn mobility. The vapor deposition of Zn onto the Fe3O4 surface was confirmed by H-2 generation reaction with Zn and Fe3O4 set separately. XPS measurements suggested that the surface of Fe3O4 is covered by Zn before the reaction with steam. The rapid reaction process has been supported by this Zn deposition, which greatly enlarges the number of sites of Zn/Fe3O4 pair that is ready to react with steam. In order to keep the Zn from vaporizing off the system, the Zn/Fe3O4 mixture was covered with additional Fe3O4 to capture the Zn vapor. This resulted in improved H2 yield of 99.5%. (C) 2002 Published by Elsevier Science Ltd on behalf of the International Association for Hydrogen Energy.

    DOI: 10.1016/S0360-3199(02)00012-5

    Web of Science

    researchmap

  • The magnetic coagulation reaction between paramagnetic particles and iron ions coprecipitates 査読

    N Gokon, A Shimada, N Hasegawa, H Kaneko, Y Tamaura, K Ito, T Ohara

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS246 ( 1-2 ) 275 - 282   2002年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The relationship between the particle size of iron ion coprecipitates and magnetic coagulation reaction has been studied for application to water purification using magnetic separation system. The Fe(III) phosphate complex (IP) precipitate was used as a paramagnetic substance. At a high magnetic field of 8 T, the IP amount recovered by magnetic separation gradually increased with increasing Fe(III) ion concentration in the solution (by increasing the Fe/P mole ratio). However, at a low magnetic field of 0.8 T, it remained constant at about 30%. The magnetic coagulation reaction of the paramagnetic particles of the IP (Fe/P = 1.68) was enhanced by the addition of ferrimagnetic Fe3O4 particles, and that the recovery efficiency became higher with a smaller particle size of Fe3O4. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(02)00074-4

    Web of Science

    researchmap

  • Magnetic coagulation and reaction rate for the aqueous ferrite formation reaction 査読

    N Gokon, A Shimada, H Kaneko, Y Tamaura, K Ito, T Ohara

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS238 ( 1 ) 47 - 55   2002年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The aqueous ferrite formation reaction with addition of Fe(II) and Fe(111) ions in an alkaline solution in a high magnetic field has been investigated at iron ion concentrations of 150, 750 and 1500 ppm and at Fe(II)/Fe(III) mole ratio of 1 (chemical composition of the stoichiometric Fe3O4) and 2/1 (chemical composition of GR-I In the case of 2 Fe(II)/Fe(III) = 1/2, the magnetic coagulation reaction occurring in the magnetic field range of 0-1 T is different from that in the range of 2-10 T. The higher magnetic field enhanced the reaction rate of the aqueous ferrite formation due to the increase in the intermediate concentration at Fe(II)/Fe(III) = 2/1. The increase in the initial reaction rate can be explained in terms of the increase in the nucleus numbers in the nuclei formation period. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0304-8853(01)00703-X

    Web of Science

    researchmap

  • Water Splitting by Using a Metal Oxide for Solar Thermal/Chemical Energy Conversion 査読

    Hiroshi Kaneko, Nobuyuki Gokon, Noriko Hasegawa, Masafumi Inoue, Reiko Uehara, Yutaka Tamaura

    Eco-Engineering14 ( 4 ) 3 - 9   2002年

     詳細を見る

    記述言語:英語  

    DOI: 10.11450/seitaikogaku.14.4_3

    researchmap

  • フェリ磁性体を用いた環境水中のリン及び重金属イオンの磁気分離 査読

    郷右近 展之, 島田 綾乃, 長谷川 紀子, 金子 宏, 小原 健司, 玉浦 裕

    水環境学会誌25 ( 1 ) 33 - 38   2002年

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.2965/jswe.25.33

    researchmap

  • Methane reforming with CO2 in molten salt using FeO catalyst 査読

    N Gokon, Y Oku, H Kaneko, Y Tamaura

    SOLAR ENERGY72 ( 3 ) 243 - 250   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Methane dry reforming with CO2 using FeO powder in molten salt has been investigated at various flow rates of CH4/CO3 mixed gases (CH4/CO2 = 1) between 50 and 400 ml/min at 1223 K in an infrared furnace. This work is carried out to determine the usefulness of this method for the chemical storage of solar energy. The CH4/CO2 mixed gases passing through the molten salt (Na2CO3/K2CO3 = 1) containing the FeO powder were catalytically decomposed into CO, H-2 and H2O. The product gas mole ratios, CO/H-2/H2O, were shown to be 3:1:1 for a high flow rate of 200 ml/min and to be CO/H-2 = 2:1 for a low flow rate of 50 ml/min. The results were explained in terms of the kinetics of the CH4-reforming reaction and the thermodynamics of the redox process of FeO powder mixed in the molten salt;
    CH4 + 2FeO double right arrow 2Fe + H-2 + CO + H2O
    Fe + CO2 double right arrow FeO + CO
    for a high How rate, and
    FeO + CH4 double right arrow Fe + 2H(2) + CO
    Fe + CO4 double right arrow FeO + CO
    for a low flow rate. (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0038-092X(01)00097-4

    Web of Science

    researchmap

  • Thermodynamic study based on the phase diagram of the Na2O-MnO-Fe2O3 system for H-2 production in three-step water splitting with Na2CO3/MnFe2O4/Fe2O3 査読

    H Kaneko, Y Ochiai, K Shimizu, Y Hosokawa, N Gokon, Y Tamaura

    SOLAR ENERGY72 ( 4 ) 377 - 383   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The phase diagram of the Na2O-MnO-Fe2O3 system forms the basis for thermodynamic consideration of H-2 production in water splitting with the Na2CO3/MnFe2O4/Fe2O3 system. Sodium iron manganese oxides Na0.7-1 (Mn1-x, Fe-x)O2+delta. were observed in the phase diagram at T = 1273 K under P-O2 = 1.23 X 10(-5) atm. Confirmation of this phase, especially for x > 0.5, suggests the possibility of H-2 generation under this oxygen partial pressure and results in a value of 1:37 for the ratio of P-H2:P-H2O in the H-2 generation step of water splitting. This oxygen partial pressure is realized by the decomposition of carbon dioxide (CO2 = CO + 0.5O(2)) and it is concluded that the H-2 generation step can proceed under CO2 atmosphere. (C) 2002 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0038-092X(02)00012-9

    Web of Science

    researchmap

  • 強磁場におけるFe2+ / Fe3+懸濁溶液を用いた湿式フェライト生成反応 査読

    郷右近 展之, 長谷川 紀子, 金子 宏, 玉浦 裕, 小原 健司

    粉体および粉末冶金49 ( 8 ) 710 - 716   2002年

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.2497/jjspm.49.710

    Scopus

    researchmap

  • Ferrimagnetic coagulation process for phosphate ion removal using high-gradient magnetic separation 査読

    N Gokon, A Shimada, N Hasegawa, H Kaneko, M Kitamura, Y Tamaura

    SEPARATION SCIENCE AND TECHNOLOGY37 ( 16 ) 3781 - 3791   2002年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:MARCEL DEKKER INC  

    An efficient magnetic separation system for phosphate ion removal has been studied for developing a practical environmental protection technology for water purification in rivers, lakes, etc. using ferrimagnetic fine particles (FMFPs), which can be prepared from FeCl2 and FeCl3,aqueous solutions. With 15 mg/L of FeCl3 solution, without the addition of FMFP, phosphate ion recovery increased from 20 to 80% with increasing magnetic field from 0.8 to 8 T. By the addition of 5 mg/L of FMFP with 15 mg/L of FeCl3 solution, above 95% recovery was achieved in a wide range of magnetic field (H = 0.8-8 T). A high magnetic field gradient generated in the vicinity of steel wool caused the enhancement of the magnetic coagulation of the complex with phosphate ion and Fe(III) ion, and the paramagnetic iron-phosphate complexes were attracted to FMFP in the reactor, which resulted in high (95%) recovery in a wide range of magnetic fields.

    DOI: 10.1081/SS-120014831

    Web of Science

    researchmap

  • Studies on metal oxides suitable for enhancement of the O-2-releasing step in water splitting by the MnFe2O4-Na2CO3 system 査読

    H Kaneko, Y Hosokawa, N Kojima, N Gokon, N Hasegawa, M Kitamura, Y Tamaura

    ENERGY26 ( 10 ) 919 - 929   2001年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Reactivities of three metal oxides (Fe2O3, TiO2 and MnO2) with Na2CO3, and of their reaction products with CO2, have been studied to enhance the O-2-releasing step in the two-step water splitting by the MnFe2O4-Na2CO3 system. X-ray diffraction analysis and thermogravimetric measurements showed that the reaction of alpha -Fe2O3 with Na2CO3 (mole ratio=1:1) completed within 10 min at 1073 K to produce NaFeO2 (Fe2O3+Na2CO3--> NaFeO2+CO2). Also, the regeneration of Fe2O3 and Na2CO3 proceeded readily by passing CO2 gas through NaFeO2 (71% yield). TiO2 reacted with Na2CO3 (mole ratio=1:1) at 1073 K for 1 h to form Na8Ti5O14 and Na2TiO3 (93% yield). However, in the reaction of the products with CO2, the starting material (TiO2) was not reproduced at the temperature range from 673 K to 1073 K, but Na4Ti5O12 (having a lower Na content than the form Na8Ti5O14) was formed. In the case of MnO2 with Na2CO3 (mole ratio=2:1), Na0.7MnO2-2.05 and NaMnO2 were produced at 1073 K for 1 h (80% yield), but the reaction between these products and CO2 hardly proceeded. (C) 2001 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0360-5442(01)00041-X

    Web of Science

    researchmap

  • Stoichiometric studies of H-2 generation reaction for H2O/Zn/Fe3O4 system 査読

    Y Tamaura, N Kojima, N Hasegawa, M Inoue, R Uehara, N Gokon, H Kaneko

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY26 ( 9 ) 917 - 922   2001年9月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Water splitting with H2O/Zn/Fe3O4 reaction system is suggested for H-2 generation in order to utilize concentrated solar heat. This system has the possibility of generating more H-2 per 1 mol of Zn than Zn/H2O reaction system at the same temperature, which is noted recently. When a mixture of Zn and FC3O4 was heated to 873 K and steam was passed through, H-2 was obtained in 93.4% of the theoretical yield. The formation of Zn-ferrites with high content of zinc (ZnxFe3-xO4; 0.2 less than or equal to x less than or equal to 1) and ZnO was determined by XRD and Mossbauer spectroscopy. The yield of ZnO was 26-29%, which shows that the ratio of the competition-reaction (Zn/H2O system) has less effects on the total H-2 yield. The stoichiometry and the reaction mechanism of the system are discussed upon the analyses for the solid product. (C) 2001 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0360-3199(01)00039-8

    Web of Science

    researchmap

  • Enhancement of Op-releasing step with Fe2O3 in the water splitting by MnFe2O4-Na2CO3 system 査読

    H Kaneko, Y Hosokawa, N Gokon, N Kojima, N Hasegawa, M Kitamura, Y Tamaura

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS62 ( 7 ) 1341 - 1347   2001年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    In the O-2-releasing step of water splitting system, MnFe2O4 was completely regenerated from Na(Mn1/3Fe2/3)O2+delta by enhancement of O-2-releasing step with Fe2O3 at 1273 K. Thermodynamic data for the enhancement of the O-2-releasing step with alpha -Fe2O3 in the water splitting with the MnFe2O3-Na2CO3 system are experimentally confirmed. The amount of released oxygen attained to the theoretical value at around 1273 K (Po-2 = 10(-6)) and about 1240 K (Po-2 = 10(-7)). At higher temperature above 1273 K (Po-2 = 10(-6)) and 1240 K (Po-2 = 10(-7)), the released oxygen amount increased. In the three-step water splitting system with MnFe2O3-Na2CO3-Fe2O3, we proposed that there are some advantages required for application to the solar thermochemical process. (C) 2001 Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0022-3697(01)00034-8

    Web of Science

    researchmap

  • Solar Hydrogen Generation with H2O/ZnO/MnFe2O4 System 査読

    M. Inoue, R. Uehara, N. Hasegawa, N. Gokon, H. Kaneko, Y. Tamaura

    International Solar Energy Society 2001 Solar World Congress, Adelaide, Australia, November 25-30, 2001.   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Oxygen uptake and release mechanism of lithium manganese ferrite in the low temperature range of 573-773 K 査読

    T Sano, M Tsuji, N Gokon, H Kaneko, Y Tamaura

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY83 ( 10 ) 2509 - 2514   2000年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CERAMIC SOC  

    Oxygen uptake and release of (Li,Mn) ferrite [LMF; (Li0.60Mn1.20Fe1.20)(1-delta)O-4; delta = 0.007 to 0.033] was investigated concerning the relations between redox reactions of ferrite and cation migration. Mossbauer spectroscopy and X-ray diffractometry showed that some of the Li+ and Fe3+ ions migrated from the A sites to the B sites of the spinel-type structure and Mn4+ ions migrated from the B sites to the A sites during oxygen uptake at 573 K. The cation-deficient LMF formed by the oxygen uptake released oxygen molecules in He gas only at 660 K. The cation migration during the oxygen release was in the opposite direction of the movement during oxygen uptake at 573 K.

    Web of Science

    researchmap

  • Growth behavior of fine grains formed by diffusion induced recrystallization in the Cu(Zn) system 査読

    N Goukon, T Ikeda, M Kajihara

    ACTA MATERIALIA48 ( 11 ) 2959 - 2968   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The growth behavior of fine grains produced due to diffusion induced recrystallization (DIR) was experimentally studied for the Cu(Zn) system using single crystal Cu specimens. The Cu specimens were annealed at 693 K for various times together with st Zn source alloy by a capsule zincification technique and then DIR was observed to take place on the surfaces of the specimens. The DIR region consists of an almost single layer of fine grains. Although the average height I and the average diameter s of the fine grains increase with increasing annealing time, the aspect ratio s/l is kept to be nearly unity during annealing. The Zn concentration on the specimen surface is smaller than that in the Zn source alloy at early stages of the reaction. Such lower Zn concentrations could be explained using the maximum driving force model proposed by Kajihara and Gust (Acta metall. mater., 1991, 39, 2565). The composition on the specimen surface gradually approaches the equilibrium value with increasing annealing time. This means that the amount of the Zn source alloy is large enough to maintain the supply of Zn atoms to the specimen in each zincification capsule. The kinetic model by Li and Hillert (Acta metall., 1981, 29, 1949) and the extended model by Kawanami ct al. (ISIJ int., 1997, 37, 921) could rather well reproduce the annealing time dependence of the growth rate of the DIR region. The contribution of volume diffusion to the transfer of Zn atoms from the surface to the moving boundaries in the DIR region was estimated to be negligible. Thus, the chemical driving force is considered to be the most important driving force for the grain boundary migration and the boundary diffusion along the grain boundaries in the DIR region is recognized to be the rate controlling process of DIR. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Lid. AII rights reserved.

    DOI: 10.1016/S1359-6454(00)00096-3

    Web of Science

    researchmap

  • Boundary energies of Sigma 11 [110] asymmetric tilt boundaries in Cu determined from the shape of boundary silica particles 査読

    N Goukon, T Yamada, M Kajihara

    ACTA MATERIALIA48 ( 11 ) 2837 - 2842   2000年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The boundary energies of Sigma 11 [110] asymmetric tilt boundaries with a misorientation angle of theta = 50.5 degrees in Cu have been experimentally determined by a silica particle observation method for various inclination angles between phi = 0 and 90 degrees. This method has no drawbacks that are inevitable in boundary grooving and tri-junction methods. In the boundary energy vs inclination angle diagram, three deep cusps exist at phi = 10, 64.8 and 90 degrees whereas a shallow cusp appears at phi = 35.3 degrees. Such inclination angle dependence of the boundary energy has been utilized to analyze the faceting of the boundary. The observations on the faceting reported for Sigma 11 [110] tilt boundaries in face-centered cubic (f.c.c.) metals have been quantitatively accounted for by the present analysis. (C) 2000 Acta Metallurgica inc. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S1359-6454(00)00103-8

    Web of Science

    researchmap

  • Characteristic features of diffusion induced grain boundary migration for Sigma 9 [110] asymmetric tilt boundaries in the Cu(Zn) system 査読

    N Goukon, T Ikeda, M Kajihara

    ACTA MATERIALIA48 ( 7 ) 1551 - 1562   2000年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The characteristic features of diffusion induced grain boundary migration (DIGM) in the Cu(Zn) system were experimentally studied for [110] asymmetric tilt boundaries using Cu bicrystals annealed at 693 K for various times by a capsule zincification technique. The experiment was carried out for the boundaries with inclination angles of phi = 0, 20, 35, 55, 65 and 90 degrees and with a constant misorientation angle of theta = 39 degrees (Sigma 9). During annealing, the grain boundary migrates towards a crystal grain of larger coherency strain energy with higher probability due to DIGM. Taking elastic anisotropy of each crystal grain into consideration, the difference between the probabilities of grain boundary migration towards both side grains can be accounted for by the coherency strain model proposed by Hillert. The migration rate v of the moving boundary is almost constant regardless of the annealing time t between t = 72 and 384 h (2.59 x 10(5) and 1.38 x 10(6) s). The value of v monotonically decreases with increasing inclination angle. This implies that the boundary diffusion coefficient of Zn in Cu is a monotone decreasing function of the inclination angle. The experimental results on the kinetics at the steady state stage were theoretically analyzed using the energy balance model proposed by Kajihara and Gust (Scripta mater., 1998, 38, 1621. The analysis indicates that the effective driving force Delta(ef)G for the grain boundary migration is merely one-thirtieth of the chemical driving force, whereas it still remains three times greater than the minimum value corresponding to the coherency strain energy during DIGM under the present, experimental conditions. The mobility of the moving boundary was evaluated to be M = 3.77 x 10(-17) m(4)/Js from the values of v and Delta(ef)G according to the relationship M = v/Delta(ef)G. This value of M is close to the results estimated by Yamamoto et al, (Acta mater., 1999, 47, 1757) for the [100] twist and random boundaries in the Cu(Zn) system. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S1359-6454(99)00424-3

    Web of Science

    researchmap

  • Cu双結晶における[110]ねじれ粒界および傾角粒界の材料組織学的性質 査読

    郷右近展之

    東京工業大学   2000年

     詳細を見る

    記述言語:日本語   掲載種別:学位論文(博士)  

    researchmap

  • Solar H2 Production by Two Step Water Splitting with Zn-Ferrite-Fe3O4 System 査読

    Y. TAMAURA, N. HASEGAWA, N. KOJIMA, N.GOKON, H. KANEKO

    International Conference on Ferrite, Kyoto, September 18-21, 2000.   2000年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • Methane Reforming with CO2 in Molten Salt Using FeO Catalyst 査読

    N. GOKON, Y. OKU, H. KANEKO, Y. TAMAURA

    International Conference on Ferrite, Kyoto, September 18-21, 2000.   2000年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

  • H2 Generation by H2O/Zn/Fe3O4 Reaction System 査読

    N. KOJIMA, N. HASEGAWA, R. UEHARA, N. GOKON, H. KANEKO, Y. TAMAURA

    International Conference on Ferrite, Kyoto, September 18-21, 2000.   2000年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    researchmap

▶ 全件表示

書籍等出版物

  • アンモニアを用いた水素エネルギーシステム

    児玉 竜也, 郷右近展之( 担当: 分担執筆 ,  範囲: 第3章 高温熱化学水素製造)

    シーエムシー出版  2015年6月  ( ISBN:9784781310732

     詳細を見る

    総ページ数:vi, 239p  

    CiNii Books

    researchmap

  • 水素エネルギーの開発と応用

    郷右近 展之, 児玉 竜也( 担当: 分担執筆 ,  範囲: 第10章 二段階水熱分解ソーラー水素製造システムの開発)

    シーエムシー出版  2014年8月  ( ISBN:9784781309750

     詳細を見る

    総ページ数:vii, 218p   記述言語:日本語

    CiNii Books

    researchmap

  • 水素利用技術集成 vol.4 高効率貯蔵技術、水素社会構築を目指して

    岡野一清, 井関孝弥, 阿部竜, 児玉竜也, 郷右近展之, 中村優美子, 伊藤直次, 市川貴之, 高野俊夫, Eコンテイナー, 池田哲史, 利用技術研究組, 秋葉悦男, 笠井秀明, ほ

    エヌ・ティー・エス  2014年4月  ( ISBN:4864690820

     詳細を見る

    総ページ数:354  

    ASIN

    researchmap

  • 太陽熱発電・燃料化技術―太陽熱から電力・燃料をつくる (-)

    吉田 一雄, 郷右近 展之, 児玉 竜也, 日本エネルギー学会( 担当: 共著)

    コロナ社  2012年7月  ( ISBN:4339068306

     詳細を見る

    総ページ数:174  

    ASIN

    researchmap

  • 医療用マテリアルと機能膜

    西尾広介, 池田森人, 成松宏樹, 壺内信吾, 郷右近展之, 半田宏( 担当: 分担執筆 ,  範囲: 第7章 磁性ビーズ開発と医療への展開)

    シーエムシー出版  2005年5月 

     詳細を見る

  • ナノ粒子・マイクロ粒子の最先端技術

    壷内信吾, 西尾広介, 池田森人, 成松宏樹, 郷右近展之, 半田 宏( 担当: 分担執筆 ,  範囲: 4.創薬に向けた磁気アフェニティビーズの創製)

    シーエムシー出版  2004年10月 

     詳細を見る

▶ 全件表示

MISC

講演・口頭発表等

  • SolarPACES2020報告 -Gen3 CSP liquid pathway projectについて― 招待

    郷右近 展之

    太陽熱・蓄熱技術研究会  2021年3月24日 

     詳細を見る

    開催年月日: 2021年

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 潜熱蓄熱・化学蓄熱関連研究-SolarPACES2019国際会議- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2020年7月9日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 熱媒体関連研究の概要-SolarPACES2019における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2020年2月19日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2018における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2019年1月31日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 太陽集熱の水素エネルギー変換プロセス 招待

    郷右近 展之

    一般社団法人水素エネルギー協会(HESS)「第157回定例研究会」  2018年11月5日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • EXPERIMENTAL AND NUMERICAL SIMULATION OF MELTING PROCESS OF PHASE CHANGE MATERIAL FOR LATENT HEAT STORAGE SYSTEM DESIGN IN CONCENTRATED SOLAR POWEREXPERIMENTAL AND NUMERICAL SIMULATION OF MELTING PROCESS OF PHASE CHANGE MATERIAL FOR LATENT HEAT STORAGE S 招待 国際会議

    郷右近 展之

    3rd Japanese-German Workshop on Renewable Energies  2018年10月18日 

     詳細を見る

    記述言語:英語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 太陽熱発電における化学蓄熱研究の概説-SolarPACES2014-2017における研究動向を中心に- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2018年9月26日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2014-2016における研究動向- 招待

    郷右近 展之

    内閣府・戦略的イノベーション創造プログラム(SIP)における高温集熱グループ研究会  2017年6月9日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2017における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2017年 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2016における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2016年 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • R&D ACTIVITIES on CSP and solar chemistry in Japan 招待 国際会議

    郷右近 展之

    International Green Energy Business Conference  2015年4月1日 

     詳細を見る

    記述言語:英語   会議種別:口頭発表(招待・特別)  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2015における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2015年 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 潜熱・化学蓄熱関連研究の概要-SolarPACES2014における研究動向- 招待

    郷右近 展之

    集光型太陽熱技術研究会  2014年 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

▶ 全件表示

産業財産権

▶ 全件表示

受賞

  • 平成28年度 進歩賞(学術部門)

    2017年2月   日本エネルギー学会   「熱化学プロセスによる高温太陽集熱の化学燃料転換技術の開発」

    郷右近 展之

     詳細を見る

  • 第6回インテリジェント・コスモス奨励賞

    2007年5月   「温暖化ガスを排出しない再生可能エネルギーの水素燃料への転換技術の構築」

    郷右近 展之

     詳細を見る

  • 手島記念研究賞(博士論文賞)

    2001年3月   「Cu双結晶における[110]ねじれ粒界および傾角粒界の材料組織学的性質」

     詳細を見る

    受賞国:日本国

    researchmap

共同研究・競争的資金等の研究

  • 太陽熱発電のための潜熱利用型の高密度蓄熱システムの開発

    研究課題/領域番号:20K05398  2020年04月 - 2023年03月

    日本学術振興会  科学研究費助成事業 基盤研究(C)(研究分担者)  基盤研究(C)

    籏町 剛

      詳細を見る

    担当区分:研究分担者 

    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

    researchmap

  • 高温太陽集熱による未利用炭素資源の流動層ソーラーガス化水素製造システムの開発

    2019年04月 - 2022年03月

    科学研究費補助金 基盤研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • 太陽集熱による熱化学水素製造に関する研究

    2018年04月 - 2022年03月

    JXTGエネルギー株式会社 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者 

    researchmap

  • 次世代型蓄エネルギー技術実用化推進事業

    2018年04月 - 2019年03月

    環境省委託事業(研究分担者) 

    エネルギー総合工学研究所

      詳細を見る

    資金種別:競争的資金

    researchmap

  • 高熱伝導性蓄熱体を備えたソーラー天然ガス改質反応システムの開発

    2016年04月 - 2019年03月

    科学研究費補助金 基盤研究(C)(研究分担者) 

    旗町 剛

      詳細を見る

    資金種別:競争的資金

    researchmap

  • 高温太陽集熱による流動層ガス化水素製造システムの開発

    2016年04月 - 2019年03月

    科学研究費補助金 基盤研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • ソーラー水素製造用の太陽熱/光分解性反応性セラミックの開発

    2014年04月 - 2016年03月

    科学研究費助成事業 挑戦的萌芽研究 (研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • 高温太陽集熱による新型ソーラーガス化反応器の開発

    2012年04月 - 2015年03月

    科学研究費補助金 基盤研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • ソーラー水素製造のためのプロトタイプ流動層反応器の開発

    2010年04月 - 2012年03月

    科学研究費補助金 若手研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • 高温太陽熱/水素転換のための内循環流動層反応器の開発

    2008年04月 - 2010年03月

    科学研究費補助金 若手研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

  • 反応性セラミック粉体による新型ソーラー水熱分解器の開発

    2006年04月 - 2008年03月

    科学研究費補助金 若手研究(B)(研究代表者) 

    郷右近 展之

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

    researchmap

▶ 全件表示

その他研究活動

  • Associate Professor

    2009年04月
    -
    現在

     詳細を見る

    Research institute of promotion/Graduate school of science and technology, Niigata University

    researchmap

  • Associate Professor

    2005年04月
    -
    2009年03月

     詳細を見る

    Graduate school of science and technology, Niigata University

    researchmap

  • Asistant Professor

    2003年06月
    -
    2005年03月

     詳細を見る

    Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology

    researchmap

  • Research assistant

    2003年04月
    -
    2003年05月

     詳細を見る

    Graduate School of Science and Engineering,Tokyo Institute of Technology

    researchmap

  • Doctoral research fellow

    2000年04月
    -
    2003年03月

     詳細を見る

    Research Center for Carbon Recycling & Utilization(Energy), Tokyo Institute of Technology

    researchmap

 

担当経験のある授業科目

  • 技術文献リサーチC

    2020年
    -
    現在
    機関名:新潟大学

  • 技術文献リサーチA

    2020年
    -
    現在
    機関名:新潟大学

  • 技術文献リサーチD

    2020年
    -
    現在
    機関名:新潟大学

  • エネルギー材料解析化学

    2020年
    -
    現在
    機関名:新潟大学

  • 技術文献リサーチB

    2020年
    -
    現在
    機関名:新潟大学

  • 熱エネルギー材料科学

    2020年
    -
    現在
    機関名:新潟大学

  • 物理化学実験(工)

    2019年
    -
    現在
    機関名:新潟大学

  • リメディアル演習

    2018年
    機関名:新潟大学

  • 工学リテラシー入門(化学材料分野)

    2017年
    -
    現在
    機関名:新潟大学

  • 物理化学II

    2016年
    -
    現在
    機関名:新潟大学

  • 自然科学総論Ⅱ

    2015年
    機関名:新潟大学

  • 水素エネルギーシステムデザイン演習・実習Ⅰ

    2014年
    -
    現在
    機関名:新潟大学

  • 最先端技術を支える化学 I

    2011年
    -
    現在
    機関名:新潟大学

  • 反応速度論

    2009年
    -
    現在
    機関名:新潟大学

  • 卒業研修

    2009年
    -
    現在
    機関名:新潟大学

  • 化学技術英語

    2008年
    -
    現在
    機関名:新潟大学

  • 応用化学演習III

    2007年
    -
    現在
    機関名:新潟大学

  • 卒業研究

    2007年
    -
    現在
    機関名:新潟大学

  • 論文輪講I

    2007年
    -
    2019年
    機関名:新潟大学

  • 物理化学実験

    2007年
    -
    2018年
    機関名:新潟大学

  • 論文輪講II

    2007年
    -
    2018年
    機関名:新潟大学

  • 卒業基礎研究

    2007年
    -
    2008年
    機関名:新潟大学

  • 応用化学実習

    2007年
    機関名:新潟大学

▶ 全件表示

 

学術貢献活動

  • NISTEP専門調査員

    学術調査立案・実施

    文部科学省 科学技術・学術政策研究所 科学技術予測センター  2018年4月 - 現在

     詳細を見る

    種別:学術調査 

    researchmap