Faculty Profiles - GOKON Nobuyuki

Papers - GOKON Nobuyuki

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Thermal Properties of Cu–Al–Ge Alloy PCM for Improving Thermal Energy Storage of Current CSP Reviewed

Nobuyuki Gokon, Taisei Yuzawa, Takumi Kamada, Yuma Ikeuchi, Tsuyoshi Hatamachi

SolarPACES Conference Proceedings 2 2024.9

Authorship：Lead author,　Last author,　Corresponding author Language：English Publishing type：Research paper (international conference proceedings) Publisher：TIB Open Publishing

Metallic phase change material was proposed and examined at melting/eutectic temperatures less than 600 °C for latent heat storage in concentrated solar power. The PCM alloy can potentially charge/discharge thermal energy as a sensible/latent heat at the temperature range of 414-527 °C. The working temperatures of PCM alloy are in operation temperatures of current molten-salt based CSP plant. In this study, thermal response testing of PCM alloy and sensible/latent storage unit that PCM alloy was loaded in a ceramic honeycomb were prepared in a laboratory scale. The thermal charging/discharging performance of PCM alloy and sensible/latent storage unit were experimentally examined and compared. The storage unit provided thermal release/absorption behaviour at close to temperatures of the thermodynamic equilibrium state.

DOI： 10.52825/solarpaces.v2i.799

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Temperature impacts on reactivity of La0.7A0.3Mn0.9Cr0.1O3-δ of perovskite oxides in a thermochemical two-step H2O/CO2 splitting Reviewed

Hiroki Sawaguri, Yoshikazu Iwamura, Selvan Bellan, Nobuyuki Gokon

AIP Conf. Proc., SolarPACES: SOLAR POWER & CHEMICAL ENERGY SYSTEMS: 27th International Conference on Concentrating Solar Power and Chemical Energy Systems 2815 130007 - 130007 2023.10

Effects of heating rate and drying condition on thermochemical pyrolysis of spent coffee grounds in a windowed internally-circulating fluidized bed reactor Reviewed

Nobuyuki Gokon, Yusuke Sasada, Hiroshi Seto, Tadaaki Shimizu, Selvan Bellan

AIP Conf. Proc., SolarPACES: SOLAR POWER & CHEMICAL ENERGY SYSTEMS: 27th International Conference on Concentrating Solar Power and Chemical Energy Systems 2815 130003 - 130003 2023.10

Redox performance and optimization of the chemical composition of lanthanum-strontium-manganese-based perovskite oxide for two-step thermochemical CO2 splitting Invited Reviewed

Hiroki Sawaguri, Daichi Yasuhara, Nobuyuki Gokon

Processes 11 2717 2023.9

Progress in concentrated solar power, photovoltaics, and integrated power plants towards expanding the introduction of renewable energy in the Asia/Pacific region Invited Reviewed

Nobuyuki Gokon

Current Sustainable Renewable Energy Reports 10 250 - 263 2023.8

Comparative Study of Heat-Discharging Kinetics of Fe-Substituted Mn2O3/Mn3O4 Being Subjected to Long-Term Cycling for Thermochemical Energy Storage Invited Reviewed

Nobuyuki Gokon, Fumiya Ohashi, Hiroki Sawaguri, Kosuke Hayashi

Energies 16 ( 8 ) 3367 2023.4

Long-Term Thermal Cycling Test and Heat-Charging Kinetics of Fe-Substituted Mn2O3 for Next-Generation Concentrated Solar Power Using Thermochemical Energy Storage at High Temperatures Invited Reviewed

Nobuyuki Gokon, Kosuke Hayashi, Hiroki Sawaguri, Fumiya Ohashi

Energies 15 ( 13 ) 4812-1 - 4812-24 2022.6

A review on high‐temperature thermochemical heat storage: Particle reactors and materials based on solid–gas reactions

Selvan Bellan, Tatsuya Kodama, Nobuyuki Gokon, Koji Matsubara

WIREs Energy and Environment 11 ( 5 ) 2022.5

Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

In order to produce electricity beyond insolation hours and supply to the electrical grid, thermal energy storage (TES) system plays a major role in CSP (concentrated solar power) plants. Current CSP plants use molten salts as both sensible heat storage media and heat transfer fluid, to operate up to 560°C. To meet the future high operating temperature and efficiency, thermochemical storage (TCS) emerged as an attractive alternatives for next generation CSP plants. In these systems, the solar thermal energy is stored by endothermic reaction and subsequently released when the energy is needed by exothermic reversible reaction. This review compares and summarizes different thermochemical storage systems that are currently being investigated, especially TCS based on metal oxides. Various experimental, numerical, and technological studies on the development of particle reactors and materials for high‐temperature TCS applications are presented. Advantages and disadvantages of different types heat storage systems (sensible, latent, and thermochemical), and particle receivers (stacked, fluidized, and entrained), have been discussed and reported.

This article is categorized under:Sustainable Energy > Solar Energy

Emerging Technologies > Energy Storage

Emerging Technologies > Materials

DOI： 10.1002/wene.440

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1002/wene.440

Two-step thermochemical CO2 splitting using partially-substituted perovskite oxides of La0.7Sr0.3Mn0.9X0.1O3 for solar fuel production Invited Reviewed

Hiroki Sawaguri, Nobuyuki Gokon, Kosuke Hayashi, Yoshikazu Iwamura, Daichi Yasuhara

Frontiers in Energy Research, section Solar Energy 10 872959-1 - 872959-21 2022.5

Fluidization behavior of redox metal oxide and spinel particles to develop high-energy-density thermal energy storage system for concentrated solar power applications

Genta TSURUMAKI, Selvan BELLAN, Koji MATSUBARA, Tatsuya KODAMA, Mitsuho NAKAKURA, Nobuyuki GOKON, Hyun SEOK CHO, Karthik MANI, Sakthivel SHANMUGASUNDARAM

Journal of Thermal Science and Technology 17 ( 2 ) 22 - 00061 2022

Development of Synthesis and Fabrication Process for Mn-CeO2 Foam via Two-Step Water-Splitting Cycle Hydrogen Production

Hyun-Seok Cho, Tatsuya Kodama, Nobuyuki Gokon, Selvan Bellan, Jong-Kyu Kim

Energies 14 ( 21 ) 6919 - 6919 2021.10

Publishing type：Research paper (scientific journal) Publisher：MDPI AG

The effects of doping manganese ions into a cerium oxide lattice for a thermochemical two-step water-splitting cycle to produce oxygen and hydrogen and new synthesis methods were experimentally investigated. In order to comparison of oxygen/hydrogen producing performance, pristine CeO2, a coprecipitation method for Mn-CeO2, and a direct depositing method for Mn-CeO2 with different particle sizes (50~75, 100–212, over 212 μm) and doping extents (0, 5, 15 mol%) were tested in the context of synthesis and fabrication processes of reactive metal oxide coated ceramic foam devices. Sample powders were coated onto zirconia (magnesium partially stabilized zirconia oxide, MPSZ) porous foam at 30 weight percent using spin coating or a direct depositing method, tested using a solar reactor at 1400 °C as a thermal reduction step and at 1200 °C as a water decomposition step for five repeated cycles. The sample foam devices were irradiated using a 3-kWth sun-simulator, and all reactive foam devices recorded successful oxygen/hydrogen production using the two-step water-splitting cycles. Among the seven sample devices, the 5 mol% Mn-CeO2 foam device, that synthesized using the coprecipitation method, showed the greatest hydrogen production. The newly suggested direct depositing method, with its contemporaneous synthesis and coating of the Mn-CeO2 foam device, showed successful oxygen/hydrogen production with a reduction in the manufacturing time and reactants, which was lossless compared to conventional spin coating processes. However, proposed direct depositing method still needs further investigation to improve its stability and long-term device durability.

DOI： 10.3390/en14216919

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Phase change material of copper-germanium alloy as solar latent heat storage at high temperatures Invited Reviewed

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

Frontiers in Energy Research, section Solar Energy 9 696213-1 - 696213-19 2021.6

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers Media SA

A copper–germanium alloy (Cu–Ge alloy) was examined as a phase change material, at temperatures exceeding 600°C, for latent heat storage in solar thermal applications. First, the thermo-physical properties of the Cu–Ge alloy were examined using differential scanning calorimetry, thermomechanical analysis, and laser flash analysis. Second, to evaluate the thermal response and reliability of the Cu–Ge alloy, the cyclic properties of thermal charge/discharge were examined under various thermal conditions. The alloys obtained after the tests were examined for their chemical compatibility with the stainless steel container using an electron probe micro analyzer. The elemental distribution of each Cu–Ge alloy was evaluated using cyclic performance tests. Finally, the chemical compatibility of the Cu–Ge alloy was evaluated using a high-temperature test with candidate materials of a phase change material container vessel [stainless steel (SUS310S), Inconel625, silicon carbide (SiC), and alumina (Al2O3)]. The Cu–Ge alloy exhibited significant potential as a latent heat storage material in next-generation solar thermal power plants because it demonstrates various advantages, including a superior storage capacity at a temperature of 644°C, temperature coherence to the phase diagram, a quick thermal response, satisfactory cyclic behavior of charge/discharge modes, a thermodynamically stable metallographic structure, and non-reactivity with container ceramic materials (SiC and Al2O3).

DOI： 10.3389/fenrg.2021.696213

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Chemical compatibility of Cu-Ge alloy with container materials for latent heat storage system Reviewed

Nobuyuki Gokon, Chew Shun Jie, Selvan Bellan, Tatsuya Kodama, Tsuyoshi Hatamachi, Hyunseok Cho