The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Kazunari Sasaki - One of the best experts on this subject based on the ideXlab platform.
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simulation of sofc performance using a modified Exchange Current Density for pre reformed methane based fuels
International Journal of Hydrogen Energy, 2020Co-Authors: K Takino, Yuya Tachikawa, Yusuke Shiratori, K Mori, Stephen Matthew Lyth, Shunsuke Taniguchi, Kazunari SasakiAbstract:Abstract Numerical simulations can be used to visualize and better understand various distributions such as gas concentration and temperature in solid oxide fuel cells (SOFCs) under realistic operating conditions. However, pre-existing models generally utilize an anode Exchange Current Density equation which is valid for humidified hydrogen fuels – an unrealistic case for SOFCs, which are generally fueled by hydrocarbons. Here, we focus on developing a new, modified Exchange Current Density equation, leading to an improved numerical analysis model for SOFC anode kinetics. As such, we experimentally determine the Exchange Current Density of SOFC anodes fueled by fully pre-reformed methane. The results are used to derive a new phenomenological anode Exchange Current Density equation. This modified equation is then combined with computational fluid dynamics (CFD) to simulate the performance parameters of a three-dimensional electrolyte-supported SOFC. The new modified Exchange Current Density equation for methane-based fuels reproduces the I–V characteristics and temperature distribution significantly better than the previous models using humidified hydrogen fuel. Better simulations of SOFC performance under realistic operating conditions are crucial for the prediction and prevention of e.g. fuel starvation and thermal stresses.
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Exchange Current Density of sofc electrodes theoretical relations and partial pressure dependencies rate determined by electrochemical reactions
Journal of The Electrochemical Society, 2015Co-Authors: T Hosoi, T Yonekura, K Sunada, Kazunari SasakiAbstract:As a theoretical consideration on electrode defect chemistry, general relations of Exchange Current Density quantitatively representing Solid Oxide Fuel Cell (SOFC) electrode performance are systematically derived as a function of gas partial pressures, equilibrium constants of adsorption and dissociation reactions on electrode surfaces, and electrochemical reaction rate constants for possible elementalreactionsatthecathodeandtheanode,inthecasethatanelectrochemicalreactionistherate-determiningelectrodereaction. Simplified expressions are also derived, under the condition that one kind of neutral or charged adsorbed species is predominant at the electrode, to derive gas partial pressure dependence of Exchange Current Density for given rate-determining electrochemical reactions. Importance of considering elementary steps is highlighted to derive rate equations and to clarify various dependencies. Partial pressure dependencies of the Exchange Current Density are compiled and discussed by simulating normalized Exchange Current Density values for given partial pressures. The applicability and limitation of the Butler-Volmer type expressions of Exchange Current Density for SOFC electrodes are carefully discussed. © The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons
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Exchange Current Density of solid oxide fuel cell electrodes
12th International Symposium on Solid Oxide Fuel Cells SOFC-XII - 219th ECS Meeting, 2011Co-Authors: Takahiro Yonekura, Yuya Tachikawa, Tomoo Yoshizumi, Yusuke Shiratori, Kazunari SasakiAbstract:It is desired to develop computational procedures to simulate internal Current Density, anode/cathode gas concentrations, and temperature distribution in solid oxide fuel cell (SOFC) systems. In this study, the influences of various operational conditions on the Exchange Current Density, the essential parameter to simulate SOFC performance, are revealed and discussed. The anodic Exchange Current Density depended strongly on the humidity of H2-based fuel gas, and it exhibited the highest value at around 40% H2O. The cathodic Exchange Current Density was strongly affected by the operational temperature. Parameters necessary to describe dependencies of Exchange Current Density on various operational parameters were determined by fitting measured Exchange Current Density values with empirical equations.
M. V. Sangaranarayanan - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Exchange Current Density for ferric/ferrous reaction at electrode surfaces—influence of ionic desolvation and dipolar adsorption
Journal of colloid and interface science, 2004Co-Authors: S. Harinipriya, M. V. SangaranarayananAbstract:The dependence of the Exchange Current Density of the ferric/ferrous reaction on electrode surfaces has been investigated using the work functions of metals, surface potentials of the reactants, adsorption characteristics of water dipoles, hydration numbers, etc. The extent of dehydration of the reactant species at the reaction zone, as well as the influence of desorption of water dipoles from the electrode surface on the magnitude of Exchange Current Density, is demonstrated.
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estimation of Exchange Current Density for ferric ferrous reaction at electrode surfaces influence of ionic desolvation and dipolar adsorption
Journal of Colloid and Interface Science, 2004Co-Authors: S. Harinipriya, M. V. SangaranarayananAbstract:The dependence of the Exchange Current Density of the ferric/ferrous reaction on electrode surfaces has been investigated using the work functions of metals, surface potentials of the reactants, adsorption characteristics of water dipoles, hydration numbers, etc. The extent of dehydration of the reactant species at the reaction zone, as well as the influence of desorption of water dipoles from the electrode surface on the magnitude of Exchange Current Density, is demonstrated.
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Influence of the work function on electron transfer processes at metals: Application to the hydrogen evolution reaction
Langmuir, 2002Co-Authors: S. Harinipriya, M. V. SangaranarayananAbstract:The Exchange Current Density and the corresponding free energy of activation for the hydrogen evolution reaction at metal surfaces is estimated using the work function of the substrate, desolvation energy of the reactant, solvation numbers, and so forth. The computed values are in satisfactory agreement with experimental data for a large number of metals.
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electron transfer reactions at metal electrodes influence of work function on free energy of activation and Exchange Current Density
Journal of Chemical Physics, 2001Co-Authors: S. Harinipriya, M. V. SangaranarayananAbstract:The dependence of the free energy of activation on the work function of electrodes, solvation energies, and surface potentials of the reactant species pertaining to electron transfer reactions at metal/solution interfaces is derived using thermodynamic considerations. The standard Exchange Current Density is calculated for Fe3++e↔Fe2+ at different metal electrodes and compared with experimental data as well as molecular dynamics simulations.
Yuya Tachikawa - One of the best experts on this subject based on the ideXlab platform.
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simulation of sofc performance using a modified Exchange Current Density for pre reformed methane based fuels
International Journal of Hydrogen Energy, 2020Co-Authors: K Takino, Yuya Tachikawa, Yusuke Shiratori, K Mori, Stephen Matthew Lyth, Shunsuke Taniguchi, Kazunari SasakiAbstract:Abstract Numerical simulations can be used to visualize and better understand various distributions such as gas concentration and temperature in solid oxide fuel cells (SOFCs) under realistic operating conditions. However, pre-existing models generally utilize an anode Exchange Current Density equation which is valid for humidified hydrogen fuels – an unrealistic case for SOFCs, which are generally fueled by hydrocarbons. Here, we focus on developing a new, modified Exchange Current Density equation, leading to an improved numerical analysis model for SOFC anode kinetics. As such, we experimentally determine the Exchange Current Density of SOFC anodes fueled by fully pre-reformed methane. The results are used to derive a new phenomenological anode Exchange Current Density equation. This modified equation is then combined with computational fluid dynamics (CFD) to simulate the performance parameters of a three-dimensional electrolyte-supported SOFC. The new modified Exchange Current Density equation for methane-based fuels reproduces the I–V characteristics and temperature distribution significantly better than the previous models using humidified hydrogen fuel. Better simulations of SOFC performance under realistic operating conditions are crucial for the prediction and prevention of e.g. fuel starvation and thermal stresses.
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Exchange Current Density of solid oxide fuel cell electrodes
12th International Symposium on Solid Oxide Fuel Cells SOFC-XII - 219th ECS Meeting, 2011Co-Authors: Takahiro Yonekura, Yuya Tachikawa, Tomoo Yoshizumi, Yusuke Shiratori, Kazunari SasakiAbstract:It is desired to develop computational procedures to simulate internal Current Density, anode/cathode gas concentrations, and temperature distribution in solid oxide fuel cell (SOFC) systems. In this study, the influences of various operational conditions on the Exchange Current Density, the essential parameter to simulate SOFC performance, are revealed and discussed. The anodic Exchange Current Density depended strongly on the humidity of H2-based fuel gas, and it exhibited the highest value at around 40% H2O. The cathodic Exchange Current Density was strongly affected by the operational temperature. Parameters necessary to describe dependencies of Exchange Current Density on various operational parameters were determined by fitting measured Exchange Current Density values with empirical equations.
Yusuke Shiratori - One of the best experts on this subject based on the ideXlab platform.
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simulation of sofc performance using a modified Exchange Current Density for pre reformed methane based fuels
International Journal of Hydrogen Energy, 2020Co-Authors: K Takino, Yuya Tachikawa, Yusuke Shiratori, K Mori, Stephen Matthew Lyth, Shunsuke Taniguchi, Kazunari SasakiAbstract:Abstract Numerical simulations can be used to visualize and better understand various distributions such as gas concentration and temperature in solid oxide fuel cells (SOFCs) under realistic operating conditions. However, pre-existing models generally utilize an anode Exchange Current Density equation which is valid for humidified hydrogen fuels – an unrealistic case for SOFCs, which are generally fueled by hydrocarbons. Here, we focus on developing a new, modified Exchange Current Density equation, leading to an improved numerical analysis model for SOFC anode kinetics. As such, we experimentally determine the Exchange Current Density of SOFC anodes fueled by fully pre-reformed methane. The results are used to derive a new phenomenological anode Exchange Current Density equation. This modified equation is then combined with computational fluid dynamics (CFD) to simulate the performance parameters of a three-dimensional electrolyte-supported SOFC. The new modified Exchange Current Density equation for methane-based fuels reproduces the I–V characteristics and temperature distribution significantly better than the previous models using humidified hydrogen fuel. Better simulations of SOFC performance under realistic operating conditions are crucial for the prediction and prevention of e.g. fuel starvation and thermal stresses.
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Exchange Current Density of solid oxide fuel cell electrodes
12th International Symposium on Solid Oxide Fuel Cells SOFC-XII - 219th ECS Meeting, 2011Co-Authors: Takahiro Yonekura, Yuya Tachikawa, Tomoo Yoshizumi, Yusuke Shiratori, Kazunari SasakiAbstract:It is desired to develop computational procedures to simulate internal Current Density, anode/cathode gas concentrations, and temperature distribution in solid oxide fuel cell (SOFC) systems. In this study, the influences of various operational conditions on the Exchange Current Density, the essential parameter to simulate SOFC performance, are revealed and discussed. The anodic Exchange Current Density depended strongly on the humidity of H2-based fuel gas, and it exhibited the highest value at around 40% H2O. The cathodic Exchange Current Density was strongly affected by the operational temperature. Parameters necessary to describe dependencies of Exchange Current Density on various operational parameters were determined by fitting measured Exchange Current Density values with empirical equations.
Javier B. Giorgi - One of the best experts on this subject based on the ideXlab platform.
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Solid oxide fuel cell with NiCo–YSZ cermet anode for oxidation of CO/H2 fuel mixtures
Journal of Power Sources, 2012Co-Authors: Julie S. O’brien, Javier B. GiorgiAbstract:The suggestion has been made in the literature that solid oxide fuel cells (SOFCs) operated with syngas as fuel may be viable in certain gas ratio regimes. We have explored this hypothesis with a promising bimetallic anode material. SOFCs with Ni0.7Co0.3–YSZ cermet anodes were operated with CO/H2 mixtures in the full concentration range. Electrochemical impedance spectroscopy and voltammetry measurements were employed to measure the Exchange Current Density (i0) values of each fuel mixture. The fuel mixtures of CO/H2 ratios corresponding to the range 20/80 and 30/70 were found to have i0 values larger than that of pure H2 with the same cell. For these two fuel ratios, an improvement of 5–8 times, respectively, in the Exchange Current Density has been observed. Higher CO/H2 fuel ratios in the range of 60/40–80/20 produced i0 values lower than H2, as carbon poisoning is operational in this region. Continuous running of a cell with fuel ratio 25/75 CO/H2 for 7 days produced i0 values above the values for pure H2 as has been recently suggested.
