On Modeling Multi-Component Diffusion Inside the Porous Anode of Solid Oxide Fuel Cells Using Fick’s Model

2008 ◽  
Author(s):  
Fatma N. Cayan ◽  
Suryanarayana R. Pakalapati ◽  
Francisco Elizalde-Blancas ◽  
Ismail Celik
Keyword(s):  
Diffusion Flux ◽  
Knudsen Diffusion ◽  
Effective Diffusivity ◽  
Maxwell Model ◽  
Solid Oxide ◽  
Methane Steam Reforming ◽  
Diffusivity Coefficient ◽  
Oxide Fuel ◽  
Current Densities ◽  
Porous Anode

Stefan-Maxwell Model (SMM) and simple Fick’s Model (FM) type of relations both including Knudsen diffusion for the calculation of species mole fraction distribution inside the porous anode of a solid oxide fuel cell (SOFC) were compared and it was found that at low current densities the models agree well but as current increases the differences also increase. Based on the findings an empirical correction is proposed for the effective diffusivity used in Fick’s Model. The corrected diffusivity coefficient gave better agreement with the Stefan-Maxwell model and even at higher current densities the error is less than 5%. This correction was implemented via a three-dimensional, in-house SOFC simulation code (DREAM-SOFC) which uses Fick’s Model type relations for diffusion flux calculations. The code also takes into account methane steam reforming (MSR) and water gas shift (WGS) reactions and the electrochemical oxidation of both H2 and CO. As an application, a SOFC button cell which is being tested at West Virginia University was simulated. The results with and without the proposed correction for effective diffusivity are compared.

Effect of Bi-Layer Interconnector Design on the Current Density of Solid Oxide Fuel Cells

2009 ◽  
Author(s):  
Qiuyang Chen ◽  
Jian Zhang ◽  
Qiuwang Wang ◽  
Min Zeng
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Current Density ◽  
Porous Electrode ◽  
Solid Oxide ◽  
The Novel ◽  
Oxide Fuel ◽  
Plane Normal ◽  
Three Phase ◽  
Porous Anode

The concentration gradient of fuel and oxidant gas is great in the plane normal to the solid oxide fuel cells (SOFC) three-phase-boundary (TPB) layer, especially in the porous electrode. We present a novel interconnector design, termed bilayer interconnector, for SOFC. It can distribute the fuel and air gas in the plane normal to the SOFC TPB layer. In this paper, we develop a 3D model to study the current density of the SOFC with conventional and novel bi-layer interconnectors. The numerical results show that the novel SOFC design Rib1 can slightly enhance the mass transfer in the porous anode and current density. The novel SOFC design Rib2 can improve the current density significantly under low electrical conductivity of interconnector.

Application of an Anode Model to Investigate Physical Parameters in an Internal Reforming Solid-Oxide Fuel Cell

2005 ◽  
Vol 2 (2) ◽  
pp. 136-140 ◽  
Author(s):  
Eric S. Greene ◽  
Maria G. Medeiros ◽  
Wilson K. S. Chiu
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Structural Parameters ◽  
Porous Electrode ◽  
Cell Voltage ◽  
Solid Oxide ◽  
Physical Parameters ◽  
Oxide Fuel ◽  
Internal Reforming ◽  
Porous Anode

A one-dimensional model of chemical and mass transport phenomena in the porous anode of a solid-oxide fuel cell, in which there is internal reforming of methane, is presented. Macroscopically averaged porous electrode theory is used to model the mass transfer that occurs in the anode. Linear kinetics at a constant temperature are used to model the reforming and shift reactions. Correlations based on the Damkohler number are created to relate anode structural parameters and thickness to a nondimensional electrochemical conversion rate and cell voltage. It is shown how these can be applied in order to assist the design of an anode.

Design of Anodes for IT SOFC: Effect of Complex Oxide Promoters and Pd on Activity and Stability in Methane Steam Reforming of Ni/YSZ (ScSZ) Cermets

2006 ◽  
Vol 972 ◽  
Author(s):  
Vladislav A Sadykov ◽  
Natalia V Mezentseva ◽  
Rimma v Bunina ◽  
Galina M Alikina ◽  
Anton I Lukashevich ◽  
...  
Keyword(s):  
Solid Oxide Fuel Cells ◽  
Steam Reforming ◽  
Complex Oxide ◽  
Solid Oxide ◽  
Coke Deposition ◽  
Methane Steam Reforming ◽  
Oxide Fuel ◽  
Oxygen Mobility ◽  
Methane Steam ◽  
Spatial Uniformity

AbstractEffect of fluorite-like or perovskite-like complex oxide promoters and Pd on the performance of Ni/YSZ and Ni/ScSZ cermets in methane steam reforming or selective oxidation by O2 into syngas at short contact times was studied. Spatial uniformity of dopants distribution in composites was controlled by TEM combined with EDX, while the lattice oxygen mobility and reactivity was elucidated by CH4 and H2 TPR. Oxide promoters allow to operate even at stoichiometric H2O/CH4 ratio by suppressing coke deposition through modification of Ni surface, while doping by Pd ensures reasonable performance at moderate (∼550 °C) temperatures required for Intermediate–Temperature Solid Oxide Fuel Cells (IT SOFC).

A Phenomenological Model for Degradation of Solid Oxide Fuel Cell Anodes Due to Impurities in Coal Syngas

2009 ◽  
Author(s):  
Fatma N. Cayan ◽  
Suryanarayana R. Pakalapati ◽  
Francisco Elizalde-Blancas ◽  
Ismail Celik
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Knudsen Diffusion ◽  
Solid Oxide ◽  
Ni Catalyst ◽  
Model Parameters ◽  
Oxide Fuel ◽  
Coal Syngas ◽  
Reaction Rate Constants ◽  
Degradation Rates

A new phenomenological one-dimensional model is formulated to simulate the typical degradation patterns observed in Solid Oxide Fuel Cell (SOFC) anodes due to coal syngas contaminants such as arsenic (As) and phosphorous (P). The model includes ordinary gas phase diffusion including Knudsen diffusion and surface diffusion within the anode and the adsorption reactions on the surface of the Ni-YSZ based anode. Model parameters such as reaction rate constants for the adsorption reactions are calibrated to match the degradation rates reported in the literature. Preliminary results from implementation of the model demonstrated that the deposition of the impurity on the Ni catalyst starts near the fuel channel/anode interface and slowly moves toward the active anode/electrolyte interface which is in good agreement with the experimental data. Parametric studies performed at different impurity concentrations, operating temperatures and current densities showed that the coverage rate increases with increasing temperature, impurity concentration and current density, as expected.

Deposition of Porous Anode Electrode of a Solid Oxide Fuel Cell by Ultrasonic Spray Pyrolysis

2010 ◽  
Author(s):  
Lin Liu ◽  
Gap-Yong Kim ◽  
Abhijit Chandra
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Spray Pyrolysis ◽  
Precursor Solution ◽  
Gas Diffusion ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Anode Electrode ◽  
Porous Anode ◽  
Anode Film

A modified spray pyrolysis approach has been utilized to fabricate anode electrode of a Solid Oxide Fuel Cell (SOFC). It was designed to control the anode microstructure to achieve large triple phase boundaries (TPBs) and high gas diffusion capability, which are critical in enhancing the performance of a SOFC. Deposition of porous anode film of Nickel and Ce0.9Gd0.1O1.95 on dense 8 mol.% yttria stabilized zirconia (YSZ) substrate was carried out using the modified spray pyrolysis. Effects of precursor solution feed rates, precursor solution concentrations and deposition temperatures on the TPB formation and porosity were investigated. The composition of the deposited anode film was evaluated by energy dispersive X-ray spectroscopy (EDS). Scanning electron microscope (SEM) examinations revealed that the deposition temperature and precursor solution concentration were the most critical parameters that influenced the morphology, porosity and the particle size of the anode film.

Development of Porous Anode Layers for the Solid Oxide Fuel Cell by Plasma Spraying

2006 ◽  
Vol 15 (4) ◽  
pp. 604-609 ◽  
Author(s):  
H. Weckmann ◽  
A. Syed ◽  
Z. Ilhan ◽  
J. Arnold
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Plasma Spraying ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Porous Anode

Investigation of methane steam reforming in planar porous support of solid oxide fuel cell

2009 ◽  
Vol 29 (5-6) ◽  
pp. 1106-1113 ◽  
Author(s):  
Yongping Yang ◽  
Xiaoze Du ◽  
Lijun Yang ◽  
Yuan Huang ◽  
Haizhen Xian
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Steam Reforming ◽  
Solid Oxide ◽  
Methane Steam Reforming ◽  
Oxide Fuel ◽  
Porous Support ◽  
Methane Steam
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