Three-Dimensional CFD Modeling of Transport Phenomena  in a Cross-Flow Anode-Supported Planar SOFC

Zhang, Zhonggang; Chen, Jingfeng; Yue, Danting; Yang, Guogang; Ye, Shuang; He, Chao; Wang, Weiguo; Yuan, Jinliang; Huang, Naibao

doi:10.3390/en7010080

Cited by 30 publications

(18 citation statements)

References 18 publications

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“…Flexibility of simulations and predictions of the I-V behaviour of a cell was presented in the paper 20 . A 3D CFD model was also applied to an anode-supported planar SOFC to investigate transport phenomena inside a fuel cell fed with hydrogen and to evaluate its overall performance 21 . It was found that temperature gradients existed along the length of the cell and therefore the maximum value of temperature for the cross-fl ow was at the outlet of the cell.…”

Section: Introductionmentioning

confidence: 99%

“…The maximum current density resulted in a large overpotential and heat source in the electrodes, which was harmful to the overall performance of the fuel cell. Zhang et al 21 proposed a new type of fl ow structure to make the current fl ow more evenly distributed and promote most of the triple phase boundary areas to take part in electrochemical reactions.…”

Section: Introductionmentioning

confidence: 99%

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CFD modelling of hydrogen starvation conditions in a planar Solid Oxide Fuel Cell

Pianko‐Oprych

Zinko

Jaworski

2017

Polish Journal of Chemical Technology

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The aim of this study was to highlight the interest of using CFD technique as a diagnostic tool of a malfunctioning Solid Oxide Fuel Cells. Hydrogen starvation of a SOFC due to nitrogen dilution is one of the cell dysfunctions and can lead to its degradation. Identifi cation of the starvation point allows to improve cell performance and establish the best conditions for degradation tests. To illustrate a potential of the CFD tool, several simulations of a single planar SOFC and its behaviour under hydrogen starvation were performed and analysed. The results showed that at lower cell voltage values of 0.3 and 0.5 V signifi cant gradients in the electric current were noticed due to a local reduction in hydrogen concentration. The CFD analysis allowed defi ning desirable mass fl ow rate of hydrogen to SOFCs to avoid fuel starvation. The model constitutes a helpful tool for optimizing cell design and operational conditions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CFD modelling of hydrogen starvation conditions in a planar Solid Oxide Fuel Cell

Pianko‐Oprych

Zinko

Jaworski

2017

Polish Journal of Chemical Technology

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“…4,10,36 Numerical methods have the advantages over continuum methods in terms of more flexible definition of gas-wall interactions, which are not explicitly modelled in this study. However, the problem of boundary conditions in Knudsen regime remains for LBM because the pore wall morphology is voxelized, which hinders proper handling of redirection collisions as reported by Berson et al 37 In binary mixtures, Fick's law (FL) is the most widely used diffusion model to calculate the diffusion flux of molecular diffusion due to its simplicity.…”

Section: Theorymentioning

confidence: 99%

“…[2][3][4] In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices in terms of electrochemical impedance, 5 concentration polarization loss, 4,6 and electrochemical simulation. [7][8][9][10] Concentration polarization is caused by the consumption of the fuel gas resulting in a reduction of concentration at the anode/electrolyte interface. In solid oxide fuel cell (SOFC) anodes, concentration polarization is governed by the diffusion of fuel gas (e.g.…”

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confidence: 99%

3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

Tjaden

Bertei

et al. 2017

J. Electrochem. Soc.

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In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices. This study aims to characterize the diffusion regimes and the possible inaccuracies of the mass transport calculation in Solid Oxide Fuel Cell (SOFC) anodes when a volume-averaged pore diameter is used. 3D pore size distribution is measured based on the extracted pore phase from an X-ray CT scan, which is further used for the calculation of a Knudsen number (K n ) map in the porous medium, followed by the voxel-based distribution of the effective diffusion coefficients for different fuel gases. Diffusion fluxes in a binary gas mixture using the lower boundary, upper boundary and average effective coefficients are compared, and the impact on overpotential is analyzed. The results show that pore diameters from tens to hundreds of nanometers result in a broad range of Knudsen number (1.1 ∼ 4.8 and 0.6 ∼ 3 for H 2 and CH 4 respectively), indicative of the transitional diffusion regime. The results highlight that for a porous material, such as an SOFC anode where Knudsen effects are non-negligible, using a volume-averaged pore size can overestimate the mass flux by ±200% compared to the actual value. The characteristic pore size should be chosen sensibly in order to improve the reliability of the mass transport and electrochemical performance evaluation. Mass transport can significantly limit the reaction rate and lead to concentration polarization in electrochemical devices such as fuel cells, electrolysers and oxygen transport membranes, especially under the conditions of high operating current density and fuel conversion ratios.1 Besides the material-specific transport properties of chemical species (e.g., diffusivity, viscosity, etc.), mass transport is mainly dependent on microstructural parameters of the electrode such as porosity, tortuosity and pore size. [2][3][4] In recent years great effort has been taken to understand the effect of gas transport on the performance of electrochemical devices in terms of electrochemical impedance, 5 concentration polarization loss, 4,6 and electrochemical simulation. 7-10Concentration polarization is caused by the consumption of the fuel gas resulting in a reduction of concentration at the anode/electrolyte interface. In solid oxide fuel cell (SOFC) anodes, concentration polarization is governed by the diffusion of fuel gas (e.g. H 2 ) from the gas inlet to the triple phase boundary. A faster diffusion rate can contribute to a larger partial pressure of the fuel gas within the pores and thus a larger limiting current density, which in turn mitigates the polarization loss. 11The effective diffusivity is closely related to the temperature, pressure, gas species as well as to the microstructure of the porous material.12 A considerable amount of work has been reported to measure the diffusivity, such as the experimental methods including diffusion cells, 13 gas chromatography, 14 thermo-gravimetric analysis, 15 as well as theoretical calculations ...

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“…In recent years, significant strides have been made in improving SOFC performance [1][2][3]. In other words, for a given operating voltage, the output current density has been increased drastically.…”

Section: Introductionmentioning

confidence: 99%

A Simple Expression for the Tortuosity of Gas Transport Paths in Solid Oxide Fuel Cells’ Porous Electrodes

Kong

Zhang

et al. 2015

Energies

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Based on the three-dimensional (3D) cube packing model, a simple expression for the tortuosity of gas transport paths in solid oxide fuel cells' (SOFC) porous electrodes is developed. The proposed tortuosity expression reveals the dependence of the tortuosity on porosity, which is capable of providing results that are very consistent with the experimental data in the practical porosity range of SOFC. Furthermore, for the high porosity (>0.6), the proposed tortuosity expression is also accurate. This might be helpful for understanding the physical mechanism for the tortuosity of gas transport paths in electrodes and the optimization electrode microstructure for reducing the concentration polarization.

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Three-Dimensional CFD Modeling of Transport Phenomena in a Cross-Flow Anode-Supported Planar SOFC

Cited by 30 publications

References 18 publications

CFD modelling of hydrogen starvation conditions in a planar Solid Oxide Fuel Cell

CFD modelling of hydrogen starvation conditions in a planar Solid Oxide Fuel Cell

3D Characterization of Diffusivities and Its Impact on Mass Flux and Concentration Overpotential in SOFC Anode

A Simple Expression for the Tortuosity of Gas Transport Paths in Solid Oxide Fuel Cells’ Porous Electrodes

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