Numerical Analysis of Heat/Mass Transfer and Electrochemical Reaction in an Anode-Supported Flat-Tube Solid Oxide Fuel Cell

Three-dimensional heat and mass transfer and electrochemical reaction in an anode-supported flat-tube solid oxide fuel cell (FT-SOFC) are studied. Transport and reaction phenomena mainly change in the streamwise direction. Exceptionally, hydrogen and water vapor have large concentration gradients also in the cross section perpendicular to the flow direction, because of the insufficient mass diffusion in the porous anode. Based on these results, we develop a simplified one-dimensional cell model. The distributions of temperature, current, and overpotential predicted by this model show good agreement with those obtained by the full three-dimensional simulation. We also investigate the effects of pore size, porosity and configuration of the anode on the cell performance. Extensive parametric studies reveal that, for a fixed three-phase boundary (TPB) length, rough material grains are preferable to obtain higher output voltage. In addition, when the cell has a thin anode with narrow ribs, drastic increase in the volumetric power density can be achieved with small voltage drop.

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A Study of Transport Geometry on Heat/Mass Transfer and Polarization of a Solid Oxide Fuel Cell

ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts A and B ◽

10.1115/fuelcell2006-97256 ◽

2006 ◽

Author(s):

Yan Ji ◽

J. N. Chung ◽

Kun Yuan

Keyword(s):

Mass Transfer ◽

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Heat Mass Transfer ◽

Three Dimensional ◽

Solid Oxide ◽

Oxide Fuel ◽

Transfer Coefficients ◽

Cell Efficiency ◽

Current Path

The main objective of this paper is to examine the effects of transport geometry on the efficiency of an electrolyte-supported solid oxide fuel cell. A three-dimensional thermo-fluid-electrochemical model is developed to the influences of channel dimensions, rib width and electrolyte thickness on the temperature, mass transfer coefficients, species concentration, local current density and power density. Results demonstrate that decreasing the height of flow channels can significantly lower the average solid temperature and improve the cell efficiency due to higher heat/mass transfer coefficient between the channel wall and flow stream, and a shorter current path. However, this improvement is limited for the smallest channel. The cell with a thicker rib width and a thinner electrolyte layer has higher efficiency and lower average temperature. Numerical simulation will be expected to help optimize the design of a solid oxide fuel cell.

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Interdigitated Heat/Mass Transfer and Chemical/Electrochemical Reactions in a Planar Type Solid Oxide Fuel Cell

Heat Transfer: Volume 1 ◽

10.1115/ht2003-47436 ◽

2003 ◽

Cited By ~ 2

Author(s):

Pei-Wen Li ◽

Laura Schaefer ◽

Minking K. Chyu

Keyword(s):

Mass Transfer ◽

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Current Density ◽

Heat Mass Transfer ◽

High Current Density ◽

Flow Direction ◽

Solid Oxide ◽

Oxide Fuel ◽

Operation Conditions

The details of the heat/mass transfer in a planar type solid oxide fuel cell that controls the energy conversion performance are studied by employing a three-dimensional numerical computation for the fields of velocity, gas mass fractions and temperature. The SOFC under investigation is a unit working in a SOFC stack. It has the tri-layer of anode-electrolyte-cathode and interconnects having multiple channels for fuel and air. Two designs of the tri-layer, anode-supported and electrolyte-supported, are studied. Pre-reformed fuel gas with components of H2, H2O, CO, CO2 and CH4 is arranged in cross-flow direction with airflow. Further reforming and shift reaction in fuel channels were considered at chemical equilibrium. It was found that the consumption and production of gas species are different in the different channels. High current density was located in the upstream area of fuel channels. The operation conditions of current density affected the temperature level significantly.

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A computational fluid dynamics model of a solid oxide fuel cell

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/095765005x7583 ◽

2005 ◽

Vol 219 (3) ◽

pp. 159-167 ◽

Cited By ~ 5

Author(s):

K Sudaprasert ◽

R P Travis ◽

R F Martinez-Botas

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Thermal Stresses ◽

Flow Direction ◽

Three Dimensional ◽

Solid Oxide ◽

Oxide Fuel ◽

Three Dimensional Model

In this work a three-dimensional model of a solid oxide fuel cell (SOFC) has been developed and is used to predict the temperature, concentration distribution and velocity profile across the cell. This model employs Users’ Subroutines in a commercial computational fluid dynamics (CFD) code to simulate the electrochemical reactions. The results show both fuel concentration and current density decreasing along the flow direction. The temperature differences are significant with the hottest point located in middle of the active area. Increasing the operating temperature is shown to reduce the effect of polarization that hampers the cell performance, although other issues such as thermal stresses and reduced material choices are more significant.

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