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Research Papers

Development of a Detailed Planar Solid Oxide Fuel Cell Computational Fluid Dynamics Model for Analyzing Cell Performance Degradation

[+] Author and Article Information
Vittorio Verda1

Department of Energy Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italyvittorio.verda@polito.it

Michael R. von Spakovsky

Center for Energy Systems Research, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061vonspako@vt.edu

1

Corresponding author.

J. Fuel Cell Sci. Technol 6(1), 011005 (Nov 04, 2008) (9 pages) doi:10.1115/1.2971046 History: Received March 03, 2007; Revised January 13, 2008; Published November 04, 2008

Abstract

Solid oxide fuel cells (SOFC) are a promising technology for distributed electricity generation and cogeneration. Numerous papers have been published in the past several years proposing mathematical/computational fluid dynamics (CFD) models for predicting the transient and steady-state performance of such cells. In this paper, a detailed steady-state CFD model of a planar anode supported SOFC is proposed, which accounts for mass, thermal, and charge transport as well as electrochemistry and the chemistry of internal fuel reforming. Its main characteristics include the use of a continuous model for the electrochemistry, allowing one to examine different three-phase boundary geometries. This is an improvement over the typical model reported in literature, which utilizes an equivalent resistive circuit approach or a homogeneous distribution of three-phase boundaries. The model proposed here is used to simulate the degradation of anode, cathode, and electrolyte due to instabilities (e.g., anode oxidation due to fuel depletion) or to the delamination of the electrodes from the electrolyte. Such degradations result in a drop in cell performance but are difficult to predict without the use of models that can be helpful for diagnosis. The model is applied to experimental data available in literature both for the nondegraded and degraded cases.

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Figures

Figure 1

2D schematic of a single cell of a planar SOFC

Figure 2

Example of a cathode reacting layer

Figure 3

Shape of the triple-phase boundary

Figure 4

Example of the discretization of the region where the electrochemical reactions occur

Figure 5

Fluid velocity in the cell (m/s)

Figure 6

Temperature field in the cell (K)

Figure 7

Hydrogen mass fraction

Figure 8

Boundary conditions imposed on the model

Figure 9

Potential losses along the cell

Figure 10

Polarization curves for Cases 1 and 2

Figure 11

Current density distribution in the anode for the case of delamination (Case 2)

Figure 12

Current flows for the case of delamination (Case 2)

Figure 13

Polarization curves for Cases 1 and 3

Figure 14

Polarization curves for Cases 1 and 4

Figure 15

Current density distribution in the cathode for the case of increased contact resistance

Figure 16

Differences between the mass fractions calculated with the two approaches

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