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Research Papers

# Thermofluid-Dynamic Analysis of Circular-Planar Type Intermediate-Temperature Solid Oxide Fuel Cells

[+] Author and Article Information
Stefano Campanari, Andrea Lucchini, Matteo Romano

Politecnico di Milano, Department of Energetics, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

Paolo Iora1

Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, Italyiora@ing.unibs.it

The velocity is especially low in terms of Mach number, i.e., compared with the sound speed, resulting in a negligibly compressible behavior.

The geometric domain has been generated using GAMBIT ®2.2.30; the FLUENT ® version is 6.2.16.

Data plotted in Fig. 9 refer to the air flux channel $(Pr=0.73)$. However, as explained before, due to the weak influence of Pr on Nu, data can also be considered valid in first approximation for the fuel flow $(Pr=0.57)$.

For instance, when $θ=0$ the local temperature is equal to the mean PEN structure temperature while for $θ>0$$(θ<0)$ the local temperature is higher (lower) than the average PEN structure temperature.

1

Corresponding author.

J. Fuel Cell Sci. Technol 6(1), 011009 (Nov 06, 2008) (7 pages) doi:10.1115/1.2971050 History: Received April 06, 2007; Revised January 17, 2008; Published November 06, 2008

## Abstract

This work presents a computational thermofluid-dynamic analysis of circular-planar type intermediate-temperature solid oxide fuel cells (SOFCs), based on the Hexis design. A single cell, representative of the average conditions of a real stack, is simulated in detail considering the real anode and cathode channel design, featuring an array of square pegs supporting the interconnection layers. The analysis is developed starting from cell operating data assumed from real test experimental information for an anode-supported SOFC with a $100cm2$ active area, fed with pure hydrogen, and is extended to different reactant flow rates and generated heat flux power densities to evidence a generalized correlation for the thermofluid-dynamic behavior of the fuel cell under variable operating conditions. Aiming to provide a set of general results for the calculation of the heat transfer coefficient, which is applicable for the purpose of a complete thermal and electrochemical finite volume analysis, the simulation calculates local temperature distributions depending on radial and angular positions. The fluid-dynamic analysis evidences the existence of preferential flow paths and nonuniformity issues of the gas flow field, which may affect significantly the cell performances, and indicates possible cell design improvements.

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## Figures

Figure 1

Fuel cell geometry from the upper view (lengths in millimeters)

Figure 2

Upper view of the domain and boundary conditions

Figure 3

Detail of the mesh and aspect ratio of the elements used to define the surfaces surrounding the control volume

Figure 4

Percentage distribution of grid elements in the same skewness range. The recommended skewness value is below 0.85 for triangular and rectangular cells (11).

Figure 5

Velocity vectors, in a mean horizontal section of the channel, at the cell inlet

Figure 6

Velocity field in a mean horizontal section of the channel and PEN structure temperature field (nondimensionalized by means of the maximum temperature) for different mass flow rates (from up to down: 0.01g∕s, 0.06g∕s, and 0.16g∕s)

Figure 7

Influence of heat flux Q on Nusselt number along the radial coordinate of the cell in case of the air mass flow rate of 0.02g∕s

Figure 8

Nusselt number as a function of the Reynolds number in three different radial positions

Figure 9

Variation of the Nusselt number with Re for the five radial coordinates considered in case of air flow (Pr=0.73)

Figure 10

Circumferential distribution of the dimensionless temperature at r=39mm

Figure 11

Circumferential distribution of the dimensionless temperature at r=52.5mm

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