Solid oxide fuel cell configurations

Fig. 7. Solid oxide fuel cell configurations. A Siemens-Westinghouse tubular cell B Tubular integrated interconnector concept. Similar interconnected systems exist in planar geometry C Planar SOFC designs, differing only in gas flow manifolding.

VIII. Solid Oxide Fuel Cell Configurations and Perfonnance... 

VIII. SOLID OXIDE FUEL CELL CONFIGURATIONS AND PERFORMANCE... 

Performance of an Anode-supported Solid Oxide Fuel Cell in a Mixed-gas Configuration... 

Itoh H, Yamamoto T, and Mori M. Configurational and electrical behavior of Ni-YSZ cermet with novel microstructure for solid oxide fuel cell anodes. J Electrochem 5ocl997 144 641-646. 

Chung BW, Pham A-Q, Haslam JJ, and Glass RS. Influence of electrode configuration on the performance of electrode-supported solid oxide fuel cells. J Electrochem Soc 2002 149 A325-A330. 

A 2002 study for the National Energy Technology Laboratory found that coal gasification systems with C02 capture could reach efficiencies of 60% or more in cogenerating hydrogen and electricity using different configurations of turbines and solid oxide fuel cells (SOFCs). 

Sealless Tubular Configuration The most developed solid oxide fuel cell is the Siemens Westinghouse tubular cell. This approach results in eliminating seal problems between adjacent cells. A schematic representation of the cross section of the present Siemens Westinghouse... 

Solid oxide fuel cells (SOFC) use a hard, non-porous ceramic compound as the electrolyte. Since the electrolyte is a solid, the cells do not have to be constructed in the plate-like configuration typical of other fuel cell types. SOFCs are expected to be around 50-60 percent efficient at converting fuel to electricity, however, calculations show that over 70 percent may be achievable. In applications designed to capture and utilize the system s waste heat (co-generation), overall fiiel use efficiencies could top 80-85 percent. 

Fig. 1.6 Illustration of a planar-stack, solid-oxide fuel cell (SOFC), where an membrane-electrode assembly (MEA) is sandwiched between an interconnect structure that forms fuel and air channels. There is homogeneous chemical reaction within the flow channels, as well as heterogeneous cehmistry at the channel walls. There are also electrochemical reactions at the electrode interfaces of the channels. A counter-flow situation is illustrated here, but co-flow and cross-flow configurations are also common. Channel cross section dimensions are typically on the order of a millimeter.

SOFC can be manufactured in different geometrical configurations, i.e. planar, tubular or monolithic. Regardless of the geometrical configuration, a solid oxide fuel cell is always composed of two porous electrodes (anode and cathode), a dense electrolyte, an anodic and a cathodic gas channel and two current collectors. For the sake of simplicity the planar configuration is taken as reference, as shown in Figure 3.1. 

Bove R., Sammes N.M, 2005. The effect of current collectors configuration on the performance of a tubular SOFC. In Proceedings of the Ninth International Symposium on Solid Oxide Fuel Cells (SOFC IX), May 15-20, Quebec City, Canada, S.C. Singhal and J. Mizusaki (Eds.), Electrochemical Society, Vol. 1, pp. 780-781. 

Ciano C., Cali M., Melhus O., Verda V., 2006. A model for the configuration design of a tubular Solid Oxide Fuel Cell Stack. ASME Paper IMECE2006-16141, Chicago, IL, November 5-10, 2006. 

Solid oxide fuel cell — Figure 2. Configuration for a planar design SOFC [ii]... 

Figure 8.7 Schematic diagrams showing two electrocatalytic membrane reactor configurations (a) eicctrochemicai oxygen pumping and (b) solid oxide fuel cell operation.

Figure 2 The configuration of solid oxide fuel cell 1-quartz tube 2-YSZ tube 3-Ag wire 4-multimeter used as galvanometer 5-multimeter used as voltmeter 6-resistance box...

Dogan, F., and Anderson, H.U. (2003) Comparison of anode and electrolyte support configuration of singleInternational Symposium on Solid Oxide Fuel Cells, SOFC-Vlll, Paris, France,... 

Braun, R.J., Klein, S.A., and Reindl, D.T. (2006) Evaluation of system configurations for solid oxide fuel cell-based micro-combined heat and power generators in residential applications. J. Power Sources, 158, 1290-1305. 

In this code, a 1-dimensional electrochemical element is defined, which represents a finite volume of active unit cell. This 1-D sub-model can be validated with appropriate single-cell data and established 1-D codes. This 1-D element is then used in FLUENT, a commercially available product, to carry out 3-D similations of realistic fuel cell geometries. One configuration studied was a single tubular solid oxide fuel cell (TSOFC) including a support tube on the cathode side of the cell. Six chemical species were tracked in the simulation H2, CO2, CO, O2, H2O, and N2. Fluid dynamics, heat transfer, electrochemistry, and the potential field in electrode and interconnect regions were all simulated. Voltage losses due to chemical kinetics, ohmic conduction, and diffusion were accounted for in the model. Because of a lack of accurate and detailed in situ characterization of the SOFC modeled, a direct validation of the model results was not possible. However, the results are consistent with input-output observations on experimental cells of this type. 

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