Single-cell fuel cells

It would certainly be desirable to evaluate catalyst performance and understand size and stmctural effects directly under the conditions of fuel cell operation. However, determination of kinetic parameters in a single-cell fuel cell is associated with a number of limitations. Let us consider some of them. 

Collection of in situ XAS data using a single cell fuel cell avoids problems associated with bubble formation found in liquid electrolytes as well as questions regarding the influence of adsorption of ions from the supporting electrolyte. However, the in situ study of membrane electrode assemblies (MEAs) in a fuel cell environment using transmission... 

Measure single cell fuel cell performance with hydrogen and gasoline reformate... 

Approach Durability Gasoline Reformate Production and Single Cell Fuel Cells... 

Power AND Energy Efficiency Analysis OF Direct Methanol Fuel Cell (DMFC) FROM Single Cell, Fuel Cell Stack TO DMFC System... 

FIGURE 6.20 Example of a generalized equivalent circuit model for a single-cell fuel cell. Models regarding real fuel cells often contain constant phase elements (CPE). (Adapted from Scribner Associates, 2010. http //www. scribner.com/technical-papers.html)... 

Axial symmetric representation is typically considered for single tubular fuel cell modeling because it allows one to design, mesh and compute only a portion of the cell taking advantage of the symmetry condition. The partial differential equations are written in cylindrical coordinates and solved in two dimensions (radial and axial). This assumption is possible when there are no significant circumferential variations in the boundary conditions. Such a hypothesis is reasonable when the... 

It has even been proposed to give up the separation of the gas chambers.156-158 Then one has to completely rely on selective catalytic activity of electrocatalysts to activate reduction or oxidation processes. In Ref.158 considerable power densities have been achieved in this way. This single chamber fuel cell concept might be indeed relevant for reduced temperature application. 

Single-cycle fuel cell efficiencies range from 47 to 50%. The efficiency of combined-cycle fuel cells is about 60%, and if the generated heat is also recovered (in the form of hot water), the total efficiency can be around 80%. In comparison, the efficiency of gasoline engines is around 25%, of nuclear power plants about 35%, and of subcritical fossil fuel power plants, 37%. 

Huang, K.Q. et al.. Electrode performance test on single ceramic fuel cells using as electrolyte Sr- and Mg-doped LaGaOj, J. Electrochem. Soc., 144, 3620-3624 (1997). 

Huang, K.Q., Tichy, R., and Goodenough, J.B., Superior perovskite oxide-ion conductor strontium- and magnesium-doped LaGaOj. III. Performance tests of single ceramic fuel cells. Journal of the American Ceramic Society, 1998, 81, 2581-2585. 

The anode catalyst should possess high electrochemical oxidation activity and minimal conventional oxidation activity the cathode catalysts should exhibit selectivity for the reduction of O2 to. Single chamber fuel cell studies using Ni-SDC as an anode and Smo.sSr 0.5C0O3 as a cathode showed that the anode catalyst was active for partial oxidation of C2H6 to produce CO and H2 for further electrochemical oxidation on the anode catalyst surface. 

Figure 3.51. Single PEM fuel cell performance. Current-voltage relationship (open symbols) and implied power density (filled symbols), are shown for different operational temperatures in the range of 45-90°C, for a cell with a catalyst layer with incorporated PTFE (polytetrafluoroethene) to reduce water flooding, a low loading of a carbon-supported Pt catalyst layer (120 pg Pt cm ) and finally Nation intrusions. (From Z. Qi and A. Kaufman (2003). Low Pt loading high performance cathodes for PEM fuel cells. /. Power Sources 113,37-43. Used with permission from Elsevier.)...

This negative potential is easy to understand and is actually used today in the single-chamber fuel cell [14] oxygen is consumed by the catalytic reaction of CH3OH oxidation much faster on the Pt catalyst-electrode than on the Ag counterelectrode (Ag is also a catalyst for CH3OH oxidation and partial oxidation, but much less... 

Z. P. Shao, J. Mederos, W. C. Chueh, S. M. Haile, High Power-Density Single-Chamber Fuel Cells Operated on Methane. J. Power Sources, 162, 589-96 (2006). 

In the following Sections the most relevant studies of alcohol oxidation in both half cells and single monoplanar fuel cells using electrodes containing Pd-based electrocatalysts are reviewed. 

Basic Principles of Single-Chamber Fuel Cell Operation... 

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