Monolithic fuel cells

Dees DW, Balachandran U, Dorris SE, Heiberger JJ, McPheeters CC, and Picciolo JJ. Interfacial effects in monolithic solid oxide fuel cells. In Singhal SC, editor. Proceedings of the First International Symposium on Solid Oxide Fuel Cells, Pennington, NJ The Electrochemical Society, 1989 89(11) 317-321. 

N. Minh et al., "Monolithic Solid Oxide Fuel Cell Development Recent Technical Progress," AlliedSignal, Fuel Cell Seminar Program and Abstracts, 1992 Fuel Cell seminar, 1992. 

Thermal-Hydraulic Model of a Monolithic Solid Oxide Fuel Cell... 

S. Ahmed, C. McPheeters, and R. Kumar, Thermal-Hydraulic Model of a Monolithic Solid Oxide Fuel Cell, ... 

There are many chemically reacting flow situations in which a reactive stream flows interior to a channel or duct. Two such examples are illustrated in Figs. 1.4 and 1.6, which consider flow in a catalytic-combustion monolith [28,156,168,259,322] and in the channels of a solid-oxide fuel cell. Other examples include the catalytic converters in automobiles. Certainly there are many industrial chemical processes that involve reactive flow tubular reactors. Innovative new short-contact-time processes use flow in catalytic monoliths to convert raw hydrocarbons to higher-value chemical feedstocks [37,99,100,173,184,436, 447]. Certain types of chemical-vapor-deposition reactors use a channel to direct flow over a wafer where a thin film is grown or deposited [219]. Flow reactors used in the laboratory to study gas-phase chemical kinetics usually strive to achieve plug-flow conditions and to minimize wall-chemistry effects. Nevertheless, boundary-layer simulations can be used to verify the flow condition or to account for non-ideal behavior [147]. 

Planar SOFC, in particular, monolithic designs (MHI) are capable of high (volumetric) power densities most favoured by direct and short current paths across the stack components. The PEN is principally square, rectangular and circular (Ceramic Fuel Cells Limited (CFCL), Mitsubishi Materials Corp., SulzerHexis) in shape with active surface areas of 100-200 cm2 (15.5-31 in2). A drawback of this design is that it often necessitates the use of high temperature sealants for application at the in-... 

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. 

Murthy S., Fedorov G, 2003. Radiation heat transfer analysis of the monolith type solid oxide fuel cell. Journal of Power Sources 124(2), 453—458. 

Ahmed S., McPheeters C., Kumar R. (1991) Thermal hydraulic model of a monolithic solid oxide fuel cell. Journal of the Electrochemical Society 138(9), 2712-2718. 

Tonkovich et al. [123] claimed a 90% size reduction due to the introduction of micro channel systems into their device, which made use of the hydrogen off-gas of the fuel cell anode burnt in monoliths at palladium catalyst to deliver the energy for the fuel evaporation. A metallic nickel foam 0.63 cm high was etched and impregnated with palladium to act as a reactor for the anode effluent It was attached to a micro structured device consisting of liquid feed supply channels and outlet channels for the vapor, the latter flowing counter-flow to the anode effluent... 

For cargo and passenger boats, conversion to fuel cells and electric drive will follow as a consequence of the more favorable economics of the lessened fuel consumption. Hence, the rate-determining step is the manufacture of sufficiently large fuel cells once more the prospects look good for the monolithic solid oxide cell. 

A schematic diagram of a cross-flow monolith fuel cell reactor is given in Figure 1. The reactor consists of two sets of channels in the x and y direction, respectively. 

Figure 1. Schematic diagram of cross-flow monolith fuel cell Z=5 series connection 100 unit cells per battery. Dark areas indicate conductive metal film coating.

Note that, despite the typically high operating temperatures of fuel cells, radiative heat transfer was neglected. Lee and Aris (16) have discussed such effects in parallel-channel monoliths. The importance of radiative transport depends on the emissivity of the surface for the low (about 0.1) emissivity of Pt-coated catalyst-electrodes, their analysis suggests that radiative effects can be neglected. 

Activation energy, stability in trickle-bed reactors, 76 Activation overpotential, cross-flow monolith fuel cell reactor, 182 Activity balance, deactivation of non-adiabatic packed-bed reactors, 394 Adiabatic reactors stability, 337-58 trickle-bed, safe operation, 61-81 Adsorption equilibrium, countercurrent moving-bed catalytic reactor, 273 Adsorption isotherms, countercurrent moving-bed catalytic reactor, 278,279f... 

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