Supported Continuous Fiber Burner

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energy convertersS or as an interconnect material in solid oxide fuel cells. 6 This perovskite is refractory (melting point temperature = 2510 oC), 7 and has a high electronic conductivity which is consistent with a high emissivity, and can be fabricated in strong fibrous form~ SUPPORTED CONTINUOUS FIBER BURNER We have identified a rather broad range of optical characteristics available from refractory ceramic oxides that can be fabricated in strong fibrous mantle form. From Eq. (1), it is apparent that as we make larger mantles, their ability to withstand mechanical damage suffers. A requirement for a large emitter system may be met with an array of mantles but this approach generally causes added complexity and, in some applications, a degraded view factor. Figure 3 is an approach8 that preserves the desirable properties of fibers in planar, robust emitters of arbitrary size. We begin with a substrate selection based on mechanical durability, porosity, cost, etc. but not for optical nor thermal considerations because the substrate does not, to first order, participate in the emission process. We have selected an extruded cordierite product from Corning called Celcor that is promoted as a catalyst support. This material is available in a variety of pore densities, and we have chosen a pore density of 300 per square inch. A slice, 10 to 15 rom thick, is cut from the typical 6 inch square extruded form. The imbibed precursor rayon yarn bundle is routed along alternate diagonals until the active area is filled. The continuous fiber bundle is looped into each cell like a hooked rug and is referred to as an uncut looped pile. Typically, the cellulosic precursor is 300 denier, 50 fibril continuous filament rayon yarn (8 twists per inch). The imbibing solution for the highly emissive fiber could be equal volumes of 1 molar solutions of La(N03 )3 and Cr(N03 )3. The extension of the fiber loops on the burner side must anticipate the process shrinkage, and the fiber loops on the plenum side are routed in close proximity to the webs in the substrate. Note that all fiber manipulation in this process is accomplished while the fiber is in the imbibed rayon state. Sintered ceramic fibers cannot withstand the tension and close radius bending required for this construction. The substrate-rayon fiber assembly is processed in a SD.B. Meadowcroft, "Some Properties of Strontium-doped Lanthanum Chromite," British Journal of Applied Physics (J. Phys. D), Sere 2, Vol. 2, 1969. pp. 1225-1233. 6N. Q • Minh, "High Temperature Fuel Cells; Part 2: The Solid Oxide Cell," Chemtech, Vol. 21, No.2, February, 1991. pp. 120-126. 7R. S . Roth, T. Negas, and L.P. Cook, Phase Diagrams for Ceramists, Volume IV. Published by The American Ceramic Society, Columbus, OH 43214, 1981. p. 121. 8This configuration is the subject of a patent application filed with the U.S. Patent Office.