Patent ID: 8309266

Claim:
A fuel cell device comprising: an elongate ceramic substrate having an exterior surface, an interior solid ceramic support structure, and a length that is the greatest dimension whereby the elongate ceramic substrate exhibits thermal expansion along a dominant axis that is coextensive with the length, a reaction zone along a first portion of the length configured to be exposed to a heat source to heat the reaction zone to an operating reaction temperature, and at least one cold zone along a second portion of the length configured to be shielded from the heat source to remain at a temperature below the operating reaction temperature when the reaction zone is heated; one or more fuel passages extending within the interior solid ceramic support structure, each having a first fuel pathway extending from a fuel inlet in the at least one cold zone through the reaction zone and a second fuel pathway extending from the reaction zone to a fuel outlet, each first fuel pathway having an associated anode in the reaction zone; one or more oxidizer passages extending within the interior solid ceramic support structure, each having a first oxidizer pathway extending from an oxidizer inlet in the at least one cold zone through the reaction zone and a second oxidizer pathway extending from the reaction zone to an oxidizer outlet, each first oxidizer pathway having an associated cathode in the reaction zone positioned in opposing relation to a respective one of the associated anodes; an electrolyte disposed between each opposing anode and cathode within the interior solid ceramic support structure in the reaction zone, the electrolyte being monolithic with the interior solid ceramic support structure, and wherein each of the one or more fuel and oxidizer passages includes a neck-down point in the respective second fuel and oxidizer pathways having a smaller cross-sectional area than a cross-sectional area of the respective first fuel and oxidizer pathways.