Hybrid Ceramic/Metallic Recuperator for SOFC Generators

Solid oxide fuel cells (SOFCs) are one of the most efficient and cleanest power generating systems under development. A key component in the SOFC generator is the cathode-air heat exchanger or recuperator, which ensures that the cathode air (and, thereby, the cells) is at a sufficient temperature to permit ion mobility and improve overall SOFC system efficiency by reducing stack losses. However, commercially-available metallic recuperators represent a significant fraction of the overall cost of an SOFC generator, and a highly-effective, low cost, long life alternative is needed. This project will develop and demonstrate a ¿hybrid¿ recuperator that combines a high-temperature ceramic section with a low-temperature metallic section to reduce overall costs, while achieving the high effectivenss and long life required of an SOFC generator. This arrangement takes advantage of the high-temperature low-fouling capability of a ceramic heat exchanger core ¿ while allowing lower-grade metallic materials, with high extended surface area, to be used in medium-to-low temperature regions. By incorporating the ceramic and metallic sections into a single unit, costly interconnect ducting and fittings (along with associated support structure and insulation) will not be required, significantly reducing the cost over non-integrated solutions. In Phase I, metallic and ceramic heat exchanger cores will be designed, manufactured, and tested. These cores will then be assembled into an integrated "hybrid" recuperator, and the performance of the unit will be verified. In Phase II, fabrication techniques for the integrated recuperator, in particular the method of attaching to and sealing the ceramic core, will be further refined and developed. Commercial Applications and Other Benefits as described by the awardee: The ¿hybrid¿ recuperator should significantly reduce the cost of a key component in Solid Oxide Fuel Cell generators. It is estimated that a cost reduction of $100/kW (compared with state-of-the-art metallic recuperators) can be achieved with this technology, increasing the economic and commercial viability of this low-emission, high-efficiency, power-generation technology. In addition to its use in SOFC generators, the technology also should find use in other high temperature applications such as metal melting furnaces, glass furnaces, chemical process reactors, and forge furnaces.