Low-Cost High-Temperature Heat Exchanger for Solid Oxide Fuel Cells using a Near-Net-Shape Ceramic Powder Forming Process

79788S The DOE-sponsored Solid State Energy Conversion Alliance (SECA) seeks to develop commercially-viable 3 to 10 kW Solid Oxide Fuel Cell (SOFC) systems by the year 2010. One of the weak links in this system is the heat exchanger, which typically consumes more than 30% of the installed cost ($ 400/kW) and fails before the 40,000 hour design lifetime goal. While traditional ceramic materials would eliminate failure due to creep and sulfidation, their high cost and low thermal shock resistance have inhibited their use. A commercially available, low-cost Si-SiC material with a proven life history, greater than 100,000 hours operation in high temperature natural gas and air environments, will be used to manufacture a highly efficient (approaching 90%), low-cost (< 10% of SOFC system cost), high-temperature heat exchanger with a life expectancy that meets the goals of the DOE sponsored SECA. In Phase I, computational and analytical methods will be used to design a heat exchanger with an effective surface area approaching five times that of a typical shell and tube design. Near-net-shape prototypes will be made fabricated and tested for thermal shock, creep, sulfidation attack, and heat transfer effectiveness. Commercial Applications and other Benefits as described by the awardee: The low cost heat exchanger should find use in the in the 3 kW to 10 kW solid oxide fuel cell systems targeted for a diverse range of applications: (1) stationary residential, office, and industrial electricity generation (2) transportation in the form of auxiliary power units for diesel trucks and automobiles, and (3) military remote power generators using logistic fuels.