Low-Cost, High-Temperature Recuperators for SOFC Fabricated from Ti3AlC2 Machinable Ceramic

Achieving the low-cost and high-efficiency potential of Solid Oxide Fuel Cell (SOFC) systems requires novel approaches to recuperator materials. In these systems, large recuperators are needed to pre-heat the high-flow-rate air to approximately 700% above that dictated by reaction stoichiometry alone. The high-temperature operation requires the use of expensive, heat-resistant metal alloys ¿ which are difficult to machine and cannot be cast into near-net shape, leading to bulky heat exchanger designs. Moreover, recent studies indicate that the metal alloys might reduce the stack power density of the solid oxide fuel cell system. Ceramic materials have been proposed, but their fragility restricts the allowable temperature rise for the air stream. This project will develop and optimize a recuperator based on a new class of machinable, easily-fabricated ceramic materials with good high temperature properties. Titanium silicon carbide and titanium aluminum carbide are examples of this material class that are particularly well suited for the recuperator application. In Phase I, the feasibility of high temperature recuperators, made with the titanium aluminum carbide material, will be demonstrated for SOFC systems. Materials testing will be performed to evaluate high temperature strength, resistance to thermal gradients, and thermal shock and material compatibility. The feasibility of manufacturing and assembling compact heat exchanger configurations with titanium aluminum carbide will be evaluated by a combination of analysis and small scale experiments. Commercial Applications and Other Benefits as described by the awardee: In addition to the application to Solid Oxide Fuel Cells systems, the recuperator should find use in other high temperature applications, e.g., microturbines