An integrated CFD-approch to deisgn micro-tubular Solid Oxide Fuel Cells

The development of kW-size stacks of Solid Oxide Fuel Cells (SOFCs) requires the solution of many and different technological issues to improve reliability and reduce costs. The use of micro-tubular technology may help to solve some of these issues, especially by utilizing a modular approach to build the largest as possible "repeatable units". However, reactant flows and geometries must be carefully designed to get a good behavior in terms of power output and homogeneity of exploitation of all the electrochemical material. An integrated CFD approach based on multi-dimensional analysis to design modular micro-tubular SOFCs is proposed in this paper. It is composed by two distinct tools (namely detailed and fast): they are characterized by different accuracy and computational expenses. The whole model is first validated with a specifically implemented experiment of a single channel SOFC. Then, it is applied to analyze the coupling among heat transfer, fluid-dynamics and electrochemistry of increasingly complex systems (micro and midi-reactors, constituting respectively 15 and 45 tube assemblies). Finally, it is utilized to optimize the geometry of the cited modular systems in terms of air and heat release management to get the maximum performance in terms of power density keeping as low as possible the impact of thermal stresses on cell durability.