MACROSCOPIC SIMULATIONS OF TRANSPORT PROCESSES IN PLANAR SOLID OXIDE FUEL CELLS: AN EVALUATION OF PERFORMANCE-LIMITING FACTORS

Development of highly efficient and commercially viable solid oxide fuel cells (SOFCs) requires throughout optimization of all their components from micro- to macro-level, taking into account the device type, fabrication technologies, materials and application conditions. This work was focused on numerical modeling of the distributions of current density, temperature, fuel and oxidant concentrations in a planar SOFC with supporting solid-electrolyte membrane of stabilized zirconia, bilayered electrodes and stainless steel interconnectors of the Crofer 22 APU alloy. The simulations by the finite volume method, performed in order to determine major optimization factors of the single SOFC construction, made it possible to obtain realistic integral parameters close to the experimental data on la-boratory-scale SOFCs. The fact that the massive metallic current collectors in the planar SOFC configuration significantly suppress local inhomogeneities in the temperature field within entire examined current range was confirmed. The key optimization tasks include width and geometry of the contacts between interconnectors and electrodes, optimum gas-channel size for various fuels and catalysts, an evaluation of technologically feasible alternative types of the current collector configurations in order to avoid partly blocked edge zones with a low local current density, and experimental studies of the porous electrodes near the “current collector | electrode” interface edge where sintering and degradation processes may be induced by high currents. The boundary conditions for such simulations should be selected in the intermediate current range around the SOFC power density maximum in order to minimize limiting effects of mass-transport processes and to achieve the regimes necessary for practical applications.

твердооксидный топливный элемент (ТОТЭ), планарная конфигурация, численное моделирование, распределение тока, массоперенос, solid oxide fuel cells (SOFCs), planar configuration, numerical modelling, current distribution, mass transfer

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