A simultaneous solution of all transport processes in a solid oxide fuel

The KAMELEON SOFCSIM computer code was developed and used to find simultaneous solutions of all conservation equations for mass, energy and momentum in a quasi three dimensional, single, flat solid oxide fuel cell (height 7.5 mm and length 5.00 cm). The thickness of the electrolyte and the electrodes was 500 mu m. interconnectors included six transverse ribs through channels for coflow of fuel and air. A rectangular grid with 2448 points was used for the simulations. For a given cell voltage, we found that the rib design had a major impact on current production. An optimum rib size was predicted, A negligible current was calculated in the shadow beneath the ribs. An optimum gas velocity is expected for a diffusion controlled reaction. Pressure gradients of about 10(4) Pa m(-1) across the electrolyte may give gas leakage through cracks. Longitudinal and transverse temperature gradients in the solid materials are such that thermal stresses should be evaluated. The results for the two-dimensional system are all relevant for three-dimensional stack design. Electrochemical reaction modelling can not be seen separate from velocity and temperature field calculations.