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The results of numerical calculations performed for planar solid oxide fuel cells are presented. Two different approaches are developed: (i) A detail numerical method and (ii) a presumed flow method. In the first approach, a commercial computational fluid dynamics code is employed, and user-defined-functions are developed to account for electro-chemical considerations. In the second approach, where the momentum equations do not require to be solved, an in-house code is developed and used to perform calculations. In both cases the following coupled physicochemical phenomena are modelled; heat and mass transfer, electrochemistry and electric potential. The polarisation curve is generally accepted as an important performance measure of the fuel cell. Performance predictions for this characteristic made by the two different approaches are compared. Results show voltage losses due activation, Ohmic resistance, and mass transfer in a typical solid oxide fuel cell, over a range of current density values. The results for the detailed numerical method are discussed in some detail with regard to the influence of different parameters on the overall performance of the device.

Transport phenomena play an important role in the performance of the proton exchange membrane fuel cell. Water generated by electrochemical reactions and transported by osmotic drag and back diffusion can cause saturation or flooding, preventing oxygen from reaching catalysis sites. Dehydration may also occur, resulting in poor proton conductivity. Balancing water content within the membrane involves judicious water and heat management strategies. In this paper, detailed mathematical models for the prediction of all significant aspects of physicochemical hydrodynamics for a proton exchange membrane fuel cell are employed. Fully coupled heat and mass transfer and electrochemistry are considered, and the dependence of water transport on these factors is taken into account. Two distinct approaches were considered: a fully three-dimensional approach and a hybrid scheme, whereby the electrochemistry and electric fields are treated as locally one dimensional in the membrane assembly. Comparisons between the two approaches are presented and discussed. The numerical results suggest a dependence of the rate-of-water removal on temperature, current density, and inlet humidification levels, and also that the oxygen concentration in the air channels significantly affects current density distribution.