Investigation of the effect of multidimensionality in PEM fuel cells

Highlights: • A computational study to investigate the multidimensional effects on PEM fuel cells. • Multidimensional effects were investigated by developing two similar models. • Cathode region is the most sensitive to the multidimensional effects. • Multidimensional effect is more prominent at lower velocity values at cathode. • Water at cathode is the most sensitive species to the multidimensional effects. - Abstract: Modeling can assist in achieving better understanding of various complex physicochemical processes occurring in fuel cells, which is critical in improving the fuel cell performance and making them more cost effective. Modeling efforts in PEM fuel cell area have been focused on developing both single and multidimensional (2D and 3D) PEM fuel cell models. The higher dimensional models include more realistic and accurate descriptions of the fuel cell processes; however, they also involve more complexity and require considerably extensive computational resources. Hence, despite the availability of higher dimensional fuel cell models, the lower dimensional models still retain their relevance and are being extensively used. Past studies commented on the effect of multidimensionality by comparing the results of higher and lower dimensional models which had differences in fuel cell geometry, operating conditions, modeling assumptions and properties. Owing to these differences between models, the difference in their results could not be solely attributed to the effect of multidimensionality. The present study was motivated by recognizing this gap in literature. The multidimensional effect is analyzed by developing two similar steady state 2D and 3D models in COMSOL. Both of these models have similar geometry and are simulated under similar operating conditions. The effect of multidimensionality on species concentration is investigated at various inlet stoichiometries, membrane conductivities and relative humidity values. The multidimensional effect, as represented by difference in species distribution in the two models, is found to be significant at lower operating voltages and more prominent at the cathode side. The inlet stoichiometry at the cathode and membrane conductivity values, are also found to influence the multidimensionality effects