Modelling of gas transport in proton exchange membrane fuel cells

A three-dimensional numerical model has been developed to simulate a proton exchange membrane fuel cell. The governing equations were discretised and solved using a finite-volume technique and the numerical results were verified by empirical test results. In the numerical procedure, the species, temperature and protonic conductivity distribution in various voltages were modelled with great accuracy. The results have shown that by lowering the cell voltage, the maximum temperature at the cathode catalyst-membrane interface will increase. The effects of semicircular and semi-elliptical gas channel cross-sections on cell performance were studied and compared with base model results. This showed that the elliptical model generates more current density at the same voltage. On the other hand, oxygen distribution is more uniform in geometries in which the value of cathode overpotential has a direct link with oxygen magnitude. Cathode overpotential is also sensitive to shoulder width and oxygen distribution; so the elliptical model presents better performance than the other models. Ultimately, all the numerical and experimental results are compared with published experimental data by Wang et al., which demonstrate desirable agreement.