One of the design parameters of fuel cell is GDL (gas diffusion layer) porosity which helps to remove the water produced and accumulated in the catalyst layers toward the flow channels. In this study, a three-dimensional, isothermal model of a proton exchange membrane (PEM) fuel cell with a straight flow field channel has been developed to investigate the influence of the GDL parameters on performance of PEM fuel cells. The effects of the GDL porosity ranging from 0.3 to 0.6 at different gas channel width were examined. The cell performance is evaluated by the cell voltage–current density curves. The results showed that both the porosity of the GDL and flow field channel affect the fuel cell performance significantly. With porosity in the range 0.3-0.6, a better cell performance can be obtained with higher porosity of gas diffusion layer. And also it was noticed that increasing the channel width while the cell width remains constant decreases the current density.
