Effect of assembly pressure on performance of polymer electrolyte membrane fuel cells

Polymer electrolyte membrane fuel cell (PEMFC) has been widely considered as one of the most promising clean energy power sources, especially for portable electronic products, small fixed station and automobiles, because of its high power density, capability of quick start-up, and advantages of clean and quiet operation. In this paper, the test system was established to investigate the performance of self-assembled PEMFC under different operating conditions. By combining FEM model and two-phase flow model, the changes of porosity of gas diffusion layer (GDL) has been analyzed based on variation in thickness resulting from assembly pressure. The effects of assembly pressure have been investigated with relation to permeability, diffusivity, electrical conductivity, and the changes in water content in the cathode diffusion layer. It is found that with increasing assembly pressure, the porosity of GDL tends to decrease gradually and the water contents tend to increase. In addition, an increase in current density will result in an increase of water content in catalyst layer as well as in GDL, leading to much more difficulties in water management.