Effect of placing different obstacles in flow fields on performance of a PEM fuel cell

A complete two-dimensional and two phase model for proton exchange membrane (PEM) fuel cells is used to investigate the effect of using different obstacles on the performances, current density and gas concentration for different Aspect Ratios. The proposed model is a full cell model, which includes all the parts of the PEM fuel cell, flow channels, gas diffusion electrodes, catalyst layers and the membrane. Coupled transport and electrochemical kinetics equations are solved in a single domain; therefore no interfacial boundary condition is required at the internal boundaries between cell components. This computational fluid dynamics code is used as the direct problem solver, which is used to simulate the two-dimensional mass, momentum and species transport phenomena as well as the electron- and proton-transfer process taking place in a PEMFC. The results show that the predicted polarization curves by using this model are in good agreement with the experimental results. Also the results show that the local current density reduces more obviously at a higher overpotential than at a lower overpotential because of the more obvious reflection phenomena in the downstream region. At lower operating voltage conditions, the overall cell performance decreases as the aspect ratio decreases.

PEM fuel cell, rectangular obstacle, triangle obstacle, numerical modeling, current density and gas concentration