Effects of membrane swelling on structural deformation and performance of proton exchange membrane fuel cell

The change of relative humidity (RH) leads to the expansion and shrinkage of the membrane, resulting in hygrothermal stress, performance degradation and mechanical damage of proton exchange membrane (PEM) fuel cell. In this study, a two-dimensional PEM fuel cell deformation model and a three-dimensional computational fluid dynamics (CFD) model are coupled to study the performance of fuel cell. Emphasis is placed on the influence of membrane swelling and clamping force on the performance of fuel cell. It is found that membrane swelling leads to the structural change of membrane electrode assembly (MEA) and stress in the MEA. The simulated fuel cell performance considering membrane swelling is lower than that of the undeformed membrane, due to smaller electrochemical reaction rate under the rib and higher ionic resistance. The membrane deformation and PEM fuel cell performance under different RHs are also investigated, and medium RH values are found to achieve good fuel cell performance if considering the membrane swelling effect.