Computational analysis of the impact of a micro porous layer (MPL) on the characteristics of a high temperature PEMFC

Abstract

High-temperature PEM fuel cells (HT-PEMFCs) are of current interest due to their favorable characteristics in relation to PEM fuel cells operating at a low temperature (LT-PEMFCs). The benefits concern poisoning of the CO catalyst, water management, thermal management and humidity issues. The major challenge facing these fuel cells is to have the membrane performing well at high temperature. This manuscript reveals the impact of an added micro porous layer (MPL) at both the cathode and anode electrodes by using a three-dimensional (3-D) numerical single-phase model. The bipolar plates have serpentine flow channels for the reactants. The most important result is that the MPL, known as the water management layer (WML) in LT-PEMFCs, improves the performance of an HT-PEMFC in terms of enhanced mass and heat transfer. The difference in the polarization curve and the three overpotentials (activation, ohmic, concentration) between two cases, i.e., with and without MPL, prove that the HT-PEMFC performance improvement is most significant for the ohmic overpotential (about 130% decrease at high current densities). In addition, a more uniform temperature distribution is obtained within the fuel cell components, especially in the membrane electrode assembly (MEA). This improved the performance of the membrane and accordingly a slight improvement of the fuel cell performance. The result shows a difference (at the point of maximum power) between the curves of with and without MPL of about 35%.