Measurements of Electrode Temperatures, Heat and Water Fluxes in PEMFCs: Conclusions about Transfer Mechanisms

The objective of this work was to investigate experimentally water and heat transfers in a proton exchange membrane fuel cell. The experiment consisted in measuring, at the anode and at the cathode, the average temperature of the electrodes using small platinum wires, heat fluxes using heat flux sensors and water fluxes by means of water balance. Three thermal configurations related to the temperature imposed to the plates were studied. The measurements put forward a strong influence of the temperature profile on the water transport. On the whole, water fluxes were oriented in the same direction as the heat fluxes which depend on the temperature difference between the MEA and the plates. The results allowed confirming - at least for the materials and the operating conditions used in this work - that water produced by the electrochemical reaction crossed the diffusion layers in vapor phase. In addition, the effective thermal conductivity of porous layers, a key parameter for the analysis of heat transfer in the fuel cell, was estimated in situ.