Thermal modelling of the cathode in air-breathing PEM fuel cells

A thermal two-dimensional model has been built for an air-breathing proton exchange membrane (PEM) fuel cell that has been reported in the literature. The objective of the study is to investigate the thermal situation over the cathode surface of the fuel cell. The Joule heating was found to be significant and therefore it must be incorporated into the model, especially at high current densities. Such incorporation leads to a more accurate estimation of the heat transfer coefficient, which is a major performance indicator for air-breathing PEM fuel cells. The heat transfer coefficient was found to be less sensitive to the entropic heat of the fuel cell; however, this effect cannot be overlooked, especially at low current densities. Finally, the orientation was shown to have a significant effect on the thermal dissipation from the air-breathing PEM fuel cells: the heat is dissipated far more effectively if the fuel cell is oriented vertically or horizontally facing upwards than if it is oriented horizontally facing downwards.