In-plane temperature gradient does not necessarily affect cell performance: a stack-scale study

Current density and temperature heterogeneities are investigated experimentally at the stack scale using a large Proton Exchange Membrane Fuel Cell (PEMFC). For a wide range of operating conditions, including different coolant temperature gradients (between stack outlet and inlet), coolant outlet temperatures, and gas relative humidities, and for two Membrane Electrode Assemblies (MEAs), the stack performance is characterized and the distributions of temperature and current production in the middle cell of the stack are measured. Simulation results from previous studies are used to better understand the experimental results, in particular for the water distribution in the cells, which cannot be easily measured experimentally. The results show that both uniform current density and temperature distributions are not obviously correlated to performance. • Experimental study of PEMFC stacks in real operating conditions • Analysis combining experimental results and simulations • Water content and performance evaluated against coolant operating conditions • Effects of the coolant temperature gradient on operating uniformity are elucidated. • Operating uniformity is not obviously correlated to performance of PEMFC.