The performance and stability of a PEMFC depends on many operating parameters. The measurement of local currents in PEMFC cells is an important tool for diagnoses and development of fuel cells. In this study, a segmented cell was developed, which could serve as an essential instrument to investigate the different operating conditions in the cells and stacks of technical relevance. In addition, the effects of different feed gas humidity and temperatures were investigated to analyze the steady-state performance, uniformity, and the local stability of PEMFC with the use of eight segmented regions. With this research method, the resistance in each segment could be measured by ac impedance as well as make a comparison between Nafion® 117 and 112 membranes in PEMFC. In the experiment, by probing into the high frequency internal resistance and performance of this cell, the effects of flow rates of fuels, oxidants, relative humidity, and directional channel flows were investigated for performance and stability of local segmented regions. The results of the experiments demonstrate that the local current distribution is strongly influenced by the relative humidity of fuel, the stoichiometric of the processed air, and the mode of operation. The cell was operated at a cell temperature of 50 °C with low relative humidity of 33% and 0%, causing the drying of the membrane (and increase of its resistance) at the top-stream path. The membrane conductivity was enhanced due to the water product increase by the reaction in the middle- and down-stream paths, because the down-stream has higher current than the top-stream. The relative humidity of the air increased along the path due to the product water, therefore, the current density increased as well. The local segmented cell could maintain stable performance at low hydrogen stoichiometry of 1.05 for low humidity gases. As the counter-flow and inverse gravity direction of hydrogen fuel was operated, the fuel cell showed the much more stable and uniform local performance.
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