Liquid water in channels is known to significantly impact performance in PEMFCs. This study strives to understand the effect of water interaction between channel, GDL and CL on cell performance by completing coupled cell performance evaluation, liquid water visualization by NRG method and numerical modeling based on M2 model. NRG results showed a peak towards the CL in through-plane distribution of liquid water in the MEA. On the other hand, numerical results suggested very uniform distribution. This disparity was successfully explained with consideration of a porosity distribution of GDL and/or a gap between CL/GDL, indicating that the higher porosity surface of GDL and/or the gap led to lower performance as a result of high liquid water saturation in CL. It appears therefore important to appropriately engineer the boundary between CL and GDL in order to realize high current density operation.
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