Development of maldistribution of humid nitrogen condensing flow and the blockage in parallel channels

Maldistribution in parallel flow fields reduces the performance of proton exchange membrane fuel cells (PEMFCs) and heat exchangers. In this study, a condensing flow experiment was conducted in which water vapor condensed while humid nitrogen flowed through a parallel flow field with eight channels. The flow maldistribution across channels and blockage in channels induced by condensed water were investigated by measuring the flow rates in the channels and the pressure drop across the flow field. The results show that the development of the condensing flow can be divided into developing and quasi-steady stages according to the evolution of the flow rate and pressure drop. At a high nitrogen flow rate, the maldistribution was more severe during the developing stage than during the quasi-steady stage. In contrast, at a low nitrogen flow rate, the maldistribution was more severe in the quasi-steady stage, which can be attributed to the complete blockage induced by liquid water in the channels in this stage. Finally, at low nitrogen flow rates, the extent of maldistribution and duration of complete blockage decreased remarkably with an increase in the water molar fraction.