Design of a partially narrowed flow channel with a sub-distribution zone for the water management of large-size proton exchange membrane fuel cells

Abstract

With increased power density and flow field size of proton exchange membrane fuel cells (PEMFCs), water management becomes increasingly important for the exacerbated water accumulation in flow channels (FCs). Therefore, this study proposes a novel partially narrowed channel (PNC) with a sub-distribution zone as a promising alternative for FC design. In addition, a modified volume of fluid (VOF) method is developed using an equivalent contact angle to represent the effect of the rough surface of gas diffusion layer (GDL) on water drainage. Then, a comparison among different FCs and design of structural parameters are conducted. The results show that the highest water drainage efficiency of 9.88 % ms−1 is achieved with the liquid removed in a film state at the pressure drop of 5.01 kPa. Considering the sub-distribution zone, the location and interval of baffles significantly affect water drainage efficiency, while the shape has minimal effect. The highest water drainage efficiency is observed when the baffles are located between the channels with an interval of 2 and 3 mm at low and high airflow inlet velocities, respectively. The PNC with a sub-distribution zone removes liquid rapidly at a moderate pressure drop, thereby reducing pumping losses and risks of membrane degradation.