Three-dimensional numerical study of serpentine flow-fields with vertical/lateral synergetic extended structures for PEM fuel cells

As a core component of PEMFC, the flow field plays a crucial role in gas distribution and thermoelectric coupling. To enhance water and gas transport capabilities in both the lateral and vertical directions, thereby improving battery performance, a bent serpentine periodic extended structure (BSPES) flow field with undulating press-bend patterns on the rib surfaces is developed. Considering the influence of extended unit shapes and press-bend depths on the flow field, three different shapes and four levels of press-bend depths are configured in the flow field models. Three-dimensional numerical models are established to evaluate and compare the comprehensive performance of different flow fields. The results show that the extended flow field optimizes water and gas transport and thermal conductivity, reduces pressure loss, and increases energy efficiency. The press-bend depth enhances vertical transport performance but also increases pressure drop. Compared to traditional serpentine flow channels, under the same press-bend depth, BSPES-T (BSPES-Triangle) achieved peak current density and power density improvements of 7.32 % and 6.32 %, respectively, surpassing BSPES-S (BSPES-Square) and BSPES-R (BSPES-Round Arc). For triangular extended shape, a press-bend depth of 0.25 mm resulted in a peak current density increase of 8.98 % and a power density increase of 7.66 %. BSPES-R demonstrated the best balance between pressure loss and performance enhancement.