A numerical investigation of serpentine flow channel with different bend sizes in polymer electrolyte membrane fuel cells

Bipolar plates are one of the key parts of a PEMFC (polymer electrolyte membrane fuel cell). The flow fields of the bipolar plates distribute reactant gasses on the electrode surfaces. The flow channels should have an appropriate design to decrease the mass transport loss at a minimum pressure drop. Among different flow channels, serpentine flow channel received considerable attention for application in electrochemical cells. In this work, a three-dimensional numerical model is proposed and applied for studying the effect of bend sizes on a PEM (polymer electrolyte membrane) fuel cell. The obtained results show that as bend size increases from 1 mm to 1.2 mm, not only does the over potential reduce significantly but temperature gradient is also alleviated. These welcome effects are largely due to a more even distribution of electrolytes over the electrode surface which eventually increases the power density of the fuel cell about 1.78% compared to channels with 0.8 mm square bend size. Moreover, it is shown that the serpentine flow channels with 1.2 mm square bend size act successfully in preventing secondary flows internal thereby decreasing pressure drop about 90.6% compared to serpentine flow channels with a bend size of 0.8 mm.