Performance and flow characteristics of large-sized PEM fuel cell having branch channel

• The reduction in the number of stack layers can shrink stack components.
• To reduce the number of stack layers, a large bipolar plate is needed.
• This study presents the design of a new bipolar plate to obtain a lower pressure drop.

In order to further commercialize fuel cell systems, the price of the systems needs to be reduced. In particular, problems concerning the high price of the stack, part of the fuel cell system, need to be resolved. The reduction of the number of stack layers can achieve shrinkage of the stack components, including the bipolar plate, MEA, and gasket, with a significant reduction in the price of the stack. Accordingly, to determine a way to reduce the number of stack layers, the bipolar plate needs to be large; this study thus presents a new channel pattern to restrain the increase of the differential pressure of the cathode that would be caused by a large-sized bipolar plate. Computational analysis shows that, in the case where a branching factor (f) of the branch channel is changed from 1 to 0.5 in its exit part, the performance of the channel is similar, but the pressure drop is reduced by 78.33% compared to a serpentine channel. Test results suggest that while the serpentine channel produces the electric power of 139.8 W due to the pressure drop, a blower consumes electric power of 9.12 W and, in case of the branch channel with the f value of 0.5 in its exit part, the blower consumes the electric power of 4.38 W, which is a 3.55% greater performance compared to the serpentine channel.