Effects of serpentine flow-field designs with different channel and rib widths on the performance of a direct methanol fuel cell

This study experimentally and numerically investigates the effects of the four different types of serpentine flow-field geometry on the performance of a direct methanol fuel cells (DMFCs). To elucidate the effect of different channel/rib aspect ratios, the through/in-plane transport of methanol and air, the current density distribution, the anode and cathode polarization, the impedance and the cathode pressure drop are numerically and/or experimentally observed. The sub-rib convection significantly affects the cell performance with the serpentine flow fields. Thus, a narrow rib width and a suitable channel/rib aspect ratio are needed to increase the cell performance of serpentine DMFCs. This flow channel, for example, an F2-type flow channel (channel width: 1.0 mm, rib width: 0.5 mm), leads to formation of a narrower rib chain as well as a higher current density distribution in the rib, and thereby it brings about improvement of the two-phase flow in DMFCs, which is supported through the high performance difference in the high current density regions and the long-term stability test of 700 h. (C) 2012 Elsevier BA/. All rights reserved.