Dynamic relationship between the CO2 gas bubble behavior and the pressure drop characteristics in the anode flow field of an active liquid-feed direct methanol fuel cell

Abstract

Gas management is one of the bottlenecks hindering the development of direct methanol fuel cells (DMFCs). This work investigates the effects of anode serpentine flow field design on the cell performance, gas bubble behavior and pressure drop characteristics of an active liquid-feed DMFC. Three types of flow field setup based on the traditional right-angle serpentine flow field (RASFF), rounded-corner serpentine flow field (RCSFF), and step-wise broadening serpentine flow field (SBSFF) are tested. The results show that the fillet corner of the RCSFF and broadening channels of the SBSFF contribute to the CO2 emission and uniform distribution of reactants, respectively. The use of RCSFF and SBSFF yields a higher cell performance than that of RASFF under most of our testing conditions. There exists a strong relationship between the gas bubble behavior and the pressure drop characteristics. Gas slugs are conducive to reducing the pressure drop between the inlet and outlet on the anode side, whereas gas bubbles are counterproductive. The results also indicate that with increasing current density, the gas slugs gradually play a dominant role instead of gas bubbles in each flow field but the opposite is true when the methanol feed rate increases.