Effect of a direct current electric field on CO₂ bubble evolution in a direct methanol fuel cell

In direct methanol fuel cell (DMFC) anode microchannels, the retention of CO₂ leads to an anodic polarization reaction. Controlling CO₂ discharge in the anode channel by a direct current (DC) electric field is beneficial for reducing the anodic polarization reaction. In this work, numerical simulation was the main scientific research method, and the leaky dielectric model was used to characterize the effect of the electric field force. An unsteady theoretical model was established by bidirectionally coupling the electric field and multiphase flow field, which, for this research, indicates the formation of CO₂ Taylor bubble flow in a methanol aqueous solution within a DMFC anodic microchannel. Based on this theoretical model, the regulation mechanism of the DC electric field on the dynamic behavior of Taylor bubble formation in DMFC anode microchannels was studied. In the anode channel, the electric field increases the likelihood that the neck of the CO₂ bubble will fracture during Taylor bubble formation. The higher electric field intensity increases the formation rate of CO₂ bubbles and reduces their size. In addition, the electric field reduces the number of satellite bubbles in the anode channel and promotes the mass transfer rate of the methanol aqueous solution. The results show that the movement characteristics of CO₂ can be effectively controlled by applying a DC electric field in the DMFC anode microchannel, which provides a new way to reduce the anodic polarization effect of the DMFC.