Modelling of a porous flowing electrolyte layer in a flowing electrolyte direct-methanol fuel cell

•A flowing electrolyte channel is modelled as a 2D isothermal porous domain.•Flow generally has a flat profile with minimal boundary layers and entry length.•Pressure drop is most strongly affected by volume flux and permeability.•The design goal is to minimize methanol crossover, ohmic losses, and pressure drop.•A thin channel with sufficiently high volume flux and permeability is suggested.

The flowing electrolyte-direct methanol fuel cell is a developing technology that may have practical uses in the future. Its main advantage over a direct methanol fuel cell is that it limits methanol crossover using a flowing electrolyte layer. The flowing electrolyte layer (or flowing electrolyte channel) involves an ion-conducting fluid that allows protons to be transported from the anode to the cathode, and flows through a porous material to wash away crossed-over methanol. In this study, the flowing electrolyte layer is modelled as a porous domain in ANSYS CFX. General flow behaviour and the effects of volume flux, channel thickness, and porous material properties are investigated. It is found that the flow has a flattened velocity profile with thin boundary layers that are virtually independent of volume flux and channel thickness. The pressure drop is mainly dependent on the volume flux and the permeability. It is recommended that cell performance could be improved by using a flowing electrolyte channel that is thinner, and selecting a sufficiently high volume flux and a sufficiently permeable porous material to achieve an optimal combination of pressure drop and methanol removal characteristics.