Modelling of a Porous Flowing Electrolyte Layer in a Flowing Electrolyte-Direct Methanol Fuel Cell

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 the parasitic losses that are due to methanol crossover using a flowing electrolyte layer. The flowing electrolyte layer (or flowing electrolyte channel) involves an ion-conducting fluid, such as sulphuric acid, that easily allows protons to be transported from the anode to the cathode, and flows through a matrix of porous material to wash away crossed-over methanol. In this study, the flowing electrolyte layer is modeled 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 of the volume flux and the permeability. It is recommended that cell performance could likely be improved by using a flowing electrolyte channel that is as thin as reasonably achievable, and selecting a sufficiently high volume flux in conjunction with a porous material of sufficiently high permeability to achieve an optimal combination of pressure drop and methanol removal characteristics.