Improving fuel usage in microchannel based fuel cells

In this work the COMSOL Fluid Dynamics and Chemical Engineering modules are used to model the fluid flow through a microchannel based fuel cell. The particular design employed exploits the laminar nature of the fluid flow at small Reynolds numbers to keep the fuel and oxidizer confined in the vicinity of the corresponding electrodes, without the need for a proton exchange membrane (PEM). The performance of these cells is evaluated as a function of the aspect ratio of the channel used and the flow rates through it. Based on the reactants’ consumption rates, the best performing cells are the ones with high aspect ratio operated at high Péclet numbers. The formation of a depletion boundary layer close to the electrodes of the cell is found to be the main factor limiting the efficiency of this type of cells.