Simulation of the Effect of Novel Porous Channels and Their Optimizations on the Performance of Direct Ethanol Fuel Cells

Abstract

The design of a channel has significant effects on mass transfer and water and heat management inside fuel cells. In this study, novel three-dimensional porous channels and their optimizations (coupling design of the geometric structure and surface shape) by the computational fluid dynamics (CFD) method are proposed to improve the comprehensive performance of direct ethanol fuel cells (DEFCs). The overall electrical performance of tubular DEFCs is significantly better than that of parallel channels because of the better capacity for oxygen convection and water removal of three-dimensional (3D) porous channels. Among porous channels of different shapes, the square and triangular shapes were found to perform the best. Through optimization, the oxygen mass transfer capacity was enhanced remarkably owing to better convection, while the velocity distribution was disordered in some cases. The results also indicate that square porous channels and their optimizations have a power density growth rate of 15.99% and 40.86%, respectively, at 0.2 V, compared to parallel channels. Therefore, the square tapered design further improves the pressure drop inside the electrode layers, provides a more uniform distribution of oxygen, and allows liquid water to concentrate at the outlet, and has thus been proven to be the optimal choice.