Geometrical design of membraneless micro fuel cell to reduce mixing and depletion region

Abstract

A comprehensive numerical study of membraneless micro fuel cells with various geometries is carried out with the aim of reducing the mixing of the anode and cathode fluids and increasing their fuel utilization. Designs with blocks or obstacles in the main channel or a main channel with a wavy shape result in very little improvement in these properties or even in their deterioration. However, some designs with other types of channel cross-section exhibit much less mixing of the two fluids in the main channel. The H-shaped cross-section exhibits much less mixing in the main channel and much higher fuel utilization. The fuel cell with a trident-shaped cross-section has two inlets for the anode and cathode fluids and a third inlet for the proton-conducting fluid, and is found to be the best design in that the anode and cathode fluids are more restricted to their respective electrodes (reaction surfaces). MEMS fabrication and experiment are carried out. H shape membraneless micro fuel cell is fabricated because H shape is easier to fabricate. The H shape increases current density and power density compared with rectangular shape. Mixing region of membraneless micro fuel cell decreases in H shape by flow visualization.