Flow field design with 3D geometry for proton exchange membrane fuel cells

It has been well recognized that the power density of fuel cells is limited by two key issues known as water flooding and oxygen starvation. Since flow field plays a critical role on the mass transport in fuel cells, a flow field design enabling improved water management and enhanced oxygen transport is highly desired to address these problems. In this work, two types of flow fields with three-dimensional channel geometry are proposed and developed. One flow field is designed to own waved channels to induce local oxygen convection flux from flow channel/diffusion layer interface to catalyst layer in order to enhance the oxygen supply. The other one owns the waved channels with gradient channel depth that results in increasing flow velocity at both in-plane and through-plane directions from upstream region to downstream region, accommodating the uneven distribution of oxygen concentration. The experimental results clearly demonstrate that the 3D channel geometry is capable of improving cell performance especially at high current densities, which can be attributed to the enhanced oxygen transport and water removal as illumined by a numerical simulation.