Numerical Study of Pressure Drop Mechanism and Cross Flow Behavior in the Gas Channel and Porous Medium of a Polymer Electrolyte Membrane Fuel Cell

Abstract

The three-dimensional, transient, isothermal, gas-flow behavior in the serpentine channel and porous gas-diffusion layer (GDL) of a polymer electrolyte membrane fuel cell was investigated numerically. Decreasing the pitch length of the channel increases the pressure drop. In the serpentine channel, reactant gas is distributed from one part of the channel to another through the GDL by cross flow induced by a pressure differential between adjacent channels. The amount of cross-flow, quantified in terms of the volume mass flux through the GDL under the rib and between two channels, is controlled predominantly by the thickness of the GDL, the pitch length of the channel, and the permeability. The permeability of the GDL has marked effects on the pressure drop and on cross flow. The cross flow rate through the GDL increases when decreasing the pitch length of a serpentine channel. Cross flow reduces the pressure gradient in the channel, whereas bends improve the pressure gradient. The pressure gradient in the channel increased with decreasing cross flow.