Investigation of Channel‐to‐Channel Cross Convection in Serpentine Flow Fields

Abstract

Channel‐to‐channel cross convection in serpentine flow fields of polymer electrolyte fuel cells (PEFC) can influence the overall cell performance. The effect strongly depends on the gas transport properties of the gas diffusion layer (GDL). For the first time measured anisotropic, compression dependent permeability and effective diffusivity of GDLs are used to quantify the influence of cross convection on the local current distribution and performance. A model was developed to examine different channel‐rib geometries and GDL characteristics. The results show that cross convection can significantly increase the current density and consequently the power density of PEFCs. A strong sensitivity to GDL compression, flow velocity and rib width was found. As an optimised case the GDL thickness under the rib was increased resulting in about 20% higher current densities. Precise knowledge of the GDL characteristics and its compression are key to understand channel‐to‐channel cross convection and optimise perfomance.

In-situ measurements of GDL effective permeability and under-land cross-flow in a PEM fuel cell

“…On the contrary, the cross-flow existed under several lands and the effect of changing the aspect ratio on the fuel cell performance became significant for the triple serpentine flow field. Tehlar et al [8] used a quasi-3D model to investigate the channel to channel pressure difference and the GDL compression effect for a serpentine flow field. They concluded that the cross-flow enhanced the overall current density and led to a more uniform current distribution.…”

A review of recent development: Transport and performance modeling of PEM fuel cells

“…This is since increasing the crosssection area of channel forces more air to flow through the fuel cell, and the water distribution is then more uniform through the catalyst layer. Tehlar et al [69] established an isothermal model to examine different channel-rib geometries and gas diffusion layer characteristics. Their results showed that cross convection in a serpentine channel can significantly increase the current density and consequently the power density of PEM fuel cells.…”

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

“…Their results indicate that the trapezoidal cross-sectional shape ratio has a significant effect on the pressure variation in the flow field in both the presence and absence of cross over. The cross convection under the rib can significantly improve the performance and consequently the power density of PEFCs [19]. Experimental investigations on liquid water removal from gas diffusion layer by the cross flow have been carried out by Jiao et al [20].…”