Stochastic Analysis of the Gas Flow at the Gas Diffusion Layer/Channel Interface of a High-Temperature Polymer Electrolyte Fuel Cell

Dieter Froning,Junliang Yu,Werner Lehnert,Uwe Reimer

doi:10.3390/app8122536

Abstract

Gas diffusion layers (GDLs) play a significant role in the efficient operation of high-temperature polymer electrolyte fuel cells. They connect the electrodes to the gas channels of the bipolar plate by porous material with a meso-scale geometric structure. The electrodes must be sufficiently supplied by gases from the channels to operate fuel cells efficiently. Furthermore, reaction products must be transported in the other direction. The gas transport is simulated in the through-plane direction of the GDL, and its microstructure created by a stochastic model is equivalent to the structure of real GDL material. Continuum approaches in cell-scale simulations have model parameters for porous regions that can be taken from effective properties calculated from the meso-scale simulation results, as one feature of multi-scale simulations. Another significant issue in multi-scale simulations is the interface between two regions. The focus is on the gas flow at the interface between GDL and the gas channel, which is analyzed using statistical methods. Quantitative relationships between functionality and microstructure can be detected. With this approach, virtual GDL materials can possibly be designed with improved transport properties. The evaluation of the surface flow with stochastic methods offers substantiated benefits that are suitable for connecting the meso-scale to larger spatial scales.

Highlights

In all types of polymer electrolyte fuel cells (PEFC), called proton exchange membrane (PEM)fuel cells, the gas diffusion layers (GDLs) are components with high relevance for efficient operation of fuel cells
Through-plane transport was simulated in 25 realizations created by the geometry model, oriented in reverse order to distinguish the GDL/channel surface from the GDL/electrode surface presented by Froning et al [26]
The conditions led to a Reynolds number of 2.4 × 10−4. This in turn led to velocity vectors at the GDL exit that were almost parallel to the through-plane direction

Summary

Introduction

In all types of polymer electrolyte fuel cells (PEFC), called proton exchange membrane (PEM). Fuel cells, the gas diffusion layers (GDLs) are components with high relevance for efficient operation of fuel cells. One is the electric contact to be provided between the bipolar plates and the catalyst layer (CL). This determines the choice of the material. The second requirement is to facilitate efficient mass transport. For this purpose, an appropriate microstructure is required. Carbon fibers are typically used for the fabrication of different types of GDLs, e.g., paper, woven, or non-woven textiles.

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Conclusion