FRACTAL ANALYSIS OF GAS FLOW THROUGH THE GAS DIFFUSION LAYER IN PROTON EXCHANGE MEMBRANE FUEL CELLS WITH ROUGHENED MICRO-CHANNELS

Abstract

The effective permeability is one of the key parameters for porous fibrous gas diffusion layer (GDL), which plays a crucial role in the proton exchange membrane fuel cells (PEMFCs). However, the effect of the surface morphology of porous fibrous GDL on gas transport behaviors is so far been neglected. In order to take that into consideration, a new analytical model is presented for gas flow in porous fibrous GDL with roughened micro-channels based on the fractal scaling laws. Due to the existence of very small pores in the porous fibrous GDL, gas slippage effects through the small pores are also taken into account. The fractal gas permeability is expressed in terms of the relative roughness, other microstructural parameters as well as gas properties. The proposed fractal model is validated by comparing the model prediction with available experimental data. The effect of relative roughness and other micro-structural parameters of GDL on the permeability is analyzed in detail.