M.S. Ismail

Through-Plane Permeability for Untreated and PTFE-Treated Gas Diffusion Layers in Proton Exchange Membrane Fuel Cells

The through-plane permeability has been experimentally measured for untreated and polytetrafluoroethylene-treated (PTFE-treated) gas diffusion layers (GDLs), as used in proton exchange membrane fuel cells. Contrary to what the literature has previously shown, the results suggest that there exists an optimum value for the wet-proofing agent, PTFE, at which the though-plane permeability of the GDL is a maximum. The analysis that is undertaken to investigate the effect of the air compressibility shows that there is an underestimation in the through-plane permeability of the tested GDLs by of the order of 9% if the density of the air is assumed to be constant. Also, a nondimensionalisation analysis shows that ignoring the non-Darcy effects at the maximum reported flow rates result in negligible errors for the untreated and treated GDLs.

Transparent PEM Fuel Cells for Direct Visualization Experiments

This paper reviews some of the previous research works on direct visualization of water behavior inside proton exchange membrane (PEM) fuel cells using a transparent single cell. Several papers which have employed the method have been selected and summarized, and a comparison between the design of the cell, materials, methods, and visual results are presented. The important aspects, advantages of the method, and a summary on the previous investigations are discussed. Some initial works on transparent PEM fuel cell design using a single serpentine flow-field pattern are described. The results show that the direct visualization via transparent PEM fuel cells could be one potential technique for investigating the water behavior inside the channels and a very promising way forward to provide useful data for validation in PEM fuel cell modeling and simulation.

Through-plane permeability for untreated and PTFE-treated gas diffusion layers in proton exchange membrane fuel cells

The through-plane permeability has been experimentally measured for untreated and PTFE-treated gas diffusion layers (GDLs), as used in proton exchange membrane fuel cells. Contrary to what the literature has previously shown, the results suggest that there exists an optimum value for the wet-proofing agent, PTFE, at which the though-plane permeability of the GDL is a maximum. The analysis that is undertaken to investigate the effect of the air compressibility shows that there is an underestimation in the through-plane permeability of the tested GDLs by of the order of 9% if the density of the air is assumed to be constant. Also, a non-dimensionlisation analysis shows that ignoring the non-Darcy effects at the maximum reported flow rates results in negligible errors for the untreated and treated GDLs.Copyright

The effects of shape on the performance of cathode catalyst agglomerates in polymer electrolyte fuel cells: A micro-scale FEM study

Purpose – The purpose of this paper is to numerically investigate the effects of the shape on the performance of the cathode catalyst agglomerate used in polymer electrolyte fuel cells (PEFCs). The shapes investigated are slabs, cylinders and spheres. Design/methodology/approach – Three 1D models are developed to represent the slab like, cylindrical and spherical agglomerates, respectively. The models are solved for the concentration of the dissolved oxygen using a finite element software, COMSOL Multiphysics®. “1D” and “1D axisymmetric” schemes are used to model the slab like and cylindrical agglomerates, respectively. There is no one-dimensional scheme available in COMSOL Multiphysics® for spherical coordinate systems. To resolve this, the governing equation in “1D” scheme is mathematically modified to match that of the spherical coordinate system. Findings – For a given length of the diffusion path, the variation in the performances of the investigated agglomerates is dependent on the operational overp...

Transparent PEM fuel cells for direct visualisation experiments

This paper reviews some of the previous research works on direct visualisation inside PEM fuel cells via a transparent single cell for the water behaviour investigation. Several papers which have employed the method have been selected and summarised and a comparison between the design of the cell, materials, methods and visual results are presented. The important aspects, advantages of the method and a summary on the previous work are discussed. Some initial work on transparent PEM fuel cell design using a single serpentine flow-field pattern is described. The results show that the direct visualisation via transparent PEM fuel cells could be one potential technique for investigating the water behavior inside the channels and a very promising way forward to provide useful data for validation in PEM fuel cell modelling and simulation.Copyright