Laser Structured Gas Diffusion Layers for Improved Water Transport and Fuel Cell Performance

Author(s):  
Christoph Csoklich ◽  
Hong Xu ◽  
Federica Marone ◽  
Thomas J. Schmidt ◽  
Felix N. Büchi
Author(s):  
R. Roshandel ◽  
B. Farhanieh ◽  
E. Saievar-Iranizad

Gas diffusion layers are one of the important parts of the PEM fuel cell as they serve to transport to transport the reactant gases to the catalyst layer. Porosity of this layer has a large effect on the PEM fuel cell performance. The spatial variation in porosity arises due to two effects: 1. Compression of the electrode on the solid landing areas and 2. Water produced at the cathode side of gas diffusion layers. Both of these factors change the porosity of gas diffusion layers affects fuel cell performance. To implement this performance analysis, a mathematical model which considers oxygen and hydrogen mass fraction in gas diffusion layer and the electrical current density in the catalyst layer, and the fuel cell potentials is investigated. The porosity variation in the GDL is calculated by considering the applied pressure and the amount of the water generated in the cell. The validity of the model is assessed by comparing the computed results with experimental data. The obtained results show that the decrease in the average porosity causes the reduction in oxygen consumption, so that a lower electrical current density is generated. It is also shown that when the electrical current density is low, the porosity variation in gas diffusion layer has no significant influence on the level of polarization whereas at higher current density the influence is very significant. The porosity variation causes non-uniformity in the mass transport which in turn reduces the current density and a lower fuel cell performance is obtained.


Author(s):  
Luis Breziner ◽  
Peter Strahs ◽  
Parsaoran Hutapea

The objective of this research is to analyze the effects of vibration on the performance of hydrogen PEM fuel cells. It has been reported that if the liquid water transport across the gas diffusion layer (GDL) changes, so does the overall cell performance. Since many fuel cells operate under a vibrating environment –as in the case of automotive applications, this may influence the liquid water concentration across the GDL at different current densities, affecting the overall fuel cell performance. The problem was developed in two main steps. First, the basis for an analytical model was established using current models for water transport in porous media. Then, a series of experiments were carried, monitoring the performance of the fuel cell for different parameters of oscillation. For sinusoidal vibration at 10, 20 and 50Hz (2 g of magnitude), a decrease in the fuel cell performance by 2.2%, 1.1% and 1.3% was recorded when compared to operation at no vibration respectively. For 5 g of magnitude, the fuel cell reported a drop of 5.8% at 50 Hz, whereas at 20 Hz the performance increased by 1.3%. Although more extensive experimentation is needed to identify a relationship between magnitude and frequency of vibration affecting the performance of the fuel cell as well as a throughout examination of the liquid water formation in the cathode, this study shows that sinusoidal vibration, overall, affects the performance of PEM fuel cells.


Author(s):  
Sun-Joon Byun ◽  
Zhen Huan Wang ◽  
Jun Son ◽  
Young-Chul Kwon ◽  
Dong-Kurl Kwak

We propose a wave-like design on the surface of cathode channels (wave form cathode channels) to improve oxidant delivery to gas diffusion layers (GDLs) [1-2]. We performed experiments using PEMFCs combined with wave form surface design on cathodes. We varied the factors of the distance between wave-bumps (the Adhesive distance, AD), and the size of the wave-bumps (the Expansion ratio, ER). The ADs are 3, 4, and 5 times the size of the half-circle bump’s radius, and the ERs are 1/1.5, 1/2, and 1/3 times the channel’s height. We evaluated the performances of the fuel cells, and compared the current-voltage (I-V) relations. For comparison, we prepared PEMFCs with conventional flat-surfaced oxygen channels. Our aim in this work is to identify fuel cell operation by modifying the surface design of channels, and ultimately to find the optimal design of cathode channels that will maximize fuel cell performance.


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