The Role of Compressive Stress on Gas Diffusion Media Morphology and Fuel Cell Performance

2017 ◽  
Vol 1 (1) ◽  
pp. 191-201 ◽  
Author(s):  
Robert W. Atkinson ◽  
Yannick Garsany ◽  
Benjamin D. Gould ◽  
Karen E. Swider-Lyons ◽  
Iryna V. Zenyuk
Keyword(s):  
Fuel Cell ◽  
Compressive Stress ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Fuel Cell Performance ◽  
Diffusion Media

Effects of Flow Field and Diffusion Layer Properties on Water Accumulation in a PEM Fuel Cell

2007 ◽  
Author(s):  
J. P. Owejan ◽  
T. A. Trabold ◽  
D. L. Jacobson ◽  
M. Arif ◽  
S. G. Kandlikar
Keyword(s):  
Fuel Cell ◽  
Flow Field ◽  
Pem Fuel Cell ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Cell Performance ◽  
Water Volume ◽  
Fuel Cell Performance ◽  
Diffusion Media ◽  
And Diffusion

Water is the main product of the electrochemical reaction in a proton exchange membrane (PEM) fuel cell. Where the water is produced over the active area of the cell, and how it accumulates within the flow fields and gas diffusion layers, strongly affects the performance of the device and influences operational considerations such as freeze and durability. In this work, the neutron radiography method was used to obtain two-dimensional distributions of liquid water in operating 50 cm2 fuel cells. Variations were made of flow field channel and diffusion media properties, to assess the effects on the overall volume and spatial distribution of accumulated water. Flow field channels with hydrophobic coating retain more water, but the distribution of a greater number of smaller slugs in the channel area improves fuel cell performance at high current density. Channels with triangular geometry retain less water than rectangular channels of the same cross-sectional area, and the water is mostly trapped in the two corners adjacent to the diffusion media. Also, it was found that cells constructed using diffusion media with lower in-plane gas permeability tended to retain less water. In some cases, large differences in fuel cell performance were observed with very small changes in accumulated water volume, suggesting that flooding within the electrode layer or at the electrode-diffusion media interface is the primary cause of the significant mass transport voltage loss.

GDM Intrusion Into Reactant Gas Channels and the Effect on Fuel Cell Performance

2006 ◽  
Author(s):  
Pinkhas Rapaport ◽  
Yeh-Hung Lai ◽  
Chunxin Ji
Keyword(s):  
Fuel Cell ◽  
Gas Flow ◽  
Flow Distribution ◽  
Pem Fuel Cell ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Fuel Cell Performance ◽  
Diffusion Media ◽  
Reactant Flow

This paper reports on the study of gas diffusion media (GDM) intrusion into reactant gas channels and its effect on the performance of the proton exchange membrane (PEM) fuel cell. The PEM fuel cell under consideration consists of a membrane electrode assembly (MEA) sandwiched between two layers of gas diffusion media commonly made of carbon paper or cloth. The GDM/MEA/GDM assembly is then compressed between two adjacent bi-polar plates. In this configuration, the compression pressure is transmitted under the lands of the reactant gas flow-field onto GDMs on which the portion over the channels remain unsupported. Because of the relatively low bending and compressive stiffness, it is found that GDMs can easily intrude into the reactant gas channels. The direct consequence of GDM intrusion is the pressure drop increase in the reactant gases in the intruded channels. This is further compounded by cell-to-cell or channel-to-channel variation in GDM thickness and mechanical properties, which results in non-uniform reactant gas flow distribution and ultimately negatively impacts the fuel cell performance. In this study, we have developed a GDM intrusion model based on the finite element method (FEM. We have also devised an experimental setup to measure the GDM intrusion, in which we found good agreement between the model prediction and experimental measurement. Combining the FEM based intrusion model and a flow redistribution model we have investigated the effect of GDM channel intrusion on the reactant flow distribution and the impact on the fuel cell performance. It is found that a 20% reduction of reactant flow can be induced with a 5% additional blockage in channels by GDM intrusion. Based on the findings from the current study, we attribute the significant performance variation in a 30-cell fuel cell stack to the variation in reactant flow induced by the variation in GDM intrusion. The results from the analytical study and fuel cell testing both suggested that the product variations in GDM would need to be significantly reduced and the stiffness of the GDM would need to be increased if the PEM fuel cells of high power density were to be used reliably at a relatively low stoichiometry.

Channel intrusion of gas diffusion media and the effect on fuel cell performance

2008 ◽  
Vol 184 (1) ◽  
pp. 120-128 ◽  
Author(s):  
Yeh-Hung Lai ◽  
Pinkhas A. Rapaport ◽  
Chunxin Ji ◽  
Vinod Kumar
Keyword(s):  
Fuel Cell ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Fuel Cell Performance ◽  
Diffusion Media

The Influence of Gas Diffusion Media Morphology on Hydrogen Fuel Cell Performance

2018 ◽  
Vol 941 ◽  
pp. 2226-2231
Author(s):  
Benjamin Gould ◽  
Yannick Garsany ◽  
Megan Sassin ◽  
Robert Atkinson III ◽  
Iryna Zenyuk ◽  
...  
Keyword(s):  
Fuel Cell ◽  
High Power ◽  
Product Distribution ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Hydrogen Fuel Cell ◽  
Reaction Products ◽  
Power Performance ◽  
Fuel Cell Performance ◽  
Diffusion Media

Gas diffusion media (GDM) is an integral part of all gas diffusion electrodes because it facilitates both the transport of reactants to the electrocatalyst surface and the removal of reaction products from the system. Proper reactant/product distribution is critical for high power operation in polymer electrolyte fuel cells (PEMFCs) because oxygen transport and water rejection determine the maximum current density that can be obtained from PEMFCs. This paper will discuss NRL’s research on how GDM morphology influences cell performance in both closed-cathode fuel cell and open-cathode fuel cell designs. The comprehensive study linking the influence of compression on the GDM micro and macro structure morphology will be presented using micro X-ray computed tomography (μ-CT), scanning electron microscopy (SEM), N2Physisorption (BET) and traditional electrochemical characterization techniques (CV, Pol. Curves, etc.). Optimal GDM selection for the challenge of open-cathode operation will be presented and related to water retention through rational morphology selection. The relationship between high power performance and water transport will be elucidated and the goals for future GDM properties will be proposed for use in unmanned systems

Effect of Vibration on the Liquid Water Transport of PEM Fuel Cells

2009 ◽  
Author(s):  
Luis Breziner ◽  
Peter Strahs ◽  
Parsaoran Hutapea
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Water Transport ◽  
Liquid Water ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Cell Performance ◽  
Sinusoidal Vibration ◽  
Fuel Cell Performance ◽  
Liquid Water Transport

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.

Predicting Liquid Water Saturation Through Differently Structured Cathode Gas Diffusion Media of a Proton Exchange Membrane Fuel Cell

2012 ◽  
Vol 9 (2) ◽  
Author(s):  
N. Akhtar ◽  
P. J. A. M. Kerkhof
Keyword(s):  
Fuel Cell ◽  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Water Saturation ◽  
Catalyst Layer ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Diffusion Media ◽  
Exchange Membrane

The role of gas diffusion media with differently structured properties have been examined with emphasis on the liquid water saturation within the cathode of a proton exchange membrane fuel cell (PEMFC). The cathode electrode consists of a gas diffusion layer (GDL), a micro-porous layer and a catalyst layer (CL). The liquid water saturation profiles have been calculated for varying structural and physical properties, i.e., porosity, permeability, thickness and contact angle for each of these layers. It has been observed that each layer has its own role in determining the liquid water saturation within the CL. Among all the layers, the GDL is the most influential layer that governs the transport phenomena within the PEMFC cathode. Besides, the thickness of the CL also affects the liquid water saturation and it should be carefully controlled.

The Effect of Catalyst Coated Diffusion Media on PEM Fuel Cell Performance

2009 ◽  
Author(s):  
Derek W. Fultz ◽  
Po-Ya Abel Chuang
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Thermal Contact ◽  
Electrical Contact ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Hot Press ◽  
Fuel Cell Performance ◽  
Diffusion Media ◽  
A Cell

Two fuel cell architectures, differing only by the surfaces onto which the electrodes were applied, have been analyzed to determine the root causes of dissimilarities in performance. The basic proton exchange membrane fuel cell (PEMFC) is comprised of the proton transporting membrane, platinum-containing anode and cathode electrodes, porous carbon fiber gas diffusion media (GDM), and flow fields which deliver the reactant hydrogen and air flows. As no optimal cell design currently exists, there is a degree of latitude regarding component assembly and structure. Catalyst coated diffusion media (CCDM) refers to a cell architecture option where the electrode layers are coated on the GDM layers and then hot-pressed to the membrane. Catalyst coated membrane (CCM) refers to an architecture where the electrodes are transferred directly onto the membrane. A cell with CCDM architecture has tightly bonded interfaces throughout the assembly which can result in lower thermal and electrical contact resistances. Considering the fuel cell as a 1-D thermal system, the through-plane thermal resistance was observed to decrease by 5–10% when comparing CCDM to CCM architectures. This suggests the thermal contact resistance at the electrode interfaces was significantly reduced in the hot-press process. In addition, the electrical contact resistances between the electrode and GDM were observed to be significantly reduced with a CCDM architecture. This study shows that these effects, which have a potential to increase performance, can be attributed to the hot-press lamination process and use of CCDM architecture.

Role of Biocatalyst in Microbial Fuel Cell Performance

2019 ◽  
pp. 85-105
Author(s):  
M. Amirul Islam ◽  
Ahasanul Karim ◽  
Puranjan Mishra ◽  
Che Ku Mohammad Faizal ◽  
Maksudur Rahman Khan ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Microbial Fuel Cell ◽  
Cell Performance ◽  
Fuel Cell Performance
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