A Mathematical Model of Ultra-Thin Catalyst Layer in PEFC

2007 ◽  
Vol 539-543 ◽  
pp. 1397-1402 ◽  
Author(s):  
Qian Pu Wang ◽  
Michael Eikerling ◽  
Da Tong Song ◽  
Zhong Sheng Liu
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Current Distribution ◽  
Catalyst Layer ◽  
Polarization Curves ◽  
Mesoscopic Scale ◽  
Poisson Equations ◽  
Catalyst Layers ◽  
Pt Utilization ◽  
Catalyst Utilization

A mathematical model for an ultra-thin catalyst layer in PEFCs is introduced. It utilizes Nernst-Planck and Poisson equations. Calculated polarization curves are shown to compare favourably with published experimental data for ultra-thin catalyst layers. Aspects of current conversion, reactant, current distribution, and catalyst utilization are explored. The effect of catalyst layers thickness on the Pt utilization is discussed. This study gives us a better understanding of transport and reaction at the mesoscopic scale and it furnishes the directions for optimization of this type of catalyst layer.

Effectiveness factor of Pt utilization in cathode catalyst layer of polymer electrolyte fuel cells

2008 ◽  
Vol 86 (7) ◽  
pp. 657-667 ◽  
Author(s):  
Zetao Xia ◽  
Qianpu Wang ◽  
Michael Eikerling ◽  
Zhongsheng Liu
Keyword(s):  
Fuel Cells ◽  
Polymer Electrolyte ◽  
Catalyst Layer ◽  
Polymer Electrolyte Fuel Cells ◽  
Effectiveness Factor ◽  
Cathode Catalyst ◽  
Catalyst Layers ◽  
Effectiveness Factors ◽  
Cathode Catalyst Layer ◽  
Pt Utilization

In this work, we analyze effectiveness factors of Pt utilization in perfluorosulfonate ionomer (PFSI) bonded thin film cathode catalyst layers of polymer electrolyte fuel cells. We define the effectiveness factor of Pt utilization as the apparent rate of current conversion exhibited by a specific catalyst layer design divided by the ideal rate obtained if all Pt atoms were used equally in electrochemical reactions at the specified electrode overpotential and externally provided reactant concentrations. This definition includes statistical factors at all relevant scales as well as non-uniformities of reaction rate distributions under operation. Our model is based on the random composite agglomerated morphology of the catalyst layer. It accounts for the interplay of transport phenomena and electrochemical kinetics. At the mesoscopic scale, limited effectiveness of Pt utilization in agglomerates is mainly an electrostatic effect. We determined spatial distributions of effectiveness factors of agglomerates in the through-plane direction, and thereafter calculated overall effectiveness factors of the cathode catalyst layer. Our results show that small agglomerate radius, low operating current density, high operating temperature, and high oxygen partial pressure result in high effectiveness factors of Pt utilization. Finally, we compared PFSI-bonded thin film cathode catalyst layers with ultrathin two-phase cathode catalyst layers in terms of effectiveness factors. Including the surface to volume atom ratio of Pt nanoparticles, the two different types of structures exhibit similar effectiveness factors of Pt utilization, which are found to be distinctly below 10%.Key words: polymer electrolyte fuel cells, fuel cell modeling, cathode catalyst layer, Pt utilization, effectiveness factor.

A Parametric Study of PEM Fuel Cell Performances

2002 ◽  
Author(s):  
Lin Wang ◽  
Attila Husar ◽  
Tianhong Zhou ◽  
Hongtan Liu
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Parametric Study ◽  
Proton Exchange Membrane ◽  
Pem Fuel Cell ◽  
Proton Exchange ◽  
Polarization Curves ◽  
Exchange Membrane

The effects of different parameters on the performances of proton exchange membrane fuel cells were studied experimentally. Experiments with different fuel cell temperatures, humidification temperatures and backpressures of reactant gases have been carried out. Polarization curves from experimental data are presented and the effects of the parameters on the performance of the PEM fuel cell are discussed. The experimental data obtained in this work are used to validate our 3-D mathematical model. It is found that modeling results agree well with our experimental data.

Effect of Agglomerate Microstructure on Oxygen Reduction in Catalyst Layers of Polymer Electrolyte Fuel Cells

2012 ◽  
Author(s):  
Ehsan Sadeghi ◽  
Andreas Putz ◽  
Michael Eikerling
Keyword(s):  
Experimental Data ◽  
Fuel Cells ◽  
Oxygen Reduction ◽  
Polymer Electrolyte ◽  
Catalyst Layer ◽  
Polymer Electrolyte Fuel Cells ◽  
Effectiveness Factor ◽  
Catalyst Layers ◽  
Cylindrical Pores ◽  
Interfacial Charge

Cathode catalyst layers (CCLs) contribute to a major proportion, 30%–40%, of voltage losses in Polymer Electrolyte fuel cells (PEFC). The objectives of the present study are to investigate how the catalyst layer performance depends on electrostatic interaction between reacting protons and the charged metal phase and how these relations are affected by composition and microstructure of agglomerates. A model is developed to study oxygen reduction in catalyst layers based on a novel agglomerate microstructure with conical pores. The model consists of coupled relations for reactant transport, metal charging behaviour, and interfacial charge transfer kinetics, evaluated under steady state conditions. Results show an enhancement in the effectiveness factor of conical pores compared to cylindrical pores. Results of the model are evaluated by comparison with existing experimental data. The effectiveness factor calculated for catalyst layer is 3% which is comparable to existing experimental data.

Carbon nanotube containing Ag catalyst layers for efficient and selective reduction of carbon dioxide

2016 ◽  
Vol 4 (22) ◽  
pp. 8573-8578 ◽  
Author(s):  
Sichao Ma ◽  
Raymond Luo ◽  
Jake I. Gold ◽  
Aaron Z. Yu ◽  
Byoungsu Kim ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Charge Transfer ◽  
Carbon Nanotube ◽  
Selective Reduction ◽  
Catalyst Layer ◽  
Ag Electrode ◽  
Catalyst Layers ◽  
Ag Catalyst ◽  
Catalyst Utilization

The incorporation of MWCNT in the Ag electrode catalyst layer improves charge transfer within the catalyst layer, therefore significantly enhancing catalyst utilization for the electroreduction of CO2to CO.

The substantiation of the formalized estimation of effectiveness of technological and production systems

2018 ◽  
Vol 15 (1) ◽  
pp. 169-181
Author(s):  
M. I. Sidorov ◽  
М. Е. Stavrovsky ◽  
V. V. Irogov ◽  
E. S. Yurtsev
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Production Systems ◽  
Van Der Pol

Using the example of van der Pol developed a mathematical model of frictional self-oscillations in topochemically kinetics. Marked qualitative correspondence of the results of calculation performed using the experimental data of researchers.

scholarly journals Effect of Stratification of Cathode Catalyst Layers on Durability of Proton Exchange Membrane Fuel Cells

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2975
Author(s):  
Zikhona Nondudule ◽  
Jessica Chamier ◽  
Mahabubur Chowdhury
Keyword(s):  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Electrochemical Impedance ◽  
Catalyst Layer ◽  
Cost Effective ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Potential Cycling ◽  
Catalyst Layers ◽  
Exchange Membrane

To decrease the cost of fuel cell manufacturing, the amount of platinum (Pt) in the catalyst layer needs to be reduced. In this study, ionomer gradient membrane electrode assemblies (MEAs) were designed to reduce Pt loading without sacrificing performance and lifetime. A two-layer stratification of the cathode was achieved with varying ratios of 28 wt. % ionomer in the inner layer, on the membrane, and 24 wt. % on the outer layer, coated onto the inner layer. To study the MEA performance, the electrochemical surface area (ECSA), polarization curves, and electrochemical impedance spectroscopy (EIS) responses were evaluated under 20, 60, and 100% relative humidity (RH). The stratified MEA Pt loading was reduced by 12% while maintaining commercial equivalent performance. The optimal two-layer design was achieved when the Pt loading ratio between the layers was 1:6 (inner:outer layer). This MEA showed the highest ECSA and performance at 0.65 V with reduced mass transport losses. The integrity of stratified MEAs with lower Pt loading was evaluated with potential cycling and proved more durable than the monolayer MEA equivalent. The higher ionomer loading adjacent to the membrane and the bi-layer interface of the stratified catalyst layer (CL) increased moisture in the cathode CL, decreasing the degradation rate. Using ionomer stratification to decrease the Pt loading in an MEA yielded a better performance compared to the monolayer MEA design. This study, therefore, contributes to the development of more durable, cost-effective MEAs for low-temperature proton exchange membrane fuel cells.

A framework ensemble facilitates high Pt utilization in a low Pt loading fuel cell

2021 ◽  
Vol 11 (8) ◽  
pp. 2957-2963
Author(s):  
Jian Wang ◽  
Guangping Wu ◽  
Wenhui Xuan ◽  
Lishan Peng ◽  
Yong Feng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Phase Field ◽  
Active Sites ◽  
Catalyst Layer ◽  
Three Phase ◽  
Pt Utilization ◽  
The Cross ◽  
Low Pt Loading ◽  
Effective Transfer

Rationally designing the structure of catalyst layer in MEA to achieve the dispersion of active sites at the cross of three-phase field and the effective transfer network paths for protons through catalysts and catalyst layer.

scholarly journals Exhaust Noise Reduction by Application of Expanded Collecting System in Pneumatic Tools and Machines

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1592
Author(s):  
Dominik Gryboś ◽  
Jacek S. Leszczyński ◽  
Dorota Czopek ◽  
Jerzy Wiciak
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Noise Reduction ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Pressure Level ◽  
Computational Results ◽  
Noise Measurements ◽  
Exhaust Noise ◽  
Collecting System

In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

Sign in / Sign up

Export Citation Format

Share Document