scholarly journals Impact of the Cathode Pt Loading on PEMFC Contamination by Several Airborne Contaminants

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1060 ◽  
Author(s):  
Jean St-Pierre ◽  
Yunfeng Zhai
Keyword(s):  
Mass Transfer ◽  
Steady State ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Catalyst Loading ◽  
Transfer Resistance ◽  
Voltage Loss ◽  
Program Costs ◽  
Exchange Membrane

Proton exchange membrane fuel cells (PEMFCs) with 0.1 and 0.4 mg Pt cm−2 cathode catalyst loadings were separately contaminated with seven organic species: Acetonitrile, acetylene, bromomethane, iso-propanol, methyl methacrylate, naphthalene, and propene. The lower catalyst loading led to larger cell voltage losses at the steady state. Three closely related electrical equivalent circuits were used to fit impedance spectra obtained before, during, and after contamination, which revealed that the cell voltage loss was due to higher kinetic and mass transfer resistances. A significant correlation was not found between the steady-state cell voltage loss and the sum of the kinetic and mass transfer resistance changes. Major increases in research program costs and efforts would be required to find a predictive correlation, which suggests a focus on contamination prevention and recovery measures rather than contamination mechanisms.

Transient Computational Analysis of Proton Exchange Membrane Fuel Cells During Load Change and Non-Isothermal Start-Up

2009 ◽  
Author(s):  
Arnab Roy ◽  
Mustafa Fazil Serincan ◽  
Ugur Pasaogullari ◽  
Michael W. Renfro ◽  
Baki M. Cetegen
Keyword(s):  
Fuel Cells ◽  
Steady State ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Species Concentration ◽  
Load Change ◽  
Start Up ◽  
Exchange Membrane

An investigation of the transient performance characteristics of proton exchange membrane fuel cells (PEMFC) undergoing load change and during above freezing low-temperature start-ups are presented. A transient, non-isothermal, three dimensional, single phase computational fluid dynamics based model is developed to describe the transient processes of a PEMFC with conventional channels in co-flow configuration. The model equations are solved using a multi-domain approach incorporating water transport through membrane and multi-component species transport through porous diffusion layer. The dynamic response of the characteristic parameters such as membrane hydration, species concentration, cell voltage and temperature are simulated undergoing step changes in operating current density and also during start up and the results are discussed in detail. Accumulation of water in the polymer electrolyte seems to control the response time for load response and also start-up times along with the temperature of the cell. Steady state and transient simulations are compared. Steady state predictions are compared with benchmark experimental data from literature and the species concentration distributions were found to be in good agreement.

scholarly journals Degradation Investigation of Electrocatalyst in Proton Exchange Membrane Fuel Cell at a High Energy Efficiency

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3932
Author(s):  
Jie Song ◽  
Qing Ye ◽  
Kun Wang ◽  
Zhiyuan Guo ◽  
Meiling Dou
Keyword(s):  
Energy Efficiency ◽  
Single Cell ◽  
Proton Exchange Membrane ◽  
Cell Voltage ◽  
High Energy ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Operation Conditions ◽  
High Efficient ◽  
Exchange Membrane

The development of high efficient stacks is critical for the wide spread application of proton exchange membrane fuel cells (PEMFCs) in transportation and stationary power plant. Currently, the favorable operation conditions of PEMFCs are with single cell voltage between 0.65 and 0.7 V, corresponding to energy efficiency lower than 57%. For the long term, PEMFCs need to be operated at higher voltage to increase the energy efficiency and thus promote the fuel economy for transportation and stationary applications. Herein, PEMFC single cell was investigated to demonstrate its capability to working with voltage and energy efficiency higher than 0.8 V and 65%, respectively. It was demonstrated that the PEMFC encountered a significant performance degradation after the 64 h operation. The cell voltage declined by more than 13% at the current density of 1000 mA cm−2, due to the electrode de-activation. The high operation potential of the cathode leads to the corrosion of carbon support and then causes the detachment of Pt nanoparticles, resulting in significant Pt agglomeration. The catalytic surface area of cathode Pt is thus reduced for oxygen reduction and the cell performance decreased. Therefore, electrochemically stable Pt catalyst is highly desirable for efficient PEMFCs operated under cell voltage higher than 0.8 V.

scholarly journals Experimental Study on Critical Membrane Water Content of Proton Exchange Membrane Fuel Cells for Cold Storage at −50 °C

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4520
Author(s):  
Xiaokang Yang ◽  
Jiaqi Sun ◽  
Guang Jiang ◽  
Shucheng Sun ◽  
Zhigang Shao ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Water Content ◽  
Cold Storage ◽  
Proton Exchange Membrane ◽  
Membrane Resistance ◽  
Charge Transfer Resistance ◽  
Proton Exchange ◽  
Freezing Damage ◽  
Transfer Resistance ◽  
Exchange Membrane

Membrane water content is of vital importance to the freezing durability of proton exchange membrane fuel cells (PEMFCs). Excessive water freezing could cause irreversible degradation to the cell components and deteriorate the cell performance and lifetime. However, there are few studies on the critical membrane water content, a threshold beyond which freezing damage occurs, for cold storage of PEMFCs. In this work, we first proposed a method for measuring membrane water content using membrane resistance extracted from measured high frequency resistance (HFR) based on the finding that the non-membrane resistance part of the measured HFR is constant within the range of membrane water content of 2.98 to 14.0. Then, freeze/thaw cycles were performed from −50 °C to 30 °C with well controlled membrane water content. After 30 cycles, cells with a membrane water content of 8.2 and 7.7 exhibited no performance degradation, while those higher than 8.2 showed significant performance decay. Electrochemical tests revealed that electrochemical surface area (ECSA) reduction and charge transfer resistance increase are the main reasons for the degradation. These results indicate that the critical membrane water content for successful cold storage at −50 °C is 8.2.

scholarly journals Pore-Filled Proton-Exchange Membranes with Fluorinated Moiety for Fuel Cell Application

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4433
Author(s):  
Hyeon-Bee Song ◽  
Jong-Hyeok Park ◽  
Jin-Soo Park ◽  
Moon-Sung Kang
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Continuous Process ◽  
Oxidation Stability ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Cross Linking ◽  
Polymer Backbone ◽  
Transfer Resistance ◽  
Exchange Membrane

Proton-exchange membrane fuel cells (PEMFCs) are the heart of promising hydrogen-fueled electric vehicles, and should lower their price and further improve durability. Therefore, it is necessary to enhance the performances of the proton-exchange membrane (PEM), which is a key component of a PEMFC. In this study, novel pore-filled proton-exchange membranes (PFPEMs) were developed, in which a partially fluorinated ionomer with high cross-linking density is combined with a porous polytetrafluoroethylene (PTFE) substrate. By using a thin and tough porous PTFE substrate film, it was possible to easily fabricate a composite membrane possessing sufficient physical strength and low mass transfer resistance. Therefore, it was expected that the manufacturing method would be simple and suitable for a continuous process, thereby significantly reducing the membrane price. In addition, by using a tri-functional cross-linker, the cross-linking density was increased. The oxidation stability was greatly enhanced by introducing a fluorine moiety into the polymer backbone, and the compatibility with the perfluorinated ionomer binder was also improved. The prepared PFPEMs showed stable PEMFC performance (as maximum power density) equivalent to 72% of Nafion 212. It is noted that the conductivity of the PFPEMs corresponds to 58–63% of that of Nafion 212. Thus, it is expected that a higher fuel cell performance could be achieved when the membrane resistance is further lowered.

scholarly journals Heat and Mass Transfer and Two Phase Flow in Hydrogen Proton Exchange Membrane Fuel Cells and Direct Methanol Fuel Cells

2003 ◽  
Author(s):  
Hang Guo ◽  
Chong Fang Ma ◽  
Mao Hai Wang ◽  
Jian Yu ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Direct Methanol Fuel Cells ◽  
Proton Exchange ◽  
Phase Flow ◽  
Two Phase ◽  
Direct Methanol ◽  
Methanol Fuel Cells ◽  
Exchange Membrane

Fuel cells are related to a number of scientific and engineering disciplines, which include electrochemistry, catalysis, membrane science and engineering, heat and mass transfer, thermodynamics and so on. Several thermophysical phenomena such as heat transfer, multicomponent transport and two phase flow play significant roles in hydrogen proton exchange membrane fuel cells and direct methanol fuel cells based on solid polymer electrolyte membrane. Some coupled thermophysical issues are bottleneck in process of scale-up of direct methanol fuel cells and hydrogen proton exchange membrane fuel cells. In present paper, experimental results of visualization of condensed water in fuel cell cathode microchannels are presented. The equivalent diameter of the rectangular channel is 0.8mm. Water droplets from the order of 0.08mm to 0.8mm were observed from several different locations in the channels. Several important problems, such as generation and change characteristics of water droplet and gas bubble, two phase flow under chemical reaction conditions, mass transfer enhancement of oxygen in the cathode porous media layer, heat transfer enhancement and high efficiency cooling system of proton exchange membrane fuel cells stack, etc., are discussed.

scholarly journals Open-Source Dynamic Matlab/Simulink 1D Proton Exchange Membrane Fuel Cell Model

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3478 ◽  
Author(s):  
Arne L. Lazar ◽  
Swantje C. Konradt ◽  
Hermann Rottengruber
Keyword(s):  
Fuel Cell ◽  
Open Source ◽  
Real Time ◽  
Proton Exchange Membrane ◽  
Cell Model ◽  
Cell Voltage ◽  
Proton Exchange ◽  
Cell Parameters ◽  
Real Time Analysis ◽  
Exchange Membrane

This work presents an open-source, dynamic, 1D, proton exchange membrane fuel cell model suitable for real-time applications. It estimates the cell voltage based on activation, ohmic and concentration overpotentials and considers water transport through the membrane by means of osmosis, diffusion and hydraulic permeation. Simplified equations reduce the computational load to make it viable for real-time analysis, quick parameter studies and usage in complex systems like complete vehicle models. Two modes of operation for use with or without reference polarization curves allow for a flexible application even without information about cell parameters. The program code is written in MATLAB and provided under the terms and conditions of the Creative Commons Attribution License (CC BY). It is designed to be used inside of a Simulink model, which allows this fuel cell model to be used in a wide variety of 1D simulation platforms by exporting the code as C/C++.

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