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Polymer Electrolyte Membrane Fuel Cells (polymer + electrolyte_membrane_fuel_cell)

Distribution by Scientific Domains

Chemistry	68%
Polymers and Materials Science	18%

Selected Abstracts

Evaluation of RuxWySez Catalyst as a Cathode Electrode in a Polymer Electrolyte Membrane Fuel Cell

FUEL CELLS, Issue 1 2010
K. Suárez-Alcántara
Abstract The oxygen reduction reaction (ORR) on RuxWySez is of great importance in the development of a novel cathode electrode in a polymer electrolyte membrane fuel cell (PEMFC) technology. The RuxWySez electrocatalyst was synthesised in an organic solvent for 3,h. The powder was characterised by transmission electron microscopy (TEM), and powder X-ray diffraction (XRD). The electrocatalyst consisted of agglomerates of nanometric size (,50,150,nm) particles. In the electrochemical studies, rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) techniques were used to determine the oxygen reduction kinetics in 0.5,M H2SO4. The kinetic studies include the determination of Tafel slope (112,mV,dec,1), exchange current density at 25,°C (1.48,×,10,4,mA,cm,2) and the apparent activation energy of the oxygen reaction (52.1,,,0.4,kJ,mol,1). Analysis of the data shows a multi-electron charge transfer process to water formation, with 2% H2O2 production. A single PEMFC with the RuxWySez cathode catalysts generated a power density of 180,mW,cm,2. Performance achieved with a loading of 1.4,mg,cm,2 of a 40,wt% RuxWySez and 60,wt% carbon Vulcan (i.e. 0.56,mg,cm,2 of pure RuxWySez). Single PEMFC working was obtained with hydrogen and oxygen at 80,°C with 30,psi. [source]

A Review of Mathematical Models for Hydrogen and Direct Methanol Polymer Electrolyte Membrane Fuel Cells

FUEL CELLS, Issue 1-2 2004
K.Z. Yao
Abstract This paper presents a review of the mathematical modeling of two types of polymer electrolyte membrane fuel cells: hydrogen fuel cells and direct methanol fuel cells. Models of single cells are described as well as models of entire fuel cell stacks. Methods for obtaining model parameters are briefly summarized, as well as the numerical techniques used to solve the model equations. Effective models have been developed to describe the fundamental electrochemical and transport phenomena occurring in the diffusion layers, catalyst layers, and membrane. More research is required to develop models that are validated using experimental data, and models that can account for complex two-phase flows of liquids and gases. [source]

Mathematical Modelling and Simulation of Polymer Electrolyte Membrane Fuel Cells.

FUEL CELLS, Issue 2 2002
Part I: Model Structures, Solving an Isothermal One-Cell Model
Abstract Amongst the various types of fuel cells, the polymer electrolyte membrane fuel cell (PEM-FC) can be used favourably in vehicles and for in house energy supply. The focus of the development of these cells is not only to provide cost-effective membranes and electrodes, but also to optimise the process engineering for single cells and to design multi-cell systems (cell stacks). This is a field in which we have successfully applied the methods of mathematical modelling and simulation. Initially, in this work, a partial model of a single membrane-electrode unit was developed in which the normal reaction technology fields (concentration, temperature, and flow-speed distributions) were calculated, but also the electrical potential and current density distribution in order to develop model structures for technically interesting PEM-FC. This allows the simulation of the effects that the geometric parameters (electrode and membrane data and the dimensions of the material feed and outlet channels) and the educt and coolant intake data have on the electrical and thermal output data of the cell. When complete, cell stacks consisting of a number of single cells, most of which have bipolar switching, are modelled the distribution of the gas flows over the single cells and the specific conditions of heat dissipation must also be taken into consideration. In addition to the distributions mentioned above, this simulation also produces characteristic current-voltage and power-voltage curves for each application that can be compared with the individual process variations and cell types, thus making it possible to evaluate them both technically and economically. The results of the simulation of characteristic process conditions of a PEM-FC operated on a semi-technical scale are presented, which have been determined by means of a three-dimensional model. The distributions of the electrical current density and all component voltage drops that are important for optimising the conditions of the process are determined and also the water concentration in the membrane as an important factor that influences the cell's momentary output and the PEM-FC's long-term stability. [source]

Study of the Catalytic Layer in Polybenzimidazole-based High Temperature PEMFC: Effect of Platinum Content on the Carbon Support

FUEL CELLS, Issue 2 2010
J. Lobato
Abstract In this work, the effect of platinum percentage on the carbon support of commercial catalyst for electrodes to be used in a Polybenzimidazole (PBI)-based PEMFC has been studied. Three percentages were studied (20, 40 and 60%). In all cases, the same quantity of PBI in the catalyst layer was added, which is required as a ,binder'. From Hg porosimetry analyses, pore size distribution, porosity, mean pore size and tortuosity of all electrodes were obtained. The amount of mesopores gets larger as the platinum percentage in the catalytic layer decreases, which reduces the overall porosity and the mean pore size and increases the tortuosity. The electrochemical characterisation was performed by voltamperometric studies, assessing the effective electrochemical surface area (ESA) of the electrodes, by impedance spectroscopy (IS), determining the polarisation resistance, and by the corresponding fuel cell measurements. The best results were obtained for the electrodes with a content of 40% Pt on carbon, as a result of an adequate combination of catalytic activity and mass transfer characteristics of the electrode. It has been demonstrated that the temperature favours the fuel cell performance, and the humidification does not have remarkable effects on the performance of a PBI-based polymer electrolyte membrane fuel cell (PEMFC). [source]

Evaluation of RuxWySez Catalyst as a Cathode Electrode in a Polymer Electrolyte Membrane Fuel Cell

Mathematical Modelling and Simulation of Polymer Electrolyte Membrane Fuel Cells.

Improving the Hydrogen Reaction Kinetics of Complex Hydrides

ADVANCED MATERIALS, Issue 29 2009
Jun Yang
Abstract Alanates, borohydrides, and amides are complex hydrides with high concentration hydrogen that have been actively investigated for materials-based hydrogen storage on-board polymer electrolyte membrane fuel cell (PEMFC) vehicle applications. The major challenge is to release hydrogen at fuel cell working temperature range at fast enough rate without simultaneous desorption of fuel cell poisoning impurities. We review recent progress in hydrogen reaction mechanism and schemes for complex hydride hydrogen storage. [source]

Modification of Nafion membrane using poly(4-vinyl pyridine) for direct methanol fuel cell

POLYMER INTERNATIONAL, Issue 5 2006
Jeon Chan Woong
Abstract Perfluorinated membrane such as Nafion (from Du-Pont) has been used as a polymer electrolyte membrane. Nafion 117 membrane, which was usually used as the electrolyte membrane for the polymer electrolyte membrane fuel cell (PEMFC), was modified by using poly(4-vinyl pyridine) (P4VP) to reduce the methanol crossover, which cause fuel losses and lower power efficiency, by the formation of an ionic crosslink structure (sulfonic acid-pyridine complex) on the Nafion 117 surface. Nafion film was immersed in P4VP/N -methyl pyrrolidone (NMP) solution. P4VP weight percent of modified membrane was controlled by changing the concentration of P4VP/NMP solution and the dipping time. P4VP weight percent increased with increasing concentration of dipping solution and dipping time. The thickness of the P4VP layer increased with increasing concentration of dipping solution and dipping time when the concentration of the dipping solution was low. At high P4VP concentration, the thickness of the P4VP layer was almost constant owing to the formation of acid,base complex which interrupted the penetration of P4VP. FTIR results showed that P4VP could penetrate up to 30 µm of Nafion 117 membrane. Proton conductivity and methanol permeability of modified membrane were lower than those of Nafion 117. Both decreased with increasing concentration of dipping solution and dipping time. Methanol permeability was observed to be more dependent on the penetration depth of P4VP. Water uptake of the modified membrane, the important factor in a fuel cell, was lower than that of Nafion 117. Water uptake also decreased with increasing of P4VP weight. On the basis of this study, the thinner the P4VP layer on the Nafion 117 membrane, the higher was the proton conductivity. Methanol permeability decreased exponentially as a function of P4VP weight percent. Copyright © 2006 Society of Chemical Industry [source]

Numerical model for polymer electrolyte membrane fuel cells with experimental application and validation

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009
Javier Alonso Mora
Abstract The aim of this paper is to present a simple 3D computational model of a polymer electrolyte membrane fuel cell (PEMFC) that simulates over time the heat distribution, energy, and mass balance of the reactant gas flows in the fuel cell including pressure drop, humidity, and liquid water. Although this theoretical model can be adapted to any type of PEMFC, for verification of the model and to present different analysis it has been adapted to a single cell test fixture. The model parameters were adjusted through a series of experimental tests and the model was experimentally validated for a well-defined range of operating conditions: H2/air O2 as reactants, flow rates of 0.5,1.5 SLPM, dew points and cell temperatures of 30,80 °C, currents 0,5 A and with/without water condensation. The model is especially suited for the analysis of liquid water condensation in the reactant channels. A key finding is that the critical current at which liquid water is formed is determined at different flows, temperatures, and humidity. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Insight into Proton Conduction of Immobilised Imidazole Systems Via Simulations and Impedance Spectroscopy,

FUEL CELLS, Issue 3-4 2008
W. L. Cavalcanti
Abstract The proton conduction in immobilised imidazole systems has been investigated in order to support the design of new membrane materials for polymer electrolyte membrane fuel cells (PEMFC). In the experimental part of this work, proton conductivities are measured via impedance spectroscopy. The simulation and modelling are performed combining molecular dynamics simulations and energy barrier calculations; the analysis is done via the proton jump energy barrier, collision ratio and radial distribution function. The dependence of the proton mobility on the temperature, spacer length and the density of conducting groups per area is presented. Donors and acceptors groups approach to each other within a distance from 2.8 to 3,Å where the energy barrier for a proton transfer is very low, which favours the proton jump under the studied conditions. The proton conductivity increases with increase in the spacer length. The simulation results are in good agreement with the proton conductivities presented. [source]

A Review of Mathematical Models for Hydrogen and Direct Methanol Polymer Electrolyte Membrane Fuel Cells

Non-isothermal multi-phase modeling of PEM fuel cell cathode

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2010
Nada Zamel
Abstract In this study, numerical simulation has been carried out for the heat transfer and temperature distribution in the cathode of polymer electrolyte membrane fuel cells along with the multi-phase and multi-species transport under the steady-state condition. The commercial software, COMSOL Multiphysics, is used to solve the conservation equations for momentum, mass, species, charge and energy numerically. The conservation equations are applied to the solid, liquid and vapor phases in the bipolar plate and gas diffusion (GDL) and catalyst layers of a two-dimensional cross section of the cathode. The catalyst layer is assumed to be a finite domain and the water production in the catalyst layer is considered to be in the liquid form. The temperature distribution in the cathode is simulated and then the effects of the relative humidity of the air stream, the permeability of the cathode and the flow channel shoulder to channel width ratio are investigated. It is shown that the highest temperature change, both in the in-plane and across-the-plane directions, occurs in the GDL, while the highest temperature is reached in the catalyst layer. The distribution of temperature in the bipolar plate is shown to be relatively uniform due to the high thermal conductivity of the plate. A decrease in the inlet relative humidity of the air stream results in the decrease of the maximum temperature due to the absorption of heat during the evaporation of liquid water in the GDL and catalyst layer. The non-uniformity of the temperature distribution, especially in the catalyst layer, is observed with the increase of the permeability of the cathode. Similarly, the decrease of the channel shoulder to channel width ratio leads to a non-uniform distribution of temperature especially under the channel areas. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Parameter optimization for a PEMFC model with a hybrid genetic algorithm

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2006
Zhi-Jun Mo
Abstract Many steady-state models of polymer electrolyte membrane fuel cells (PEMFC) have been developed and published in recent years. However, models which are easy to be solved and feasible for engineering applications are few. Moreover, rarely the methods for parameter optimization of PEMFC stack models were discussed. In this paper, an electrochemical-based fuel cell model suitable for engineering optimization is presented. Parameters of this PEMFC model are determined and optimized by means of a niche hybrid genetic algorithm (HGA) by using stack output-voltage, stack demand current, anode pressure and cathode pressure as input,output data. This genetic algorithm is a modified method for global optimization. It provides a new architecture of hybrid algorithms, which organically merges the niche techniques and Nelder,Mead's simplex method into genetic algorithms (GAs). Calculation results of this PEMFC model with optimized parameters agreed with experimental data well and show that this model can be used for the study on the PEMFC steady-state performance, is broader in applicability than the earlier steady-state models. HGA is an effective and reliable technique for optimizing the model parameters of PEMFC stack. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Fan the flame with water: Current ignition, front propagation and multiple steady states in polymer electrolyte membrane fuel cells

AICHE JOURNAL, Issue 12 2009
Jay Benziger
First page of article [source]

Synthesis and characterization of high molecular weight hexafluoroisopropylidene-containing polybenzimidazole for high-temperature polymer electrolyte membrane fuel cells

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2009
Guoqing Qian
Abstract A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F-PBI) was synthesized from 3,3,-diaminobenzidine (TAB) and 2,2-bis(4-carboxyphenyl) hexafluoropropane (6F-diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F-PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064,4073, 2009 [source]