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Membrane Fuel Cell (membrane + fuel_cell)

Distribution by Scientific Domains

Chemistry	47%
Polymers and Materials Science	14%

Kinds of Membrane Fuel Cell

electrolyte membrane fuel cell

exchange membrane fuel cell

polymer electrolyte membrane fuel cell

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]

Titelbild: A Soluble and Highly Conductive Ionomer for High-Performance Hydroxide Exchange Membrane Fuel Cells (Angew. Chem.

ANGEWANDTE CHEMIE, Issue 35 2009
35/2009)
Ein hydroxidleitendes und stabiles Ionomer wird benötigt, um die Leistung von Hydroxidaustausch-Membranbrennstoffzellen (HEMFCs) zu maximieren. Y.,S. Yan et,al. berichten in ihrer Zuschrift auf S.,6621,ff. über die Synthese eines solchen Ionomers , ein Polysulfonmethylenphosphoniumhydroxid , sowie dessen Wirkungsweise, die auf der Erzeugung einer effizienten Dreiphasengrenze in der Katalysatorschicht beruht. [source]

A Soluble and Highly Conductive Ionomer for High-Performance Hydroxide Exchange Membrane Fuel Cells

ANGEWANDTE CHEMIE, Issue 35 2009
Shuang Gu Dr.
Einfach besser: Das neue polymere Ionomer TPQPOH mit einer Tris(2,4,6-trimethoxyphenyl)phosphonium-Einheit ist in einigen niedrig siedenden wasserlöslichen Lösungsmitteln ausgezeichnet löslich, zeigt eine hohe Ionenleitfähigkeit und ist im Alkalischen außerordentlich stabil. Eine Hydroxidaustausch-Membranbrennstoffzelle mit diesem Ionomer weist eine erhöhte Leistungsdichte und einen verringerten inneren Widerstand auf. [source]

High-Performance Alkaline Polymer Electrolyte for Fuel Cell Applications

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2010
Jing Pan
Abstract Although the proton exchange membrane fuel cell (PEMFC) has made great progress in recent decades, its commercialization has been hindered by a number of factors, among which is the total dependence on Pt-based catalysts. Alkaline polymer electrolyte fuel cells (APEFCs) have been increasingly recognized as a solution to overcome the dependence on noble metal catalysts. In principle, APEFCs combine the advantages of and alkaline fuel cell (AFC) and a PEMFC: there is no need for noble metal catalysts and they are free of carbonate precipitates that would break the waterproofing in the AFC cathode. However, the performance of most alkaline polyelectrolytes can still not fulfill the requirement of fuel cell operations. In the present work, detailed information about the synthesis and physicochemical properties of the quaternary ammonia polysulfone (QAPS), a high-performance alkaline polymer electrolyte that has been successfully applied in the authors' previous work to demonstrate an APEFC completely free from noble metal catalysts (S. Lu, J. Pan, A. Huang, L. Zhuang, J. Lu, Proc. Natl. Acad. Sci. USA2008, 105, 20611), is reported. Monitored by NMR analysis, the synthetic process of QAPS is seen to be simple and efficient. The chemical and thermal stability, as well as the mechanical strength of the synthetic QAPS membrane, are outstanding in comparison to commercial anion-exchange membranes. The ionic conductivity of QAPS at room temperature is measured to be on the order of 10,2,S cm,1. Such good mechanical and conducting performances can be attributed to the superior microstructure of the polyelectrolyte, which features interconnected ionic channels in tens of nanometers diameter, as revealed by HRTEM observations. The electrochemical behavior at the Pt/QAPS interface reveals the strong alkaline nature of this polyelectrolyte, and the preliminary fuel cell test verifies the feasibility of QAPS for fuel cell applications. [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

Investigation of a Novel Catalyst Coated Membrane Method to Prepare Low-Platinum-Loading Membrane Electrode Assemblies for PEMFCs

FUEL CELLS, Issue 2 2009
X. Leimin
Abstract In this work, a novel catalyst coated membrane (CCM) approach,a catalyst-sprayed membrane under irradiation (CSMUI),was developed to prepare MEAs for proton exchange membrane fuel cell (PEMFC) application. Catalyst ink was sprayed directly onto the membrane and an infrared light was used simultaneously to evaporate the solvents. The resultant MEAs prepared by this method yielded very high performance. Based on this approach, the preparation of low-platinum-content MEAs was investigated. It was found that for the anode, even if the platinum loading was decreased from 0.2 to 0.03,mg,cm,2, only a very small performance decrease was observed; for the cathode, when the platinum loading was decreased from 0.3 to 0.15,mg,cm,2, just a 5% decrease was detected at 0.7,V, but a 35% decrease was observed when the loading was decreased from 0.15 to 0.06,mg,cm,2. These results indicate that this approach is much better than the catalyst coated gas diffusion layer (GDL) method, especially for the preparation of low-platinum-content MEAs. SEM and EIS measurements indicated ample interfacial contact between the catalyst layer and the membrane. [source]

Modelling Approach for Planar Self-Breathing PEMFC and Comparison with Experimental Results,

FUEL CELLS, Issue 4 2004
A. Schmitz
Abstract This paper presents a model-based analysis of a proton exchange membrane fuel cell,(PEMFC) with a planar design as the power supply for portable applications. The cell is operated with hydrogen and consists of an open cathode side allowing for passive, self-breathing, operation. This planar fuel cell is fabricated using printed circuit board,(PCB) technology. Long-term stability of this type of fuel cell has been demonstrated. A stationary, two-dimensional, isothermal, mathematical model of the planar fuel cell is developed. Fickian diffusion of the gaseous components,(O2, H2, H2O) in the gas diffusion layers and the catalyst layers is accounted for. The transport of water is considered in the gaseous phase only. The electrochemical reactions are described by the Tafel equation. The potential and current balance equations are solved separately for protons and electrons. The resulting system of partial differential equations is solved by a finite element method using FEMLAB,(COMSOL Inc.) software. Three different cathode opening ratios are realized and the corresponding polarization curves are measured. The measurements are compared to numerical simulation results. The model reproduces the shape of the measured polarization curves and comparable limiting current density values, due to mass transport limitation, are obtained. The simulated distribution of gaseous water shows that an increase of the water concentration under the rib occurs. It is concluded that liquid water may condense under the rib leading to a reduction of the open pore space accessible for gas transport. Thus, a broad rib not only hinders the oxygen supply itself, but may also cause additional mass transport problems due to the condensation of water. [source]

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]

Polarization characteristics and property distributions of a proton exchange membrane fuel cell under cathode starvation conditions

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2010
Dongsoo Ko
Abstract Property distribution and polarization characteristics of a proton exchange membrane fuel cell (PEMFC) under cathode starvation conditions were investigated numerically and experimentally for a unit cell. The polarization curves of a lab-scale PEMFC were measured with increasing current density for different cell temperatures (40°C, 50°C, and 60°C) at a relative humidity of 100%. To investigate the local temperature, water content and current density on the membrane, and gas velocity in the channel of the PEMFC, numerical studies using the es-pemfc module of the commercial flow solver STAR-CD, which were matched with experimental data, were conducted. Temperature, current density on the membrane, and water content in the MEA were examined to investigate the effect of cell temperature on performance under the cathode starvation condition. At cathode starvation conditions, the performance of a higher cell temperature condition might drop significantly and the mean temperature on the membrane increase abruptly with increasing cell temperature or current density. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Experiment and simulation investigations for effects of flow channel patterns on the PEMFC performance

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2008
Yuh-Ming Ferng
Abstract Experiments and simulations are presented in this paper to investigate the effects of flow channel patterns on the performance of proton exchange membrane fuel cell (PEMFC). The experiments are conducted in the Fuel Cell Center of Yuan Ze University and the simulations are performed by way of a three-dimensional full-cell computational fluid dynamics model. The flow channel patterns adopted in this study include the parallel and serpentine flow channels with the single path of uniform depth and four paths of step-wise depth, respectively. Experimental measurements show that the performance (i.e. cell voltage) of PEMFC with the serpentine flow channel is superior to that with the parallel flow channel, which is precisely captured by the present simulation model. For the parallel flow channel, different depth patterns of flow channel have a strong influence on the PEMFC performance. However, this effect is insignificant for the serpentine flow channel. In addition, the calculated results obtained by the present model show satisfactory agreement with the experimental data for the PEMFC performance under different flow channel patterns. These validations reveal that this simulation model can supplement the useful and localized information for the PEMFC with confidence, which cannot be obtained from the experimental data. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Numerical simulation of thermal,hydraulic characteristics in a proton exchange membrane fuel cell

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 5 2003
Y.M. Ferng
Abstract The thermal,hydraulic characteristics of a proton exchange membrane fuel cell (PEMFC) are numerically simulated by a simplified two-phase, multi-component flow model. This model consists of continuity, momentum, energy and concentration equations, and appropriate equations to consider the varying flow properties of the gas,liquid two-phase region in a PEMFC. This gas,liquid two-phase characteristic is not considered in most of the previous simulation works. The calculated thermal,hydraulic phenomena of a PEMFC are reasonably presented in this paper, which include the distributions of flow vector, temperature, oxygen concentration, liquid water saturation, and current density, etc. Coupled with the electrochemical reaction equations, current flow model can predict the cell voltage vs current density curves (i.e. performance curves), which are validated by the single-cell tests. The predicted performance curves for a PEMFC agree well with the experimental data. In addition, the positive effect of temperature on the cell performance is also precisely captured by this model. The model presented herein is essentially developed from the thermal,hydraulic point of view and can be considered as a stepping-stone towards a full complete PEMFC simulation model that can help the optima design for the PEMFC and the enhancement of cell efficiency. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Carbon monoxide poisoning of proton exchange membrane fuel cells

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2001
J. J. Baschuk
Abstract Proton exchange membrane fuel cell (PEMFC) performance degrades when carbon monoxide (CO) is present in the fuel gas; this is referred to as CO poisoning. This paper investigates CO poisoning of PEMFCs by reviewing work on the electrochemistry of CO and hydrogen, the experimental performance of PEMFCs exhibiting CO poisoning, methods to mitigate CO poisoning and theoretical models of CO poisoning. It is found that CO poisons the anode reaction through preferentially adsorbing to the platinum surface and blocking active sites, and that the CO poisoning effect is slow and reversible. There exist three methods to mitigate the effect of CO poisoning: (i) the use of a platinum alloy catalyst, (ii) higher cell operating temperature and (iii) introduction of oxygen into the fuel gas flow. Of these three methods, the third is the most practical. There are several models available in the literature for the effect of CO poisoning on a PEMFC and from the modeling efforts, it is clear that small CO oxidation rates can result in much increased performance of the anode. However, none of the existing models have considered the effect of transport phenomena in a cell, nor the effect of oxygen crossover from the cathode, which may be a significant contributor to CO tolerance in a PEMFC. In addition, there is a lack of data for CO oxidation and adsorption at low temperatures, which is needed for detailed modeling of CO poisoning in PEMFCs. Copyright © 2001 John Wiley & Sons, Ltd. [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]

Plasma Sputtering Deposition of PEMFC Porous Carbon Platinum Electrodes,

FUEL CELLS, Issue 2 2008
H. Rabat
Abstract A novel method is proposed to fabricate the active catalytic layers of proton exchange membrane fuel cells (PEMFC). A plasma sputtering technique is used to deposit a porous columnar carbon film (column diameter of 20,nm) followed by the catalyst (platinum) deposition directly on the proton-conducting membrane. The study of Pt diffusion shows that the optimised catalysed layers correspond to low plasma pressure operation (0.5,Pa) below a platinum loading limit of about 90,,g,cm,2. The initial carbon porosity is then maintained and Pt nanoparticles are present in all parts of the carbon layer. A membrane electrode assembly (MEA) is then achieved by alternate depositions of carbon and platinum onto both sides of the membrane. The results show the importance of the porous carbon structure. A significant increase in the catalyst efficiency is observed compared to a commercial fuel cell when measuring open circuit voltage. [source]

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

Lithium-Catalyzed Dehydrogenation of Ammonia Borane within Mesoporous Carbon Framework for Chemical Hydrogen Storage

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
Li Li
Abstract Ammonia borane (AB) has attracted tremendous interest for on-board hydrogen storage due to its low molecular weight and high gravimetric hydrogen capacity below a moderate temperature. However, the slow kinetics, irreversibility, and formation of volatile materials (trace borazine and ammonia) limit its practical application. In this paper, a new catalytic strategy involved lithium (Li) catalysis and nanostructure confinement in mesoporous carbon (CMK-3) for the thermal decomposition of AB is developed. AB loaded on the 5% Li/CMK-3 framework releases ,7,wt % of hydrogen at a very low temperature (around 60,°C) and entirely suppresses borazine and ammonia emissions that are harmful for proton exchange membrane fuel cells. The possible mechanism for enhanced hydrogen release via catalyzed thermal decomposition of AB is discussed. [source]

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]

Natural gas internal combustion engine hybrid passenger vehicle

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2008
S. Wright
Abstract The implementation of hybrid electric vehicles powered with alternative fuels is critical in reducing national dependence on imported crude oil, addressing the detrimental environmental impact of increasing petroleum usage worldwide, and sustaining the national economy. The question is not whether changes should be made, but instead centers on identifying pathways that will lead to the greatest environmental and economic benefits. To avoid misuse of limited infrastructure investment, the objective of this research is to consider a broad range of relevant factors to determine desirable power plant,fuel combinations for hybrid electric vehicles. In the long term, fuel cells may dominate this application, but at least in the short term, proton exchange membrane fuel cells (PEMFCs) will not likely offer immediate substantial benefit over internal combustion (IC) engines. Environmentally friendly operation of the PEMFC results partly due to low-temperature operation but primarily due to the requirement of a clean fuel, hydrogen. In addition, the differential benefits from power plant choice can be overshadowed by the advantages obtained from hybrid electric vehicle technology and alternative fuels. Consequently, the fuel flexibility of IC engines provides an advantage over the relatively fuel inflexible PEMFC. The methane/hythane IC engine hybrid option, as developed and presented here, is a promising pathway that avoids the barriers encountered with conventional non-hybrid natural gas vehicles, namely range, power and fueling infrastructure difficulties. Dynamometer testing of the natural gas hybrid prototype on the certification FTP-72 duty cycle revealed very low emissions and mileage greater than 33 miles per gallon gasoline equivalent. This hybrid option utilizes a domestic, cost-effective fuel with renewable sources. With multi-fuel capability (methane, hythane and gasoline) it is also designed for use within the emerging hydrogen market. This hybrid option offers reliability and cost-effective technology with immediate wide spread market availability. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Recent advances in microdevices for electrochemical energy conversion and storage

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6-7 2007
Gerardo Jose La O'
Abstract The application of silicon microfabrication technologies to electrochemical devices allows reduction of overall device package to potentially increase volumetric power densities. This review first focuses on some exciting developments in microfuel cells, in particular, solid oxide fuel cells (SOFCs) and proton exchange membrane fuel cells (PEMFCs). The emphasis is given to innovative 2D processing methods, novel 2D architectures of microfuel cells, and demonstrated performance in terms of area power densities. Emerging 3D fabrication techniques that are potentially promising to produce 3D electrochemical devices such as 3D cell and stack architectures on the micrometer scale will then be discussed. Lastly this paper highlights some new opportunities in electrode kinetics studies enabled by microfabricated devices,investigation of scaling relationship between microelectrodes and electrochemical responses, which has led to improved fundamental understanding of electrode reactions and rate-limiting steps. Copyright © 2007 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]

Along-channel mathematical modelling for proton exchange membrane fuel cells

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2005
Wenbo Huang
Abstract Proper water and thermal management is essential for obtaining high performance of proton exchange membrane fuel cells (PEMFCs). A steady, two-dimensional water and thermal management model was developed, aiming at considering pressure effects (i.e. the effects of local pressure on the cell performance), pressure drop, open circuit voltage variation with stack temperature, water vapour effects on membrane conductivity, which made the model physically more reasonable and more suitable for various operating conditions. The model could predict the distributions of a series of important parameters along the flow channel, and thus the effects of various operating and design parameters on the fuel cell performance could be investigated easily by numerical trial-and-error method. The modelling results compared well with the available experimental results from the literatures. The results also showed that the humidification of both anode and cathode is crucial for the performance of PEMFCs. The model could be a very useful engineering tool for the optimization of PEMFCs. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Carbon monoxide poisoning of proton exchange membrane fuel cells

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]