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1.
The main goal of this work is to realize a PEMFC model that can be used efficiently for the global modelling of the fuel cell system. The modelling method proposed in the paper is an approach from an empirical point of view that allows a PEMFC model of “black-box” class to be developed. Moving least squares (MLS) have therefore been employed to approximate the cell voltage characteristics V, using an experimental dataset measured in determinate conditions. The MLS approach appears to present a good balance of response surface accuracy, smoothness, robustness, and ease of use. This kind of numerical model offers good perspectives for the systems identification, the simulation of the systems, the design and the optimization of process control, etc. The results prove that the method is suitable for predicting and describing the fuel cell behaviour in all the points of the approximation domain. The proposed model can be included in a numerical application to optimize the operation of an existing fuel cell system. 相似文献
2.
Qiang Shen Ming Hou Xiqiang Yan Dong Liang Zhenming Zang Lixing Hao Zhigang Shao Zhongjun Hou Pingwen Ming Baolian Yi 《Journal of power sources》2008
In this paper, voltage sensors were developed to explore the voltage distribution characteristics inside the fuel cell under both steady and transient states. The effects of air stoichiometry and current density on the voltage distribution under steady state were discussed, and the dynamic voltage response due to the load change under transient state was also investigated. Results showed that under transient state, the fuel cell would experience a temporary voltage fluctuation due to the air starvation. Thus could probably lead to the degradation of materials, such as the catalyst, membrane, etc. To lessen the degree of air starvation, a method of pre-supplying certain amount of air before loading was adopted. The relationship between the voltage response at the loading transient and the amount of pre-supplied air was also studied, and a minimum value of the pre-supplied air was obtained. The experimental results of this paper could be applied to the optimization of vehicular fuel cell system. 相似文献
3.
This paper is to experimentally and numerically investigate the cell performance and the localized characteristics associated with a high-temperature proton exchange membrane fuel cell (PEMFC). Three experiments are carried out in order to study the performance of the PEMFC with different operating conditions and to validate the numerical simulation model. The model proposed herein is a three-dimensional (3-D) computational fluid dynamics (CFD) non-isothermal model that essentially consists of thermal–hydraulic equations and electrochemical model. The performance curves of the PEMFC predicted by the present model agree with the experimental measured data. In addition, both the experiments and the predictions precisely demonstrate the enhanced effects of inlet gas temperature and system pressure on the PEMFC performance. Based on the simulation results, the localized characteristics within a PEMFC can be reasonably captured. These parameters include the fuel gas distribution, liquid water saturation distribution, membrane conductivity distribution, temperature variation, and current density distribution etc. As the PEMFC is operated at the higher current density, the fuel gas would be insufficiently supplied to the catalyst layer, consequently causing the decline in the generation of power density. This phenomenon is so called mass transfer limitation, which can be precisely simulated by the present CFD model. 相似文献
4.
A small air-breathing proton exchange membrane fuel cell with a cylindrical configuration (Cy-PEMFC) and a helical flow-channel was developed to provide a uniform contact pressure to the membrane electrode assembly (MEA) with a thin cathode current collector. A comparison of the contact pressure and performance of the Cy-PEMFC and general planar PEMFC was performed to determine the effect of the cylindrical configuration. For the contact pressure comparison, numerical analysis was performed using commercial software. Numerical analysis showed that the Cy-PEMFC has its own structural advantage of changing the applied clamping pressure to a uniformly distributed contact pressure. The actual pressure measurements were carried out with pressure-sensitive film to support results of numerical analysis. These results also showed that the Cy-PEMFC had a uniformly distributed contact pressure, whereas the planar PEMFC did not. The polarization curves of both PEMFCs were measured to determine the performance variations caused by the uniform contact pressure and better mass transfer. The maximum power density of the Cy-PEMFC was 220 mW/cm2, which was approximately 24% higher than the planar PEMFC. 相似文献
5.
In this paper, the effect of the wall roughness on the water behavior related to the PEMFCs gas channel is investigated by the two-phase flow simulation. And, the different wetting conditions of the wall surface are considered, i.e. hydrophilic surface and hydrophobic surface. The relative roughness height and the roughness element density as well as the roughness element type are also considered in the study. And the results show: (1) for hydrophilic surface, water behavior for smooth case is different from the roughness cases, due to the effect of roughness on the water slug morphology even for r/H = 0.2% roughness. (2) r/H = 0.2% is positive for water removal and will not lead to the high pressure drop for hydrophilic surface, (3) r/H = 5% is advantageous for water removal for hydrophilic surface but disadvantageous for hydrophobic case, and the pressure drop greatly increases for both cases, (4) for hydrophobic surface, roughness of r/H = 1% and r/H = 2% slow down the water removal speed, but will not affect the amount of the removable water, (5) there is nearly no effect for r/H = 0.2% for hydrophobic case, (6) for both conditions, the average pressure drop obviously increases when r/H ≥ 2%. (7) Increase of the roughness element can help water removal for hydrophilic case but no obvious function for hydrophobic surface. (8) The triangle roughness element is better than rectangle element with the same height. 相似文献
6.
Zhen-Bo Wang Peng-Jian ZuoYuan-Yuan Chu Yu-Yan ShaoGe-Ping Yin 《International Journal of Hydrogen Energy》2009
In the present paper, a proton exchange membrane fuel cell (PEMFC) using 20 wt.% Pt/C as anode and cathode catalysts, and ambient air at cathode was operated at a current density of 160 mA cm−2 for 2250 h. The measurement results showed that electrochemically active specific areas (SEAS) of both electrode catalysts calculated from CV curves after test evidently decreased. The decay rate of SEAS of anode catalyst was much lower than that of cathode one. X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), and X-ray photoelectron spectrometry (XPS) were employed to characterize the anode and cathode catalysts before and after the life test. The XRD results showed that their crystal structures were perfect, the particle size of new Pt/C catalyst was about 2.5 nm, however, the particle sizes of anode and cathode ones markedly increased, and were about 4.9 nm and 6.8 nm, respectively, after the life test. Furthermore, the size of cathode catalyst was much bigger than that of anode one after test. The Pt element was also found in Nafion® film as shown in EDAX result. The XPS results presented that the content of Pt oxidation states in cathode was much more than that in anode, and the corrosion of carbon support in cathode was also more severe than that in anode after the life test. The experimental results indicated that the increase of particle size of Pt/C catalyst was illustrated with the dissolution/redeposition mechanism. The degradation of cathode catalyst for oxygen electroreduction was one of the main factors affecting on the performance decay of PEMFC. 相似文献
7.
Shucheng Sun Hongmei Yu Junbo Hou Zhigang Shao Baolian Yi Pingwen Ming Zhongjun Hou 《Journal of power sources》2008
Fuel cells for automobile application need to operate in a wide temperature range including freezing temperature. However, the rapid startup of a proton exchange membrane fuel cell (PEMFC) at subfreezing temperature, e.g., −20 °C, is very difficult. A cold-start procedure was developed, which made hydrogen and oxygen react to heat the fuel cell considering that the FC flow channel was the characteristic of microchannel reactor. The effect of hydrogen and oxygen reaction on fuel cell performance at ambient temperature was also investigated. The electrochemical characterizations such as I–V plot and cyclic voltammetry (CV) were performed. The heat generated rate for either the single cell or the stack was calculated. The results showed that the heat generated rate was proportional to the gas flow rate when H2 concentration and the active area were constant. The fuel cell temperature rose rapidly and steadily by controlling gas flow rate. 相似文献
8.
Qifei Jian Bi Huang Lizhong Luo Jing Zhao Songyang Cao Zipeng Huang 《International Journal of Hydrogen Energy》2018,43(29):13489-13500
The aim of this study is to investigate the thermal response characteristics of the proton exchange membrane fuel cell stack. In order to find out the regularities of temperature variation under rapidly increasing load change, a home-made 500 W open-cathode stack embedded with 30 thermocouples was made and tested. The result shows that the local temperature dominates the thermal response at the initial stage while the membrane hydration is the crucial impact factor at low power stage. Further, the anode flooding strongly affects the stability of the output performance and the change of temperature at the overloaded stage. The maximum temperature difference within one cell can reach a steady state faster than that of the temperature. At normal operation, there is little difference between the defined surfaces. The exergy analysis shows that the reaction air will have higher exergy if the temperature variation is more smooth. This experimental study contributes to the optimization of the cooling strategy and thermal management of the open-cathode stack in application. 相似文献
9.
V.H. Rangel-Hernandez C. Damian-AscencioD. Juarez-Robles A. Gallegos-MuñozA. Zaleta-Aguilar H. Plascencia-Mora 《Energy》2011,36(8):4864-4870
The present paper aims at investigating the main sources of irreversibility in a Proton Exchange Membrane Fuel Cell (PEMFC) using a Fermat spiral as flow distributor and also to direct possible improvements in its design. The numerical analysis is based on a finite volume technique with a SIMPLE algorithm as numerical procedure. In order to have a more complete and rigorous analysis a new dimensionless parameter is proposed here. The parameter represents the ratio of the entropy generation due to mass transfer to the total entropy generation is proposed here. Results demonstrate that the main sources of irreversibility in a fuel cell are the concentration losses for the most part of the operational domain, whereas the heat transfer effect is not dominant. 相似文献
10.
质子交换膜燃料电池的开发应用 总被引:1,自引:0,他引:1
王正 《能源技术(上海)》2005,26(5):213-214,219
质子交换膜燃料电池(PEMFC)作为一种新一代的发电技术,已成为世界各国特别是发达国家的研发重点被纳入发展规划,应用领域从特殊应用到商品化、产业化不断开拓.但PEMFC的产业化和推广应用受关键材料和工艺技术的制约,为了加速我国PEMFC的发展,今后必须投入足够的财力,组织相关学科的人才,制定可行的规划,加大科研力度. 相似文献
11.
Xiqiang Yan Ming Hou Liyan SunHaibo Cheng Youlu HongDong Liang Qiang ShenPingwen Ming Baolian Yi 《Journal of power sources》2007
The operations of fuel cell stacks in fuel cell vehicle are dynamic. During dynamic loading, the oxidant starvation often occurs, due to the gas response rate lagging the loading rate. To study the transient behavior of the fuel cell stack at load changes, the measuring methods of current and temperature distribution are developed. In this paper, the current distribution and temperature distribution as well as their dynamic changes in fuel cell stack have been evaluated in situ. The experimental results show that the local current and temperature rise when load rapidly. The extent of temperature fluctuation during dynamic loading is significantly influenced by air stoichiometries, loading rates, and air relative humidities. When air stoichiometry is very low, the temperature of cathode inlet rises sharply. The quicker the loading rate is, the bigger the extent of temperature fluctuation is. With increasing air relative humidity, the transient temperature of cathode inlet rises, while the transient temperature of cathode outlet decreases. This paper will provide reference for durability researches on fuel cell vehicles (FCVs). 相似文献
12.
Justo Lobato Pablo CañizaresManuel A. Rodrigo Diego ÚbedaF. Javier Pinar 《Journal of power sources》2011,196(20):8265-8271
The fuel cell performance of a composite PBI-based membrane with TiO2 has been studied. The behaviour of the membrane has been evaluated by comparison with the fuel cell performance of other PBI-based membranes, all of which were cast from the same polymer with the same molecular weight. The PBI composite membrane incorporating TiO2 showed the best performance and reached 1000 mW cm−2 at 175 °C. Moreover, this new titanium composite PBI-based membrane also showed the best stability during the preliminary long-term test under our operation conditions. Thus, the slope of the increase in the ohmic resistance of the composite membrane was 0.041 mΩ cm2 h−1 and this is five times lower than that of the standard PBI membrane. The increased stability was due to the high phosphoric acid retention capacity - as confirmed during leaching tests, in which the Ti-based composite PBI membrane retained 5 mol of H3PO4/PBI r.u. whereas the PBI standard membrane only retained 1 mol H3PO4/PBI r.u. Taking into account the results obtained in this study, the TiO2-PBI based membranes are good candidates as electrolytes for high temperature PEMFCs. 相似文献
13.
A numerical investigation on multi-phase transport phenomena in a proton exchange membrane fuel cell stack 总被引:1,自引:0,他引:1
Anh Dinh Le 《Journal of power sources》2010,195(16):5278-5291
In this study, the simulation of a fuel cell stack is performed by applying a general numerical model with VOF method that has been successfully applied to single PEMFC model to investigate the fluid dynamics, mass transport, flooding phenomenon and the effects of liquid water on the stack performance. The performance of three single cells in series connection in the fuel cell stack is examined according to the presence of liquid water in different single cells. The distributions of fluid flow, species concentration and the current density are presented to illustrate the effects of liquid water on the performance of each single cell. The numerical results locate that the low distributions of species in the flooding cell certainly degrade the performance of this cell. Moreover, it can be seen that the performance of the flooding cell will significantly affect the whole stack performance since the values of average current density must be identical in all single cells. 相似文献
14.
The 2n full factorial design was applied to identify the key parameters of the active layer affecting the performance of a proton exchange membrane (PEM) fuel cell. Three main selected parameters were considered: carbon-type (Vulcan XC 72R and Black Pearls 2000 conducting furnace blacks, Cabot Corporation Boston, MA), Pt loading (0.1 and 0.5 mg/cm2), and Nafion™ sulfonic acid fluoropolymer (Du Pont de Nemours, Wilmington, DE) ionomer content (10% and 60%) for variables A, B, and C, respectively. The results from full factorial analysis indicated that the key factors affecting the exchange current density or activation loss were Pt loading whereas the key factors controlling the resistance due to ohmic loss were Nafion content and carbon type. In addition, there are the interactions between these parameters controlling the thin-film active layer performance, especially the interaction of carbon type and Nafion content. From cyclic voltammograms and cell performance testing, a Nafion content of 30% in a catalyst layer consisting of 0.5 mg/cm2 Pt on Vulcan XC 72R is optimal. 相似文献
15.
Juanfang Liu Nobuyuki Oshima Eru Kurihara Litan Kumar Saha 《Journal of power sources》2010,195(19):6342-6348
A two-phase, one-dimensional steady model is developed to analyze the coupled phenomena of cathode flooding and mass-transport limiting for the porous cathode electrode of a proton exchange membrane fuel cell. In the model, the catalyst layer is treated not as an interface between the membrane and gas diffusion layer, but as a separate computational domain with finite thickness and pseudo-homogenous structure. Furthermore, the liquid water transport across the porous electrode is driven by the capillary force based on Darcy's law. And the gas transport is driven by the concentration gradient based on Fick's law. Additionally, through Tafel kinetics, the transport processes of gas and liquid water are coupled. From the numerical results, it is found that although the catalyst layer is thin, it is very crucial to better understand and more correctly predict the concurrent phenomena inside the electrode, particularly, the flooding phenomena. More importantly, the saturation jump at the interface of the gas diffusion layer and catalyst layers is captured, when the continuity of the capillary pressure is imposed on the interface. Elsewise, the results show further that the flooding phenomenon in the CL is much more serious than that in the GDL, which has a significant influence on the mass transport of the reactants. Moreover, the saturation level inside the cathode is determined, to a great extent, by the surface overpotential, the absolute permeability of the porous electrode, and the boundary value of saturation at the gas diffusion layer-gas channel interface. In order to prevent effectively flooding, it should remove firstly the liquid water accumulating inside the CL and keep the boundary value of liquid saturation as low as possible. 相似文献
16.
17.
Erce Şengül Hülya Erdener R. Gültekin Akay Hayrettin Yücel Nurcan Baç İncİ Eroğlu 《International Journal of Hydrogen Energy》2009
Sulfonated polyether-etherketone (SPEEK) has a potential for proton exchange fuel cell applications. However, its conductivity and thermohydrolytic stability should be improved. In this study the proton conductivity was improved by addition of an aluminosilicate, zeolite beta. Moreover, thermohydrolytic stability was improved by blending poly-ether-sulfone (PES). Sulfonated polymers were characterized by H-NMR. Composite membranes prepared were characterized by Electrochemical Impedance Spectroscopy (EIS) for their proton conductivity. Degree of sulfonation (DS) values calculated from H-NMR results, and both proton conductivity and thermohydrolytic stability was found to strongly depend on DS. Therefore, DS values were controlled time in the range of 55–75% by controlling the reaction time. Zeolite beta fillers at different SiO2/Al2O3 ratios (20, 30, 40, 50) were synthesized and characterized by XRD, EDX, TGA, and SEM. The proton conductivity of plain SPEEK membrane (DS = 68%) was 0.06 S/cm at 60 °C and the conductivity of the composite membrane containing of zeolite beta filled SPEEK was found to increase to 0.13 S/cm. Among the zeolite Beta/SPEEK composite membranes the best conductivity results were achieved with zeolite beta having a SiO2/Al2O3 ratio of 50 at 10 wt% loading. 相似文献
18.
Djamel Haddad Hocine Benmoussa Noureddine Bourmada Kafia Oulmi Bouziane Mahmah Maïouf Belhamel 《International Journal of Hydrogen Energy》2009
The objective of our study is to quantify the mass water transferred by various modes: diffusion, convection and migration. For the water transfer, the principal forces considered in the model are, the convection force, the osmotic force (i.e. diffusion) and the electric force (migration). The first of these forces results from a pressure gradient, the second of a concentration gradient and the third of a protons' migration from the anode to the cathode, which has an effect on the dipole of the water molecules (resistance force to the advancement). The numerical tool used to solve the equations' system is the finite element method. The results obtained numerically considering this method are concentration profiles and concentration variation with time and membrane thickness. These results illustrate the contribution of each mass transfer mode. 相似文献
19.
Jie Jin Dacai Zheng Suiwu Han Junjie Ma Zhengxu Zhu 《International Journal of Hydrogen Energy》2017,42(2):1142-1153
In this paper, CrNiN coatings with various Ni content are deposited on 304ss bipolar plates by closed field unbalanced magnetron sputter ion plating from CrNi alloy targets. Simulative working environment of proton exchange membrane fuel cell (PEMFC) is applied to test the electrical and corrosion properties of uncoated 304ss and CrNiN-coated samples. The influence of Ni content on microstructure, phase structure, contact angle with water and electrochemical performance is investigated. Results show that all the coated samples significantly enhanced the corrosion resistance of the 304ss, and the CrN-coated 304ss sample without Ni has the best corrosion resistance of 153.8 and ?141.9 mV in the simulated anodic and cathodic environments, respectively. Electrochemical impedance spectroscopy (EIS) studies reveal that the resistance of CrN coating is higher than that of other coated samples and 304ss in the cathodic environment. Furthermore, Interfacial contact resistance (ICR) studies revealed that CrN coating has a superior ICR of 11 mΩ cm2 at a compaction force of 160 N cm?2. In addition, the contact angle of the CrNiN coatings with water is approximately 114°, which is beneficial for water management in PEMFC. Analysis result indicates that the enhanced performance of the coated 304ss bipolar plates is related to the high film density determined by closed field unbalanced magnetron sputter ion plating, and the synergistic function of the CrNiN layered structure. 相似文献
20.
In order to determine the suitability of SS316L as a bipolar plate material in proton exchange membrane fuel cells (PEMFCs), its corrosion behavior is studied under different simulated PEMFC cathode corrosion conditions. Solutions of 1 × 10−5 M H2SO4 with a wide range of different F− concentrations at 70 °C bubbled with air are used to simulate the PEMFC cathode environment. Electrochemical methods, both potentiodynamic and potentiostatic, are employed to study the corrosion behavior. Scanning electron microscopy (SEM) is used to examine the surface morphology of the specimen after it is potentiostatic polarized under simulated PEMFC cathode environments. Auger electron spectroscopy (AES) analysis is used to identify the composition and the depth profile of the passive film formed on the SS316L surface after it is polarized in simulated PEMFC cathode environments. Photo-electrochemical (PEC) method and capacitance measurements are used to characterize the semiconductor passive films. The results of both the potentiodynamic and potentiostatic analyses show that corrosion currents increase with F− concentrations. SEM examination results indicate that pitting occurs under all the conditions studied and pitting is more severe with higher F− concentrations. From the results of AES analysis, PEC analysis and the capacitance measurements, it is determined that the passive film formed on SS316L is a bi-layer semiconductor, similar to a p-n heterojunction consisting of an external n-type iron oxide rich semiconductor layer (electrolyte side) and an internal p-type iron-chromium oxide semiconductor layer (metal side). Further analyses of the experimental results reveal the electronic structure of the passive film and shed light on the corrosion mechanisms of SS316L in the PEMFC cathode environment. 相似文献