Design and optimization of polymer electrolyte membrane (PEM) fuel cells (original) (raw)
Related papers
2013
This article presents the results of a numerical investigation, using a comprehensive two-dimensional, single phase, nonisothermal and parallel flow model of a PEM fuel cell with straight channels. The proposed model is single domain and both of the anode and the cathode humidification were involved in the domain. In this research, the cathode pressure variation effect on the inlet gas composition (water and oxygen), temperature distribution, molar concentration of species and fuel cell performance were investigated. Also for two low cell voltages (which leads to high current densities), the temperature distribution along the cell has been obtained. Additionally, species distribution such as hydrogen (at the anode side), oxygen and water (at the cathode side) and cathode over potential for various cell voltages have been presented with more details. Furthermore in order to geometrically investigation, three cases with different membrane thi cknesses were simulated. Similar boundary ...
2013
The aim of this dissertation was to investigate the performance of Polymer Electrolyte Fuel Cell (PEFC). The investigation involved understanding the mechanism of cross flow and pressure drop, addressing the contribution of cross flow on the performance, and water transport through the membrane. Computational fluid dynamics was used to study the gas flow behavior in the flow channel and porous media and information learned from the fluid dynamics study is used to design the artificial cross flow in the parallel flow field. At the beginning of the research, it was analyzed the mechanism of pressure drop and cross flow behavior in a single serpentine channel and gas diffusion layer. The dependency of physical parameters (e.g. porosity, permeability) and geometrical parameters such as gas channel pitch length and GDL thickness on the cross flow and pressure drop was studied vastly. It was explained pressure drop characteristics at the straight part of a serpentine channel and at the bend region. The role of cross flow on the pressure distribution in the gas channel also has been identified. Finally we concluded that the cross flow suppressed the pressure gradient in the straight part of serpentine channel and pressure gradient was maximum at the bend region. We also quantify the amount cross flow in terms of volume mass flux. The ratio of cross flow rate through the GDL to the total inlet flow rate increases with decreasing gas channel pitch length. Therefore, cross flow through the GDL can be enhanced by decreasing gas channel pitch length. The aim of the second part of this work was to identify the contribution of cross flow on the performance individually. For this reason, a three dimensional single phase, isothermal model has been developed with considering the electrochemical reaction occurring in fuel cell. However, to avoid complicated two phase flow phenomena it was considered the constant hydration level in the membrane. The developed model was applied to an operating fuel cell to investigate the coupled flow, species transport and current density distribution. The gas channel pitch length effect on the performance has been evaluated by this developed model. The results show that it can capture all the physics occurring in PEM fuel cell very well. Because, it can capture the physics including activation overpotential, ohmic overpotential and mass transport overpotential very well. Hence, it proofs the applicability of our developed model. The gas channel pitch has marked effect on the performance of polymer
Influence of the cathode catalyst layer thickness on the behaviour of an air breathing PEM fuel cell
Advances in Energy Research, 2014
Fuel cells of proton exchange membrane type (PEMFC) working with hydrogen in the anode and ambient air in the cathode ("air breathing") have been prepared and characterized. The cells have been studied with variable thickness of the cathode catalyst layer (L CL), maintaining constant the platinum and ionomer loads. Polarization curves and electrochemical active area measurements have been carried out. The polarization curves are analyzed in terms of a model for a flooded passive air breathing cathode. The analysis shows that L CL affects to electrochemical kinetics and mass transport processes inside the electrode, as reflected by two parameters of the polarization curves: the Tafel slope and the internal resistance. The observed decrease in Tafel slope with decreasing L CL shows improvements in the oxygen reduction kinetics which we attribute to changes in the catalyst layer structure. A decrease in the internal resistance with L CL is attributed to lower protonic resistance of thinner catalyst layers, although the observed decrease is lower than expected probably because the electronic conduction starts to be hindered by more hydrophilic character and thicker ionomer film.
2015
Polymer Exchange Membrane (PEM) fuel cells are known as the most significant alternatives to internal-combustion engines, but still there is a long way to achieve this ideal in reality. To achieve such a goal lots of optimizations are needed to be done on fuel cells. Water management is critical for achieving high performance of PEM fuel cells. In highcurrent densities, condensed water fills the pores of the Gas Diffusion Layers and thus oxygen transfer to the catalyst layers would be limited. In this study, for the sake of analyzing the PEM fuel cell characteristics and their variations, using the COMSOL software, the twophase flow regime in PEM fuel cells was simulated. To determine the saturation level in the cathode, a separate differential equation for mass conservation of liquid water was solved and due to the dependencies of other parameters of the mixture on the saturation level, these parameters are determined.
Fuel and Energy Abstracts
In this work, a three-dimensional, non-isothermal and two-phase computational fluid dynamics model of a proton exchange membrane (PEM) fuel cell with straight flow field channel is developed and validated. The model is used to predict the performance of the PEM fuel cell with changing parameters of the cathode catalyst layer which was usually assumed to be composed of spherical agglomerates. The effect of cathode catalyst layer parameters such as catalyst layer thickness, ionomer film thickness, agglomerate size and porosity, on the current density and power output of the PEM fuel cell is investigated. The numerical results reveal that competitive influence of resistances to transport of species, electron and proton within the cathode catalyst layer determines the performance of the PEM fuel cell in terms of area specific power density (W cm −2 ) and mass specific power density (kW g −1 Pt ).
A mathematical model and optimization of the cathode catalyst layer structure in PEM fuel cells
Electrochimica Acta, 2004
A spherical flooded-agglomerate model for the cathode catalyst layer of a proton exchange membrane fuel cell, which includes the kinetics of oxygen reduction, at the catalyst|electrolyte interface, proton transport through the polymer electrolyte network, the oxygen diffusion through gas pore, and the dissolved oxygen diffusion through electrolyte, is considered. Analytical and numerical solutions are obtained in various control regimes. These are the limits of (i) oxygen diffusion control, (ii) proton conductivity control, and (iii) mixture control. The structure and material parameters, such as porosity, agglomerate size, catalyst layer thickness and proton conductivity, on the performance are investigated under these limits. The model could help to characterize the system properties and operation modes, and to optimize catalyst layer design. Crown
Optimization of Fuel Cell Performance Using Computational Fluid Dynamics
Membranes, 2021
A low cost bipolar plate materials with a high fuel cell performance is important for the establishment of Proton Exchange Membrane (PEM ) fuel cells into the competitive world market. In this research, the effect of different bipolar plates material such as Aluminum (Al), Copper (Cu), and Stainless Steel (SS) of a single stack of proton exchange membrane (PEM) fuel cells was investigated both numerically and experimentally. Firstly, a three dimensional (3D) PEM fuel cell model was developed, and simulations were conducted using commercial computational fluid dynamics (CFD) ANSYS FLUENT to examine the effect of each bipolar plate materials on cell performance. Along with cell performance, significant parameters distributions like temperature, pressure, a mass fraction of hydrogen, oxygen, and water is presented. Then, an experimental study of a single cell of Al, Cu, and SS bipolar plate material was used in the verification of the numerical investigation. Finally, polarization curv...
International Journal of Hydrogen Energy, 2010
This work presents experimental performance results for a 50 cm 2 Polymer Electrolyte Membrane (PEM) Fuel Cell, including polarization curves and Electrochemical Impedance Spectroscopy (EIS) analysis of the Fuel Cell. EIS results were used for the determination of the cell ohmic resistance as well as charge transfer resistances under different operating conditions. Different combinations of operating conditions and bipolar plate designs were analysed. In particular, the effect of the cathode oxygen concentration, reactant gases humidification, and bipolar plate (BP) design were assessed. ButlereVolmer (BV) kinetic parameters such as the charge transfer coefficient were also determined from Tafel plots. The electronic contact resistances were measured for both Bipolar Plate designs, and the membrane protonic resistances were calculated. Its dependence on the BP flow field design and operating conditions is addressed. The results obtained in this work are aimed both at gaining insight into the fundamental processes determining the fuel cell performance, and at determining parameters needed for Computational Fuel Cell Dynamics (CFCD) numerical simulations.
NEW FUEL CELL ARCHITECTURES AND THE ROLE OF ELECTROKINETIC FLOWS IN ITS PERFORMANCE
2000
This papers discusses the role of: transport phenomena, electrokinetic flows, gas-liquid interface area, convective mix, and the electrical boundary layer (EBL) in fuel cell performance. The electrokinetic phenomena analysis is based in a new model of electrocapillary flow, and its preliminary experimental tests. With this model, oxygen transport and convective ionic current in high specific area electrodes are analyzed. The paper also shows the use of the Critical Chain Method (CCM) in the appraisal of feasibility, costs and risks of innovative fuel cell set ups.