Influence of Operating and Electrochemical Parameters on PEMFC Performance: A Simulation Study (original) (raw)
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Flow rate and humidification effects on a PEM fuel cell performance and operation
Journal of Power Sources, 2007
A new algorithm is presented to integrate component balances along polymer electrolyte membrane fuel cell (PEMFC) channels to obtain three-dimensional results from a detailed two-dimensional finite element model. The analysis studies the cell performance at various hydrogen flow rates, air flow rates and humidification levels. This analysis shows that hydrogen and air flow rates and their relative humidity are critical to current density, membrane dry-out, and electrode flooding. Uniform current densities along the channels are known to be critical for thermal management and fuel cell life. This approach, of integrating a detailed two-dimensional across-the-channel model, is a promising method for fuel cell design due to its low computational cost compared to three-dimensional computational fluid dynamics models, its applicability to a wide range of fuel cell designs, and its ease of extending to fuel cell stack models.
On the influence of temperature on PEM fuel cell operation
Journal of Power Sources, 2006
The 3D implementation of a previously developed 2D PEMFC model [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A twodimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89] has been used to analyze the various pathways by which temperature affects the operation of a proton exchange membrane fuel cell [M. Coppo, CFD analysis and experimental investigation of proton exchange membrane fuel cells, Ph.D. Dissertation, Politecnico di Torino, Turin, Italy, 2005]. The original model, implemented in a specially modified version of CFDesign ® [CFDesign ® V5.1, Blue Ridge Numerics, 2003], accounts for all of the major transport processes including: (i) a three-phase model for water transport in the liquid, vapor and dissolved phases, (ii) proton transport, (iii) gaseous species transport and reaction, (iv) an agglomerate model for the catalyst layers and (v) gas phase momentum transport. Since the details of it have been published earlier [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A two-dimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89; N.P. Siegel, Development and validation of a computational model for a proton exchange membrane fuel cell, Ph.D. Dissertation, ], only new features are briefly discussed in the present work.
Defect and Diffusion Forum, 2008
In the present work, a three dimensional model examining the fluid flow along with the fundamental transport phenomena occurring in a typical polymer electrolyte fuel cell (PEMFC), i.e. heat transfer, mass transport and charge transfer, has been developed. The flow field was simulated according to the well known Navier-Stokes equations, while the heat transfer was described by the typical conduction/convection equation and the mass transport by the convection/diffusion one. Furthermore, reaction kinetics were studied by the Butler-Volmer equation for the heterogeneous reactions occurring at the porous electrodes. The developed model was numerically solved by using the commercially available CFD package CFD-RC © , which is based on the multi-step finite volume method. The fuel cell performance in terms of velocity, temperature, mass fractions of active compounds and electric field has been investigated as well.
Investigation of gas diffusion media inside PEMFC using CFD modeling
Journal of Power Sources, 2006
The performance of a gas diffusion layer comprised of a macro porous and micro porous layer has been studied both experimentally and by numerical simulation. Experimental data at different humidification conditions have been compared to full cell, three-dimensional computational fluid dynamics calculations to validate the physical model of the cell. Local distributions of current density, electrochemical variables, temperature, and gas composition are discussed in detail. Model calculations agree well with experimental data and the solutions with and without the micro porous layer show that this layer has an effect on the overall performance and the local distributions show differences. The effect of hydrogen dilution is also explored in this paper with micro/macro gas diffusion media. The results reveal that proton exchange membrane fuel cell (PEMFC) performance depends not only on the oxygen but also on the hydrogen partial pressure.
Transport phenomena effect on the performance of proton exchange membrane fuel cell (PEMFC)
International Journal of Hydrogen Energy, 2013
Performance Finite volume method PEMFC a b s t r a c t The aim of this work is to present a two-dimensional transient model, of heat and mass transfer in a proton exchange membrane fuel cell (PEMFC). The model includes various conservation equations such as mass (hydrogen, oxygen, water concentration), Momentum and energy equations this model is combined with the electrochemical model. The objective of this work is to know the hydrogen, oxygen water concentration, temperature and pressure to determine the performance conditions of the fuel cell under the current density and permeability effect. A program based on the finite volume method was performed to simulate these equations system. The numerical results show that the gas distribution in the assembly membrane electrode (MEA) and the power density is affected by the nature of porous middle (permeability).
Effects of Flow Characteristics in Polymer Electrolyte Membrane Fuel Cell
An experimental and numerical study of polymer electrolyte membrane fuel cell (PEMFC) is presented and compared with the experimental data to investigate the effects of pressure gradient, flow rate, humidification and supplied oxidant type for the practical application. The membrane and electrolyte assembly (MEA) materials are implemented by double-tied catalyst layers. A single-phase two-dimensional steady-state model is is implemented for the numerical analysis. Testing condition is fixed at 60sccm and 70°C in anode and cathode, respectively. It is found that the performance of PEMFC depend highly on the conditions as gas pressure, temperature, thickness, supplied oxidant type (Oxygen/Air) as well as humidification. The results show that the humidification effect enhances the performance more than 20% and the pure oxygen gas as fuel improves current density more than 25% compared to ambient air suppliance as oxidant.
Computational fluid dynamics (CFD) study of segmented proton exchange membrane fuel cell (PEMFC) performance has been carried out, based on experimental setup and operating parameters from previous studies. Two different temperature boundary conditions were considered e isothermal and, a novel, non-uniform temperature profile calculated from Mollier h-u chart. Implementation of non-uniform terminal temperature boundary conditions resulted in close to 100% relative humidity along the cathode channel, resulting in improvement of PEMFC performance without the need for external humidification. Model polarization curve and relative humidity distribution along the cathode channel length are in good agreement with experimental results. It was found that different current collector materials, i.e., their thermal conductivity have major influence on temperature, thus on relative humidity distributions along reactant gas channels. The membrane thickness affects the net water transport across the membrane, thus also has influence on temperature and relative humidity distribution along the reactant gas channels.
International Journal of Heat and Technology, 2013
A full numerical, three-dimensional, single phase computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) with both the gas distribution flow channels and the Membrane Electrode Assembly (MEA) has been developed. A single set of conservation equations which are valid for the flow channels, gas-diffusion electrodes, catalyst layers, and the membrane region are developed and numerically solved using a finite volume based computational fluid dynamics technique. The present simulated single straight channel PEMFC model, accounts the major transport phenomena and the performance. Additionally, the effect of anode transfer coefficient, α an , reduction has been investigated on the fuel cell performance and species distribution. The results showed that, decreasing the anode transfer coefficient leads to lower magnitude of the oxygen and water mass fraction. In this way, the current density, which generating by the cell decreases too.
Performance effects of proton exchange membrane fuel cell at various operating temperatures
Performance effects of proton exchange membrane fuel cell (PEMFC) at various temperatures of the gases feeding the electrodes were investigated. Experiments have been carried out on two different homemade PEMFCs with hydrogen/oxygen and hydrogen/air feed. On each PEMFC with different feed that have an active area of 9 cm 2 Nafion™ NE-1035 as proton exchange membrane (PEM) and electrodes with platinum load of 0.9 mg/cm 2 were used. Temperature of humidified gases in 1 atm pressure that feed the PEMFCs kept at ambient temperature (25 o C) varies from ambient temperature to 95 o C by 10 o C step. During the experiment backpressures of each type of the PEMFCs held constant at 1 atm and the external load resistance (RL) varies from 0 to 1000 K. In high temperatures the diffusivity of gases increase and mass transport resistance decrease. However, the ion-conductivity of the PEM in ohmic region increases. As a result it was concluded that performance of the PEMFCs depends on the concentration of gases and on the discharge of water (H2O) content formed by electro-chemical reactions.
Hemijska industrija, 2012
A full numerical, three-dimensional, single phase computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) with both the gas distribution flow channels and the Membrane Electrode Assembly (MEA) has been developed. A single set of conservation equations which are valid for the flow channels, gas-diffusion electrodes, catalyst layers, and the membrane region are developed and numerically solved using a finite volume based computational fluid dynamics technique. The present simulated single straight channel PEMFC model, accounts the major transport phenomena and the performance. Additionally, the effect of anode transfer coefficient, α an , reduction has been investigated on the fuel cell performance and species distribution. The results showed that, decreasing the anode transfer coefficient leads to lower magnitude of the oxygen and water mass fraction. In this way, the current density, which generating by the cell decreases too.