Molecular Dynamics Simulation of Water Behavior as a Function of Temperatures and Monomer Numbers in Nafion 117

2007 ◽  
Author(s):  
Kyung Su Oh ◽  
Seungho Park ◽  
Ohmyoung Kwon ◽  
Young Ki Choi ◽  
Joon Sik Lee
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Molecular Model ◽  
Critical Role ◽  
Proton Exchange ◽  
Dynamics Simulation ◽  
Sulfonate Group ◽  
Efficient Operation ◽  
Self Diffusion ◽  
Set Up

The proton exchange membrane plays a critical role as an electrolyte for proton transports in the PEMFC. Generally, the membrane, such as Nafion 117, consists of a polytetrafluoro-ethylene (PTFE) backbone and side-chains terminated with a sulfonate group (SO3−). Operating the fuel cell, the membrane preferentially becomes hydrated by absorbing water. Then, the hydrogen atom on the SO3− part of the side-chain can detach from its own position and hop to the next SO3− site. The water management is the key to the efficient operation of the fuel cell, since the water content is the one of decisive factors for membrane’s lifetime and efficient operations of fuel cells as well. In this report, we set up the molecular model for hydrated Nafion 117 and simulate the molecular movements for various temperatures and monomer numbers. Here, we obtain the mean square displacements of water molecules and estimate the self-diffusion coefficients of water in the Nafion 117.

CFD Investigation of a PEMFC Stack Assembly

2019 ◽  
Author(s):  
Kevin R. Anderson ◽  
Andrew Murphy
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Pt Catalyst ◽  
Cfd Modeling ◽  
Software Module ◽  
Contour Plots ◽  
Set Up ◽  
Voltage Performance ◽  
Exchange Membrane

Abstract In this study 3-D CFD modeling of a cylindrical stack Proton-exchange membrane fuel cell (PEMFC) is provided. The H2O-O2 PEMFC uses a 10.8 mm2 area membrane and Platinum (Pt) catalyst. The paper presents the methodology for the PEMFC commercial software module, the set-up of the Computational Fluid Dynamics (CFD) geometry, mesh and boundary conditions. Results for the current-voltage performance curves and 3-D contour plots of the fluid, heat and species concentrations within the PEMFC are given. Results are presented for a low-temperature fuel cell using NAFION membrane and a high-temperature fuel cell using BZY membrane.

Analysis of the Co-Generation Potential of a 5 kW PEMFC From Experimentally Determined Performance Data

2004 ◽  
Author(s):  
L. G. Do Val ◽  
A. F. Orlando ◽  
C. E. R. Siqueira ◽  
J. Oexmann
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Total Efficiency ◽  
Fuel Processor ◽  
A Value ◽  
Cell Energy ◽  
Set Up ◽  
Energy Balances ◽  
Exchange Membrane

A 5 kW proton exchange membrane fuel cell (PEMFC) with a reformer has been installed and tested at the Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Brazil, aiming the experimental determination of its performance and co-generation potential to increase the fuel chemical energy usage. The unit uses a fuel processor to convert energy from natural gas into hydrogen rich reformate. The fuel cell is totally instrumented, supplying data for calculating the overall system efficiency (total efficiency), reformer efficiency, stack efficiency, conversion efficiency (DC/AC), and co-generation potential, at previously set up output powers of 2,5 kW and 4 kW. The paper details the equations required for calculating the parameters, both theoretically, from thermodynamics and electrochemics points of view, and experimentally, from mass and energy balances, comparing the results. Steady state data were taken at 13 different days, resulting in reformer, stack, conversion and total average efficiencies, together with the calculated standard deviation. It was also found that the energy loss in the reformer and in the stack are approximately the same. The co-generation potential was estimated by calculating the heat rejected by the stack and the heat rejected in the reformer, giving a value of 67,5% and 68,9%, respectively for 2,5 kW and 4 kW. Therefore, co-generation can substantially reduce the fuel cell energy cost, and thus increasing the feasibility of its use.

Life Cycle Cost Analysis of the Fuel Cell Bus Based on Chinese Bus Cycle

2011 ◽  
Vol 403-408 ◽  
pp. 3220-3223
Author(s):  
Rui Chen ◽  
Ning Wang ◽  
Jun Ma
Keyword(s):  
Life Cycle ◽  
Fuel Cell ◽  
Life Cycle Cost ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Maintenance Cost ◽  
Fuel Cell Bus ◽  
Consumption Cost ◽  
The Government ◽  
Set Up

During the project: Electric Hybrid Proton Exchange Membrane (PEM) Fuel Cell Transit Buses in China, the authors set up a model to calculate the life cycle cost of fuel cell bus (FCB). The model includes acquisition cost, fuel consumption cost and maintenance cost. In addition, the authors also take the government subsidies into account. After calculating, we see the cost of fuel cell is the most sensitive part of FCB life cycle cost. Using the model, we compared different bus life cycle costs. The result shows that FCB life cycle cost is 5 times more than the current diesel bus.

An Experimental Study of Operational Parameters on the Performance of PEMFCs

2010 ◽  
Author(s):  
Emad G. Barakat ◽  
Ali K. Abdel-Rahman ◽  
Mahmoud A. Ahmed ◽  
Ahmed Hamza H. Ali
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Operating Pressure ◽  
Operational Parameters ◽  
Cell Temperature ◽  
Power Increase ◽  
Set Up ◽  
Exchange Membrane ◽  
Gas Humidification

The performance of Proton exchange membrane fuel cell (PEMFC) has been experimentally investigated. An experimental set-up was designed to study the effects of operating parameters such as cell temperature, gas humidification, and cell operating pressure on the performance of fuel cell. The results indicated that the output power increase with the increase of humidification ratio. Furthermore, an increase of cell pressure results in a significant increase of cell power. The results indicated that increasing of the temperature leads to a decrease of cell power. The results are explained and discussed in more details for different operational parameters.

Development and Experimental Validation of a Simulation Tool for a Fuel Cell Based Power System

Volume 1 ◽  
2004 ◽  
Author(s):  
Luca Andreassi ◽  
Stefano Cordiner ◽  
Massimo Feola ◽  
Fabio Romanelli
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Numerical Models ◽  
Critical Issue ◽  
Proton Exchange ◽  
Design Parameters ◽  
Operating Pressure ◽  
Research Activity ◽  
Set Up

Fuel cells (FC) technology applied to energy production could represent an effective solution to face greenhouse gas emissions and to differentiate energy sources. However, real performances of FC systems still represent a critical issue in the definition of an assessed and economically competitive technology. In fact, FC performances depend on many variables such as temperature, pressure, current, membrane humidification, stoichiometry of the reactant gas, etc.; additionally, many of these influencing parameters depend one on the other, further complicating the analysis. Numerical simulation could greatly contribute to a better understanding of the influence of design parameters. Nevertheless, the availability of experimental data to validate and to verify the numerical models is an imperative issue. The primary target of the research activity described in this paper is the set up of an experimental test bench for Proton Exchange Membrane Fuel Cell (PEM FC) at the Department of Mechanical Engineer of the University of Roma Tor Vergata aiming to completely test 8 cells 0.1 kW stack: the measured data are fundamental to validate the numerical models which have been developed by the Authors following different hierarchical levels (both semi-empirical and dimensional analytical approach) with different predictive capabilities. This apparatus allows the control of the reactant gas mass flow rates, stack pressure, humidity, current, temperature and voltage. In this way it is possible to assess a mixed experimental-numerical methodology allowing a tuning procedure for the developed models making a wide use of dedicated experimental data. The preliminary results in terms of comparisons between experimental and computational data show a good agreement even by varying some of the most performance-affecting parameters such as operating pressure and temperature.

Investigation of Atomistic Scale Transport Phenomena of the Proton Exchange Membrane Fuel Cell

2006 ◽  
Vol 4 (4) ◽  
pp. 474-480 ◽  
Author(s):  
Chin-Hsien Cheng ◽  
Che-Wun Hong
Keyword(s):  
Fuel Cells ◽  
Diffusion Coefficients ◽  
Atomistic Simulation ◽  
Proton Exchange Membrane ◽  
Transport Phenomena ◽  
Proton Exchange ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Self Diffusion ◽  
Exchange Membrane

This paper studies the transport phenomena inside the electrolyte of proton exchange membrane fuel cells (PEMFCs) using atomistic simulation techniques. The investigated material of the electrolyte is Nafion®, which is the most widely adapted polymer membrane in low-temperature fuel cells. The molecular dynamics simulation system includes part of the Nafion structure, numerous water molecules, and the transporting cations. The cations are assumed to be hydroxoniums (H3O+), which are a hydrogen proton combined with a water molecule. Simulation results indicated that the electrostatic energy dominated the other potential energies in the total internal energy analysis. Clusters of water molecules tend to move toward the sulfonic acid group in the Nafion fragment, where the hydrophilic/hydrophobic characteristics can be observed. The transport phenomena of hydroxoniums are classified into two categories—continuous migration and noncontinuous hopping. The self-diffusion coefficients of the hydroxoniums and the water molecules in the membrane were evaluated to be 3.476×10−5cm2∕s and 4.993×10−5cm2∕s respectively, based on the Einstein relation. The calculated self-diffusion coefficients are of the same order of magnitude as the experimental results, which indicates this atomistic simulation is reaching more and more practical in engineering analysis.

scholarly journals Control por Modos Deslizantes de la Relación de Exceso de Oxígeno en una PEMFC Interconectada a un Motor de CD mediante un Convertidor Boost

2019 ◽  
pp. 25-32
Author(s):  
María Cervera-Ceballos ◽  
Marco Antonio Rodriguez-Blanco ◽  
José Vazquez-Ávila ◽  
Hussain Alazki
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Sliding Mode ◽  
Electric Energy ◽  
Pem Fuel Cells ◽  
Dc Motor ◽  
Proton Exchange ◽  
Excess Oxygen ◽  
Efficient Operation ◽  
Cell Components

In this work, a proton exchange membrane fuel cell (PEMFC) is used to electric energy supply to a permanent magnet DC motor in a sustainable way and the inlet air flow in the cathode is manipulated to ensure the PEM fuel cells efficient operation. A boost-type DC/DC converter is connected to the PEMFC, it is used with a PI linear control loop to regulate the speed of the DC motor under some possible load disturbances. In addition, a nonlinear sliding mode control (SMC) is designed for regulated the excess oxygen ratio considering constant the temperature and humidity of membrane, to achieve the PEM full cell operate in the ohmic region of the polarization curve, to avoid the oxygen starvation at the cathode and to prevent damage to fuel cell components. The results are validated using the internal models of the PEMFC and the power electronics from SimPowerSystems library of Matlab/Simulink.

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