1. PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC)
MODELING and SIMULATION
using COMSOL MULTIPHYSICS
Ercüment SÖNMEZ – Coşkun TOPRAK
Supervisor : Prof. Dr. Mustafa DEMİRCİOĞLU
Ege University, Engineering Faculty, Department of Chemical Engineering, 35100 Bornova, İZMİR
ABSTRACT ÖZET
ABSTRACT/ÖZET
Energy generation and consumption plays an important role worldwide in both the advancement of modern technology and the Enerjinin üretimi ve tüketimi; teknolojinin gelişimi ve global ekonomiye etkiyen eğilimler üzerinde büyük rol oynamaktadır. Fosil
trends on global economy. Fossil fuel sources have been drastically used during last century which has caused a series of yakıt kaynakları son yüzyıl içerisinde büyük ölçeklerde kullanılmış olup, etkileri ciddi çevresel sorunlara neden olmaktadır. Sonuç
environmental problems. As a concequence, alternative energy sources have been sought to diminish these problems. Research olarak, bu sorunları azaltmak için alternatif enerji kaynakları üzerinde çalışmalar devam ediyor. Yakıt hücreleri üzerindeki
on fuel cell technology has been boomed recently to supply a response both economically and environmentally solutions to the araştırmalar; artan enerji talebine, hem ekonomik hemde çevresel etki yönünden bir cevap olabilmesi için, son zamanlarda artış
increasing energy demand. In this project, the effects of various design parameters and operating conditions on PEM fuell cell göstermiştir. Bu projede, PEM yakıt hücresinin performansını etkileyen çeşitli çalışma koşulları ve tasarım değişkenleri üzerinde
performance have been studied by using a pionering software “COMSOL Multiphysics” which requires integrated engineering çalışılmış olup; diğer mühendislik dalları ile etkileşimli ve ileri derecede mühendislik bilgisi gerektiren ve bu konuda öncü bir yazılım
disciplineand sound knowledge. olan “COMSOL Multiphysics”kullanılmıştır.
AC/DC MODULE ACOUSTICS MODULE CHEMICAL ENGINEERING MODULE EARTH SCIENCE MODULE
Contains built‐in application modes and Models single and coupled processes
Simulates electrical components and Analyzes CFD,mass and energy balances
boundary settings for the modeling of for geologic and environmental
devices that depend on electrostatics, coupled to chemical reaction kinetics.
acoustic wave propagation in solids and phenomena particularly based around
magnetostatics and electromagnetic Incorporates a plethora of application
stationary fluids. sub‐surface flow.
quasi‐statics applications, particulary modes for the field of the transport
coupled to other physics. phenomena including ionic transport
Generator Flow Duct Centrifugal Pump Discrete Fracture
and multicomponent diffusion.
COMSOL
HEAT TRANSFER MODULE COMSOL MULTIPHYSICS MEMS MODULE
A finite‐element based program for simulating unlimited multiphysics and single‐physic applications. It incorporates Represents coupled processes in micro‐
Consists of advanced application modes
easy‐to‐use application interfaces, complete control over meshing and powerful solvers. COMSOL Multiphysics electro‐mechanical and microfluidic
for the analysis of heat transfer by
also offers an extensive and well‐managed interface to MATLAB and its toolboxes for a large variety of devices. Incorporates specific
conduction, convection, and radiation.
programming, preprocessing and post‐processing possibilities. multiphysics couplings for applications
Specific for industrial applications such
Similar interfaces are offered with COMSOL Multiphysics which are COMSOL Script, such as electroosmotic flow, film
as electronics cooling and process
COMSOL Reaction Engineering Lab.
Brake Disc of a Car Comb Drive damping, and fluid‐structure interaction.
engineering.
RF MODULE CAD IMPORT MODULE
STRUCTUAL MECHANICS MODULE MATERIAL LIBRARY
Characterizes electromagnetic fields, Internal material property database with more than
Performs classical stress‐strain analyses Facilities the reading of most
currents, and waves for RF, microwave, 2500 materials and 20000 properties. The database
with full multiphysics capabilities. industry‐standard CAD formats.
optical and other high frequency contains temperature dependence of electrical, thermal,
Comprises nonlinear material models, Includes add‐on packages that
devices. and structural properties of solid materials.
large deformation and contact abilities; support the file formats for specific
all able to be freely coupled to other CAD programs geometry kernels.
Communication
physics.
Microwave Oven Car Wheel Rim
Mast
FUEL CELL PEM FUEL CELL
A fuel cell is an energy generation device that converts hydrogen and PEM fuel cell use a solid polymer membrane (a thin plastic film) as the
oxygen into usable electric power by way of simple chemical reactions. As a electrolyte. This polymer is permeable to protons when it is saturated
simple electrochemical device, a fuel cell does not actually burn fuel, with water, but it does not conduct electrons.
‐ ‐
‐
‐
allowing it to operate pollution‐free. The only emissions produced by a fuel
cell are pure water and heat. This also makes a fuel cell quiet, dependable, The fuel for the PEMFC is hydrogen and the charge carrier is the hydrogen
and very fuel‐efficient. ion (proton). At the anode, the hydrogen molecule is split into hydrogen
Fuel Hydrogen Oxygen (O2)
‐
ions (protons) and electrons. The hydrogen ions permeate across the
‐
(H2) İn the air
A fuel cell has two electrodes, one positive and one negative, called the electrolyte to the cathode while the electrons flow through an external
++
PEMFC
cathode and the anode. The reactions that produce electricity take place at circuit and produce electric power. Oxygen, usually in the air, is supplied
‐
the electrodes. Every fuel cell also has an electrolyte, which carries to the cathode and combines with the electrons and the hydrogen ions to
‐
electrically charged particles from one electrode to the other, and a produce water. The reactions at the electrodes are as follows:
catalyst, which accelerates the reactions at the electrodes. 2H2 4H+ + 4e‐
Anode Reactions:
++
Cathode Reactions: O2 + 4H+ + 4e‐
Some types of fuel cell: 2H2O
Used Fuel
Air + Water Vapor
Recirculates
Alkaline Fuel Cells (AFCs) Overall Cell Reactions: 2H2 + O2 2H2O
Phosphoric Acid Fuel Cells (PAFCs)
PEMFC General Properties
Molten‐Carbonate Fuel Cells (MCFCs) Flow Field Plate Flow Field Plate
Operating
SystemOutput Efficiency Applications Advantages Disadvantages
Solid Oxide Fuel Cells (SOFCs) Temperature
Anode Cathode
Polymer Electrolyte Membrane Fuel Cells (PEMFCs) •Solid electrolyte
Catalyst Catalyst • Requires
• Back‐up power
reduces corrosion &
Direct Methanol Fuel Cells (DMFCs) expensive catalysts
• Portable power
(Platinum) (Platinum) electrolyte
• High sensitivity to
• Small
Proton Exchange Membrane management
40‐60%
50 ‐ 100°C 1kW – 250kW
Zinc Air Fuel Cells (ZAFCs) fuel impurities
distributed
problems
electric
• Low temperature
generation
• Low temperature
Biological Fuel Cells (BFCs) Proton Exchange Membrane Fuel Cell (PEMFC) waste heat
• Transportation
• Quick start‐up
DRAW and MESH MODE
MODELING PROCESS SUBDOMAIN MODE
The model uses current balances, mass balances (Maxwell‐Stefan diffusion for reactant, water and nitrogen
2D design is selected using
gas), and momentum balances (gas flow) to simulate a 2D PEM fuel cell’s behavior.
rectangular coordinates. After
Application Modes Module Dependent Variables Governing Equations
specifying geometry (1) mesh
As created in draw mode, three
COMSOL Conductive Media DC Solid Phase
Electromagnetics
mode (2) is applied to control
Multiphysics (Electrodes) Potential
subdomains (1, 2, 3) are defined as
the distribution of elements
anode, membrane, and cathode. In each
COMSOL Conductive Media DC Electrolyte
PEM MODELING
Electromagnetics
easily. A mesh is a partition of
Multiphysics (Membrane) Potential
Subdomain, material properties and
the geometry model into small
Chemical Momentum
boundaries are determined freely.
Darcy’s Law Pressure
Engineering Module balance
units of simple shapes. Dividing
Maxwell‐Stafen Diffusion
Chemical Mass Fraction of
current geometry into meshes
Mass balance and Convection
Engineering Module H2 and H2O
(Anode side) [Msa]
(small shapes) provides full
Maxwell‐Stafen Diffusion
( 1) ( 2)
Chemical Mass Fraction of
control of boundaries and easy‐
Mass balance and Convection
Engineering Module O2, H2O and N2
(Cathode side) [MSc]
solve problem.
PARAMETRIC INVESTIGATION
BOUNDARY MODE SOLVE and POST MODE
SOLVE MODE
Electrodes Membrane Darcy MSa MSc
COMSOL Multiphysics includes a set
Boundary Type Boundary Type Boundary Type Boundary Type Boundary Type
of solvers for PDE‐based problems
1‐7,9,14‐
EI 11,12 EI 1 P 1 MF 13 F
for linear and non‐linear equations.
16,18‐22
In post mode, given a solver/mesh
8 EP 10 ICF 4 P 4 CF 21 CF
pair, a variety of tools are available
10 ICF 13 ICF 10 I/O 10 F 22 MF
for data visualization. In PEM
13 ICF 13 I/O
Modeling, power generation,
Various parameters such as temperature , pressure,
efficiency, geometry and raw
17 EP 21 P
geometry/mesh, properties of used materials ( porosity,
material properties are analyzed .
22 P
conductivity etc.) is investigated to analyze the effects on
CF : Convective Flow EI : Electric Insulation EP : Electric Potential F : Flux
PEM fuel cell performance.
ICF : Inward Current Flow I/O : Inflow/Outflow MF : Mass Fraction P : Pressure
DESIGNING & BUILDING FUEL CELLS, Colleen S. Spiegel , McGraw Hill Book Co. , 2007 ‐ INTRODUCTION TO CHEMICAL ENGINEERING COMPUTING, Bruce A. Finlayson, John Wiley Inc., 2006 ‐ CONTROL OF FUEL CELL POWER SYSTEMS (Priciples, Modeling, Analysis
REFERENCES
and Feedback Design)”, Jay T. Pukrushpan, Anna G. Stefanopoulou, Huei Peng, Springer, 2005 ‐ PROCESS MODELıNG AND SıMULATıON WıTH FıNıTE ELEMENT METHODS, William B. J. Zimmerman, World Scientific Publishing Co., 2004 ‐ FUEL CELL HANDBOOK,
EG&G Technical Services, Inc., Seventh Edition, U.S. Department of Energy Office of Fossil Energy National Energy Technology Laboratory, November 2004 ‐ AN INTRODUCTION TO FUEL CELLS AND HYDROGEN TECHNOLOGY, Brian Cook, Heliocentris, December 2001