This document describes a diploma project modeling a proton exchange membrane fuel cell (PEMFC) using COMSOL Multiphysics. It presents a two-dimensional, non-isothermal model of the porous cathode-anode gas diffusion layer. The model accounts for single-component species diffusion but not liquid water transport. Tables provide reactions on fuel cell electrodes and parameters used in the COMSOL model. The effect of changing operating conditions like humidity is explored. It is found that humidity has a major impact on electrical potential and current density across the electrodes.

1. T. R.
EGE UNIVERSITY
FACULTY OF ENGINEERING
DEPARTMENT OF CHEMICAL ENGINEERING
DIPLOMA PROJECT
PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC)
MODELING AND SIMULATION
USING COMSOL MULTIPHYSICS
Prepared by
01‐4340 Ercüment SÖNMEZ
02‐5079 Coşkun TOPRAK
Supervisor
Prof. Dr. Mustafa DEMİRCİOĞLU
Bornova, İZMİR
June, 2008

2.
TABLE of CONTENTS
List of Tables i
Abstract ii
Acknowledgement ii
1‐ INTRODUCTION TO FUEL CELL ____________________________________________________ 3
2‐ WHAT IS A FUEL CELL? __________________________________________________________ 4
3‐ HISTORY OF FUEL CELL __________________________________________________________ 7
4‐ TYPES OF FUEL CELL ____________________________________________________________ 8
5‐ FUEL CELL APPLICATIONS _______________________________________________________ 17
6‐ ADVANTAGES AND DISADVANTAGES OF FUEL CELL __________________________________ 19
7‐ PROTON EXCHANGE MEMBRANE FUEL CELLS (PEMFC) _______________________________ 20
8‐ MODELING OF PEMFC _________________________________________________________ 22
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9‐ INTRODUCTION TO COMSOL MULTIPHYSICS _______________________________________ 28
10‐ COMSOL MULTIPHYSICS TAKEN MODULES (PEM FC MODELING) _______________________ 42
11‐ COMSOL GRAPHICAL RESULTS ___________________________________________________ 43
12‐ NUMERICAL PROCEDURE _______________________________________________________ 50
13‐ MODELING PEM FC USING COMSOL MULTIPHYSICS STEP BY STEP ______________________ 51
14‐ DISCUSSION AND RECOMMENDATIONS ___________________________________________ 61
15‐ NOMENCLATURE _____________________________________________________________ 62
16‐ R E F E R E N C E S _____________________________________________________________ 64
PEM FC Modeling and Simulation Using Comsol Multiphysics

3.
LIST of TABLES
TABLE 4‐1 REACTIONS ON ELECTRODES 8
TABLE 4‐2 REACTIONS ON (PAFC) ELECTRODES 10
TABLE 4‐3 REACTIONS ON (MCFC) ELECTRODES 12
TABLE 4‐4 REACTIONS ON (SOFC) ELECTRODES 13
TABLE 4‐5 REACTIONS ON (DMFC) ELECTORDES 14
TABLE 4‐6 REACTIONS ON (ZAFC) ELECTRODES 16
TABLE 7‐2 REACTIONS ON (PEMFC) ELECTRODES 20
TABLE 9‐1 SUPPORTED FILE FORMATS BY COMSOL PRODUCTS 34
TABLE 10‐1 COMSOL MODULES USED IN THE PROJECT 42
TABLE 13‐1 GEOMETRY MODELING 51
TABLE 13‐2 CONSTANTS 52
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i
TABLE 13‐3 SCALAR EXPRESSIONS 53
TABLE 13‐4 SUBDOMAIN EXPRESSIONS 54
TABLE 13‐5 BOUNDARY EXPRESSIONS 54
TABLE 13‐6 BOUNDARY CONDITIONS ELECTRODES 55
TABLE 13‐7 BOUNDARY CONDITIONS MEMBRANE 55
TABLE 13‐8 SUBDOMAIN SETTINGS DARCY 56
TABLE 13‐9 BOUNDARY CONDITIONS DARCY 56
TABLE 13‐10 SUBDOMAIN SETTINGS MSA 57
TABLE 13‐11 BOUNDARY SETTINGS MSA 57
TABLE 13‐12 SUBDOMAIN SETTINGS MSC 58
TABLE 13‐13 BOUNDARY SETTINGS MSC 58
PEM FC Modeling and Simulation Using Comsol Multiphysics

4.
Abstract
Fuel cell power generation systems provide a clean alternative to the conventional
fossil fuel based systems. Fuel cell systems have a high efficiency and use easily available
hydrocarbons like methane. Moreover, since the by‐product is water, they have a very low
environmental impact. The fuel cell system consists of several subsystems requiring a lot of
effort from engineers in diverse areas.
This thesis proposes a two‐dimensional, non‐isothermal, single‐phase flow model of a
porous cathode‐anode gas diffusion layer of a polymer electrolyte‐ membrane fuel cell is to
be presented and solved numerically using computational fluid dynamics coding and
sequentially solver scripting with the help of COMSOL Multiphysics. The model accounts for
single‐component species diffusion. Phase change and transport of water are not
accounted for in terms of liquid phase water saturation level due to not including heat
balances in this project.
COMSOL provides an inexpensive and accurate representation of a PEM FC under
steady state and transient conditions
The effect of changing physical parameters and operating conditions is explored. It is
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found that the main parameter “humidity level” in the inlet hydrogen gas has a major effect ii
on the electrical potential and total current density over the surface of electrodes.
ACKNOWLEDGEMENT
We are very grateful to our advisor and mentor Prof.Dr. Mustafa DEMİRCİOĞLU, who
patiently guided us during our research work and provided invaluable technical inputs.
PEM FC Modeling and Simulation Using Comsol Multiphysics