Table Of ContentENHANCING THE STEAM-REFORMING PROCESS WITH ACOUSTICS: AN
INVESTIGATION FOR FUEL CELL VEHICLE APPLICATIONS
By
PAUL ANDERS ERICKSON
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
2002
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UNIVERSITY OF FLORIDA
3 1262 08554 4335
Copyright 2002
by
Paul Anders Erickson
This dissertation is dedicated to my wife, Dena.
ACKNOWLEDGMENTS
Anyone with a semblance oftrue wisdom knows that one in and ofoneselfis a
very small thing. Such is the case with this study, as many people have contributed
directly or indirectly to this dissertation. I acknowledge the following individuals and
institutions who have extended themselves to give support to the present study.
I acknowledge the support, encouragement, and patience put forth by my advising
professor, Dr. Vernon P. Roan. Dr. Roan is truly a scholar and I am honored to have had
him as my mentor for the duration ofmy time at the University ofFlorida. Similarly, I
would like to thank my doctoral committee (Dr. Jean M. Andino, Dr. D.Yogi Goswami,
Dr. Ulrich H. Kurzweg and Dr. William E. Lear, Jr) for their support in this research
project and in my personal education.
I acknowledge the State ofFlorida, through the University ofFlorida and the
Mechanical Engineering Department for funding my education and allowing me to serve
as an instructor and teaching assistant. The research has been funded in part by Ford
Motor Company with their generous grant to the University ofFlorida Fuel Cell Research
and Training Laboratory for studies dealing with reformation ofhydrocarbon fuels.
I acknowledge the support and guidance I have received from my parents Lloyd
and Virginia Erickson and my siblings. Words cannot express my thanks to my wife
Dena, to whom I have dedicated this work, and my children Timothy, Eliani, and Kari.
They provide me with inspiration to fulfill my potential. My family has sacrificed much
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that I might pursue my education. Truly my family is the center ofmyjoy and happiness.
I also acknowledge support from my in-laws Fred and Jacque Wright as well as Les
Meinzer who provided computer hardware for the publication ofthe project. I
acknowledge my colleagues at the Fuel Cell Research and Training Laboratory, with
special mention ofTimothy Simmons, Daniel Betts. and Michael Heckwolfwho gave
much needed assistance with the project and encouragement at critical times.
No acknowledgment would be complete without thanking God for enlightenment,
wisdom, and vision to see me through this project. My sincere hope is that He will find
that I have used my knowledge, time and resources to help His children here on earth, and
that I will be found worthy ofHis approval through the Messiah. Despite any small
amount ofearthly knowledge I have obtained, I consider myselfa "Tool before God" and I
understand that eternal knowledge and wisdom is His to give to those who humbly and
diligently seek His will.
TABLE OF CONTENTS
page
ACKNOWLEDGMENTS
iv
LIST OF TABLES ix
LIST OF FIGURES xi
LIST OF SYMBOLS AND NOMENCLATURE xiv
ABSTRACT xv
CHAPTER
INTRODUCTION
1 1
Background
1
Fuel Cells 1
Vehicle Applications 4
Fueling Options 5
Reforming 8
Problem Definition 9
Research Objectives 10
LITERATURE REVIEW AND THEORETICAL APPROACH
2 12
Steam Reforming 12
Limiting Steps in the Reformation Process 13
Acoustics in Past Processes 18
Steam-Reforming in Combination with Acoustics 21
Increased Particle Path Length due to Acoustics 22
Increased Heat Transfer Rate due to Acoustics 25
Increased Overall Reaction Rate due to Acoustics 27
Extension ofCatalyst Life by Using Acoustics 29
Summary 30
Contribution 31
VI
3 EXPERIMENTAL APPROACH AND FACILITY 32
Experimental Approach 32
Experimental Facility 33
Pumping Subassembly 35
Vaporizer Subassembly 36
Reactor Subassembly 39
Catalyst bed 39
Acoustic components 41
Condensing Unit Subassembly 43
Instrumentation and Control Subassembly 44
Temperature control 45
Acoustic control 50
Analysis ofData 51
Gas Chromatography 52
Conversion 55
Space Velocity 56
Removal ofData Points 57
Procedures 57
Modeling the Acoustically Enhanced Reformation Process 57
Factorial Experiment Design 58
Further Data and Verification ofthe Model 60
4 PROPERTIES OF THE ACOUSTIC FIELD 62
The Use ofResonance within the Catalyst Bed 62
Transfer Functions 65
Modal Analysis 70
5 EMPIRICAL MODEL DEVELOPMENT AND ANALYSIS 73
Experimental Results and Model Correlation Factors 73
Uncertainty Analysis 76
Midpoint Curvature 78
Flow Rate 78
Sound Pressure 79
Catalyst Bed Length 80
The Effect ofFrequency 81
Summary 83
6 THE EFFECTS OF ACOUSTICS ON THE REFORMATION PROCESS 84
The Effect on Temperature Profile 84
The Effect on Conversion 88
The Effect on Controllability 92
vii
The Effect on Heat Band Power Draw 93
The Effect on Power Output 95
The Effect on Catalyst Degradation 98
Potential Benefits for a Fuel Cell Vehicle 100
7 CONCLUSIONS AND RECOMMENDATIONS 103
Conclusions 103
Recommendations 104
APPENDIX
A COMPUTER PROGRAMS 107
B CHECKLISTS AND PROCEDURES 123
C STATISTICAL DESIGN OF EXPERIMENTS 127
D EXPERIMENT RUN ORDERS 135
E TRANSFER FUNCTIONS 137
F TEMPERATURE PROFILES 147
REFERENCES 153
BIOGRAPHICAL SKETCH 158
vin
11
LIST OF TABLES
Table page
1. Types offuel cells and their operating parameters 3
1.2 Energy densities offuels (LHV) 7
3.1 Control setpoint matrix 48
3.2 Average and standard deviation for all catalyst bed temperatures utilizing a
250°C setpoint 49
3.3 Gas chromatograph calibration levels 54
3.4 Volume percent species ofthe dry product outlet gas 55
3.5 Factorial input matrix and run order 59
4.1 Waveforms and boundary conditions for a 33°C reactor containing only air .... 72
5. The input matrix and methanol conversion percentage data obtained from the
factorial experiments 74
5.2 Total average conversion, pooled standard deviation, standard error, and total
degrees offreedom from the factorial experiments 75
5.3 The effects and interactions found from the factorial experimentation 75
5.4 Signal-to-noise t-ratios and statistical significance 77
5.5 Static and kinematic Reynolds numbers and methanol conversion levels for
three frequencies 82
6.1 Extent ofconversion for catalyst bed length with and without acoustics 89
6.2 Average and standard deviation ofthe centerline temperatures with a setpoint
temperature of250°C at various locations both with and without a 165dB
acoustic field 93
IX
