Electrohydrodynamic transport in compressible nanoporous packed beds [Elektronische Ressource] / Bastian Schäfer

Bastian Meiresonne

Informations

• Publié par: karlsruher_institut_fur_technologie
• Publié le: 01 janvier 2010
• Nombre de lectures: 17
• Langue: English
• Poids de l'ouvrage: 10 Mo

Extrait

Electrohydrodynamic transport in
compressible nanoporous packed beds


zur Erlangung des akademischen Grades eines
DOKTORS DER INGENIEURWISSENSCHAFTEN (DR.#ING.)

der Fakultät für Chemieingenieurwesen und Verfahrenstechnik des
Karlsruher Instituts für Technologie (KIT)


genehmigte
DISSERTATION


von
Dipl.#Ing. Bastian Schäfer
aus Bad Neuenahr#Ahrweiler, Deutschland


Referent: Prof. Dr.#Ing. Hermann Nirschl
Korreferent: Prof. Dr.#Ing. Clemens Posten
Tag der mündlichen Prüfung: 19.02.2010
Acknowledgements
It was a pleasure for me to work with all the wonderful people at the Institute for
Mechanical Process Engineering and Mechanics in Karlsruhe. First, I would like to
thank my supervisor Prof. Hermann Nirschl for his scientific support, enthusiasm and
straightforwardness. He gave me the freedom to develop my own scientific objectives
and created the general framework for me so that I find my own way in the scientific
world. I would like to express my gratitude to Prof. Clemens Posten for doing the
second review of my thesis.
This work would not have been possible without the extensive support by my
colleagues in Prof. Nirschl’s team, the workshops, the laboratories and the administra#
tion. My colleagues supported me with great ideas and created a warm atmosphere,
making it a pleasure to work at the institute. I would like to show my special gratitude
to Friedhelm Flügel for the outstanding support in realizing new experimental setups
and solving unexpected experimental problems, even on Sunday evenings. I am
grateful to Harald Anlauf and Prof. Werner Stahl for their advice and to Franky
Ruslim for proofreading this thesis.
I would like to thank Martin Hecht and Jens Harting for their help in the numerical
part of this thesis. My student collaborators helped my to collect the experimental and
numerical data presented in this thesis. Thank you for the hard work.
I am grateful to the German Science Foundation (DFG) for financial support of my
work within the priority program “Nano# & Microfluidics” (SPP 1164).
I owe my deepest gratitude to my family for always backing me. And last but not least
I would like to thank my wife Bhawna for being my biggest fan and my greatest critic.


Düsseldorf, April 2010 Contents
1 Introduction ..........................................................................................................1
1.1 Physical background......................................................................................2
1.2 Approach.......................................................................................................3
1.3 Outline...........................................................................................................4
2 Fundamentals and state#of#the#art .......................................................................5
2.1 Origin and structure of the electrochemical double layer ...............................5
2.2 Stability of suspensions against agglomeration ..............................................8
2.3 Influence of agglomeration on the formation and pore structure of packed
beds. 11
2.4 Pore structure evaluation..............................................................................14
2.5 Electrohydrodynamic transport ....................................................................16
2.5.1 Pressure#driven flow.............................................................................17
2.5.2 Electroosmotic flow..............................................................................19
2.5.3 Streaming current .................................................................................22
2.5.4 Electric conduction...............................................................................22
2.5.5 Streaming potential...............................................................................24
2.5.6 Electroviscous flow retardation ............................................................24
2.6 Simulation methods for colloidal systems....................................................25
2.6.1 Phenomenological models ....................................................................25
2.6.2 Finite volume method...........................................................................26
2.6.3 Finite differences method .....................................................................26
2.6.4 Molecular dynamics .............................................................................27
2.6.5 Monte Carlo simulations.......................................................................27
2.6.6 Stokesian dynamics ..............................................................................28
2.6.7 Brownian dynamics ..............................................................................28
2.6.8 Dissipative particle dynamics ...............................................................28
2.6.9 Stochastic rotation dynamics ................................................................29
2.6.10 Lattice gas automata .............................................................................29
2.6.11 Lattice Boltzmann method....................................................................30
3 Experiments........................................................................................................31
3.1 Experimental apparatuses ............................................................................31
3.1.1 Electro#compression#permeability cell.................................................31
3.1.2 Nutsche filter........................................................................................35
3.1.3 AcoustoSizer II for measuring the zeta potential...................................35
3.1.4 Nanotrac for agglomerate size measurement.........................................36
3.1.5 Photometer ...........................................................................................38
3.2 Materials......................................................................................................38
3.2.1 Particles................................................................................................38
3.2.2 Electrolyte solutions .............................................................................42
3.2.3 Preparation of the suspensions..............................................................42
3.2.4 Membranes...........................................................................................43
3.3 Results.........................................................................................................45
3.3.1 Dissolution of boehmite in aqueous suspensions...................................45
3.3.2 Zeta potential of the particles................................................................46
3.3.3 Agglomeration of suspensions ..............................................................48
3.3.4 Filtration behavior and membrane resistance ........................................48
3.3.5 Porosity ................................................................................................52
3.3.6 Pressure#driven flow............................................................................55
3.3.7 Electric conduction...............................................................................59 3.3.8 Capillary model ....................................................................................63
3.3.9 Electroosmotic flow..............................................................................68
3.3.10 Streaming current .................................................................................71
3.3.11 Streaming potential...............................................................................71
3.3.12 Electroviscous flow retardation ............................................................74
3.3.13 Influence of the membranes on the electrohydrodynamic transport.......76
3.4 Conclusions .................................................................................................77
4 Simulation ..........................................................................................................81
4.1 Choice of the simulation methods ................................................................81
4.2 Simulation domain and boundary conditions ...............................................83
4.2.1 Molecular dynamics simulation of the solid particles............................84
4.2.2 Stochastic rotation dynamics simulation of the fluid.............................87
4.2.3 Coupling of the solid and fluid simulations...........................................89
4.2.4 Scaling of the physical parameters........................................................90
4.2.5 Lattice Boltzmann simulation of the permeation...................................94
4.3 Validation of the simulation.........................................................................97
4.4 Results.......................................................................................................101
4.4.1 Agglomeration of colloidal particles...................................................101
4.4.2 Structure of the packed beds ........................................................