Icing on materials surface causes operational failures as well as technical and safety issues. Furthermore, it reduces the energy efficiency of the power supply and passenger/freight transportation systems. Conventional active deicing methods are widely used to remove ice, but are often associated with uneconomically high energy consumption and high maintenance costs, often not being aware of their environmental impact. Instead, passive anti-icing methods are being sought to prevent or delay ice formation by means of physico-chemical surface treatment. Pyroelectric materials can be used as possible anti-icing surfaces after their ability to inhibit ice nucleation has been experimentally demonstrated. This makes use of the effect of the pyroelectrically induced surface charge, which changes with the ambient temperature and thus, hypothetically, exerts an influence on the dipole orientation of the water molecules at the surface. This is expected to affect the hydrogen bonding network of the interfacial water in the supercooled liquid phase, depending on the sign of surface charge. However, the Classical Nucleation Theory predicts an increased nucleation rate with increasing electric field strength of the pyroelectric surface charge irrespective of its polarity, as confirmed by many experiments. This raises the question of what exactly influences the ice nucleation. The main purpose of this thesis is to find a relationship between the pyroelectricity and the ice nucleation rate. Various theoretical and experimental investigation methods have been used to examine which of the possible influencing factors related to the pyroelectric material surface plays a major role in promoting or inhibiting ice nucleation.:Contents
Abstract i
List of figures xi
List of tables xv
1 Introduction 1
1.1 Motivation 1
1.2 Objective and Tasks 4
1.3 Structure of the thesis 6
2 Basics 7
2.1 Pyroelectric materials 7
2.1.1 Fundamental properties 7
2.1.2 Lithium niobate, LiNbO3 14
2.2 Ice nucleation and water freezing 21
2.2.1 Thermodynamics of ice nucleation 21
2.2.2 Factors influencing ice nucleation 26
3 Materials and Methods 29
3.1 Sample materials used for the investigation 29
3.2 Theoretical methods 31
3.2.1 Theoretical background of computational quantum mechanical modeling 31
3.2.2 LiNbO3 model system 38
3.2.3 DFT implementation in CP2K 41
3.3 Experimental methods 42
3.3.1 Optical and vibrational spectroscopy 43
3.3.2 X-ray spectroscopy 47
3.3.3 Atomic force microscopy 48
3.3.4 Environmental scanning electron spectroscopy 51
3.3.5 Pyroelectric measurement 52
3.3.6 Contact angle measurement 53
3.3.7 Icing temperature measurement 54
3.4 Tabular overview of the different methods 57
ix4 Results and Discussion 59
4.1 Results 59
4.1.1 Several results of DFT calculations 59
4.1.2 MD simulations of interfacial water 75
4.1.3 Results of optical and vibrational spectroscopy 80
4.1.4 X-ray spectroscopy on LiNbO3 surfaces 96
4.1.5 Extended treatment of the Classical Nucleation Theory 100
4.1.6 Results of atomic force microscopy 108
4.1.7 ESEM images of ice crystals grown on LiNbO3 116
4.1.8 Results of pyroelectric measurements 122
4.1.9 Results of contact angle measurements 124
4.1.10 Results of icing temperature measurements 126
4.2 Discussion 135
4.2.1 Surface charge 135
4.2.2 Surface structure 144
4.2.3 Surface reactivity 149
4.3 Conclusion of the findings and remarks 151
5 Summary and Outlook 157
5.1 Conclusion of the thesis 157
5.2 Recommendations for further investigations 161
5.3 Outlook 164
Appendix 167
A.1 Additional information to the DFT calculations 167
A.2 Background spectrum for ATR spectroscopy 175
A.3 Additional information to SFG/SHG spectroscopy 176
A.4 Additional information to the XPS results 181
A.5 Additional information to the AFM measurement 182
A.6 ESEM images of ice accretion in the sample system 187
A.7 FEM simulation of local temperature and flow velocity distribution 190
A.8 Additional information to the icing temperature measurement 203
A.9 Temperature-dependent pH variation of water at LiNbO3 surface 207
List of abbreviations and symbols 213
References 217
Publications 276
Acknowledgements 277
Erklärung 281 / Vereisung auf Werkstoffoberflächen führt einerseits zu Betriebsausfällen und andererseits zur Reduzierung der Energieeffizienz von Energieversorgungs- sowie Personen- und Gütertransportsystemen. Sie stellt nicht selten ein sicherheitstechnisches und gesundheitliches Risiko dar. Da die konventionellen aktiven Enteisungsmethoden mit hohem Energieaufwand und hohen Wartungskosten verbunden sind, wird nach passiven Anti-icing-Methoden als vorbeugende Maßnahmen zur Vermeidung/Verzögerung von Eisbildung auf physikalisch-chemisch behandelten Oberflächen gesucht. Der Einsatz dieser Werkstoffoberflächen senkt nicht nur den Energieverbrauch, sondern soll auch die Umwelt schonen. Pyroelektrische Materialien kommen als passive Anti-icing-Oberflächen in Frage, nachdem ihre eiskeimbildungshemmende Fähigkeit experimentell nachgewiesen wurde. Dabei wird der Effekt der pyroelektrisch induzierten Oberflächenladung ausgenutzt, die sich mit der Umgebungstemperatur ändert und somit, hypothetisch gesehen, einen Einfluss auf die Dipolorientierung der Wassermoleküle an der Oberfläche ausübt. Das hat je nach Vorzeichen der Oberflächenladung Auswirkungen auf das Wassermolekülbindungsnetzwerk des Grenzflächenwassers in der unterkühlten flüssigen Phase. Da die klassische Keimbildungstheorie jedoch eine erhöhte Keimbildungswahrscheinlichkeit mit zunehmender Stärke des elektrischen Feldes der pyroelektrischen Oberflächenladung unabhängig von ihrem Vorzeichen voraussagt, wie es ebenfalls in vielen Experimenten nachgewiesen wurde, stellt sich die Frage, was genau die Eiskeimbildung beeinflusst. Das Hauptanliegen dieser Arbeit ist, einen Zusammenhang zwischen der Pyroelektrizität der Oberfläche und der Eiskeimbildungsrate zu finden. Mithilfe einer Vielzahl von verschiedenen theoretischen und experimentellen Methoden wird untersucht, welcher der möglichen Einflussfaktoren im Zusammenhang mit der pyroelektrischen Materialoberfläche eine große Rolle bei der Eiskeimbildung spielt.:Contents
Abstract i
List of figures xi
List of tables xv
1 Introduction 1
1.1 Motivation 1
1.2 Objective and Tasks 4
1.3 Structure of the thesis 6
2 Basics 7
2.1 Pyroelectric materials 7
2.1.1 Fundamental properties 7
2.1.2 Lithium niobate, LiNbO3 14
2.2 Ice nucleation and water freezing 21
2.2.1 Thermodynamics of ice nucleation 21
2.2.2 Factors influencing ice nucleation 26
3 Materials and Methods 29
3.1 Sample materials used for the investigation 29
3.2 Theoretical methods 31
3.2.1 Theoretical background of computational quantum mechanical modeling 31
3.2.2 LiNbO3 model system 38
3.2.3 DFT implementation in CP2K 41
3.3 Experimental methods 42
3.3.1 Optical and vibrational spectroscopy 43
3.3.2 X-ray spectroscopy 47
3.3.3 Atomic force microscopy 48
3.3.4 Environmental scanning electron spectroscopy 51
3.3.5 Pyroelectric measurement 52
3.3.6 Contact angle measurement 53
3.3.7 Icing temperature measurement 54
3.4 Tabular overview of the different methods 57
ix4 Results and Discussion 59
4.1 Results 59
4.1.1 Several results of DFT calculations 59
4.1.2 MD simulations of interfacial water 75
4.1.3 Results of optical and vibrational spectroscopy 80
4.1.4 X-ray spectroscopy on LiNbO3 surfaces 96
4.1.5 Extended treatment of the Classical Nucleation Theory 100
4.1.6 Results of atomic force microscopy 108
4.1.7 ESEM images of ice crystals grown on LiNbO3 116
4.1.8 Results of pyroelectric measurements 122
4.1.9 Results of contact angle measurements 124
4.1.10 Results of icing temperature measurements 126
4.2 Discussion 135
4.2.1 Surface charge 135
4.2.2 Surface structure 144
4.2.3 Surface reactivity 149
4.3 Conclusion of the findings and remarks 151
5 Summary and Outlook 157
5.1 Conclusion of the thesis 157
5.2 Recommendations for further investigations 161
5.3 Outlook 164
Appendix 167
A.1 Additional information to the DFT calculations 167
A.2 Background spectrum for ATR spectroscopy 175
A.3 Additional information to SFG/SHG spectroscopy 176
A.4 Additional information to the XPS results 181
A.5 Additional information to the AFM measurement 182
A.6 ESEM images of ice accretion in the sample system 187
A.7 FEM simulation of local temperature and flow velocity distribution 190
A.8 Additional information to the icing temperature measurement 203
A.9 Temperature-dependent pH variation of water at LiNbO3 surface 207
List of abbreviations and symbols 213
References 217
Publications 276
Acknowledgements 277
Erklärung 281
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:74198 |
| Date | 18 March 2021 |
| Creators | Goldberg, Phil |
| Contributors | Cuniberti, Gianaurelio, Meyer, Dirk C., Wiesmann, Hans-Peter, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | info:eu-repo/grantAgreement/Sächsische Aufbaubank, Sächsische Ministerium für Wissenschaft und Kunst/ESF-Innovationspromotion/100284305//RL ESF Hochschule und Forschung 2014 bis 2020 |
Page generated in 0.0033 seconds