This dissertation investigates the effect of electromagnetic braking and gas injection on the fluid flow in a continuous casting slab mold numerically and makes verifications on basis of a small Liquid Metal Model for Continuous Casting of steel (mini-LIMMCAST). Numerical calculations were performed by means of the software package CFX with an implemented RANS-SST turbulence model. The non-isotropic nature of the MHD turbulence was taken into account by specific modifications of the turbulence model. The numerical results were validated by flow measurements at the mini-LIMMCAST facility. Numerical simulations disclose the damping effect on the flow closely depending on the wall conductance ratio. In addition, specific modifications of the turbulence model play a crucial role in reconstructing the peculiar phenomenon of an excitation of nonsteady, nonisotropic, large-scale flow perturbations caused by the application of the DC magnetic field.

Stahl wird heutzutage fast ausschließlich im kontinuierlichen Stranggussprozess zu Halbzeugen verschiedener Geometrien verarbeitet. Flüssiger Stahl wird dabei über ein Tauchrohr in eine wassergekühlte, nach unten offene Kokille gefüllt und erstarrt an deren Wänden. Der innen noch flüssige Strang wird kontinuierlich nach unten aus der Kokille abgezogen und ist erst nach mehreren Metern komplett erstarrt. Die Qualität des Halbzeugs wird vorwiegend durch die Strömung in der Kokille beeinflusst. In der Industrie werden seit langer Zeit verschiedene elektromagnetische Aktuatoren eingesetzt, um die Strömungsstruktur in der Kokille mithilfe von Lorentzkräften zu beeinflussen. Bedingt durch die hohe Temperatur des flüssigen Stahls und dessen Undurchsichtigkeit lässt sich die Strömungsstruktur im realen Prozess jedoch kaum untersuchen. Zur Optimierung sowie zum besseren Verständnis der Vorgänge in der Kokille sind daher numerische Simulationen und Modellexperimente notwendig. In dieser Arbeit werden die Ergebnisse experimenteller Untersuchungen zum kontinuierlichen Stranggießen von Stahl unter dem Einfluss verschiedener elektromagnetischer Aktuatoren präsentiert. Die Experimente wurden an der Mini-LIMMCAST-Anlage des Helmholtz-Zentrum Dresden-Rossendorf (HZDR) durchgeführt. Mini-LIMMCAST ist ein Modell einer Strangguss-Anlage, welches isotherm mit der bei Raumtemperatur flüssigen Metalllegierung GaInSn betrieben wird. Durch die Verwendung von flüssigem Metall als Modellfluid können die Auswirkungen elektromagnetischer Aktuatoren untersucht werden, jedoch kann aufgrund der Undurchsichtigkeit des Modellfluids die Geschwindigkeitsverteilung in der Kokille nicht mittels optischer Verfahren erfasst werden. Daher wird zur Messung der Geschwindigkeitsverteilung in der Kokille die Ultraschall-Doppler-Velocimetrie eingesetzt. Die Ergebnisse von Messungen an zwei verschiedenen Kokillen-Geometrien werden vorgestellt: zum Einen solche an einer zylindrischen Kokille, bei welcher auf verschiedene Arten eine Drehströmung erzeugt wurde. Dies erfolgte durch elektromagnetisches Rühren in der Kokille sowie durch ein Tauchrohr mit spiralförmigen Auslässen. Zum Anderen wird eine Kokille mit rechteckigem Querschnitt, wie sie in Brammen-Anlagen verwendet wird, betrachtet. In dieser wird die Strömung sowohl durch ein statisches Magnetfeld, einer sogenannten elektromagnetischen Bremse, als auch durch elektromagnetische Wechselfelder beeinflusst. Die Ergebnisse dieser Arbeit zeigen eine Reihe zuvor nicht beschriebener Phänomene, wie das zeitliche Verhalten des Jets in der Rundkokille mit elektromagnetischem Rührer oder den Mechanismus der in der Brammen-Geometrie mit elektromagnetischer Bremse für eine Veränderung der Geschwindigkeit an der freien Oberfläche der Kokille sorgt. Umfassende experimentelle Parameterstudien erlauben detaillierte Einblicke in die beim Stranggießen auftretenden Strömungsstrukturen, wie sie mit numerischen Simulationsmodellen nur unter einem immensen Einsatz von Rechenleistung zu erzielen wären. / Today, steel is almost exclusively processed into semi-finished products of various geometries by the continuous casting process. Liquid steel is filled through a submerged entry nozzle into a water-cooled, downwardly open mould and solidifies on its walls. The strand, which is still liquid on the inside, is continuously drawn downwards out of the mould and is then completely solidified after several metres. The quality of the semi-finished product is mainly influenced by the flow in the mould. For many years, various electromagnetic actuators have been used in industry to influence the flow structure in the mould by the application of Lorentz forces. Due to the high temperature of the liquid steel and its opacity, however, the flow structure can hardly be investigated in the real process. Therefore, numerical simulations and model experiments are necessary to optimise and better understand the processes in the mould. In this dissertation the results of experimental investigations on continuous casting of steel under the influence of different electromagnetic actuators are presented. The experiments were performed at the Mini-LIMMCAST facility of the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Mini-LIMMCAST is a model of a continuous casting machine which is operated isothermally with the metal alloy GaInSn, which is liquid at room temperature. By using liquid metal as model fluid, the effects of electromagnetic actuators can be investigated, but due to the opacity of the model fluid, the velocity distribution in the mould cannot be determined by optical methods. Therefore, ultrasonic Doppler velocimetry is used to measure the velocity distribution in the mould. The results of measurements using two different mould geometries are presented. One is a cylindrical mould in which a rotational flow was generated in different ways. This was achieved by electromagnetic stirring in the mould and by an submerged entry nozzle with spiral-shaped outlets. On the other hand, a mould with a rectangular cross-section, as used for slab casting, is considered. Here the flow is influenced by a static magnetic field, a so-called electromagnetic brake, as well as by alternating electromagnetic fields. The results of this work show a number of previously undescribed phenomena, such as the temporal behaviour of the jet in the round mould with an electromagnetic stirrer or the mechanism that causes a change in the speed at the free surface of the mould in the slab geometry with an electromagnetic brake. Comprehensive experimental parameter studies allow detailed insights into the flow structures occurring during continuous casting, which could only be achieved with numerical simulation models with an immense input of computing power.

Die vorliegende Arbeit beschäftigt sich mit DC/DC-Wandlern zur Einbindung von Doppelschichtkondensatoren in das Fahrzeugenergiebordnetz. Zunächst werden die Anforderungen an derartige DC/DC-Wandler anhand dreier entsprechender Beispielanwendungen zusammengestellt und verglichen. Für die Anwendung zur Entkopplung transienter Hochleistungsverbraucher, wie beispielsweise eine elektrische Lenkung, wird ein DC/DC-Wandler-Konzept entwickelt. Es findet ein Vergleich von drei geeigneten Topologien mittels einer hierfür erarbeiteten Methode statt, mit dem Ziel die beste Lösung für den betrachteten Anwendungsfall zu ermitteln. Um adäquate Kritierien für die Wahl der Schaltfrequenz und der Induktivitäten von Speicherdrosseln aufzustellen, erfolgt eine Untersuchung des Einflusses des Drosselstromwechselanteils auf das Schaltverhalten der MOSFETs sowie auf bestimmte Bereiche der EMV-Störemissionen. Als Methoden zur Optimierung des Synchrongleichrichterbetriebs werden das Parallelschalten von Schottky-Dioden und Synchrongleichrichtern sowie die Variation der Ausschalttotzeiten von Synchrongleichrichtern untersucht. Weiterhin wird unter Berücksichtigung der Besonderheiten der Anwendung und Topologie ein Konzept für die Regelung des Wandlers entwickelt. Abschließend findet eine Vorstellung ausgewählter Aspekte zur Umsetzung des DC/DC-Wandler-Konzepts sowie der Ergebnisse experimenteller Untersuchungen statt.

Purpose: Previous clinical studies have suggested a positive effect of low-frequency pulsed electromagnetic fields (PEMF) on wound healing and inflammation in the eye. We tried to test the value of PEMF treatment in a hyphema animal model with well-defined conditions. Methods: After injection of citrated autologous blood for the production of hyphema, 16 rabbit eyes were treated with 10 or 20 mT for 60 min on 4 days within the postoperative week. Two control groups with hyphema alone (n = 8) and PEMF irradiation without hyphema (n = 4) were also included. The rate of resorption was recorded daily. Histopathologic evaluation was performed. Results: The incidence of endothelial cell damage and fibrotic clots was markedly reduced in the 10-mT group while the resorption time of 8 days was identical with the control group. In the 20-mT group, the complication rate and the resorption time was increased versus the control group. Conclusions: The use of PEMF treatment is of some, however, limited value as it did not reduce the resorption time of hyphema but displayed a dose-dependent, beneficial influence on some serious side effects. Future clinical studies with low-dose PEMF irradiation are justified and should determine the optimal dosage and suitable indications of PEMFs as an adjunctive treatment in ocular inflammation or trauma. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

This dissertation aims at designing a three-phase voltage source inverter based on the SiC devices and mainly the SiC-MOSFET. The designed inverter offers a possibility to drive the power inverter with a very high efficiency, which can reach up to 99% for 16 kW rated power. The design is dedicated to the electric vehicle application, and it aims at • Providing a comparative study on some of the current discrete SiC devices in terms of the total losses and the thermal conductivity. In addition, a behavioral study of the effective channel mobility with temperature variation in the SiC MOSFET will be investigated. • Designing a gate driver which fits with the driving requirements of the SiC-MOSFET and provides a trade-off between the switching losses and the EMI behavior. • Designing a three-phase voltage source inverter with 16 kW rated power; the design includes minimizing the inverter losses and extracts the EMI model of the power inverter by considering the effects of the parasitic parameters; moreover a short guideline for selecting the heat-sink based on the static network is introduced. • Proposing a new and simplified carried-based PWM, this will reduce the harmonics in the output waveforms and enhance the utilization of the DC-link voltage. • Proposing a new strategy for compensating the dead-time effect in carrier based-PWM and to find out the proper dead-time level in VSI based on SiC –MOSFET. • Designing faults diagnosis and protection circuits in order to protect the power inverter from the common faults; overcurrent, short-circuit, overvoltage, and overtemperature faults.

Folien aus mehrwandigen Kohlenstoffnanoröhren, auch Buckypaper genannt, stellen eine vielversprechende Alternative zu herkömmlichen Schirmmaterialien für elektromagnetische Strahlung dar. Zum Aufbau eines grundlegenden Verständnisses und zur Verbesserung der Verarbeitbarkeit gegenüber kommerziell erhältlichem Buckypaper, wurden nach Auswahl eines geeigneten Herstellungsverfahrens Buckypaper aus unterschiedlichen Nanomaterialien hergestellt. Zur Untersuchung der Auswirkung ausgewählter Herstellungsparameter erfolgte dabei eine Parametervariation mittels statistischer Versuchsplanung. Zusätzlich wurden im Vorfeld weitere Einflussfaktoren betrachtet. Dadurch konnten unterschiedliche Einwaagemengen und Rohmaterialien, verschiedene Lösungsmittel und Konzentrationen der Nanomaterialien sowie diverse Prozessparameter des angewandten Nassprozesses untersucht werden. Im Rahmen der Charakterisierung der hergestellten Proben, mittels unter anderem Vierleiter- und Schirmdämpfungsmessung sowie Rasterelektronenmikroskopie, wurden die signifikanten Einflüsse der untersuchten Parameter identifiziert und beschrieben. Es konnten dadurch sehr homogene Buckypaper mit hoher Leitfähigkeit und guter Schirmungseffektivität hergestellt werden, die eine verbesserte Grundlage für die weitere Entwicklung mikrostrukturierter Schutzfolien bilden. Aus dem Ergebnis der Arbeit lassen sich optimale Herstellungsparameter von Buckypaper für den Einsatz als Schirmmaterial im Bereich der elektromagnetischen Verträglichkeit ermitteln. / Freestanding multiwalled carbon nanotube sheets, also known as buckypaper, represent a promising alternative for various applications, especially for electromagnetic interference shielding. In order to develop a fundamental understanding and improve the processability compared to commercially available buckypaper, sheets from different nanotube materials were produced after a suitable manufacturing process had been selected. Design of experiments was used to investigate the effects of various manufacturing parameters. Other influencing factors were considered in advance. Several raw materials of different weights, varying solvents and concentrations of the nanomaterials as well as various processing parameters of the applied wet process were thereby examined. Significant influences on the properties of produced buckypaper were identified during characterization by, among other means, four-point probe, shielding attenuation measurements and scanning electron microscopy. From the result, optimal manufacturing parameters can be determined. Thus, very homogeneous buckypaper with high electrical conductivity as well as good mechanical strength and shielding effectiveness could be produced. This provides a solid foundation for further development of frequency selective electromagnetic interference shields.

Geophysical methods are essential for exploration and monitoring of subsurface formations, e.g. in carbon dioxide sequestration or enhanced geothermal energy. One of the keys to their successful application is the knowledge of how the measured physical quantities are related to the desired reservoir parameters. The work presented in this thesis shows that the presence of carbon dioxide (CO2) in pore space gives rise to multiple processes all of which contribute to the electrical rock conductivity variation. Basically, three mechanisms take place: (1) CO2 partially replaces the pore water, which is equivalent to a decrease in water saturation. (2) CO2 chemically interacts with the pore water by dissolution and dissociation. These processes change both the chemical composition and the pH of the pore filling fluid. (3) The low-pH environment can give rise to mineral dissolution and/or precipitation processes and changes the properties of the grain-water interface. Investigations on the pore water phase show that the reactive nature of CO2 in all physical states significantly acts on the electrical conductivity of saline pore waters. The physico-chemical interaction appears in different manifestations depending mainly on the pore water composition (salinity, ion types) but also on both temperature and pressure. The complex behaviour includes a low- and a high-salinity regime originating from the conductivity increasing effect of CO2 dissociation, which is opposed by the conductivity decreasing effect of reduced ion activity caused by the enhanced mutual impediment of all solutes. These results are fundamental since the properties of the water phase significantly act on all conduction mechanisms in porous media. In order to predict the variation of pore water conductivity, both a semi-analytical formulation and an empirical relationship for correcting the pore water conductivity, which depends on salinity, pressure and temperature, are derived. The central part of the laboratory experiments covers the spectral complex conductivity of water-bearing sand during exposure to and flow-through by CO2 at pressures up to 30MPa and temperatures up to 80°C. It is shown that the impact of CO2 on the real part of conductivity of a clean quartz sand is dominated by the low- and high-salinity regime of the pore water. The obtained data further show that chemical interaction causes a reduction of interface conductivity, which could be related to the low pH in the acidic environment. This effect is described by a correction term, which is a constant value as a first approximation. When the impact of CO2 is taken into account, a correct reconstruction of fluid saturation from electrical measurements is possible. In addition, changes of the inner surface area, which are related to mineral dissolution or precipitation processes, can be quantified. Both the knowledge gained from the laboratory experiments and a new workflow for the description and incorporation of geological geometry models enable realistic finite element simulations. Those were conducted for three different electromagnetic methods applied in the geological scenario of a fictitious carbon dioxide sequestration site. The results show that electromagnetic methods can play an important role in monitoring CO2 sequestration. Compared to other geophysical methods, electromagnetic techniques are generally very sensitive to pore fluids. The proper configuration of sources and receivers for a suitable electromagnetic method that generates the appropriate current systems is essential. Its reactive nature causes CO2 to interact with a water-bearing porous rock in a much more complex manner than non-reactive gases. Without knowledge of the specific interactions between CO2 and rock, a determination of saturation and, consequently, a successful monitoring are possible only to a limited extend. The presented work provides fundamental laboratory investigations for the understanding of the electrical properties of rocks when the reactive gas CO2 enters the rock-water system. All laboratory results are put in the context of potential monitoring applications. The transfer from petrophysical investigations to the planning of an operational monitoring design by means of close-to-reality 3D FE simulations is accomplished.

In an effort to improve the accuracy of common 1-D analysis for frequency domain helicopter-borne electromagnetic data at reasonable computing costs, a 3-D inversion approach is developed. The strategy is based on the prior localization of an entire helicopter-borne electromagnetic survey to parts which are actually affected by expected local 3-D anomalies and a separate inversion of those sections of the surveys (cut-&-paste strategy). The discrete forward problem, adapted from the complete Helmholtz equation, is formulated in terms of the secondary electric field employing the finite difference method. The analytical primary field calculation incorporates an interpolation strategy that allows to effectively handle the enormous number of transmitters. For solving the inverse problem, a straightforward Gauss-Newton method and a Tikhonov-type regularization scheme are applied. In addition, different strategies for the restriction of the domain where the inverse problem is solved are used as an implicit regularization. The derived linear least squares problem is solved with Krylov-subspace methods, such as the LSQR algorithm, that are able to deal with the inherent ill-conditioning. As the helicopter-borne electromagnetic problem is characterized by a unique transmitter-receiver relation, an explicit representation of the Jacobian matrix is used. It is shown that this ansatz is the crucial component of the 3-D HEM inversion. Furthermore, a tensor-based formulation is introduced that provides a fast update of the linear system of the forward problem and an effective handling of the sensitivity related algebraic quantities. Based on a synthetic data set of a predefined model problem, different application examples are used to demonstrate the principal functionality of the presented algorithm. Finally, the algorithm is applied to a data set obtained from a real field survey in the Northern German Lowlands. / Die vorliegende Arbeit beschäftigt sich mit der 3-D Inversion von Hubschrauberelektromagnetikdaten im Frequenzbereich. Das vorgestellte Verfahren basiert auf einer vorhergehenden Eingrenzung des Messgebiets auf diejenigen Bereiche, in denen tatsächliche 3-D Strukturen im Untergrund vermutet werden. Die Resultate der 3-D Inversion dieser Teilbereiche können im Anschluss wieder in die Ergebnisse der Auswertung des komplementären Gesamtdatensatzes integriert werden, welche auf herkömmlichen 1-D Verfahren beruht (sog. Cut-&-Paste-Strategie). Die Diskretisierung des Vorwärtsproblems, abgeleitet von einer Sekundärfeldformulierung der vollständigen Helmholtzgleichung, erfolgt mithilfe der Methode der Finiten Differenzen. Zur analytischen Berechnung der zugehörigen Primärfelder wird ein Interpolationsansatz verwendet, welcher den Umgang mit der enorm hohen Anzahl an Quellen ermöglicht. Die Lösung des inversen Problems basiert auf dem Gauß-Newton-Verfahren und dem Tichonow-Regularisierungsansatz. Als Mittel der zusätzlichen impliziten Regularisierung dient eine räumliche Eingrenzung des Gebiets, auf welchem das inverse Problem gelöst wird. Zur iterativen Lösung des zugrundeliegenden Kleinste-Quadrate-Problems werden Krylov-Unterraum-Verfahren, wie der LSQR Algorithmus, verwendet. Aufgrund der charakteristischen Sender-Empfänger-Beziehung wird eine explizit berechnete Jakobimatrix genutzt. Ferner wird eine tensorbasierte Problemformulierung vorgestellt, welche die schnelle Assemblierung leitfähigkeitsabhängiger Systemmatrizen und die effektive Handhabung der zur Berechnung der Jakobimatrix notwendigen algebraischen Größen ermöglicht. Die Funktionalität des beschriebenen Ansatzes wird anhand eines synthetischen Datensatzes zu einem definierten Testproblem überprüft. Abschließend werden Inversionsergebnisse zu Felddaten gezeigt, welche im Norddeutschen Tiefland erhoben worden.

In an effort to improve the accuracy of common 1-D analysis for frequency domain helicopter-borne electromagnetic data at reasonable computing costs, a 3-D inversion approach is developed. The strategy is based on the prior localization of an entire helicopter-borne electromagnetic survey to parts which are actually affected by expected local 3-D anomalies and a separate inversion of those sections of the surveys (cut-&-paste strategy). The discrete forward problem, adapted from the complete Helmholtz equation, is formulated in terms of the secondary electric field employing the finite difference method. The analytical primary field calculation incorporates an interpolation strategy that allows to effectively handle the enormous number of transmitters. For solving the inverse problem, a straightforward Gauss-Newton method and a Tikhonov-type regularization scheme are applied. In addition, different strategies for the restriction of the domain where the inverse problem is solved are used as an implicit regularization. The derived linear least squares problem is solved with Krylov-subspace methods, such as the LSQR algorithm, that are able to deal with the inherent ill-conditioning. As the helicopter-borne electromagnetic problem is characterized by a unique transmitter-receiver relation, an explicit representation of the Jacobian matrix is used. It is shown that this ansatz is the crucial component of the 3-D HEM inversion. Furthermore, a tensor-based formulation is introduced that provides a fast update of the linear system of the forward problem and an effective handling of the sensitivity related algebraic quantities. Based on a synthetic data set of a predefined model problem, different application examples are used to demonstrate the principal functionality of the presented algorithm. Finally, the algorithm is applied to a data set obtained from a real field survey in the Northern German Lowlands. / Die vorliegende Arbeit beschäftigt sich mit der 3-D Inversion von Hubschrauberelektromagnetikdaten im Frequenzbereich. Das vorgestellte Verfahren basiert auf einer vorhergehenden Eingrenzung des Messgebiets auf diejenigen Bereiche, in denen tatsächliche 3-D Strukturen im Untergrund vermutet werden. Die Resultate der 3-D Inversion dieser Teilbereiche können im Anschluss wieder in die Ergebnisse der Auswertung des komplementären Gesamtdatensatzes integriert werden, welche auf herkömmlichen 1-D Verfahren beruht (sog. Cut-&-Paste-Strategie). Die Diskretisierung des Vorwärtsproblems, abgeleitet von einer Sekundärfeldformulierung der vollständigen Helmholtzgleichung, erfolgt mithilfe der Methode der Finiten Differenzen. Zur analytischen Berechnung der zugehörigen Primärfelder wird ein Interpolationsansatz verwendet, welcher den Umgang mit der enorm hohen Anzahl an Quellen ermöglicht. Die Lösung des inversen Problems basiert auf dem Gauß-Newton-Verfahren und dem Tichonow-Regularisierungsansatz. Als Mittel der zusätzlichen impliziten Regularisierung dient eine räumliche Eingrenzung des Gebiets, auf welchem das inverse Problem gelöst wird. Zur iterativen Lösung des zugrundeliegenden Kleinste-Quadrate-Problems werden Krylov-Unterraum-Verfahren, wie der LSQR Algorithmus, verwendet. Aufgrund der charakteristischen Sender-Empfänger-Beziehung wird eine explizit berechnete Jakobimatrix genutzt. Ferner wird eine tensorbasierte Problemformulierung vorgestellt, welche die schnelle Assemblierung leitfähigkeitsabhängiger Systemmatrizen und die effektive Handhabung der zur Berechnung der Jakobimatrix notwendigen algebraischen Größen ermöglicht. Die Funktionalität des beschriebenen Ansatzes wird anhand eines synthetischen Datensatzes zu einem definierten Testproblem überprüft. Abschließend werden Inversionsergebnisse zu Felddaten gezeigt, welche im Norddeutschen Tiefland erhoben worden.

Geophysical methods are essential for exploration and monitoring of subsurface formations, e.g. in carbon dioxide sequestration or enhanced geothermal energy. One of the keys to their successful application is the knowledge of how the measured physical quantities are related to the desired reservoir parameters. The work presented in this thesis shows that the presence of carbon dioxide (CO2) in pore space gives rise to multiple processes all of which contribute to the electrical rock conductivity variation. Basically, three mechanisms take place: (1) CO2 partially replaces the pore water, which is equivalent to a decrease in water saturation. (2) CO2 chemically interacts with the pore water by dissolution and dissociation. These processes change both the chemical composition and the pH of the pore filling fluid. (3) The low-pH environment can give rise to mineral dissolution and/or precipitation processes and changes the properties of the grain-water interface. Investigations on the pore water phase show that the reactive nature of CO2 in all physical states significantly acts on the electrical conductivity of saline pore waters. The physico-chemical interaction appears in different manifestations depending mainly on the pore water composition (salinity, ion types) but also on both temperature and pressure. The complex behaviour includes a low- and a high-salinity regime originating from the conductivity increasing effect of CO2 dissociation, which is opposed by the conductivity decreasing effect of reduced ion activity caused by the enhanced mutual impediment of all solutes. These results are fundamental since the properties of the water phase significantly act on all conduction mechanisms in porous media. In order to predict the variation of pore water conductivity, both a semi-analytical formulation and an empirical relationship for correcting the pore water conductivity, which depends on salinity, pressure and temperature, are derived. The central part of the laboratory experiments covers the spectral complex conductivity of water-bearing sand during exposure to and flow-through by CO2 at pressures up to 30MPa and temperatures up to 80°C. It is shown that the impact of CO2 on the real part of conductivity of a clean quartz sand is dominated by the low- and high-salinity regime of the pore water. The obtained data further show that chemical interaction causes a reduction of interface conductivity, which could be related to the low pH in the acidic environment. This effect is described by a correction term, which is a constant value as a first approximation. When the impact of CO2 is taken into account, a correct reconstruction of fluid saturation from electrical measurements is possible. In addition, changes of the inner surface area, which are related to mineral dissolution or precipitation processes, can be quantified. Both the knowledge gained from the laboratory experiments and a new workflow for the description and incorporation of geological geometry models enable realistic finite element simulations. Those were conducted for three different electromagnetic methods applied in the geological scenario of a fictitious carbon dioxide sequestration site. The results show that electromagnetic methods can play an important role in monitoring CO2 sequestration. Compared to other geophysical methods, electromagnetic techniques are generally very sensitive to pore fluids. The proper configuration of sources and receivers for a suitable electromagnetic method that generates the appropriate current systems is essential. Its reactive nature causes CO2 to interact with a water-bearing porous rock in a much more complex manner than non-reactive gases. Without knowledge of the specific interactions between CO2 and rock, a determination of saturation and, consequently, a successful monitoring are possible only to a limited extend. The presented work provides fundamental laboratory investigations for the understanding of the electrical properties of rocks when the reactive gas CO2 enters the rock-water system. All laboratory results are put in the context of potential monitoring applications. The transfer from petrophysical investigations to the planning of an operational monitoring design by means of close-to-reality 3D FE simulations is accomplished.