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DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Assoziiertes Teilprojekt D-4: Batteriethermomanagement für elektrifizierte Stadtbusse

Im Zuge der Reduzierung von Lärm-, Partikel- und Schadstoffemissionen in Innenstädten kommt dem Einsatz von elektrifizierten Stadtbussen eine besondere Bedeutung zu. Da sämtliche Aggregate eines solchen Busses von einer Batterie auf Lithium-Ionen-Basis gespeist werden, spielt das Thermomanagement der Batterie eine entscheidende Rolle. Um negative Effekte wie schnelle kalendarische und zyklische Alterung, Überhitzung durch exotherme Reaktionen (thermal runaway) oder Kurzschluss durch Lithium plating zu verhindern, muss die Betriebst-emperatur der Batterie stets im optimalen Bereich von 18°C – 25°C gehalten werden. Dies bedeutet dass die Batterie im Sommerbetrieb gekühlt und im Winterbetrieb beheizt werden muss. Im Projekt werden verschiedene Thermomangementsysteme an einem Teststand experimentell bei verschiedenen Fahrprofilen und bei unterschiedlichen Ladetechnologien und Außentemperaturen untersucht.

Partner:

Mahle Industrial Thermal Systems, Stuttgart

Bearbeiter:


Aktuelle Publikationen:
 

Schnellstart: Entwicklung eines Verfahrens zum gezielten Vorheizen einer Direkt-Methanol-Brennstoffzelle mit minimalem Energieaufwand

Eine Herausforderung bei der Etablierung von Mikrobrennstoffzellen im Massenmarkt stellt die Brennstoffversorgung. Eine potentielle Lösung bietet der Brennstoff Methanol. Methanol weist eine Energiedichte von 4400 Wh/l auf, kann regenerativ gewonnen werden und ist in Kartuschen leicht speicherbar. Zudem kann es in Direkt-Methanol-Brennstoffzellen (DMFC) bei 60–80 °C ohne eine Reformierung oder Elektrolyse zur Stromgewinnung verwendet werden. Problematisch ist die starke Abhängigkeit der Leistungsfähigkeit der Methanol-Brennstoffzelle von der Temperatur. Gerade die Startprozedur einer Zelle ist aufgrund des notwendigen Aufheizprozesses kritisch. Mit diesem von der Arbeitsgemeinschaft industrieller Gemeinschaftsforschung (AIF 18941 N) geförderten Vorhaben wird das Ziel verfolgt, für eine durchströmte μDMFC auf Silizium-Basis mit Hilfe einer zeitlich und räumlich hochaufgelösten Temperatur- und Strömungsmessung ein geeignetes Konzept für eine schnelle Vorheizung zu entwickeln und aufzubauen. Die Temperaturmessungen sollen dabei zum einen auf der Kathode über IR-Spektroskopie zum anderen auf der Anode volumetrisch über den Einsatz optischer Messtechnik und temperatursensitiver Partikel erfolgen.

Partner:

Universität der Bundeswehr München, Zentrum für Brennstoffzellentechnik Duisburg

Bearbeiter:  

Aktuelle Publikationen:

J. Massing, C.J. Kähler, C. Cierpka (2017) Vergleichende Analyse eines Ein- und Mehrkamerasystems zur simultanen, volumetrischen Temperatur- und Geschwindigkeitsmessung für die Mikrofluidik. Technisches Messen

J. Massing, D. Kaden, C.J. Kähler, C. Cierpka (2016) Luminescent two-color tracer particles for simultaneous velocity and temperature measurements in microfluidics, Measurement Science and Technology 27, 1153014

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Teilprojekt A-4: Lorentzkraft-Anemometrie in Zweiphasenströmungen flüssiger Metalle

Lorentz force velocimetry (LFV) is a well-known technique which is used to determine velocity profiles or mass flux rates in a channel filled with an opaque liquid metal. The first goal of project A1 is to apply these methods to regimes where the magnetic Reynolds number Rem becomes finite. The dynamic coupling between turbulent flow and magnetic field gives, on the one hand, rise to several nontrivial phenomena such as magnetic field expulsion or vortex shedding and, on the other hand, makes this task very difficult to solve numerically without small-scale parametrizations (project A3). A high value of Rem can be obtained in a liquid tin channel (Tintelo), where the flow can be accelerated significantly. Here we plan to measure the velocity of liquid tin at temperatures as high as 400°C in a vertical or in a horizontal test section, respectively. A pump which propels a fluid can accelerate it up to several m/s that is enough to have finite Rem. The second goal is to study the particle transport in such a liquid metal flows and to reveal how the loading with inertial particles affects the flow. We want to detect such effects with Lorentz force velocimetry. Alternative measurement techniques, such as ultrasound probing, will help to benchmark the obtained LFV results.

Partner:

Graduiertenkolleg Elektromagnetische Strömungsmessung und Wirbelstromprüfung mittels Lorentzkraft

Bearbeiter:


Aktuelle Publikationen:
 

Z. Lyu, Th. Boeck,  Ch. Karcher, A. Thess:
Electromagnetic interaction between a permanent magnet and laminar flow of a moving sphere in a conducting liquid, Magnetohydrodynamics 53, No. 4, 653-666 (2017)

Z. Lyu, Ch. Karcher:
Non-contact electromagnetic flow measurement in liquid metal two-phase flow using Lorentz force velocimetry, Magnetohydrodynamics, Bd. 53, No. 1, 67-77 (2017)

Z. Lyu, N. Tran, Th. Boeck, Ch. Karcher:
Electromagnetic interaction between a rising spherical particle in a conducting liquid and a localized magnetic field, Final LIMTECH Colloquium and International Symposium on Liquid Metal Technologies, 012025, 10 pages, (2017)

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Teilprojekt A-1: Large-scale structure formation in liquid metal convection

Local Lorentz force velocimetry (LLFV) is a non-contact electromagnetic measurement technique to determine velocity profiles in electrically conducting fluids like liquid metal melts. Using this method, we measure the force on a tiny permanent magnet that interacts with the moving melt. After having successfully tested this method in the closed test loop GALINKA under isothermal and forced convection conditions, in its third generation the project aims to extend the technique towards three new aspects: (i) flow in large-aspect-ratio closed cells, (ii) non-isothermal conditions, i.e. the effect of an externally applied temperature gradient, and (iii) the effect of an externally applied homogeneous magnetic field of high flux density. Key questions to be answered are: can LLFV be used (i) to sense flow structures driven by thermal gradients, (ii) to measure convective heat transfer coefficients, (iii) to measure in the presence of a strong magnetic background field? To address these points we plan to perform high-precision model experiments using the low-melting alloy GaInSn as a test melt.

Bearbeiter:


Aktuelle Publikationen:
 

T. Zürner, T. Vogt, Ch. Resagk, S. Eckert, J. Schumacher:
Local Lorentz force and ultrasound Doppler velocimetry in a vertical convection liquid metal flow, Experiments in fluids 59, 1, 12 pages, (2018)

T. Zürner, M. Ratajczak, Th. Wondrak, S, Eckert: Inductive detection of the free surface of liquid metals, Meas. Sci. Technol. 28., 115301, 7 pages, (2017)

T. Zürner, W. Liu, D. Krasnov and J. Schumacher, Heat and momentum transfer for magnetoconvection in a vertical external magnetic field, Phys. Rev. E 94, 043108 (2016).

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Teilprojekt B-4: Optimierung von Magnetfeldsystemen für schwach leitfähige Fluide

Lorentz force anemometry is a well-known contactless method used to determine the flow of electrically conducting fluids by measuring the Lorentz force using magnet systems. It is necessary to numerically simulate Lorentz force anemometry in order to investigate the influence of shieldings (electrically conducting tubes, for instance) on how accurately and sensitively we can perform our measurements. Our special focus lies on the optimizedmagnet systemsor experimental arrangements. The numerical investigations of Lorentz force anemometry will be extended to include moveable disturbances such as bubbles in the fluid. Bubbles can be considered using a two-phase model including the “Volume of Fluid” (VoF) method. The material properties of the bubbles produce varying results: a) The electrically conductivity is zero (saltwater, air bubbles) or b) the electrically conductivity is high (saltwater, metal particles). Project B-4 closely cooperates with the experimental project B-3. Furthermore, project B-4 contributes conceptual formulations to the theoretical project B-5, which investigates optimization methods.

Partner:

Graduiertenkolleg Elektromagnetische Strömungsmessung und Wirbelstromprüfung mittels Lorentzkraft

Bearbeiter:


Aktuelle Publikationen:
 

N.Tran, U. Lüdtke:
Numerical Simulation of Two-Phase Liquid Metal Interacting with Strongly Inhomogeneous Magnetic Fields, Proc. VIII Intl. Scientific Colloquium Modelling for Materials Processing (MMP), Riga (2017), 289-294.

Z. Lyu, N. Tran, Th. Boeck, Ch. Karcher:
Electromagnetic interaction between a rising spherical particle in a conducting liquid and a localized magnetic field, Final LIMTECH Colloquium and International Symposium on Liquid Metal Technologies,.012-025, 10 pages, (2017)

N.Tran, U. Lüdtke:
Numerische Simulation aufsteigender Gasblasen im inhomogenen Magnetfeld mittels der MHD-VoF Methode, Proc. Workshop Elektroprozesstechnik, Ilmenau (2017)

N.Tran, U. Lüdtke:
Numerical modelling of Lorentz Force Velocimetry including bubbles in liquid metal, Proc.  
XVIII International UIE-Congress - Electrotechnologies for Material Processing, Hannover (2017)

N. Tran, U. Lüdtke:
Numerical simulation of a channel induction furnace to investigate frequency-dependent efficiency. Proc. IEEE International Conference on Sustainable Energy Technologies, Hanoi, Vietnam (2016).

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Assoziiertes Teilprojekt D-1: Lokale Lorentzkraft-Anemometrie

In metallurgical industry the in-situ measurement of local velocity is still an unsolved problem. The liquid metals are typically aggressive and usually at temperatures over 1000°C making the classic contact techniques like fly-wheel, Pitot tube, and hot-wire probe useless. Even optical techniques like Particle Image Velocimetry fail due to the opaqueness of liquid metals. In order to overcome these challenges, a non-contact measurement technique has been developed called Lorentz Force Velocimetry (LFV). It works according to the principles of magnetohydrodynamics: when an electrically conductive liquid flows through a static magnetic field, eddy currents are induced and interact with the applied magnetic field generating flow-braking Lorentz forces within the fluid.On the other hand, due to Newton's third law, a counter force of the same magnitude and proportional to the velocity acts on the permanent magnet system. Depending on the volume subset of the flow that is exposed to the magnetic field, we can have access to the flow rate or to the local velocity of the metal melt. In the first case, the magnetic field penetrates the entire cross-section and in the second one, a localized magnetic field is desired. Owing to the rapid decay of magnetic fields, a localized magnetic field can be obtained by using a single magnet or magnet arrangements which are considerably smaller than the fluid domain. The magnet system is connected to a force sensor and together this device is called local Lorentz force flowmeter (L2F2). A new-generation L2F2 is able to measure all three forces as well as three torque components acting on the magnet system.

Partner:

Helmholtzzentrum Dresden-Rossendorf

Bearbeiter:


Aktuelle Publikationen:
 

D. Hernández, R. Marangoni, J. Schleichert, Ch. Karcher, Th. Fröhlich, Th. Wondrak:
Numerical and experimental study on vorticity measurement in liquid metal using local Lorentz force velocimetry, Meas. Sci. Technol. 29, Vol. 1035301, 13 pages, (2018)

D. Hernández, Th. Boeck, Ch. Karcher, Th. Wondrak:
Numerical and experimental study of the effect of the induced electric potential in Lorentz force velocimetry, Meas. Sci. Technol. 29m Vol. 1, 015301, 15 pages, (2018)

Ch. Karcher, D. Hernández:
Dynamics of falling liquid metal droplets and jets affected by a strong magnetic field, Magnetohydrodnamics 53 No. 4, 739–745, (2017)

Ch. Karcher, D. Hernández:
Dynamics of falling liquid metal droplets and jets influenced by a strong axial magnetic field, VIII International Scientific Colloquium Modelling for Materials Processing, Riga, doi:10.22364/mmp2017.31, 283-288, (2017)

J. Ketterer, D. Hernández, Ch. Karcher:
Experimentelle Untersuchungen zum Einfluss von starken axialen Magnetfeldern auf Tropfen- und Strahlströmungen von Flüssigmetallen, Proc. Workshop Elektroprozesstechnik, Ilmenau (2017)

D. Hernández, Ch. Karcher:
Dynamics of liquid metal droplets and jets influenced by a strong axial magnetic field, Final LIMTECH Colloquium and International Symposium on Liquid Metal Technologies,.012010, 10 pages, (2017)

D. Hernandez, Th. Boeck, Ch. Karcher, Th. Wondrak:
Numerical calibration of a multi-component local Lorentz force flow meter, Magnetohydrodynamics, 53, 233-243 (2017)

 

 

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Assoziiertes Teilprojekt D-2: Elektromagnetische Kontrolle von Adsorptionsprozessen in der Kältetechnik

In this project the transient modelling of a new construction of an adsorption refrigeration machine is investigated. In this machine both silica gel and activated carbon are used as adsorbents and methanol is used as the adsorbate and refrigerant. This reactor filling allows using the advantages of the physical properties of the materials. A further objective of this project is to numerically study the effects of the inductive heating of the systems walls on the adsorption and the desorption processes.

Partner:

Hochschule Ostwestfalen Höxter-Lippe in Höxter

Bearbeiter:

Aktuelle Publikationen: 

M. Ali, S. Ajib, Ch. Karcher:
Enhancing the amount of cold produced and saving of the required input heat using two different adsorbents together in the adsorption ice production AIP system, . Global J. Energy Tech. Res. Updates 4, 9-25, (2107)

M. Ali, Ch. Karcher, U. Lüdtke:
Numerical and mathematical modelling of induction heating in adsorption refrigeration systems, Proc. Workshop Elektroprozesstechnik, Ilmenau (2017)

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Assoziiertes Teilprojekt D-3: Elektromagnetische Kontrolle des konvektiven Wärmeübergangs in Motorkühlern

In engine coolers of off-highway vehicles convective heat transfer at the coolant side is a limiting factor of both efficiency and performance density of the cooler. Here, due to design restrictions, backwater areas and stagnation regions appear that are caused by flow deflections and cross-sectional expansions. As appropriate coolants, mixtures of water and glysantine are commonly used. Such coolants are characterized by their electrical conductivity of some S/m. This gives rise to control coolant flow and therefore convective heat transfer by means of Lorentz forces. These body forces are generated within the weakly conducting fluid by the interactions of an electrical current density and a localized magnetic field both of which being externally superimposed. In application this may be achieved by inserting electrodes in the cooler wall and a corresponding arrangement of permanent magnets. In this project we perform numerical simulations of such magnetohydrodynamic flow in three model geometries that are frequently apparent in engine cooling applications: Carnot-Borda diffusor, 90° bend, and 180° bend. The simulations are carried out using the software package ANSYS Fluent.

Partner:

Mahle Industrial Thermal Systems, Stuttgart

Bearbeiter:


Aktuelle Publikationen:

 J. Kühndel, B. Kerler, Ch. Karcher: Selective laser melting in heat exchanger development - Experimental investigation of heat transfer and pressure drop characteristics of wavy fins, Intl. J. Heat Mass Transfer HAMT-D-17-00245R1, to appear (2018)

Ch. Karcher, J. Kühndel: Convective heat transfer in engine coolers influencedby electromagnetic fields, Intl. J. Heat Mass Transfer, DOI 10.1007/s00231-017-2130-4 (2017)

Ch. Karcher, J. Kühndel: Control of heat transfer in engine coolers by Lorentz forces, Journal of Physics 745, IOP Publishing (2016), 032050.

J. Kühndel, B. Kerler, Ch. Karcher: Air side thermal performance of wavy fin heat exchangers produced by selective laser melting, Journal of Physics 745, IOP Publishing (2016), 032057.

DFG-Graduiertenkolleg (GRK 1567) „Elektromagnetische Strömungsmessung und Wirbelstromprüfung Lorentzkraft“ Teilprojekt B-1: Flow instabilities at the interface between liquid metal and salt solution

The research in project B-1 during the third RTG generation will focus on applying Lorentz force velocimetry (LFV) to very low conducting fluids, two-fluid systems with liquid metals and molten salts, and two-phase flows. We will apply high magnetic field LFV to a saltwater-air-bubbles flow in an electrolyte channel using superconducting magnets and weight compensation together with noise reduction and force compensation methods. Investigating hot liquid metal - salt melt systems with LFV will open new applications for energy storage facilities and liquid metal batteries. Here, it is especially important to detect impurities and to characterize interface instabilities. Finally, fundamental investigations for two-phase flow with low electrical conductivity shall identify particle dynamics, inertia, and flow profiles as well as aggregation and separation effects in salt melts and liquid metals

Bearbeiter:


Aktuelle Publikationen:
 

A. Wiederhold, C. Resagk, C. Cierpka (2018) On the influence of gas-liquid two-phase flow on Lorentz force velocimetry, Measurement Science and Technology 29, 085301

A. Wiederhold, Th. Boeck, Ch. Resagk: Detection and characterization of elongated bubbles and drops in two-phase flow using magnetic fields, Meas. Sci. Technol. 28, .085303, 9 pages (2017)