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30 results on '"Krieger, Waldemar"'

2. Visualization and Quantitative Analysis of Consecutive Reactions in Taylor Bubble Flows

Author

Schlüter, Michael, Kexel, Felix, von Kameke, Alexandra, Hoffmann, Marko, Herres-Pawlis, Sonja, Klüfers, Peter, Oßberger, Martin, Turek, Stefan, Mierka, Otto, Kockmann, Norbert, Krieger, Waldemar, Thess, André, Series Editor, Moreau, René, Founding Editor, Schlüter, Michael, editor, Bothe, Dieter, editor, Herres-Pawlis, Sonja, editor, and Nieken, Ulrich, editor

Published
2021
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13. Model-Based Decision Support System for Electric Arc Furnace (EAF) Online Monitoring and Control.

Author

Kleimt, Bernd, Krieger, Waldemar, Mier Vasallo, Diana, Arteaga Ayarza, Asier, and Unamuno Iriondo, Inigo

Subjects
ELECTRIC arc, ELECTRIC furnaces, DECISION support systems, ARC furnaces
Abstract

In this work, a practical approach for a decision support system for the electric arc furnace (EAF) is presented, with real-time heat state monitoring and control set-point optimization, which has been developed within the EU-funded project REVaMP and applied at the EAF of Sidenor in Basauri, Spain. The system consists of a dynamic process model based on energy and mass balances, including thermodynamic calculations for the most important metallurgical reactions, with particular focus on the modelling of the dephosphorisation reaction, as this is a critical parameter for production of high-quality steel grades along the EAF process route. A statistical scrap characterization tool is used to estimate the scrap properties, which are critical for reliable process performance and accurate online process control. The underlying process models and control functions were validated on the basis of historical production and measurement data of a large number of heats produced at the Sidenor plant. The online implementation of the model facilitates the accurate monitoring of the process behaviour and can be applied for exact process end-point control regarding melt temperature as well as oxygen, carbon and phosphorus content. Embedded within a model predictive control concept, the model can provide useful advice to the operator to adjust the relevant set-points for energy and resource-efficient process control. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Arduino-based slider setup for gas–liquid mass transfer investigations

Author

Krieger, Waldemar, Bayraktar, Evren, Mierka, Otto, Kaiser, Lutz, Dinter, Robin, Hennekes, Julian, Turek, Stefan, and Kockmann, Norbert

Subjects
Physikalisch-chemische Messung, Arduino based microcontroller, Local mass transfer, Numerical simulation, Gas–liquid capillary flow, Numerische Str��mungssimulation, Physics::Fluid Dynamics, Mikrocontroller, Stoff��bertragung, Gas-Fl��ssigkeit-Str��mung, Noninvasive measurement, Arduino-Plattform, Gas���liquid capillary flow
Abstract

The implementation of traditional sensors is a drawback when investigating mass transfer phenomena within microstructured devices, since they disturb the flow and reactor characteristics. An Arduino based slider setup is developed, which is equipped with a computer-vision system to track gas���liquid slug flow. This setup is combined with an optical analytical method allowing to compare experimental results against CFD simulations and investigate the entire lifetime of a single liquid slug with high spatial and temporal resolution. Volumetric mass transfer coefficients are measured and compared with data from literature and the mass transfer contribution of the liquid film is discussed., AIChE Journal;Vol. 66. 2020, issue 6, e16953

Published
2020

18. Charakterisierung von Wasserstofffallen und deren Einfluss auf die Wasserstoffversprödung in ferritischen Stählen

Author

Krieger, Waldemar

Subjects
Kelvin-Sonde, 620 Ingenieurwissenschaften, Maschinenbau, Versprödung, Hochfester Stahl, Thermische Desorptionsspektroskopie, ddc:620, Wasserstoff
Abstract

Der Bedarf an hochfesten Stählen im Bau, der Automobilindustrie sowie der Öl- und Gasindustrie wächst. Diese sind jedoch anfällig für Versprödung durch Wasserstoff (H). Für die Festigkeit ist das Gefüge mit seinen Defekten (Versetzungen, Korngrenzen und Phasengrenzen) verantwortlich. Das Gefüge steht wiederum in einer komplexen Wechselwirkung mit der Umgebung (H-Aktivität, Einsatzzeit und mechanische Belastung). Um ein besseres Verständnis dieser Wechselwirkung zu erlangen, wurde eine Fe-Ni5 Legierung systematisch in verschiedene thermomechanische Zustände versetzt und hinsichtlich ihrer H-Fallen sowie deren Bedeutung für die H-Versprödung charakterisiert. Bei der Analyse der H-Fallen kam neben einer etablierten integralen Messmethode (TDS) auch eine hochauflösende Methode (KP) zum Einsatz. Die Zugversuche zur Evaluierung der H-Versprödung erfolgten 2 h nach der elektrolytischen H-Beladung bei variierenden H-Aktivitäten, Beladungsdauern und mechanischen Lasten.

Published
2019

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