Inst. Prozess- und Verfahrenstechnik

281 Items

Recent Submissions
Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio

Eppinger, Thomas ; Jurtz, Nico ; Kraume, Matthias (2021-04-14)

Fixed bed reactors are widely used in the chemical, nuclear and process industry. Due to the solid particle arrangement and its resulting non-homogeneous radial void fraction distribution, the heat transfer of this reactor type is inhibited, especially for fixed bed reactors with a small tube to particle diameter ratio. This work shows that, based on three-dimensional particle-resolved discrete...

Biogas Plants in Renewable Energy Systems—A Systematic Review of Modeling Approaches of Biogas Production

Heiker, Mathias ; Kraume, Matthias ; Mertins, Anica ; Wawer, Tim ; Rosenberger, Sandra (2021-04-08)

Biogas production is a relevant component in renewable energy systems. The paper addresses modeling approaches from an energy system, as well as from a process optimization, point of view. Model approaches of biogas production show different levels of detail. They can be classified as white, gray, and black box, or bottom-up and top-down approaches. On the one hand, biogas modeling can supply d...

Assessment of Analytical Orientation Prediction Models for Suspensions Containing Fibers and Spheres

Dietemann, Bastien ; Bosna, Fatih ; Kruggel-Emden, Harald ; Kraft, Torsten ; Bierwisch, Claas (2021-04-13)

Analytical orientation models like the Folgar Tucker (FT) model are widely applied to predict the orientation of suspended non-spherical particles. The accuracy of these models depends on empirical model parameters. In this work, we assess how well analytical orientation models can predict the orientation of suspensions not only consisting of fibers but also of an additional second particle typ...

Preparation of a Self‐Supported SiO2 Membrane as a Separator for Lithium‐Ion Batteries

Kyeremateng, Neil Amponsah ; Gukte, Dion ; Ferch, Marc ; Buk, Jan ; Hrebicek, Tomas ; Hahn, Robert (2020-02-03)

For the first time, electrophoretic deposition (EPD) has been employed to prepare a self‐supported, inorganic membrane consisting of SiO2 nano‐fibers, as a separator for lithium‐ion batteries. The SiO2 nano‐fibers that were fabricated by a low‐cost force spinning technique were deposited by EPD directly onto LiNi0.8Co0.15Al0.05O2 cathode material. Citric acid charging agent and anhydrous aceton...

Experimental study of two cascaded organic Rankine cycles with varying working fluids

Abbas, Wameedh Khider Abbas ; Linnemann, Matthias ; Baumhögger, Elmar ; Vrabec, Jadran (2021-01-09)

Organic Rankine cycles convert low-temperature heat from different sources, like solar, geothermal or biomass, into electricity and may thus help to meet the energy demand in an environmentally friendly way. While single ORC systems have been studied extensively, there are only very few experimental works on systems consisting of two cascaded organic Rankine cycles (two-ORC). In this work, an e...

AutoPas in ls1 mardyn: Massively parallel particle simulations with node-level auto-tuning

Seckler, Steffen ; Gratl, Fabio ; Heinen, Matthias ; Vrabec, Jadran ; Bungartz, Hans-Joachim ; Neumann, Philipp (2021-01-07)

Due to computational cost, simulation software is confronted with the need to always use optimal building blocks — data structures, solver algorithms, parallelization schemes, and so forth — in terms of efficiency, while it typically needs to support a variety of hardware architectures. AutoPas implements the computationally most expensive molecular dynamics (MD) steps (e.g., force calculation)...

Comparison of macro- and microscopic solutions of the Riemann problem II. Two-phase shock tube

Hitz, Timon ; Jöns, Steven ; Heinen, Matthias ; Vrabec, Jadran ; Munz, Claus-Dieter (2020-11-27)

The Riemann problem is one of the basic building blocks for numerical methods in computational fluid mechanics. Nonetheless, there are still open questions and gaps in theory and modeling for situations with complex thermodynamic behavior. In this series, we compare numerical solutions of the macroscopic flow equations with molecular dynamics simulation data. To enable molecular dynamics for su...

ms2: A molecular simulation tool for thermodynamic properties, release 4.0

Fingerhut, Robin ; Guevara-Carrion, Gabriela ; Nitzke, Isabel ; Saric, Denis ; Marx, Joshua ; Langenbach, Kai ; Prokopev, Sergei ; Celný, David ; Bernreuther, Martin ; Stephan, Simon ; Kohns, Maximilian ; Hasse, Hans ; Vrabec, Jadran (2021-01-30)

A new version release (4.0) of the molecular simulation tool ms2 (Deublein et al. 2011; Glass et al. 2014; Rutkai et al. 2017) is presented. Version 4.0 of ms2 features two additional potential functions to address the repulsive and dispersive interactions in a more versatile way, i.e. the Mie potential and the Tang–Toennies potential. This version further introduces Kirkwood–Buff integrals bas...

Modeling process dynamics in membrane-electrolyte-assemblies of chloralkali electrolyzers considering steric and hydration effects

Budiarto, Thomas (2021)

The dynamic operation of the chloralkali electrolyzer has been considered as one of the solution for balancing the supply-demand fluctuation in the electricity grid. This opportunity becomes a motivation to study the complex transient behaviors of the electrolyzer caused by linked multiscale phenomena. Membrane of the electrolyzer, which is a crucial part of the plant operation and lifetime, is...

Towards demand-side management of the chlor-alkali electrolysis: dynamic modeling and model validation

Weigert, Joris ; Hoffmann, Christian ; Esche, Erik ; Fischer, Peter ; Repke, Jens-Uwe (2021-03-18)

The chlor-alkali electrolysis promises advantageous application of demand-side management and several research groups have proposed dynamic models to obtain optimal trajectories for such applications. However, no dynamic model of those proposed so far has yet been validated with real, industrial plant data. This is highly important to determine trajectories, which are indeed feasible. This cont...

Diffusion of the carbon dioxide–ethanol mixture in the extended critical region

Chatwell, René Spencer ; Guevara-Carrion, Gabriela ; Gaponenko, Yuri ; Shevtsova, Valentina ; Vrabec, Jadran (2021-01-18)

The effect of traces of ethanol in supercritical carbon dioxide on the mixture's thermodynamic properties is studied by molecular simulations and Taylor dispersion measurements. This mixture is investigated along the isobar p = 10 MPa in the temperature range between T = 304 and 343 K. Along this path, the mixture undergoes two transitions: First, the Widom line is crossed, marking the transiti...

Multi-Scale Studies of 3D Printed Mn−Na−W/SiO2 Catalyst for Oxidative Coupling of Methane

Karsten, Tim ; Middelkoop, Vesna ; Matras, Dorota ; Vamvakeros, Antonis ; Poulston, Stephen ; Grosjean, Nicolas ; Rollins, Benjamin ; Gallucci, Fausto ; Godini, Hamid R. ; Jacques, Simon D. M. ; Beale, Andrew M. ; Repke, Jens-Uwe (2021-02-24)

This work presents multi-scale approaches to investigate 3D printed structured Mn–Na–W/SiO2 catalysts used for the oxidative coupling of methane (OCM) reaction. The performance of the 3D printed catalysts has been compared to their conventional analogues, packed beds of pellets and powder. The physicochemical properties of the 3D printed catalysts were investigated using scanning electron micro...

Selective separation of the strategic elements germanium and rhenium from multicomponent leaching solutions by nanofiltration

Meschke, Katja (2021)

For decades, membranes have been utilized for aqueous solution treatment and hence, they seem suitable for the separation of strategic elements from complex leaching solutions. This work focuses on germanium and rhenium, which are required for high-tech products. Therefore, the demand is steadily increasing on a global scale. Considerable amounts of both elements are present in Theisen sludge, ...

Experimentelle Grundlagenuntersuchungen zur Bestimmung charakteristischer, messbarer Kennwerte für die Automatisierung des Mischprozesses in Biogasanlagen

Brehmer, Manuel (2021)

Die Erarbeitung von Grundlagen zur Automatisierung der Mischtechnik in mit Tauchmotorrührwerken ausgestatteten Biogasanlagen ist Thema dieser Dissertationsarbeit. Dabei wird intensiv auf die strukturviskosen und viskoelastischen Fließeigenschaften der Substrate sowie den Möglichkeiten zur Charakterisierung dieser eingegangen. Aufbauend auf den Ergebnissen erfolgt eine Betrachtung des ungestörte...

Dynamic Process Operation Under Demand Response – A Review of Methods and Tools

Esche, Erik ; Repke, Jens‐Uwe (2020-10-29)

Participating in electricity markets through demand response causes new requirements for optimizing process control of chemical plants. The last ten years have brought great advances in the formulation and solution of economic nonlinear model predictive control and state estimation to support operation of processes under dynamic constraints. However, gaps remain regarding the availabilities of ...

Calibration‐Free Chemical Process and Quality Control Units as Enablers for Modular Production 

Bornemann‐Pfeiffer, Martin ; Kern, Simon ; Maiwald, Michael ; Meyer, Klas (2020-12-02)

Modular chemical production is a tangible translation of the digital transformation of the process industry for specialty chemicals. In particular, it enables the speeding‐up of process development and, thus, a quicker time to market by flexibly connecting and orchestrating standardized physical modules and bringing them to life (i.e., parameterizing them) with digitally accumulated process kno...

Analysis of Mobility Effects in Particle‐Gas Flows by Particle‐Resolved LBM‐DEM Simulations 

Rosemann, Tony ; Reinecke, Simon R. ; Kruggel‐Emden, Harald (2020-12-22)

Particle‐resolved direct numerical simulations are performed to simulate the flow through particle assemblies that are either static or freely moving to demonstrate the influence of particle mobility. To obtain a comprehensive understanding for this influence essential parameters such as the Reynolds number, solids volume fraction, particle‐fluid density ratio, collision parameters and particle...

Real‐Time Visualization of Internal and External Concentration Fields in Multiphase Systems via Laser‐induced Fluorescence and Rainbow Schlieren Deflectometry During and After Droplet Production 

Heine, Jens Stefan ; Schulz, Joschka Marco ; Junne, Henning ; Böhm, Lutz ; Kraume, Matthias ; Bart, Hans‐Jörg (2020-11-27)

The applicability of laser‐induced dye fluorescence (LIF) and rainbow schlieren deflectometry (RSD) for qualitative, non‐invasive real‐time visualization of spatial concentration distributions in two standard reference systems is presented. The combination of LIF and RSD enables measurements inside and outside of droplets and is able to overcome limitations of both measurement techniques. Exper...

In-Line Analysis of Diffusion Processes in Micro Channels by Long Distance Raman Photometric Measurement Technology—A Proof of Concept Study

Deuerling, Julian ; Keck, Shaun ; Moelyadi, Inasya ; Repke, Jens-Uwe ; Rädle, Matthias (2021-01-22)

This work presents a novel method for the non-invasive, in-line monitoring of mixing processes in microchannels using the Raman photometric technique. The measuring set-up distinguishes itself from other works in this field by utilizing recent state-of-the-art customized photon multiplier (CPM) detectors, bypassing the use of a spectrometer. This addresses the limiting factor of integration tim...

Numerical Modeling of the Motion and Interaction of a Droplet of an Inkjet Printing Process with a Flat Surface

Tofan, Tim ; Kruggel-Emden, Harald ; Turla, Vytautas ; Jasevičius, Raimondas (2021-01-07)

The numerical simulation and analysis of the ejection of an ink droplet through a nozzle as well its motion through air until its contact with a surface and taking up of a stable form is performed. The fluid flow is modeled by the incompressible Navier–Stokes equations with added surface tension. The presented model can be solved using either a level set or a phase field method to track the flu...