References of "Pfennig, Andreas"
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See detailCoalescence Modelling for Design of Technical Equipment
Leleu, David ULiege; Pfennig, Andreas ULiege

in Chemical Engineering and Technology (in press)

A coalescence model in the context of the ReDrop concept (Representative Drops) is proposed to design technical equipment for separating liquid-liquid dispersions in settlers or extraction columns. A ... [more ▼]

A coalescence model in the context of the ReDrop concept (Representative Drops) is proposed to design technical equipment for separating liquid-liquid dispersions in settlers or extraction columns. A fundamental study of drop interactions has been performed to obtain the complete picture of coalescence. The model proposed accounts for collision frequency of the drops, bouncing probability, and coalescence probability, for which the film-drainage approach is applied. The model proposed allows to consider the appropriate formulation for different types of equipment. Especially noteworthy is that the coalescence probability fundamentally differs from the expression of Coulaloglou and Tavlarides, which is frequently used, but which shows inconsistencies at fundamental level. [less ▲]

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See detailDrop-Based Modelling of Extraction Equipment
Leleu, David ULiege; Pfennig, Andreas ULiege

in Moyer, Bruce A. (Ed.) Ion Exchange and Solvent Extraction, Vol. 23: Changing the Landscape in Solvent Extraction (in press)

Design of equipment for solvent extraction is a challenging task, because the details of drop interaction depend strongly on trace components. This is one reason, why equipment design in solvent ... [more ▼]

Design of equipment for solvent extraction is a challenging task, because the details of drop interaction depend strongly on trace components. This is one reason, why equipment design in solvent-extraction cannot solely rely on equilibrium information. An approach is presented, which is based on drop-based simulations, which allows to characterize the equipment performance with all details. The models parameters characterizing the specific system behavior are obtained by fitting to experimental results in dedicated lab-scale experiments. These are then the basis for simulation of drop-behavior in the different types of equipment, in which a sufficient number of individual drops are regarded, which are followed during their lifetime in the equipment. For gravity settlers and for extraction columns these approaches are presented together with results on drop behavior. The lab-scale experiments and the validation experiments in extraction equipment on pilot-plant scale lead to significant new insights into the details of drop processes. [less ▲]

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See detailSustainable Bio‐ or CO2 economy: Chances, Risks, and Systems Perspective
Pfennig, Andreas ULiege

in ChemBioEng Reviews (2019), 6(3), 90-104

To obtain a consistent view of sustainable future development, scenarios based on global balances have been derived. The world population may grow significantly faster than generally expected by many ... [more ▼]

To obtain a consistent view of sustainable future development, scenarios based on global balances have been derived. The world population may grow significantly faster than generally expected by many studies with up to 11.6 billion people in 2050. The climate goal of 1.5 °C can realistically not be reached any more and it is shown why it has been so difficult to realize that strong action would have been required years ago. Without change in behavior, a strong competition for land area will develop, mainly driven by human fertility and a large fraction of animal‐based food. While CO2‐based economy does not compete with food production for agricultural land area, its economic feasibility still needs to be demonstrated. In a bio‐based economy, third‐generation biomass alone will not be able to supply enough feedstock to fulfill all demands. Thus, competition with food production for land area will be unavoidable. Besides economic and ecological aspects, also ethics need to be considered. A holistic view is essential for deriving effective policies and ethical guidelines, but it also needs to influence personal decisions. [less ▲]

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See detailBio-Ökonomie: Chancen, Risiken und Perspektiven des gesamten Systems
Pfennig, Andreas ULiege

Conference (2019, February 26)

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See detailCharakterisierung der Fluiddynamik und des Stofftransports von wässrigen Zweiphasensystemen (ATPS) in einer flüssig-flüssig Gegenstromextraktionskolonne
Meyer, Christian; Schmidt, Markus; Eggert, Armin et al

Poster (2019, February 07)

Wässrige Zweiphasensysteme (ATPS) werden z.B. durch die Lösung eines hydrophilen Polymers und eines Salzes in Wasser gebildet. Sie bieten im Gegensatz zu organisch-wässrigen Systemen schonende ... [more ▼]

Wässrige Zweiphasensysteme (ATPS) werden z.B. durch die Lösung eines hydrophilen Polymers und eines Salzes in Wasser gebildet. Sie bieten im Gegensatz zu organisch-wässrigen Systemen schonende Umgebungsbedingungen für die Extraktion von Proteinen. [1] Dennoch geht der Einsatz von ATPS selten über die Anwendung im Labor hinaus. Dies liegt zum einen am Aufwand ein passendes Extraktionssystem auszuwählen, zum anderen an den hohen Anforderungen an die apparative Umsetzung aufgrund ihrer extremen physikalischen Eigenschaften wie geringe Dichtedifferenz und Grenzflächenspannung. [2] Zur Überprüfung der technischen Umsetzbarkeit im kontinuierlichen Betrieb wurden flüssig-flüssig Extraktionsversuche in einer vollständig temperierten DN32 Extraktionskolonne mit gerührten Einbauten durchgeführt. Ausgewählt wurde ein Stoffsystem mit Polyethylenglykol und Phosphat als Phasenbildner und Albumin als Übergangskomponente, für das zunächst die Mischungslücke in Abhängigkeit des pH-Werts und der Verteilungskoeffizient bestimmt wurden. Das ATPS wurde anschließend in der Kolonne hinsichtlich der Fluiddynamik und des Stoffaustauschs untersucht. Die Einflüsse der Flüssigkeitsbelastung, des Volumenstromverhältnisses und der Rührerdrehzahl auf die Betriebsgrenze und die Trennleistung, wurden vermessen und werden im Rahmen des Posters präsentiert. Der kontinuierliche Betrieb von ATPS in einer Gegenstromextraktionskolonne wurde erfolgreich realisiert und bei einer aktiven Höhe von 1575 mm bereits mehr als 2 theoretische Trennstufen erreicht. [1] Albertsson, P.-Å., 1986: Partition of cell particles and macromolecules (3. ed.). New York. Wiley [2] Rosa, P. A. J. et al., 2010: Aqueous two-phase systems: A viable platform in the manufacturing of biopharmaceuticals. J Chromatogr A, 1217 (16), 2296–2305 [less ▲]

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See detailBio-Ökonomie: Chancen, Risiken und Perspektiven des gesamten Systems
Pfennig, Andreas ULiege

Scientific conference (2019, January 17)

Die Herausforderungen für die Menschheit sind klar: Wir müssen den Verbrauch fossiler Ressourcen reduzieren und durch nachhaltige Technologien ersetzen. Dies impliziert den Einsatz von nachhaltigen ... [more ▼]

Die Herausforderungen für die Menschheit sind klar: Wir müssen den Verbrauch fossiler Ressourcen reduzieren und durch nachhaltige Technologien ersetzen. Dies impliziert den Einsatz von nachhaltigen Rohstoffen auch in der chemischen Industrie wie biobasierte Rohstoffe oder Kohlendioxid. Zu den verschiedenen Optionen für Rohstoffe und einzusetzende Technologien wurde viel veröffentlicht. Warum die eine oder andere aus der Vielzahl der Optionen vielversprechender ist als eine andere, ist vielleicht nicht immer offensichtlich. Um einen realistischen Einblick zu erhalten, wird der Rohstoffwandel mit den allgemeinen Herausforderungen der Menschheit in Beziehung gesetzt, nämlich Klimawandel, Energiewende und Welthunger. Dadurch wird deutlich, dass die Rohstoffumstellung innerhalb einer relativ kurzen Übergangszeit erforderlich sein kann. Die wesentlichen Rohstoff- und Technologieoptionen werden diskutiert und in Bezug zu diesen Randbedingungen und untereinander gesetzt. Der Schwerpunkt liegt auf Massenprodukten wie Kunststoffen. Es werden einige vielversprechende Hauptwege beschrieben, und die praktischen Herausforderungen bei ihrer Realisierung adressiert, z.B. Bereitstellung, Umwandlung und Verteilung. Die sich ergebenden gesellschaftlichen Anforderungen und die Verantwortlichkeit des Einzelnen resultieren zwanglos aus diesen Zusammenhängen. [less ▲]

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See detailAerated extraction columns for in situ separation of bio-based diamines from cell suspensions
Bednarz, Andreas; Jupke, Andreas; Spieß, Antje C. et al

in Journal of Chemical Technology and Biotechnology (2019), 94(2), 426-434

BACKGROUND: Extraction is the method of choice for separating sensitive products. For example, it has been applied in aromatics and rare-earth metal separation. Recently, biotechnological processes ... [more ▼]

BACKGROUND: Extraction is the method of choice for separating sensitive products. For example, it has been applied in aromatics and rare-earth metal separation. Recently, biotechnological processes entered the field of bulk chemicals andmight benefit fromprocess intensification by in situ extraction of inhibiting products, however in the presence of cells and/or aeration. This study applies reactive extraction of the polyamide monomer hexane-1,6-diamine fromcell-containingmedium. RESULTS: To prove technical feasibility of this reactive extraction, simulation of the extraction column based on single-drop measurements was validated at pilot-scale. Simulated results show good accordance with experimental data with an error below 20%. The extraction column was subsequently used as a bioreactor with integrated aeration and product extraction applying a four-phase system investigating the effect on drop distributions and holdup of the dispersed phases. Interestingly, aeration increased the holdup up to five-fold and decreased themean drop size of the organic extractive phase by 30%, thereby potentially improving extraction efficiency. CONCLUSION: The ReDrop simulation tool is capable of predicting challenging separation processes like the reactive extraction of hexane-1,6-diamine with D2EHPA diluted in oleyl alcohol from a biotransformation medium. The process design enabled four-phase operation of the column with aeration, extractive organic phase and cell-containing continuous aqueous phase. [less ▲]

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See detailSo gelingt unsere Zukunft
Pfennig, Andreas ULiege

Speech/Talk (2018)

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See detailSeparation and Purification 2018
Pfennig, Andreas ULiege

Report (2018)

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See detailDrop-Based Modelling of Coalescence in Batch Settlers Including Polydispersity
Leleu, David ULiege; Pfennig, Andreas ULiege

Scientific conference (2018, October 26)

The design of gravity settlers for the separation of liquid-liquid dispersions requires experimental characterization of coalescence behavior of any specific material system of interest, e.g. in lab-scale ... [more ▼]

The design of gravity settlers for the separation of liquid-liquid dispersions requires experimental characterization of coalescence behavior of any specific material system of interest, e.g. in lab-scale standardized settling experiments. Such experiments are required, because trace impurities strongly affect coalescence between drops as well as between drops and planar interface. To evaluate such experiments, suitable models and simulation tools are required. To be able to account for all details acting on the drops during sedimentation and coalescence, a simulation tool based on the ReDrop concept has been developed, which simulates the behavior of dedicated individual representative drops. The behavior of these drops can then be described by drop-based models, which characterize sedimentation and coalescence behavior. For characterization of coalescence, available models have been evaluated. Basis is the work of Kopriwa, who validated experimentally that the individual contributions as depicted in the schematic diagram below depend on either the fluid dynamics of the equipment or the material system. Evaluation of various literature studies revealed e.g. that the contact time as used in previous work was introduced in an inconsistent manner and that on top of the coalescence probability a probability has to be accounted for that the drops bounce when they meet and thus don’t stay in contact at all. Based on this systematic evaluation, different contributions have been proposed and combined, which allow very generally to describe coalescence under very different boundary conditions in a consistent way. This model has been implemented in a ReDrop simulation tool, which can be used to evaluate lab-scale settling tests and to design batch settlers. First results reveal that coalescence during sedimentation, which has often been neglected previously, has a significant impact on the results. It turns out that for some characteristic systems the drop size, which determines sedimentation, is actually obtained during a ripening process of several seconds, which explains the lag time often found in settling experiments. Also it turns out that the so-called close-packed zone is actually often not closely packed, i.e. that the drops in that zone are actually not in direct contact, which in turn of course influences their coalescence probability. The model concept will be presented together with exemplary simulation results. [less ▲]

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See detailBio-Economy: Chances, Risks, and Perspectives for the System as a Whole
Pfennig, Andreas ULiege

Scientific conference (2018, October 01)

The challenges for humanity are clear: We need to reduce the consumption of fossil resources and substitute them by sustainable technologies. This implies the use of renewable feedstock also in chemical ... [more ▼]

The challenges for humanity are clear: We need to reduce the consumption of fossil resources and substitute them by sustainable technologies. This implies the use of renewable feedstock also in chemical industry like bio-based raw material or carbon dioxide. On the different options for feedstock and for technologies to be applied a lot has been published. Why one or the other of the multitude of options is more promising than the other may not always be obvious. To gain some realistic insight, the feedstock change is put into perspective with the overall challenges of humanity, namely climate change, energy transition, and world hunger. As a result it becomes obvious that the feedstock change may be required within a relatively short transition period. The major feedstock and technology options are discussed and put into relation to these boundary conditions and among each other. Main focus is on bulk chemicals like polymers. Some promising principal routes are described addressing also the practical challenges of their realization, e.g. including supply, conversion, and distribution. [less ▲]

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See detailINFLUENCE OF DRYING ON THE RECOVERY OF PHOSPHORUS FROM WASTEWATER SLUDGE
Fraikin, Laurent ULiege; Shariff, Zaheer Ahmed ULiege; Pfennig, Andreas ULiege et al

Poster (2018, September 13)

The North West Europe (NWE) Interreg Phos4You (P4Y) project addresses the phosphorus (P) challenge. P is a nutrient essential for all living organisms. Though it is a finite resource on earth, P is ... [more ▼]

The North West Europe (NWE) Interreg Phos4You (P4Y) project addresses the phosphorus (P) challenge. P is a nutrient essential for all living organisms. Though it is a finite resource on earth, P is largely wasted today. The EU acknowledged this by adding phosphate rock to its list of critical raw materials in 2014. There is a need to boost the use of secondary raw P. The project addresses rural, urban and port areas in NWE. P is needed in rural areas as fertilizer or feed additive (often produced in port areas). P is transferred within food to urban areas where 82% of NWE-citizens live in (World Bank, 2015), and wasted there, via sewage and waste. P4Y specifically targets recovery from municipal waste water treatment plants. In 2015 NWE imported 100% of its mineral P-needs. 45% of the demand could be supplied by circular economy. The project will exploit the recovery potential of P in municipal sewage water (113,000 t/y P), estimated to cover 26% of the mineral P-demand in NWE. To achieve this change, P4Y supports 44 enterprises by producing demonstrators in real life conditions of 6 P-recovery technologies for municipal sewage water. One of these new technologies for P recovery will be developed at ULiège. The novelty of this process is that it treats directly the raw sludge instead of ashes obtained from incineration, as encountered in many processes. The idea is to directly leach the sludge with acids and to remove the solid residue. Afterwards, the aqueous liquor is purified thanks to an organic extraction to remove the heavy metals. Finally, the phosphorus is precipitated in calcium salts. For the development of this process one key issue is to find the optimal water content at which sludge will be leached. Indeed, the water present in the sludge will dilute the acid and reduce the leaching capacity while increasing the consumption of raw acids. On another side, a dried sludge has other properties such as wettability or porosity developed during the drying. However, dry sludge may need an additional grinding step and request other technologies to handle the so formed powder. The first leaching tests performed on sludge with different levels of dryness obtained by a combination of dewatering and convective drying are running. The influence of the drying step on the whole P recovery process will be illustrated during the presentation. [less ▲]

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Peer Reviewed
See detailSeparation efficiency and design optimization of gravity settlers – CFD modeling and experimental investigation
Charlafti, Eugenia; Leleu, David ULiege; Steinhoff, Jan et al

Conference (2018, September 12)

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See detailBio-Ökonomie: Chancen, Risiken und Blick auf das Gesamtsystem
Pfennig, Andreas ULiege

Conference (2018, September 11)

The challenges for humanity are clear: We need to reduce the consumption of fossil resources and substitute them by sustainable technologies. This implies the use of renewable feedstock also in chemical ... [more ▼]

The challenges for humanity are clear: We need to reduce the consumption of fossil resources and substitute them by sustainable technologies. This implies the use of renewable feedstock also in chemical industry like bio-based raw material or carbon dioxide. On the different options for feedstock and for technologies to be applied a lot has been published. Why one or the other of the multitude of options is more promising than the other may not always be obvious. To gain some realistic insight, the feedstock change is put into perspective with the overall challenges of humanity, namely climate change, energy transition, and world hunger. As a result it becomes obvious that the feedstock change may be required within a relatively short transition period. The major feedstock and technology options are discussed and put into relation to these boundary conditions and among each other. Main focus is on bulk chemicals like polymers. Some promising principal routes are described addressing also the practical challenges of their realization, e.g. including supply, conversion, and distribution. [less ▲]

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See detailBio‐Economy: Chances, Risks, and Perspective of the System as a Whole
Pfennig, Andreas ULiege

in Chemie Ingenieur Technik (2018), 90(9), 1140-1141

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See detailSeparation efficiency and design optimization of gravity settlers – CFD modeling and experimental investigation
Charlafti, Eugenia; Leleu, David ULiege; Steinhoff, Jan et al

in Chemie Ingenieur Technik (2018), 90(9), 1311

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See detailA discrete modeling approach for excess Gibbs-energy models based on discrete Markov-chains
Mayer, Christoph; Pfennig, Andreas ULiege; Wallek, Thomas

Conference (2018, August 28)

Detailed reference viewed: 17 (1 ULiège)
See detailSo gelingt unsere Zukunft
Pfennig, Andreas ULiege

Book published by Books on Demand (2018)

Wir können unsere Zukunft glücklich und nachhaltig gestalten, wenn wir unsere Welt als vernetztes System begreifen und danach handeln. Wie werden wir als Menschheit die nächsten hundert Jahre überleben ... [more ▼]

Wir können unsere Zukunft glücklich und nachhaltig gestalten, wenn wir unsere Welt als vernetztes System begreifen und danach handeln. Wie werden wir als Menschheit die nächsten hundert Jahre überleben? Was bedeuten die anstehenden Herausforderungen wie Klimawandel, Energiewende und Welthunger für uns individuell? Um eine positive Per-spektive für unsere Zukunft zu entwickeln, müssen wir zunächst unsere Stellung als Mensch in der Welt begreifen und erkennen, wie wir in unsere Umwelt eingebettet sind. Dazu wird eine Systemsicht der Welt anschaulich beschrieben. Unser Platz als Mensch in diesem System wird dann nachvoll-ziehbar daraus abgeleitet. Gleichzeitig erhält der Leser einen tiefen Ein-blick in das Wesen der Realität mit ihren vielfältigen Facetten. Fragen, die beantwortet werden sind: Was unterscheidet Körper und Geist? Wie kann unser Wille frei sein, wenn die Naturgesetze alles Geschehen unveränder-bar vorherbestimmen? Wie funktioniert unser Bewusstsein und wie kön-nen wir bewusste Entscheidungen treffen? Wieso sind wir für unser Tun verantwortlich? Das so entwickelte Gesamtbild zeichnet schließlich eine klare Richtung für unser Handeln vor, damit ein nachhaltiges und glückli-ches Leben auf unserem kleinen Planeten Erde auch in Zukunft gelingt. [less ▲]

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See detailOn the strong influence of molecular interactions over large distances
Pfennig, Andreas ULiege

in European Physical Journal D -- Atoms, Molecules, Clusters and Optical Physics (2018), 72(March, paper 45), 1-8

Molecular-dynamics simulations of liquid water show deterministic chaos, i.e. an intentionally introduced molecular position shift of an individual molecule increases exponentially by a factor of 10 in 0 ... [more ▼]

Molecular-dynamics simulations of liquid water show deterministic chaos, i.e. an intentionally introduced molecular position shift of an individual molecule increases exponentially by a factor of 10 in 0.23 ps. This is a Lyaponov instability. As soon as it reaches molecular scale, the direction of the resulting shift in molecular motions is unpredictable. The influence of any individual distant particle on an observed molecule will be minute, but the effect will quickly increase to molecular scale and beyond due to this exponential growth. Consequently, any individual particle in the universe will affect the behavior of any molecule within at most 33 ps after the interaction reaches it. A larger distance of the faraway particle does not decrease the influence on an observed molecule, but the effect reaches molecular scale only some ps later. Thus in evaluating the interactions, nearby and faraway molecules have to be equally accounted for. The consequences of this quickly reacting network of interactions on universal scale are fundamental. Even in a strictly deterministic view, molecular behavior is principally unpredictable, and thus has to be regarded random. Corresponding statements apply for any particles interacting. This result leads to a fundamental rethinking of the structure of interactions of molecules and particles as well as the behavior of reality. [less ▲]

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See detailOur Successful Future - Video Series on YouTube
Pfennig, Andreas ULiege

Speech/Talk (2018)

Climate change is a topic of increasing urgency. Since the COP21 Paris Agreement in 2015 everthing appears to be settled. But is this so? How can the climate issues actually be solved? How can we change ... [more ▼]

Climate change is a topic of increasing urgency. Since the COP21 Paris Agreement in 2015 everthing appears to be settled. But is this so? How can the climate issues actually be solved? How can we change our energy system to become sustainable? Which other aspects do these changes touch? What do these challenges and changes mean for myself? The first series of videos asks these questions and tries to give competent answers. The evaluations are based on publicly available data, which are put into relation such that the major drivers become obvious. The consequences and conclusions also for our individual life are explained. The structure is explained in the first video. The videos on exergy and bioeconomy regard some detailed challenges of bio-economy. The conclusions then summarize the findings and results. The final videos of the series answer on a more philosophical basis the question why we are personally responsible for our sustainable life. The videos are: 00 Very Short Summary 01 Introduction, Summary 02 World Population 03 Sustainable Energy Transition 04 Food vs. Bio-Energy & Bio-Materials 05 A Word on IPCC Scenarios 06 A Short Word on EU Sustainable Energy Strategy 07 Exergy to Quantify Energy 08 Bio- or CO2-Economy 09 Individual and Political Consequences Philosophical Aspects: 10 The Physical Basis 11 Causality 12 Consciousness 13 Free Will and Responsibility [less ▲]

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