References of "Pfennig, Andreas"
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See detailOptimization of settling behavior for an efficient solvent-extraction process for bio-based components
Bednarz, Andreas; Scherübel, Peter; Spieß, Antje C. et al

in Chemical Engineering and Technology (in press)

Extraction is a downstream-process option in bio-based processes. Since the knowledge of phase-separation behavior is essential for designing efficient separation processes, this study investigates the ... [more ▼]

Extraction is a downstream-process option in bio-based processes. Since the knowledge of phase-separation behavior is essential for designing efficient separation processes, this study investigates the settling and coalescence behavior of bio-based extraction systems using a standard lab-scale settling cell. The influence of different buffer media as well as of E. coli cells on coalescence was determined for the reactive extraction of hexane-1.6-diamine with isostearic acid and D2EHPA using kerosene and oleyl alcohol as diluents. As a result, an increasing pH value of the buffer significantly increases settling time. The presence of E. coli cells hinders the phase separation of the investigated systems, in particular with dispersed organic phases. [less ▲]

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See detailIndustrial Integration of Biotechnological Processes from Raw Material to Energy Integration: Study by Modeling Approach
Léonard, Grégoire ULg; Pfennig, Andreas ULg; Celebi, Ayse Dilan et al

in Darvishi, Farshad; Hiligsmann, Serge (Eds.) Microbial Fuels: Technologies and Applications (in press)

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See detailStandardized Settling Cell Design
Leleu, David ULg; Pfennig, Andreas ULg

Scientific conference (2017, July)

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See detailDownstream Design for Biobased Processes
Pfennig, Andreas ULg

Conference (2017, May 11)

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See detailWelcome & Overview ChemEng Liège
Pfennig, Andreas ULg

Conference (2017, May 11)

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See detailSurrogate Generation and Evaluation for Biodiesel and Its Mixtures with Fossil Diesel
Reiter, Anton M.; Schubert, Nikolai; Pfennig, Andreas ULg et al

in Energy & Fuels (2017), 31

In this paper a precedently developed surrogate optimization algorithm for fossil fuels, which originally allowed simultaneous fitting of the true boiling point (TBP) curve, the liquid density at 15 °C ... [more ▼]

In this paper a precedently developed surrogate optimization algorithm for fossil fuels, which originally allowed simultaneous fitting of the true boiling point (TBP) curve, the liquid density at 15 °C, and the cetane number, is refined toward its application to biodiesel and its mixtures with fossil diesel. For this purpose, the algorithm is extended (1) to also include fitting of the kinematic viscosity at 40 °C and (2) to account for peculiarities of biodiesel concerning its narrow boiling range and compensation of systematic errors of measured boiling curves. To illustrate these improvements, first, the algorithm is applied to property estimation and surrogate optimization of three different biodiesel fuels, for which surrogates consisting of one to three components are proposed. Second, a surrogate for a commercial European fossil diesel is calculated and produced in lab-scale. Finally, the algorithm is used for surrogate optimization and property estimation of mixtures of biodiesel and fossil diesel, considering fractions of biodiesel of 7% and 20% per volume. It is shown that the improved algorithm is capable of reliably optimizing surrogates for fuels containing both biogenic and fossil components. [less ▲]

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See detailStandardized Settling Cell Design
Leleu, David ULg; Pfennig, Andreas ULg

Scientific conference (2017, March 07)

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See detail„Branntwein AG“ an der Uni Lüttich
Pfennig, Andreas ULg; Meyer, Karin; Herff, Sandra

Speech/Talk (2017)

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See detailReactive and physical extraction of bio-based diamines from fermentation media
Bednarz, Andreas; Spieß, Antje C; Pfennig, Andreas ULg

in Journal of Chemical Technology & Biotechnology (2017), 92

BACKGROUND: The production of polymers constitutes the major mass flow in the chemical industry. The foreseeable future change from fossil to renewable resources leads to the demand for more production ... [more ▼]

BACKGROUND: The production of polymers constitutes the major mass flow in the chemical industry. The foreseeable future change from fossil to renewable resources leads to the demand for more production routes based on biotechnological conversions. These routes preferably require biocompatible components and possess certain limitations of temperature and pH value for the corresponding downstream processing, which can be met by liquid–liquid extraction. This study investigates the extraction of the monomers hexane-1,6-diamine and butane-1,4-diamine from fermentation media using bis(2-ethylhexyl) hydrogen phosphate and isostearic acid as reactive extractants and kerosene as well as oleyl alcohol as diluents. RESULTS: As expected, the degree of extraction strongly depends on the pH-value but only weakly on the diluents. A higher diluent polarity leads to a slightly higher degree of extraction at a given pH value. The fraction of reactive extractant can be used to adjust theminimal pH value to reach the desired degree of extraction. No significant influence of fermentationmedium, buffer, presence of an E. coli microorganism, or temperature was detected. CONCLUSION: Reactive extraction of bio-based diamines with organic acids is feasible. The degree of extraction can be adjusted by the fraction of reactive extractant. [less ▲]

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See detailBiobased Processes: Systematically Evaluating Chances and Challenges
Pfennig, Andreas ULg

Conference (2016, November 21)

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See detailMethodik zur schnellen Bewertung von Syntheserouten auf Basis von Exergiebilanzen
Frenzel, Philipp; Pfennig, Andreas ULg

Conference (2016, September 13)

Heutige chemische Produkte basieren fast ausschließlich auf erdölbasierten Rohstoffen. Aufgrund weltweiter Bemühungen, die Abhängigkeit von fossilen Rohstoffen zu reduzieren, wird in den letzten Jahren ... [more ▼]

Heutige chemische Produkte basieren fast ausschließlich auf erdölbasierten Rohstoffen. Aufgrund weltweiter Bemühungen, die Abhängigkeit von fossilen Rohstoffen zu reduzieren, wird in den letzten Jahren verstärkt die Nutzung alternativer Kohlenstoffquellen wie Biomasse oder CO2 erforscht. Die alternativen Kohlenstoffquellen unterscheiden sich hinsichtlich ihrer Zusammensetzung und Stoffeigenschaften teilweise deutlich von fossilen Rohstoffen. Aus diesem Grund müssen Syntheserouten und darauf aufbauende Prozesse neu entwickelt werden. Da zum einen sehr viele Syntheserouten prinzipiell denkbar sind und zum anderen die Entwicklung der entsprechenden Prozesse aufwendig ist, wird eine Möglichkeit benötigt, begrenzte Entwicklungsressourcen sinnvoll zu steuern. Dazu sollte bereits in einem frühen Entwicklungsstadium ein quantitativer Vergleich der Syntheserouten erfolgen, um diejenigen zu identifizieren, die das größte wirtschaftliche Potential versprechen. In diesem Vortrag wird eine Methodik vorgestellt, um eine schnelle erste, auf Exergie basierte Bewertung des wirtschaftlichen Potentials einer Syntheseroute bereits in einem frühen Entwicklungsstadium durchzuführen, in dem nur wenige Informationen vorliegen. Die Idee der Methodik ist, Syntheserouten in standardisierten Prozessen abzubilden, wodurch eine automatisierte Auswertung und somit ein schnelles Screening möglich wird. Die standardisierten Prozesse umfassen sowohl den Einfluss der Reaktion durch Abbildung der Reaktionsbedingungen, Stöchiometrie, Umsatz und Selektivität als auch die Auswirkungen der Trennaufgabe. Ebenso berücksichtigt wird die Rückführung von Lösungsmitteln und ggf. nicht umgesetzten Edukten. Als zentrale Bewertungsgröße zur Abschätzung des wirtschaftlichen Potentials wird eine Kombination aus Exergie- und Rohstoffeinsatz herangezogen. Der Vorteil von Exergiebilanzen gegenüber Energiebilanzen ist, dass die Produktion von Entropie berücksichtigt wird und so die Auswirkungen einzelner Prozessschritte untersucht und zwischen verschiedenen Energieformen unterschieden werden kann. Durch Berechnung der Exergieverluste, also der Verluste von Exergie aufgrund von Entropieerzeugung in den Prozessen, ergibt sich ein quantitativer Vergleich verschiedener Syntheserouten. [less ▲]

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See detailIntegrated Project with Focus on Energy Transition and Circular Economy for Developing Engineering Students' Soft Skills
Léonard, Grégoire ULg; Pfennig, Andreas ULg; Toye, Dominique ULg et al

Poster (2016, September 05)

The present work reports the experience of an integrated project developed at the University of Liege for master students in chemical engineering. The goals are to promote the acquisition of soft skills ... [more ▼]

The present work reports the experience of an integrated project developed at the University of Liege for master students in chemical engineering. The goals are to promote the acquisition of soft skills and to consolidate technical knowledge by integrating and linking chemical engineering disciplines usually taught separately. A case study was selected to address some of the challenges related to energy transition: students had to design the energy system of a remote island and make it as energy independent and CO2-neutral as possible by 2030. The course of action during the academic year, the assessment of soft skills, and the tools offered to ease the mentoring and encourage the acquisition of soft skills are described. Not all implemented techniques performed equally well, and this project finally appeared to be a challenge for the teaching team as well. 1 Introduction and background Over the last few years, University authorities, industrial partners as well as national and international experts that evaluated the education quality of our Department (AEQES, CTI) strongly suggested that opportunities should be offered to students to increase their soft skills as part of their curriculum. Moreover, many developments in chemical engineering are related to energy transition and circular economy, which are both transdisciplinary to conventional lectures. In this paper, we present methods and mentoring tools developed to teach students technical and soft skills for multi-disciplinary topics. 2 Description of the integrated project Objectives and constraints were defined at the onset of the project for both technical and soft skills. The technical objective was to propose an energy system that would make Reunion Island as energy independent and CO2-neutral as possible by 2030. This idea originated in the challenge set by the Eurecha 2015 student contest[1], for which students had to design facilities for a sheikhdom: electricity, water recycling, production of fertilizers… In our case, Reunion Island (~850 000 inhabitants) was considered as a case study as it is remote, has large biomass resources and high potential for renewable energies. Besides the objectives mentioned above and in order to force students to look at chemical engineering processes, the treatment of wastewater was imposed as well as the use of a synthetic liquid fuel as energy carrier. The targeted soft skills included working in large groups of minimum 4 students, efficient communication of results in English - both written and oral -, ability to integrate knowledge from various disciplines, development of critical mind and demonstration of independent and creative thinking. 3 Course of actions A team of 8 professors and senior scientists mentored the project and contributed to its assessment. The 10-ECTS project was divided in two parts. In the fall semester, students made global energy balances to design the energy system that would fulfill the objectives. As a result, a Sankey diagram of the energy flows on Reunion Island by 2030 was produced to allow for an overview of the available Island’s resources and needs, as well as of processes that can make the link between resources and needs. In the spring semester, two processes identified in the first part, namely the synthesis of bio-ethanol and bio-methanol, were modelled in more details using commercial software. Different tools were used to encourage student initiatives and work: • The use of a shared on-line portfolio for students to gather their documents improved their internal communication, but this remained a marginal channel for communication with teachers • In the fall semester, students orally presented progress reports every two weeks. After a feedback to students, the teaching team met to discuss the achievements and set the objectives for the next two weeks. This was very positive for the communication inside the teaching team. However, presentations every fortnight implied a work overload for students that had to constantly focus on preparing the presentations. • From the beginning, students were strongly encouraged to reach out to field experts whose contacts were provided. However, they preferred to rely mostly on Internet as their main source of information and reached out only rarely for help and usually very late. • In the fall semester, students had to designate new team leaders in turn every fortnight. This was abandoned as it prevented the establishment of clear structures in the group, reducing its efficiency. • In the spring semester, work tables allowed students to work directly with the teacher specialized in their task. This was appreciated by students and teachers, and it needs to be further encouraged. • Help in the group organization and interactions was provided by the PSGO (psychology of groups and organizations). This also included videoscopy, i.e. filming the students during their presentations and analyzing the records with them. This help was appreciated by students. The assessment was based on technical results for 60%, and soft skills for 40%. The evaluation of technical skills was done partly by all teachers equally and partly by teachers whose expertise was the closest to the technical sub-tasks. For soft skills, efficient communication, creativity in the work and results and links with conventional lectures were assessed. Critical thinking was evaluated through the relevance of qualitative and quantitative results and discussions. Group work was assessed by the teachers as well as by students through mutual evaluation. 4 Conclusions and perspectives The integrated project gave students a first opportunity to improve their soft skills along with their technical knowledge. It also improved their communication skills and their fluency in English. The teaching team proposed different mentoring techniques to encourage efficient work, with varying results. Finally, as the assessment ignored soft skills improvements, it may be modified by evaluating soft skills all year long so both the final result and the observed improvements contribute to the grade. Reference Eurecha, The European Committee for the Use of Computers in Chemical Engineering Education, 2015. Announcement for student contest problem competition 2015. http://bari.upc.es/eurecha/. [less ▲]

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See detailInternet Platforms for Education on Sustainability
Pfennig, Andreas ULg

Conference (2016, September 05)

One challenge in teaching sustainability results from the expertise being distributed in various universities. At the same time society would not require so many experts focused on sustainability that ... [more ▼]

One challenge in teaching sustainability results from the expertise being distributed in various universities. At the same time society would not require so many experts focused on sustainability that corresponding purely sustainability-oriented curricula should be offered in a majority of universities. Thus sustainability aspects have to be integrated into existing curricula e.g. in chemical engineering studies. To offer sufficiently high-level courses or teaching content, one way is to share modules dealing with sustainability aspects. The idea to share teaching capabilities on a national or international level is not new, some examples are sustainicum.at, bioenergytrain.eu. While these approaches address the topic of sustainability with a relatively wide variety of facets, it is difficult to see, how a coherent picture can be obtained and transferred in education to students and the interested public. While this is so, already regarding the most basic element of the versatile toolbox of chemical engineering, namely setting up and solving simple balances, leads to significant insights and especially a fundamental understanding on the basic interplay of at least some of the major drivers. These are – besides increasing world population, which is the main driver – the increasing energy consumption, the limited land area for food and bioenergy production, the finite size even of the atmosphere leading to an increase in CO2 concentration and climate change, to name just a few. All of these aspects refer to limited resources for which balances can be set up and solved. The balances have the advantage that they are so simple that everybody can assess their validity and implications. The experience with working out a corresponding teaching module will be presented exemplarily. To facilitate delivering the aspects to students and the interested public the teaching material including a full manuscript and power-point slides have been worked out and are supplied at sustainicum.at. To allow easy access to the content of this teaching material also corresponding lectures have been recorded and are made publicly available through YouTube. The technical boundary conditions, which were found to be quite optimal as compared to other public lectures available on the internet, will be presented. The teaching material has in the past also been used for a variety of own presentations with the aim to deliver the basic understanding to an interested public, including public conference series or school classes. From these various experiences conclusions are drawn which will be presented. Introduction: One challenge in teaching sustainability results from the expertise being distributed in various universities. At the same time society would not require so many experts focused on sustainability that corresponding purely sustainability-oriented curricula should be offered in a majority of universities. Thus sustainability aspects have to be integrated into existing curricula e.g. in chemical engineering studies. To offer sufficiently high-level courses or teaching content, one way is to share modules dealing with sustainability aspects. The idea to share teaching capabilities on a national or international level is not new, some examples are sustainicum.at, bioenergytrain.eu. While these approaches address the topic of sustainability with a relatively wide variety of facets, it is difficult to see, how a coherent picture can be obtained and transferred in education to students and the interested public. Exemplary Topic: While this is so, already regarding the most basic element of the versatile toolbox of chemical engineering, namely setting up and solving simple balances, leads to significant insights and especially a fundamental understanding on the basic interplay of at least some of the major drivers. These are – besides increasing world population, which is the main driver – the increasing energy consumption, the limited land area for food and bioenergy production, the finite size even of the atmosphere leading to an increase in CO2 concentration and climate change, to name just a few. All of these aspects refer to limited resources for which balances can be set up and solved. The balances have the advantage that they are so simple that everybody can assess their validity and implications. The experience with working out a corresponding teaching module will be presented exemplarily. Results and Conclusions: To facilitate delivering the aspects to students and the interested public the teaching material including a full manuscript and power-point slides have been worked out and are supplied at sustainicum.at. To allow easy access to the content of this teaching material also corresponding lectures have been recorded and are made publicly available through YouTube. The technical boundary conditions, which were found to be quite optimal as compared to other public lectures available on the internet, will be presented. The teaching material has in the past also been used for a variety of own presentations with the aim to deliver the basic understanding to an interested public, including public conference series or school classes. From these various experiences conclusions are drawn which will be presented. [less ▲]

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See detailSystematic Downstream Development, Optimization and Equipment Design for Biobased Products and Processes
Bednarz, Andreas; Rüngeler, Bettina; Scherübel, Peter et al

in Chemie Ingenieur Technik (2016, September), 88(9), 1375-1376

Biobased synthesis poses specific challenges due to the properties of raw materials, intermediates, and products. They are induced by the higher oxygen content as compared to fossil feedstock. Thus low ... [more ▼]

Biobased synthesis poses specific challenges due to the properties of raw materials, intermediates, and products. They are induced by the higher oxygen content as compared to fossil feedstock. Thus low vapor pressure, higher viscosity, low concentration in aqueous solution will require new, preferably liquid-based downstream processes, for which many different options can be proposed. A systematic method to evaluate such a multitude of options based on cascaded option trees is presented, which combines representation and evaluation of options on a suitably chosen level of detail. Criteria, which have to be fulfilled by the options, are flexibly evaluated ranging from input of experts to detailed simulation. Clear visualization also allows transparent communication of results to members of interdisciplinary teams and project partners. The method is demonstrated for extractive separation steps including real-world problems encountered. This includes high viscosities, presence of solids or microorganisms leading to crud formation, and optimization of process conditions solving the conflicting challenges balancing e.g. between low toxicity to microorganisms and process efficiency. [less ▲]

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See detailMethodik zur schnellen Bewertung von Syntheserouten auf Basis von Exergiebilanzen
Frenzel, Philipp; Pfennig, Andreas ULg

in Chemie Ingenieur Technik (2016), 88(9), 1381

Heutige chemische Produkte basieren fast ausschließlich auf erdölbasierten Rohstoffen. Aufgrund weltweiter Bemühungen, die Abhängigkeit von fossilen Rohstoffen zu reduzieren, wird in den letzten Jahren ... [more ▼]

Heutige chemische Produkte basieren fast ausschließlich auf erdölbasierten Rohstoffen. Aufgrund weltweiter Bemühungen, die Abhängigkeit von fossilen Rohstoffen zu reduzieren, wird in den letzten Jahren verstärkt die Nutzung alternativer Kohlenstoffquellen wie Biomasse oder CO2 erforscht. Die alternativen Kohlenstoffquellen unterscheiden sich hinsichtlich ihrer Zusammensetzung und Stoffeigenschaften teilweise deutlich von fossilen Rohstoffen. Aus diesem Grund müssen Syntheserouten und darauf aufbauende Prozesse neu entwickelt werden. Da zum einen sehr viele Syntheserouten prinzipiell denkbar sind und zum anderen die Entwicklung der entsprechenden Prozesse aufwendig ist, wird eine Möglichkeit benötigt, begrenzte Entwicklungsressourcen sinnvoll zu steuern. Dazu sollte bereits in einem frühen Entwicklungsstadium ein quantitativer Vergleich der Syntheserouten erfolgen, um diejenigen zu identifizieren, die das größte wirtschaftliche Potential versprechen. In diesem Vortrag wird eine Methodik vorgestellt, um eine schnelle erste, auf Exergie basierte Bewertung des wirtschaftlichen Potentials einer Syntheseroute bereits in einem frühen Entwicklungsstadium durchzuführen, in dem nur wenige Informationen vorliegen. Die Idee der Methodik ist, Syntheserouten in standardisierten Prozessen abzubilden, wodurch eine automatisierte Auswertung und somit ein schnelles Screening möglich wird. Die standardisierten Prozesse umfassen sowohl den Einfluss der Reaktion durch Abbildung der Reaktionsbedingungen, Stöchiometrie, Umsatz und Selektivität als auch die Auswirkungen der Trennaufgabe. Ebenso berücksichtigt wird die Rückführung von Lösungsmitteln und ggf. nicht umgesetzten Edukten. Als zentrale Bewertungsgröße zur Abschätzung des wirtschaftlichen Potentials wird eine Kombination aus Exergie- und Rohstoffeinsatz herangezogen. Der Vorteil von Exergiebilanzen gegenüber Energiebilanzen ist, dass die Produktion von Entropie berücksichtigt wird und so die Auswirkungen einzelner Prozessschritte untersucht und zwischen verschiedenen Energieformen unterschieden werden kann. Durch Berechnung der Exergieverluste, also der Verluste von Exergie aufgrund von Entropieerzeugung in den Prozessen, ergibt sich ein quantitativer Vergleich verschiedener Syntheserouten. [less ▲]

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See detailDiscrete Modeling: The Concept of Shannon Entropy used for Thermodynamic Model Development
Wallek, Thomas; Pfleger, Martin; Pfennig, Andreas ULg

Conference (2016, August)

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See detailLiquid Cation Exchanger
Erhardt, Frank; Haas, Thomas; Roos, Daniel et al

Patent (2016)

The invention relates to a method for removing an organic compound having one or more positive charges from an aqueous solution. Said method consists of the following steps a) the aqueous solution ... [more ▼]

The invention relates to a method for removing an organic compound having one or more positive charges from an aqueous solution. Said method consists of the following steps a) the aqueous solution containing the organic compound, and a hydrophobic organic solution which contains a hydrophobic liquid cation exchanger having one or more negative charges and a negative total charge, are provided, b) the aqueous solution and the organic solution are brought into contact with each other and c) the organic solution is separated from the aqueous solution. [less ▲]

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See detailGel Beads to Investigate Sedimentation
Leleu, David ULg; Pfennig, Andreas ULg

Conference (2016, March 14)

Separation of liquid-liquid dispersions with multiple phases involves different interactions between the different dispersed species present in the system, which makes it difficult to predict e.g. the ... [more ▼]

Separation of liquid-liquid dispersions with multiple phases involves different interactions between the different dispersed species present in the system, which makes it difficult to predict e.g. the separation behaviour. Nevertheless such systems are relevant in chemical engineering e.g. for systems involving gas bubbles and simultaneously solid particles like in a fermentation broth. Models for describing the sedimentation behaviour as a basis for settler design are available in principle but have not been systematically validated for variation in size-distribution and e.g. density differences between the various species in the system. Thus, to design technical separation equipment, the separation process has to be better understood, which requires the study of the sedimentation as a first step. This project is focused on the interactions which may occur between each species during the sedimentation e.g. the effect on sedimentation of descending particles when they meet ascending drops. However, a proper study of the sedimentation with fluid phases is difficult due to other phenomena occurring simultaneously, e.g. coalescence. To overcome this issue, the use of gel beads is proposed, which due to their solid interface cannot coalesce. In addition, it is easy to define their parameters which are the density, the hardness and the size distribution. Besides, they can also be preserved during an extended period of time, experiments can thus be reproduced many times with identical beads. During the project, gel beads are designed with different particle size distributions and with different densities. Different batches of the produced gel beads will be mixed to simulate systems with different dispersed phases discriminated via density and different size distributions. With these multiple dispersed phases Experiments will be performed in a settling cell in order to evaluate the overall sedimentation velocity at certain hold up. Simultaneously a new method for measurement of local hold-up profile in the dispersion is tested, which allows hold-up measurement even in opaque systems. Finally sedimentation models found in the literature are compared and adapted to experimental results for predict the sedimentation of systems which involve different dispersed phases. In the presentation the new hold-up measurement will be presented together with an error analysis, experiments on the sedimentation of multiple dispersed phases and the model evaluation will be presented. [less ▲]

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See detailDiscrete Modeling of Lattice Systems: The Concept of Shannon Entropy Applied to Strongly Interacting Systems
Wallek, Thomas; Pfleger, Martin; Pfennig, Andreas ULg

in Industrial & Engineering Chemistry Research (2016), 55(8), 2483-2492

Discrete modeling is a novel approach that uses the concept of Shannon entropy to develop thermodynamic models that can describe fluid-phase behavior. While previous papers have focused on reviewing its ... [more ▼]

Discrete modeling is a novel approach that uses the concept of Shannon entropy to develop thermodynamic models that can describe fluid-phase behavior. While previous papers have focused on reviewing its theoretical background and application to the ideal-gas model as one limiting case for fluid phases, this paper addresses its application to lattice models for strongly interacting condensed phase systems, which constitute the other limiting case for fluids. The discrete modeling approach is based on the discrete energy classes of a lattice system of finite size, represented by a distribution of discrete local compositions. In this way, the model uses the same level of discretization as classical statistical thermodynamics in terms of its partition functions, yet avoids (1) a priori averaging of local compositions by utilizing a distribution, and (2) confinement to systems of infinite size. The subsequent formulation of the probabilities of discrete energy classes serves as the basis for introducing the concept of Shannon information, equivalent to thermodynamic entropy, and for deriving the equilibrium distribution of probabilities by constrained maximation of entropy. The results of the discrete model are compared to those derived from Monte Carlo simulations and by applying the Guggenheim model of chemical theory. We point out that this applicability of discrete modeling to systems of finite size suggests new possibilities for model development. [less ▲]

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See detailCharacterization of Coalescence in Extraction Equipment Based on Lab-Scale Experiments
Kopriwa, Nicole; Pfennig, Andreas ULg

in Solvent Extraction & Ion Exchange (2016), 34(7), 622-642

Design of an extraction apparatus is significantly influenced by the coalescence behavior of a given material system. At the same time, quantifying coalescence of a systemin anextraction columnis tedious ... [more ▼]

Design of an extraction apparatus is significantly influenced by the coalescence behavior of a given material system. At the same time, quantifying coalescence of a systemin anextraction columnis tedious, as pilot-plant experiments have to be performed. These tests have to be carried out for each systemindividually, as coalescence is strongly influenced by traces of impurities. On the other hand, coalescence behavior for designing mixer–settler processes can be quantified in simple discontinuous lab-scale settling tests. Therefore, it was the objective of this work to develop a method to characterize the coalescence behavior in extraction columns with minimal effort. For this purpose, different measurement techniques for quantifying coalescence were applied and compared. In order to transfer the results obtained in lab-scale experiments to model extraction columns, models available in the literature were tested and significantly modified. The new method allows separating the coalescence behavior in extraction columns into two factors: On the one hand, hydrodynamic effects determining, for example, the frequency of drop collisions and collision intensity have to be considered which depend on the geometry of a specific column and on the operating conditions, which have to be characterized only once for each column type.On the other hand, coalescence behavior of a specific material system has to be quantified only with a simple lab-scale settling experiment, which characterizes the approach of two drops and their individual coalescence process. The results of simulations for extraction columns based on this model approach compare very well with experimental data. Thus, this new approach allows a universal characterization of coalescence for all common extraction equipment, namely mixer–settlers as well as columns, where the system-specific coalescence is characterized in a simple lab-scale experiment. [less ▲]

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