bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamische Simulation von Wärmeübertragern
Authors: Botsch Tilman Walter , Stephan Karl 
Published: December 2004

AbstractSimulation of the Dynamic Behaviour of Heat Exchangers. Four models for heat exchangers under transient conditions are presented. Three of them describe a single phase heat exchanger, and the forth one is used for the simulation of a condenser. All models are of intermediate complexity and valid for simulation of both single heat exchangers and chemical processes. They use distributed variables and incorporate the calculation of local heat transfer coefficients so that temperature profiles over the apparatus can be determined in addition to the transient behaviour of the outlet variables.
Neue Thermoplastische Elastomere: Rezeptierung, Aufbereitung und Werkstoffeigenschaften
Authors: Fritz Hans‐Gerhard 
Published: December 2004

AbstractNew Thermoplastic Elastomers: Formulation; Compounding; and Material Properties. This article described novel thermoplastic elastomers (TPO) consisting of a PP matrix and a synthetic rubber phase crosslinked in a new way with organosilanes. The mechanical and rheological properties of the blend are determined primarily by the phase structures produced in the course of compounding. PE‐ULD can also be used as synthetic rubber in place of EP(D)M, with the attendant advantage of reduced swelling in oils.
Eine gefragte Unternehmer‐Tugend: Kommunikations‐Fähigkeit
Authors: Röglin Hans‐Christian 
Published: December 2004

AbstractOur modern industrial society produces not only goods but also distrust. Its confidence crisis is an expression of unsolved communication problems. The high degree of abstraction of modern technology and organisation makes the world incomprehensible. A fundamental change of attitudes removes traditional and familiar order without providing new orientation. A surfeit of information, due in part of television, leads to further disorientation. The basic mood of such an insecure society is a diffuse „angst”︁. This presents one of the great challenges of communication. A communication which can meet this challenge requires sincerity on the part of the persons involved, must be of the nature of a dialogue, i.e. open, and must be comprehensive, i.e. must address and express negative aspects. Only then can the kind of credibility arise which permits successful communication.
Validierung in der Prozeßleittechnik
Authors: Hensel Hartmut 
Published: December 2004

AbstractProcess control systems are being increasingly introduced in pharmaceutical production plant. They exercise quality‐relevant functions and are thus subject to legal requirements of validation. It must therefore be established and documented that a process control system fulfills specific requirements. The technical part of this task lies in qualification of the process control system. The present article described the basic principles of such process control system qualification, services for setting up a process control system with obligatory validation, qualification‐oriented control system functions, and support of the control system manufacturer in validation.
Formselektives Reformieren an zeolithhaltigen Reformierkatalysatoren
Authors: Meusinger Josefin , Neubauer Torsten , Reschetilowski Wladimir 
Published: December 2004

AbstractUse of bifunctional Pt/Al2O3 catalysts in catalytic reforming units significantly improved production. During the past four decades the power of such catalyst systems has been continuously increased by the introduction of various catalyst modifications. Use of reforming catalysts containing zeolites permits combination of shape selectivity with the conventional reforming reaction. Here, the suitability of an erionite containing catalyst for the reforming processes is demonstrated. Gasolines produced with zeolite catalysts are characterised by high values of octane numbers and low content of carinogenic benzene.
Gleichzeitige Erfassung von Partikelmerkmalen und Eigenschaften mehrphasiger Strömungen mit Hilfe der Phasen‐Doppler‐Anemometrie
Authors: Bauckhage Klaus 
Published: December 2004

AbstractWhile conventional phase‐Doppler anemometry (PDA) is already widely used for nonintrusive and simultaneous particle sizing and particle velocity measurements as well as for particle flux measurements in two phase and multiphase flows, there is a lack of knowledge surrounding the additional potential of PDA for particle material recognition and for concentration as well as temperature measurements on the base of rainbow angle displacements, for particle shape diagnosis and – if PDA extensions are used – for submicron sizing. This potential makes PDA most attractive to chemical enginering, i. e. to industrial processing and to research and development. Evaluation of recent PDA literature trends and procedures for setup optimisation as well as for raw data processing will be discussed.
Massen‐ und ortsfeste Betrachtungsweisen bei der Reaktormodellierung
Authors: Platzer Bernd 
Published: December 2004

AbstractDue to the development of computers one may have the impression that the differences between methods of fluid mechanics and of chemical reaction engineering are diminished. But important differences survive, and their disregard can lead to misunderstandings. The main difference is the domination of the mass related view in reaction engineering and of the position related view in hydrodynamics. The analysis of the fundamentals result in the incorporation of the reaction kinetics and of the residence time distribution. Taking this into account, the dispersion model and the convection diffusion model are compared and the character of the axial dispersion coefficient and of the boundary conditions are discussed. It can be seen, that a direct transformation of hydrodynamics results is not possible. The simulation of the life history of molecules and particles offer an alternative for this.
Hydrodynamische Beanspruchung von Rührorganen
Authors: Pahl Manfred H. , Knoch Achim 
Published: December 2004

AbstractMechanical design of agitation equipment requires information about the hydrodynamic stresses acting on impeller shafts, baffles, and vessels. In particular, vibrations induced in the generally freely supported impeller shafts impose very strong stresses on the shaft bearings at the natural frequency of the assembly and can lead to shaft fracture in extreme cases. Depending upon the speed of rotation, the surrounding medium acts as variable damping member owing to the differing flow conditions. This situation is examined in the present article.
Zur Verfestigung von Schüttgütern – Mikroprozesse und Kinetikmodelle
Authors: Tomas Jürgen 
Published: December 2004

AbstractStorage tanks are important elements of a self‐operating closed processing system. The reliability and availability of storage equipment essentially depends on the flow behaviour of particulate solids in storage containers. A wide residence time distribution (i.e. too long a storage time at rest) in silos, bunkers or transportation containers, respectively, can lead to the hazardous problem of so‐called “time consolidation” of particulate solids. During this hardening process, solid bridges are forming with resulting solidification and solid properties of bulk material. In principle, there are four main physico‐chemical effects in bulk materials storing and handling which can produce solid briding between the particle contacts due to crystallisation, chemical reactions, solidification of high‐viscous bonding agents and sintering. Generally, new adhesion force based models are presented to describe the consolidation kinetics of particulate solids. Preliminary solutions of kinetic model equations are discussed and compared with new test results and practical conclusions are drawn concerning the reliable processing, storage and transportation of bulk materials.
Zerkleinerung von Abfällen mittels Rotorscheren, Rotorreißern und Schraubenreißern
Authors: Jäckel Hans‐Georg , Schubert Gert 
Published: December 2004

AbstractStarting from the properties of the materials constituting waste, approaches suitable for size reduction of tough materials are considered. The rotary shears, rotary shredders, and screw shredders that have recently come into use for preliminary, coarse, and medium‐level size reduction of bulky household waste, scrap wood, used tyres, biological waste, old documents are now widespread. The forces exerted by these machines and their design and important design parameters are examined. A necessary detailed comparison of the three basic types of machine depending upon the nature of the material handled (systematic size‐reduction studies) has yet to be performed.
Verfahrenstechnik im Wandel
Authors: Frey Walter , Lohe B. 
Published: December 2004

AbstractIn the era of globalization, the speed of change is closely related to both the population growth in developing countries and their desire to close the economic gap with the western hemisphere. Chemical engineering is considered a significant contributor in finding solutions to the subsequent challenges of food supply, energy demand and environmental impact. National economies and their constituent enterprises require qualified engineers to meet these urgent and economically demanding challenges. At present however, neither the number of engineering students nor the national focus of university education seem appropriate to cover future requirements. On the scientific level, new modelling techniques, CFD and novel system orientied methods provide a perpective for both product and process improvements. In addition to their technical ability, professional engineers must emply a flexible approach as well as soft skills to put innovative solutions into practice. This paper illustrates and details the contents of the „Memorandum Verfahrenstechnik”︁ [3], a list of recommendations which was prepared by representatives of both industry and university.
Füllkörper oder Packungen? Wem gehört die Zukunft?
Authors: Schultes Michael 
Published: December 2004

AbstractOver the years a large number of dumped and ordered packings have been developed for effective treatment of material in absorption, desorption, extraction and rectification columns. The task of these column packings is to improve the mass transfer between a liquid phase and a gas or vapor phase. Furthermore, they also have to assure large throughputs at low pressure drops. When elaborating possible solutions for the separation of liquid mixtures or for cleaning flows of waste air or waste water in mass transfer columns, the planning engineer repeatedly faces the question of which dumped packing or which arranged packing presents the most favorable design from a process engineering standpoint. In recent years the opinion has often been voiced that arranged packings are always more effective than dumped packings. The purpose of this paper is to show that a number of applications exist in which modern dumped packings are equal or even superior to arranged packings. On the basis of selected examples the author discusses when the use of a structured packing is preferable with regard to process engineering.
Modellbildung für die zweiphasige Strömung in geordneten Schichtungen und strukturierten Packungen
Authors: Millies Marco , Mewes Dieter 
Published: December 2004

AbstractModelling of Binary Flow in Ordered Layers and Structured Packings Ordered layers and structured packings are used as internals in numerous rectification columns. They characteristically exhibit low pressure drops and high plate numbers per unit length. The relatively high investment costs are frequently offset by small column dimensions and hence lower equipment costs. In packings of industrial dimensions unstable flow states may occur which significantly lower the plate numbers. Such instabilities can be detected experimentally by tomographic methods. Moreover, flow patterns can be predicted theoretically. A theoretical description permits the engineer to scale up such columns containing packings and to deduce the design features necessary for industrial scale columns from laboratory experiments.
Praxisrelevante Zetapotentialmessung mit unterschiedlichen Meßtechniken
Authors: Hinze Frank , Ripperger Siegfried , Stintz Michael 
Published: December 2004

AbstractPractice‐Related Zeta Potential Measurement Using Different Measurement Techniques.The importance of particle systems with particles sizes in the submicron range is steadily growing. Therefore the need for a comprehensive characterisation of these material systems is also increasing. In addition to the particle size, in dispersions the formation of a surface potential and the ensuing inclination of the particle to agglomerate is of particular interest. The zeta potential has long been used as a measurement value. The complexity of this value and the sensitive reaction of the sorption equilibria which cause the potential formation require great care in performing the measurements. In this paper the comparability of measured results gained by different measurement methods will be discussed. This will be done exemplarily with influencing factors such as sample preparation, standing time of the sample, electrolyte background, titration regime, solid concentration and measurement technique. In conclusion, some advice is given for the selection of suitable measurement parameters.
DVCV‐Gemeinschaftsausschuß „Extraktion”︁
Authors: Bart Hans‐Jörg , Schröter J. 
Published: December 2004

AbstractDie 7. Sitzung des DVCV‐Fachausschusses Extraktion fand vom 17. bis 18. September 1998 in der „Rotunde”︁ des Gebäudes 57 der Universität Kaiserslautern statt. Dort fanden die insgesamt ca. 70 Teilnehmer beste Bedingungen vor, um die elf Vorträge der beiden Schwerpunktthemen „Simulation (einschl. Short‐cut‐Methoden) und Miniplant‐Versuche zur Bewertung der Flüssig/Flüssig‐ und der Reaktivextraktion”︁ und „Koaleszenz und Phasentrennung”︁ sowie weitere fünf Fachvorträge zu diskutieren. Außerdem erfolgten zwei Computerdemonstrationen, erstens zur Datenbank „Extraktionskolonnen”︁ und zweitens zur „Auswahl selektiver Extraktionsmittel für die Metallsalzextraktion auf der Basis von Calixarenen”︁. Die Sitzung wurde von Prof. Dr. W. NITSCH, TU München, und Herrn J. SCHRÖTER, BAYER AG, eröffnet und geleitet.
International Workshop on Polymer Reaction Engineering
Authors: Moritz H.‐U. 
Published: December 2004

AbstractDer in der Zeit vom 5. bis 7. Oktober 1998 zum sechsten Mal in Berlin durchgeführte „International Workshop on Polymer Reaction Engineering”︁ der DECHEMA hat sich längst als das herausragende Forum für Diskussionen und den Ideenaustausch im Bereich der Polymerisationstechnik etabliert. Mit über 150 Teilnehmern aus 18 Ländern, die zu mehr als 50% aus der Industrie kamen, stellt der Workshop einen intensiven, internationalen Erfahrungsaustausch zwischen Industrie und Hochschule sicher. Einen thematischen Schwerpunkt bildete die Emulsionspolymerisation, wo im Vergleich mit den vorangegangenen Tagungen eine kontinuierliche Steigerung der Beiträge zu verzeichnen war. Zu der erstmals als eigenständiger Themenkreis vertretenen Olefinpolymerisation wurde auf Anhieb in zahlreichen Beitragen berichtet. Ein zunehmendes Interesse zeichnet sich ebenso für die Reaktivextrusion ab.
Fluiddynamische Aspekte in Mikrostrukturreaktoren
Authors: Walter Stefanie , Frischmann Günter , Broucek Reinhard , Bergfeld Manfred , Liauw Marcel 
Published: December 2004

AbstractFluid Dynamics in Microchannel Reactors.The possible benefits of using microchannel reactors in the chemical process industries have been under discussion for several years. Outstanding heat transfer properties, short residence times and short diffusion lengths are considered key advantages, while the cost of the approach and the pending question of long‐term stability are still major sources of skepticism. A good starting point for a feasibility study is to investigate some major fluid dynamic properties. For a unit consisting of hundreds of parallel microchannels, the pressure drop for the laminar flow is just a few millibar. However, at high gas flows the distribution over the numerous channels may become non‐uniform. It is shown how the resulting residence time distribution affects both the yield of intermediates in consecutive reactions, and step functions of the concentration during periodic operation, respectively. All in all, the results of the estimations are encouraging.
Wärmeintegration als Element der Verfahrensbearbeitung
Authors: Aust Eberhard , Scholl Stephan 
Published: December 2004

AbstractThermal Integration, an Element in Design of Chemical Engineering Processes.Thermal integration is an important element in the planning and design of chemical engineering processes. This is especially true when energy optimisation is embedded in a software environment permitting unimpeded data transfer and exchange between the design elements can take place in a straightforward and intelligent manner, i.e. in a manner supporting the user. These advantages are demonstrated for a selected process. Expert systems which can extract data relevant for thermal integration from the process data and hence generate an entry data set for subsequent processing in a thermal integration program have proved to be particularly advantageous. In addition, the process engineer also has the possibility of modifying the data manually and undertaking appropriate adaptions and corrections. Subsequent analysis of thermal integration (e.g. by the Pinch method) often suggests improvements extending beyond the pure thermal regime and lead to changes in the process flow chart.
Produktivitätssteigerung durch integrierte Produktionstechnik und Verfahrens‐Know‐how
Authors: Roos Eckhard , Wippermann Boris 
Published: December 2004

AbstractIncreasing Productivity through Integrated Production Engineering and Processing Expertise The future of production engineering is interdisciplinary. Between product innovation and product marketing there lies a design process which has to be optimised and which is interdisciplinary in character. The design process has to satisfy the demands of global markets on chemical products, which lead, for example, to shorter and shorter product life cycles, and to demands for low production costs, high and consistent product quality, and faster market launches.
Grundlagenuntersuchungen zur Herstellung von Öl/Wasser‐Emulsionen im Ultraschallfeld
Authors: Bechtel Siegfried , Gilbert Norbert , Wagner Hans‐Günter 
Published: December 2004

AbstractBasic Research on Ultrasonic Production of Oil‐in‐Water‐Emulsions This article presents basic research results for production of oil in water emulsions under ultrasonic irradiation. A new theoretical model supports experimental work. Special attention is given to the transfer of batch experiments to continuous emulsification processes. Our experimental findings prove that final drop size essentially depends on specific power density. Drop size decreases with increasing residence time in the ultrasonic field until a system specific, minimum drop size is obtained. Ultrasonic irradiation leads to turbulent flow conditions on a macroscopic and a microscopic scale. Our model based on the theory of turbulent drop break up predicts drop size and can be used to design equipment for ultrasonic emulsification.
Dexamethasone alters F‐actin architecture and promotes cross‐linked actin network formation in human trabecular meshwork tissue
Authors: Clark Abbot F. , Brotchie Daniel , Read A. Thomas , Hellberg Peggy , English‐Wright Sherry , Pang Iok‐Hou , Ethier C. Ross , Grierson Ian 
Published: December 2004

AbstractElevated intraocular pressure is an important risk factor for the development of glaucoma, a leading cause of irreversible blindness. This ocular hypertension is due to increased hydrodynamic resistance to the drainage of aqueous humor through specialized outflow tissues, including the trabecular meshwork (TM) and the endothelial lining of Schlemm's canal. We know that glucocorticoid therapy can cause increased outflow resistance and glaucoma in susceptible individuals, that the cytoskeleton helps regulate aqueous outflow resistance, and that glucocorticoid treatment alters the actin cytoskeleton of cultured TM cells. Our purpose was to characterize the actin cytoskeleton of cells in outflow pathway tissues in situ, to characterize changes in the cytoskeleton due to dexamethasone treatment in situ, and to compare these with changes observed in cell culture. Human ocular anterior segments were perfused with or without 10−7 M dexamethasone, and F‐actin architecture was investigated by confocal laser scanning microscopy. We found that outflow pathway cells contained stress fibers, peripheral actin staining, and occasional actin “tangles.” Dexamethasone treatment caused elevated IOP in several eyes and increased overall actin staining, with more actin tangles and the formation of cross‐linked actin networks (CLANs). The actin architecture in TM tissues was remarkably similar to that seen in cultured TM cells. Although CLANs have been reported previously in cultured cells, this is the first report of CLANs in tissue. These cytoskeletal changes may be associated with increased aqueous humor outflow resistance after ocular glucocorticoid treatment. Cell Motil. Cytoskeleton 60:83–95, 2005. © 2004 Wiley‐Liss, Inc.
Grain structure and texture of cast iron aluminides
Authors: Skrotzki W. , Kegler K. , Tamm R. , Oertel C.‐G. 
Published: December 2004

AbstractThe grain structure and texture of cast iron aluminides have been investigated in the scanning electron microscope by orientation contrast imaging and electron back‐scatter diffraction, respectively. Depending on the aluminum concentration the alloys exhibit a fine‐grained chill zone, medium grain size columnar zone and/or coarse‐grained equiaxed zone. The texture is random except in the columnar zone which is characterized by a <100> fibre texture in the direction of heat flow, i.e parallel to the elongated grains. The development of grain structure and texture is discussed with respect to cooling rate, thermal and constitutional undercooling, and order. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Correlation of structural and physical properties of metastable Fe‐Cr phases
Authors: Gorbunov A. , Levin A. A. , Meyer D. C. , Bischoff L. , Eckert D. , Köhler B. , Mertig M. , Weißbach T. , Wieser E. , Pompe W. 
Published: December 2004

AbstractThis paper contributes to the studies of physical properties of metastable Fe‐Cr phases which have been discovered recently in the thin films deposited from the hyperthermal Fe and Cr particle beams. The electrical resistance and the magnetic remanence are correlated with the crystallographic parameters and phase composition of the samples. It is demonstrated that the focused ion‐beam induced phase transformation in the unusual metastable Fe‐Cr alloys can be used for the fabrication of ferromagnetic arrays. © 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim