Die Brennstoffzelle ist ein elektrochemischer Reaktor und wandelt chemisch gebundene Energie direkt in elektrische Energie um. In der stationären Energieerzeugung ist der Brennstoffzellenstapel selbst nur ein kleiner Bestandteil des vollständigen Systems. Die Integration aller zusätzlichen Bestandteile, der Peripheriegeräte (Balance-of-Plant) (BoP), ist eine der Hauptaufgaben in der Studie der Brennstoffzellenkraftwerke. Diese Untersuchung betrifft die Systemstudie des auf der Schmelz-Karbonat-Brennstoffzelle (MCFC) basierten Kraftwerks. Die Systemstudie ist mit dem Simulationprogramm Aspen PlusTM durchgeführt worden. Artikel I beschreibt die Implementierung eines in Aspen PlusTM entwickelten MCFC Stapelmodells, um ein MCFC Kraftwerk zu studieren, das Erdgas als Brennstoff verwendet. Artikel II beschreibt, wie unterschiedliche Prozeßparameter, wie Brenngasnutzung und dieWahl des Brennstoffes, die Leistung eines MCFC Kraftwerks / A fuel cell is an electrochemical reactor, directly converting chemically bound energy to electrical energy. In stationary power production the fuel cell stack itself is only a small component of the whole system. The integration of all the auxiliary components, the Balance-of-Plant (BoP), is one of the main issues in the study of fuel cell power plants. This thesis concerns the systems studies of molten carbonate fuel cell (MCFC) based power plants. The system studies has been performed with the simulation software Aspen PlusTM. Paper I describes on the implementation of a developed MCFC stack model into Aspen PlusTM in order to study an MCFC power plant fueled with natural gas. Paper II describes how different process parameters, such as fuel cell fuel utilization, influence the performance of an MCFC power plant. / Bränslecellen är en elektrokemisk reaktor som kan direkt omvandla kemiskt bunden energi till elektrisk energi. I stationär kraftproduktion är själva bränslecellsstapeln endast en mindre komponent i systemet. Integrationen av kringutrustningen, den s.k. Balance-of-Plant (BoP), som tex. pumpar, kompressorer och värmeväxlare är en av huvudfrågeställningarna i studierna av bränslecellskraftverk. Denna avhandling avser systemstudier av mältkarbonatbränslecellsbaserade (MCFC) kraftverk. Systemstudierna har utförts med processimuleringprogramet Aspen PlusTM. Artikel I beskriver en utvecklad MCFC-cellmodell, som implementeras som "user model" i Aspen Plus, för att studera ett naturgasbaserat bränslecellskraftverk. Artikel II beskriver hur olika processparametrar, som tex bränsleutnyttjande och val av bränsle, påverkar ett MCFC-kraftverks prestanda. / QC 20101129

<p>Extrusion Deposition Additive Manufacturing (EDAM) is a process in which fiber-filled thermoplastic polymers pellets get molten in the extruder and deposited onto a build plate in a layer-by-layer basis. The use of short fiber composite for EDAM has enabled large-scale 3D printing structures and tools for traditional composite manufacturing processes. Successful EDAM production critically depends on the understanding of the process-structure-property relationship. Especially on the bonding between the beads which is of paramount importance in additive manufacturing since it affects primarily the fracture and strength characteristics of the printed part. Bonding is influenced mainly by the temperature history and the contact between the beads. Both of which is dependent on the fiber orientation within the bead induced by the flow deformation that occurs according to the printing parameters. This study aims to investigate and model the complex relationship between the printing conditions and inter-bead bonding in the lateral direction.</p> <p>A framework was developed to facilitate this aim, and it contains a fusion bonding model that couples the time-temperature history and the bead-to-bead contact interface. Four deposition parameters were studied: the nozzle height, ratio of the print velocity to extrudate velocity, bead-to-bead spacing, and layer time. First, a deposition flow model was developed, utilizing the anisotropic viscous flow model and smooth particle hydrodynamic finite element formulation, to predict the fiber orientation state across the deposited bead and the bead-to-bead interface for the given set of deposition parameters. Next, the effect of printing conditions on the temperature history of the bead was discovered by utilizing the heat transfer process simulation in ADDITIVE3D. Third, the experimental characterization procedure for mode I fracture toughness in the lateral direction was developed, and the fracture toughness was characterized using linear elastic fracture mechanics principles. Lastly, the phenomenological model for non-isothermal lateral fusion bonding was characterized using the bead contact interface, temperature history, and fracture toughness properties. This work showed a comprehensive effort in fusion bonding modeling while also presented a valuable process-structure-property-performance relationship in EDAM.  Guidance on the selection of printing conditions and strategy can be made using the developed model to print higher-strength parts.  </p>

Circular Economy (CE) aims at improving the resource efficiency of our society and decoupling economic growth from resource use. However, entropy and residues are still generated in CE, and resources such as energy, raw materials and water are used throughout the CE processes. The methodology developed in this thesis aims at evaluating and communicating the resource efficiency and environmental impacts of CE systems. Firstly, a digital twin of the system is created using process simulation to obtain detailed mass and energy balances. Then, a set of indicators is obtained for the evaluation of the material recoveries, residues and emissions generated, resource use and environmental impacts (LCA). Exergy indicators such as exergy dissipation and cost are also obtained from the simulation using a dedicated tool developed and implemented within this thesis. This methodology has been applied in three case studies within metallurgy and CE to evaluate, optimize and communicate their resource efficiency and environmental impacts. These case studies are the evaluation of the copper value chain, the comparison between different zinc production routes and the industrial symbiosis between the copper, zinc and cement value chains.

Ziel der vorliegenden Arbeit ist die Entwicklung eines neuartigen Ferti-gungsprozesses für hochfunktionalisierte Strukturbauteile in PFH-Technologie. Eigens für die Verarbeitung von FKV-Profilen wird das IHU/Spritzgießverfahren grundlegend analysiert und die einzelnen Pro-zessstufen durch den Einsatz geeigneter Prozessmedien und -parametrierungen modifiziert. Mit Hilfe umfangreicher analytischer und numerischer Berechnungen sowie erfolgreicher Umsetzung eines neuar-tigen Temperierungskonzeptes lassen sich erstmals FKV-Profile ohne den Einsatz von Barriereschichten, endkonturnah und reproduzierbar in seriellen Taktzeiten umformen. Zudem ist somit eine Funktionalisierung mittels Spritzgießen und ein gesamtheitliches Beherrschen des Hybrid-prozesses gegeben. Ein Vergleich der Verbindungsfestigkeiten mit hyb-riden Referenzbauteilen beweist, dass sich durch die stoffschlüssige Anbindung zeit- und kostenintensive Vorbehandlungen einsparen und gleichzeitig höhere Verbundqualitäten erzielen lassen. Um das PFH-Strukturbauteil mit montagegerechten Verbindungsschnittstellen zu werkstofflich andersgearteten Multimaterialstrukturen zu versehen, dient ein eigens entwickeltes prozesskomplementäres In-situ-Integrationsverfahren. Abschließend ist ein allgemeiner methodischer Ansatz für den technologischen Transfer und Adaption systematisch aufgeschlüsselt, sodass sich die einzelnen Entwicklungspfade nachvoll-ziehen lassen.:1 Einleitung 2 Zielsetzung 3 Stand der Wissenschaft und Technik 4 Anforderungen an einen faserverbund-gerechten IHU/Spritzgießprozess 5 Prozessentwicklung und Validierung 6 In-situ-Integrationsprozess für metallische Inserts 7 Konfiguration einer seriellen Fertigungstechnologie 8 Zusammenfassung und Ausblick Anhänge / The goal of this thesis is the development of a new production technol-ogy for highly functional lightweight structural parts. Therefor the hy-droforming supported overmolding process was chosen as a suiting manufacturing process. By usage of analytical and numerical calcula-tions as well as adapting a new kind of temperature distribution con-cept, the new Polymer-FRP-Hbyrid-Technology is enabled to manufac-ture frp-profile based structural components without the need for a barrier layer. The final product possesses its’s final shape already and has no need for further machining processes. A comparison with state-of-the-art metal-plastic-hybrid bonding systems shows a way higher value for the new technology due to the adhesive bond between the tape and injection molding polymer. Furthermore, the technology was enhanced with a process implemented insert joining process. Finally, a methodical approach for the technology transfer is presented.:1 Einleitung 2 Zielsetzung 3 Stand der Wissenschaft und Technik 4 Anforderungen an einen faserverbund-gerechten IHU/Spritzgießprozess 5 Prozessentwicklung und Validierung 6 In-situ-Integrationsprozess für metallische Inserts 7 Konfiguration einer seriellen Fertigungstechnologie 8 Zusammenfassung und Ausblick Anhänge

Aerated treatment wetlands are an increasingly recognized nature–based technology for thetreatment of domestic and industrial wastewater. As biodegradation is the most importanttreatment mechanism in aerated wetlands, these systems heavily rely on mechanical aerationmediated oxygen transfer to supply the dissolved oxygen demand of the associated microbialcommunity. In the last decade, research on aerated wetlands has evolved, however, majorquestions on aeration, the associated oxygen transfer and the quantitative link to treatmentperformance still remain unknown. Answering these questions can further improve aeratedwetland design to optimize treatment efficacy and economical efficiency. This dissertation investigated the link of oxygen transfer to the air flow rate of aerationand elucidated the associated impact on treatment performance for organic carbon and nitrogenin horizontal flow aerated wetlands. Therefore, a numerical process model includingone dimensional reactive transport was developed. This model describes the main processesinvolved in horizontal flow aerated wetlands: water flow, heat transport, transport of solubleand particulate wastewater pollutants, biodegradation by a network of bacterial communitiesand oxygen transfer through mechanical aeration. For model calibration and validation, pilot–scale experiments in horizontal flow aerated wetlands treating real wastewater were conducted.These included conservative tracer experiments as well as monitoring steady–state operationat variable air flow rates and aeration interruption. In general, the model was able to simulate conservative tracer transport as well as treatmentperformance for organic carbon and nitrogen at steady–state operation and aeration interruptionwith sufficient accuracy. A local sensitivity analysis of the calibrated parameters revealedporosity, hydraulic permeability and dispersion length as well as the oxygen transfer coefficientkLa as most important. When operating the wetland systems at steady–state, aeration provideda mostly aerobe environment, except at the influent zone. However, when aeration wasinterrupted, anaerobe process started to take over and treatment performance declined within3–4 days. The modeling elucidated that methanogenic and sulphate reducing bacteria can playa significant role for organic carbon removal during aeration interruption. Moreover, the modelrevealed a non–linear declining relationship of the air flow rate with oxygen transfer coefficientkLa and of kLa with treatment performance. The alteration of oxygen transfer by wastewaterpollutant concentration was then investigated in a laboratory–scale column experiment. Basedon this experiment, an empirical equation describing the inhibitory effect of soluble chemicaloxygen demand (CODs) on the oxygen transfer coefficient kLa was derived and incorporatedinto the process model. With the extended model several simulation scenarios were analyzedto quantify the impact of the inhibited oxygen transfer on treatment performance. It turnedout that the reduction of oxygen transfer by CODs will, most likely, be relevant only at highinfluent wastewater strength (CODs 300 mg L-1), low aeration (air flow rate 50 L m-2h-1) or when the aerated wetland design includes zoned aeration. With respect to secondarytreatment of domestic effluents at similar strength using a spatially uniform aeration, an airflow rate of approximately 150–200 L m-2 h-1 can be recommended as a reasonable compromisebetween treatment efficiency and robustness. If zoned aeration is intended (e.g. to create a redox zonation), however, the air flow rate should be increased to approximately 400 L m-2 h-1 to supress the inhibition of oxygen transfer by CODs concentration. Furthermore, the air flow rate at steady–state operation (50–500 L m-2 h-1) did not substantially affect the response in effluent concentrations for organic carbon and nitrogen. This means that at steady–state air flow rates of 50–500 L m-2 h-1 operation, treatment efficacy during aeration interruption will deteriorate and recover in a similar time. In conclusion, this dissertation provides quantitative insights into the mechanisms of aeration and treatment performance for organic carbon and nitrogen in horizontal flow aerated treatment wetlands. The findings obtained can support aerated treatment wetland design for research experiments and engineering applications. Therefore, this dissertation represents a significant advancement in the field of aerated treatment wetland research.

The technical feasibility of gasoline and diesel range hydrocarbons production through oligomerisation of olefins, starting from biomass with the intermediary steps of gasfication, water-gas shift reaction and syngas-to-olefins synthesis was investigated, through mathematical modelling and simulation on Matlab. The model for the gasifier was based on minimisation of Gibbs free energy and its results showed that higher carbon efficiencies could be achieved at lower pressures and steam inlet, and more inlet energy, by pre-heating the gasifying agents. The water-gas shift reactor was used to increase the ratio of hydrogen to carbon monoxide from the gasifier, before entering the syngas-to-olefins process. A 1-D model was employed to determine the concentration, temperature, and pressure profiles in the reactor. High inlet pressure and temperature were shown to be beneficial, by requiring smaller reactors for the desired ratios to be reached. Experimental data from scientific literature was used for empirical modelling of the Fischer-Tropsch reactor. Partial pressure of CO and H2 amounting to 1 bar, high temperature and H2/CO showed better production of the low olefins. A reaction mechanism and accordingly, rate equations were developed and employed in a plug-flow type reactor model, calculating the concentration profile of the olefins up to C20. High pressures were favourable for the production of heavier fractions, while elevated temperatures showed to cause more cracking of heavy hydrocarbons and consequently, less conversion. Based on the results of individual reactors, an integrated process flow diagram was suggested and optimised for maximum production of low olefins to the oligomerisation reactor (C2-4). The optimisation showed overall carbon efficiency of the process to be around 20%. The reason for this was associated with the choice of catalyst in the FTO process, due to its high selectivity to carbon dioxide. / Den tekniska genomförbarheten av bensin- och dieselproduktion genom oligomerisering av olefiner, från biomassa via förgasning, vatten-gasförskiftsreaktion och syngas-till-olefiner syntes undersöktes genom matematisk modellering och simulering på Matlab. Förgasningsmodellen baserades sig på Gibbs energi minimisering. Ju mindre förgasningstryck desto högre uppnås koleffektivitet. Vatten-gasskift reaktorn användas för att anpassa väte/kolmonoxid förhållande från förgasningsreaktorn till syngas till olefiner rektorn. En 1-D modell utvecklades och beräknade reaktorns koncentrationer, temperatur och tryckprofiler. Högre inlopps tryck och temperaturer leder till mindre reaktorer.   Experimentella data från vetenskaplig litteratur användes för att modellara Fischer-Tropsch reaktorn (syngas till olefiner). Partialt tryck av CO och H2 lika med 1 bar, hög temperatur och H2 / CO visade högre produktion av lätta olefiner. En reaktionsmekanism och följaktligen hastighetsekvationer utvecklades för oligomerisering och användades i en pluggflödesreaktor. Modellen beräknade koncentrationer profiler av olefiiner upp till C20.Högre tryck producerar tyngre fraktioner (diesel) medan högra temperaturer främjar krakning. Baserat på resultaten från enskilda reaktorer föreslogs ett integrerat processflödesdiagram och optimerades för maximal produktion av låga olefiner till oligomeriseringsreaktorn (C2-4). Optimeringen visade att den totala koleffektiviteten i processen var cirka 20%. Anledningen till detta var förknippat med valet av katalysator i FTO-processen på grund av dess höga selektivitet för koldioxid.

- An Plasmaschweißbrennern treten starke thermomechanische Beanspruchungen aufgrund der ablaufenden thermophysikalischen Teilprozesse auf. Diese können durch funktionsgerechte werkstoffliche, konstruktive und fertigungstechnische Brennergestaltung bewerkstelligt und die Thermobilanz und Lebensdauer der Brenner verbessert werden. - Anhand des entwickelten strömungs-thermomechanischen/magneto-hydro-dynamischen Simulationsmodells wurden werkstofflich-konstruktive Lösungsansätze für Entwicklung von physikalischen Prozesswirkprinzipien der betrachteten Plasma-Schweißprozessvarianten erarbeitet. - Differente Einflussgrößen des Plasmaschweißprozesses wurden erfasst, analysiert und ihre Wirkung auf Prozessverhalten und Brennerkonstruktion ermittelt. - Die damit gewonnenen Erkenntnisse wurden für werkstoffliche, technisch-konstruktive Brennerentwicklung bzgl. der Ausführungsgeometrien, Prozessgaszuführung und Brennerkühlung genutzt.

Τα κριτήρια σχεδιασμού στις σύγχρονες κατασκευές και κυρίως στην αεροναυπηγική και ναυπηγική βιομηχανία, στοχεύουν στην παραγωγή δομικών στοιχείων με μειωμένο βάρος και χαμηλότερο κόστος, ενώ ταυτόχρονα, απαιτείται να παρουσιάζουν υψηλότερες επιδόσεις και ικανοποιητική δομική ασφάλεια. Οι στόχοι αυτοί έχουν διαμορφώσει μια σχεδιαστική τάση η οποία οδηγεί στην αντικατάσταση των ‘παραδοσιακών’ διαφορικών δομών (differential structures) με ‘σύγχρονες’ ολοκληρωμένες δομές (integral structures). Η τάση αυτή βρίσκει εφαρμογή κατά κύριο λόγο στην αεροναυπηγική, όπου η μείωση του βάρους χωρίς υποβάθμιση της ασφαλούς λειτουργίας αποτελεί βασικό και μόνιμο στόχο. Η αυξημένη παραγωγή δομικών στοιχείων ολοκληρωμένων δομών έχει οδηγήσει σε συνεχή αύξηση της εφαρμογής διεργασιών συνένωσης με έμφαση στις προηγμένες διεργασίες συγκόλλησης. Οι διεργασίας συγκόλλησης οι οποίες, λόγω των πλεονεκτημάτων τους, βρίσκονται στην αιχμή της τεχνολογίας είναι η Συγκόλληση με Τριβή και Ανάμιξη (Friction Stir Welding – FSW) και η Συγκόλληση με Ακτίνα Λέιζερ (Laser Beam Welding – LBW). Η εφαρμογή συγκολλήσεων στην παραγωγή ολοκληρωμένων δομών έχει πολλά τεχνολογικά πλεονεκτήματα έναντι των άλλων τύπων σύνδεσης, ωστόσο, συνοδεύονται από την ανάπτυξη Παραμενουσών Τάσεων και στρεβλώσεων στο τελικό προϊόν, κάτι το οποίο, ανάλογα με την εφαρμογή, μπορεί να προκαλέσει σημαντικά προβλήματα. Συγκεκριμένα, οι στρεβλώσεις επηρεάζουν τη λειτουργικότητα του δομικού στοιχείου, αφού μεταβάλλουν την γεωμετρία του, ενώ οι παραμένουσες τάσεις, αναπροσαρμόζοντας το εσωτερικό εντατικό πεδίο, επιδρούν στη δομική τους ακεραιότητα. Όπως είναι γνωστό με κατάλληλη επιλογή των παραμέτρων της διεργασίας (π.χ. ταχύτητα συγκόλλησης, ισχύς κτλ) μπορεί να επιτευχθεί μείωση των αναπτυσσόμενων παραμενουσών τάσεων και στρεβλώσεων. Επίσης, τα τελευταία χρόνια έχει αποδειχθεί ότι η προσομοίωση μιας διεργασίας συγκόλλησης μπορεί να βοηθήσει σημαντικά στην επιλογή του βέλτιστου συνδυασμού των παραμέτρων της. Για το λόγο αυτό, μεγάλο μέρος της ερευνητικής δραστηριότητας στην περιοχή των προηγμένων διεργασιών συγκόλλησης έχει στραφεί προς την ανάπτυξη αξιόπιστων μεθοδολογιών προσομοίωσης, οι οποίες με δεδομένο (input data) τις παραμέτρους της διεργασίας μπορούν να δώσουν σαν αποτέλεσμα (output data) κρίσιμες απαντήσεις όσον αφορά στις τεχνολογικές ιδιότητες της συγκόλλησης. Βάσει των ανωτέρω, σκοπός της παρούσης διατριβής είναι η ανάπτυξη ολοκληρωμένων μεθόδων θερμομηχανικής προσομοίωσης των προηγμένων διεργασιών συγκόλλησης FSW και LBW με κύριο στόχο την πρόβλεψη των παραμενουσών τάσεων και των στρεβλώσεων καθώς και τη μελέτη της επίδρασης τους στη δομική ακεραιότητα των παραγόμενων δομικών στοιχείων. Ένα από τα σημαντικότερα και ίσως το κρισιμότερο στάδιο κατά την προσομοίωση μιας θερμομηχανικής διεργασίας είναι η εξομοίωση της θερμικής πηγής και ο υπολογισμός του θερμικού φορτίου, γιατί μια εσφαλμένη εκτίμηση του θερμικού φορτίου προκαλεί λανθασμένη πρόβλεψη της θερμοκρασιακής κατανομής και κατά συνέπεια εισάγει σφάλματα στον υπολογισμό των παραμενουσών τάσεων και των στρεβλώσεων. Στη βάση αυτή, τόσο για την περίπτωση της FSW όσο και για την LBW αναπτύχθηκαν μεθοδολογίες για τον προσδιορισμό των θερμικών πηγών τους και συνοδεύτηκαν από θερμικά μοντέλα για την πρόβλεψη του θερμοκρασιακού ιστορικού. Ακολούθως, το θερμοκρασιακό ιστορικό ασκείται υπό τη μορφή εξωτερικού φορτίου σε ένα θερμομηχανικό μοντέλο από όπου υπολογίζονται οι παραμένουσες τάσεις και οι στρεβλώσεις της διεργασίας. Τέλος, η εσωτερική εντατική κατάσταση του συγκολλημένου δομικού στοιχείου συνυπολογίζεται στο εντατικό πεδίο λόγω της φόρτισης λειτουργίας της κατασκευής και γίνεται πρόβλεψη των συντελεστών έντασης τάσης (Stress Intensity Factors - SIFs ) έτσι ώστε να εκτιμηθεί η επίδρασης της συγκόλλησης στη δομική ακεραιότητα. Τόσο το θερμομηχανικό όσο και το θραυστομηχανικό μοντέλο μπορούν να προσαρμοσθούν σε πολλούς διαφορετικούς τύπους σύνδεσης και ρηγμάτωσης, αντίστοιχα. / The design criteria in modern structures aim to the production of components with reduced weight and low cost, as well as, with higher performance and increased safety. The above goals lead to a tendency of replacing traditional differential structures with more modern integral structure, mainly in aeronautic sector where the weight and cost reduction, without decrease of safety, comprises the main target of the current research effort. The production of integral structures requires the adaptation of existing forming processes as well as the development and optimization of advanced welding processes. The most promising welding processes in aeronautics and maritime industries currently are the Friction Stir Welding–FSW and Laser Beam Welding-LBW. Despite of the many technological advantages of FSW and LBW process, their application in the production of integral structures leads to the development of Residual Stress (RS) and distortion fields which can cause significant problems. Specifically, distortions can effect on the components assembly, while, RS affect the structural integrity. However, an appropriate selection of process parameters can significantly reduce the RS and distortions levels. The usual way to optimize process parameters is experimental trial and error approach; recently, process simulation has been proven efficient, too. The present work aims to the development of efficient methodologies for the thermomechanical simulation of FSW and LBW processes in order to predict temperature history, as wells as RS and distortion fields. Consequently, the RS field is used for the determination of the welding effects on the structural integrity of the welded component. Generally, the reliability of a simulation methodology of any thermo-mechanical process, such as welding, is seriously affected by many parameters; two of them are very base, namely, the accurate determination of the heat input introduced to the material (thermal load) and the accurate representation of thermal and mechanical boundary conditions. As the boundary conditions determined by the welder and it is usually easy to transfer in a numerical model, one of the most difficult simulation issues is the appropriate determination of the heat input which will lead to an accurate prediction of the material temperature history. For this reason, one of the main objectives of the present work is to develop methodologies for the accurate thermal load calculation in both FSW and LBW processes. After the validation of the developed methodologies with respect to experimental measurements, the defined heat sources are used in global thermal models in order to predict the temperature histories which, thereinafter, are introduced in the thermo-mechanical models to predict the developed RS and distortion fields. Finally, the structural integrity of the welded component, under the effect of both RS field and service loading is studied; different possible ‘fracture scenarios’ are investigated based on the Stress Intensity Factor concept and the Elastic Fracture Mechanics principles.

This research investigates formulation, compounding and thin-wall injection moulding of Polypropylene/clay nanocomposites (PPCNs) prepared using conventional melt-state processes. An independent study on single screw extrusion dynamics using Design of Experiments (DoE) was performed first. Then the optimum formulation of PPCNs and compounding conditions were determined using this strategy. The outcomes from the DoE study were then applied to produce PPCN compounds for the subsequent study of thin-wall injection moulding, for which a novel four-cavity injection moulding system was designed using CAD software and a new moulding tool was constructed based upon this design. Subsequently, the effects of moulding conditions, nanoclay concentration and wall thickness on the injection moulded PPCN parts were investigated. Moreover, simulation of the injection moulding process was carried out to compare the predicted performance with that obtained in practice by measurement of real-time data using an in-cavity pressure sensor. For the selected materials, the optimum formulation is 4 wt% organoclay (DK4), 4 wt% compatibiliser (Polybond 3200, PPgMA) and 1.5 wt% co-intercalant (erucamide), as the maximum interlayer spacing of clay can be achieved in the selected experimental range. Furthermore, DoE investigations determined that a screw speed of 159 rpm and a feed rate of 5.4 kg/h are the optimum compounding conditions for the twin screw extruder used to obtain the highest tensile modulus and yield strength from the PPCN compounds. The optimised formulation of PPCNs and compounding conditions were adopted to manufacture PPCN materials for the study of thin-wall injection moulding. In the selected processing window, tensile modulus and yield strength increase significantly with decreasing injection speed, due to shear-induced orientation effects, exemplified by a significantly increased frozen layer thickness observed by optical microscopy (OM) and Moldflow® simulation. Furthermore, the TEM images indicate a strong orientation of clay particles in the flow direction, so the PPCN test pieces cut parallel to the flow direction have 36.4% higher tensile modulus and 13.6 % higher yield strength than those cut perpendicular to the flow direction, demonstrating the effects of shear induced orientation on the tensile properties of thin-wall injection moulded PPCN parts. In comparison to injection speed, mould temperature has very limited effects in the selected range investigated (25-55 °C), in this study. The changes in moulding conditions show no distinctive effects on PP crystallinity and intercalation behaviour of clay. Impact toughness of thin wall injection moulded PPCN parts is not significantly affected by either the changes in moulding conditions or clay concentration (1-5 %). The SEM images show no clear difference between the fracture surfaces of PPCN samples with different clay concentrations. TEM and XRD results suggest that higher intercalation but lower exfoliation is achieved in PPCN parts with higher clay content. The composites in the thin sections (at the end of flow) have 34 % higher tensile modulus and 11 % higher yield strength than in the thicker sections, although the thin sections show reduced d001 values. This is attributed to the significantly enhanced shear-induced particle/molecular orientation and more highly oriented frozen layer, according to TEM, OM and process simulation results. In terms of the reduced d001 values in the thin sections, it is proposed that the extreme shear conditions in the thin sections stretch the PP chains in the clay galleries to a much higher level, compaction of clay stacks occurs as less interspacing is needed to accommodate the stretched chains, but rapid cooling allows no time for the chains to relax and expand the galleries back. Overall, data obtained from both actual moulding and simulation indicate that injection speed is of utmost importance to the thin-wall injection moulding process, development of microstructure, and thus the resulting properties of the moulded PPCN parts, in the selected experimental ranges of this research.

Orientador: Rubens Maciel Filho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T11:34:50Z (GMT). No. of bitstreams: 1 Maia_JulioPereira_D.pdf: 8705466 bytes, checksum: e604d7a471ca19eb99492912d431174b (MD5) Previous issue date: 2013 / Resumo: Esta tese apresenta um estudo de estratégias de esquemas de controle em unidades de destilação a vácuo de refinarias de petróleo, com o uso de dados e informações de uma refinaria brasileira, de modo a se desenvolver uma simulação representativa do processo, onde uma diferença global máxima de 5% entre os resultados de simulação e os dados de saída reais foi obtida. A simulação foi executada com alto nível de detalhamento, com cálculos de queda de pressão, dimensionamento de sistemas de bombeamento e uso de internos de coluna comerciais. Uma análise paramétrica foi executada para a verificação das variáveis mais influentes do processo. A simulação em estado estacionário resultante foi então convertida para o regime dinâmico, onde um esquema de controle equivalente ao esquema de controle da planta real foi implementado. Este esquema de controle foi submetido a um conjunto de perturbações usuais ao processo real, produzindo respostas dinâmicas do processo para cada perturbação aplicada. Pela análise das dinâmicas destas respostas e das respostas do sistema em malha aberta, um esquema de controle alternativo foi proposto e verificado da mesma maneira que o esquema de controle equivalente. Malhas de controle específicas para quantificar a qualidade dos produtos, tendo por base o índice ASTM D86 foram inseridas. A comparação entre os dois esquemas de controle por meio das respostas dinâmicas na qualidade dos produtos, considerando como parâmetro o ISE (Integral Squared Error) das malhas de cada esquema para comparação, apresentou uma redução média do erro em 70% na qualidade dos produtos principais / Abstract: A petroleum vacuum distillation unit study on control scheme strategies is developed in this work. Real plant data and information is gathered from a Brazilian Refinery to develop a representative simulation of the process, which had achieved a maximum 5% overall difference from the plant results. The simulation was set to be highly detailed, including pressure drop calculations, pumping system and the use of commercial column internals (packing and plates) in it. A parametric analysis was carried in order to verify the most influent variables in the process, with respect to temperature profiles, product flows and product qualities. The resultant steady state simulation was then converted into dynamic regime, when a control scheme equivalent to the real plant control scheme was implemented. This control scheme was then subjected to a set of common perturbations that occur in the real process, producing the dynamic response of the process to each perturbation applied. By analyzing the dynamics of these responses and the open loop responses, an alternative control scheme is proposed and verified in the same manner the later one was. A specific control loop was proposed to account a petroleum product quality index, such as ASTM D86 95% recovery. The comparison of the control schemes by means of the dynamic responses considering the correlated ISE (integral squared error) of each scheme has shown an average error reduction of 70% in the main products quality / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química