Le système de fabrication des plaquettes de silicium (wafer) est la partie la plus complexe et la plus coûteuse du processus de fabrication des semi-conducteurs et son ordonnancement pour la production a un impact significatif sur la rentabilité économique. Le système d’outils Multi-cluster pour la fabrication de plaquettes est un système de type multi-boucles, largement utilisé dans la fabrication de plaquettes de 300 mm et 450 mm. Le problème d’ordonnancement dans ce système de production présente des caractéristiques pour les modèles de flux de plaquettes compliqué, des contraintes résidentielles strictes et des conflits de ressources à gérer, ce qui rend le problème très complexe. Dans cette thèse, l'outil multi-cluster est étudié et les recherches se concentrent principalement sur les caractéristiques des contraintes sur le temps de séjour, les contraintes sur les ressources utilisés et les flux plaquettes de silicium. Plus particulièrement, cette thèse traite trois problèmes d'ordonnancement: le problème d'ordonnancement cyclique unitaire pour un flux unique de plaquettes, le problème d'ordonnancement cyclique multi-unitaires dans un modèle de flux unique de plaquettes et le problème d'ordonnancement non-cyclique. Pour résoudre ces problèmes, des modèles robustes sont développés ainsi que certains algorithmes heuristiques efficaces sont construits pour atteindre les objectifs. L'objectif principal étant d'améliorer la performance des outils multi-cluster et d'augmenter le rendement des flux des plaquettes de silicium. Des tests de simulation et des analyses sont effectuées afin d’évaluer la performance des algorithmes proposés. Les résultats montrent la stabilité et l'efficacité de ces algorithmes. / Multi-cluster tool is a highly automated and costly wafer fabrication system with multi-loop coupling structure, and scheduling of such equipment directly affects the overall efficiency of semiconductor manufacturing enterprises. Multi-cluster tools scheduling problem has the features of large scale, complex wafer flow patterns, strict residency time constraints and intense resource conflict, which are significantly different from any other manufacturing system. Since the existing literatures have proved that most of the wafer fabrication systems scheduling problems are NP-hard, it’s difficult to obtain the optimal solution by using exact algorithms. Thus, how to develop an efficient heuristic algorithm to solve the multi-cluster tools scheduling problem attracts considerable attention both in academia and in industry. After reviewing the literatures, it is found that the research on the cyclic scheduling problem of multi-cluster tools rarely takes into account the characteristics of residency constraints. The scale of the object is limited to three single cluster tools, and the proposed scheduling methods are mostly mathematical programming and simple scheduling rules. Therefore, in this thesis, the multi-cluster tool is studied and our research mainly focuses on the characteristics of residency constraints, resource constraints and wafer flow patterns. Based on the descriptions of research domains, some solid models are developed for different scheduling problems and some efficient heuristic algorithms are constructed to realize the objectives. To deal with the problem, different approaches are proposed: A non-linear mixed-integer programming model, a two-stage = approximate-optimal scheduling algorithm, and a chaos-based particle swarm optimization-tabu search hybrid heuristic algorithm. Simulation experiments and analysis demonstrate the effectiveness of these algorithms. Results show the stability and efficiency of proposed algorithms.

The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots and further to affect the yield of ingot production, which is crucial for the steel making process. The formation of non-metallic inclusion and entrapment of mold flux has been considered to be affected by the flow pattern in the gating system and molds by many previous researchers. The aim of this study is to investigate the flow pattern of steel in the gating system and molds during the initial filling stage. In addition, to study the utilization of swirl blade implemented at the bottom of the vertical runner on the improvement of initial filling condition in the mold. A three dimensional model of two molds gating system for 6.2 ton ingots from Scana Steel was adopted in the present work. A reduced geometry model including one mold and a runner, based on the method from previous researchers, was also used for comparison with the current more extensive model. Moreover, a reduced geometry model including one swirl blade and a runner was simulated to find effects of an increased-length vertical runner on the flow pattern improvement at the vertical runner outlet. Flow pattern, hump height and wall shear stress were respectively studied. A reduced geometry with homogenous inlet conditions fails to describe the fluctuating conditions present as the steel enters the mold. However, the trends are very similar when comparing the (hump height-surface height) evolution over time. The implementation of swirl blades gives a chaotic initial filling condition with a considerable amount of droplets being created when steel enters the molds during the first couple of seconds. However, a more calm filling condition with less fluctuation is achieved at the molds after a short while. Moreover, the orientation of the swirl blades affects he flow pattern of the steel. A proper placement of a swirl blade improves the initial filling conditions. The utilization of swirl blades might initially result in larger hump height. However, it gives fewer fluctuations as the casting proceeds. In the model without swirl blades, the maximum wall shear stress fluctuates with a descending trend as the filling proceeds. An implementation of swirl blades can decrease and stabilize the wall shear stress in the gating system. A special attention should be made in choosing refractory at the center stone, the horizontal runner near center stone and the vertical runner at the elbow. This is where the wall shear stress values are highest or where the exposure times are long. / QC 20120203

More and more attention has been paid to decreasing the number and size of non-metallic inclusions existing in the final products recently in steel industries. Therefore, more efforts have been made to monitor the inclusions' size distributions during the metallurgy process, especially at the secondary steelmaking period. A liquid sampling procedure is one of the commonly applied methods that monitoring the inclusion size distribution in ladles, for example, during the secondary steelmaking. Here, a crucial point is that the steel sampler should be filled and solidified without changing the inclusion characteristics that exist at steel making temperatures. In order to preserve the original size and distributions in the extracted samples, it is important to avoid their collisions and coagulations inside samplers during filling. Therefore, one of the first steps to investigate is the flow pattern inside samplers during filling in order to obtain a more in-depth knowledge of the sampling process to make sure that the influence is minimized. The main objective of this work is to fundamentally study the above mentioned sampler filling process. A production sampler employed in the industries has been scaled-up according to the similarity of Froude Number in the experimental study. A Particle Image Velocimetry (PIV) was used to capture the flow field and calculate the velocity vectors during the entire experiment. Also, a mathematical model has been developed to have an in-depth investigate of the flow pattern in side the sampler during its filling. Two different turbulence models were applied in the numerical study, the realizable k-ε model and Wilcox k-ω model. The predictions were compared to experimental results obtained by the PIV measurements. Furthermore, it was illustrated that there is a fairly good agreement between the measurements obtained by PIV and calculations predicted by the Wilcox k-ω model. Thus, it is concluded that the Wilcox k-ω model can be used in the future to predict the filling of steel samplers.

Experimente mit neuartigen Messverfahren lieferten Daten über die Struktur von transienten Flüssig-keits-Gas-Strömungen für die Entwicklung und Validierung von mikroskopischen, d.h. geometrieunabhängigen Konstitutivbeziehungen zur Beschreibung des Impulsaustauschs zwischen Flüssig-phase und Gasblasen sowie zur Quantifizierung der Häufigkeit von Blasenkoaleszenz und -zerfall. Hierzu wurde eine vertikale Testsektion der Zweiphasentestschleife MTLoop in Rossendorf genutzt, wobei erstmals Gittersensoren mit einer Auflösung von 2-3 mm bei einer Messfrequenz von bis zu 10 kHz angewandt wurden. Dabei wurde die Evolution von Gasgehalts-, Geschwindigkeits- und Bla-sengrößenverteilungen entlang des Strömungsweges und bei schnellen Übergangsprozessen aufge-nommen und so die für die Modellbildung erforderlichen Daten bereitgestellt. Für den Test der Mo-dellbeziehungen wurde ein vereinfachtes Verfahren zur Lösung der Strömungsgleichungen entlang des Strömungswegs erstellt. Es basiert auf der Betrachtung einer größeren Anzahl von Blasengrö-ßenklassen. Die erhaltenen numerische Lösungen haben erstmals gezeigt, dass der bei Erhöhung der Gasvolumenstromdichte stattfindende Übergang von einer Blasenströmung mit Randmaximum zu einem Profil mit Zentrumsmaximum und anschließend zu einer Pfropfenströmung ausgehend von einem einheitlichen Satz physikalisch begründeter und geometrieunabhängiger Konstitutivgleichun-gen modelliert werden kann. Die Modellbeziehungen haben sich in einem abgegrenzten Gebiet der Volumenstromdichten als generalisierungsfähig erwiesen und sind für den Einbau in CFD-Modelle geeignet. Weiterhin wurden Arbeiten zur Kondensation durchgeführt, die direkten Bezug zu den Kon-densationsmodellen haben, die in Thermohydraulik-Codes enthalten sind. Die Untersuchung liefert darüber hinaus experimentelle Daten für die Modellvalidierung hinsichtlich des Verhaltens und des Einflusses nichtkondensierbarer Gase. Hierfür wurden spezielle Sonden für die Bestimmung der Konzentration und für die Lokalisierung von Pfropfen nichtkondensierbarer Gase entwickelt und bei transienten Kondensationsversuchen in einem leicht geneigten Wärmeübertragerrohr eingesetzt.

An experimental investigation has been carried out to study the heat transfer in a two-phase two-component mixture flowing upward inside a 1" double pipe heat exchanger. The heat transfer coefficient was measured using either air to lift the liquid (air-lift system) or a mechanical pump. The heat transfer coefficient results have been extensively studied and compared with other workers' results. An attempt was made to correlate the present heat transfer data in dimensionless correlations. Possible factors affecting the two-phase heat transfer coefficient have been studied with special attention being given to the fluid properties, particularly the liquid viscosity. Experiments were also carried out to investigate the effect of solid particles added to a liquid flow on the measured heat transfer coefficient. The present investigation was carried out using air as the gas-phase ranging from 2x 10-5 up to 80 x 10-5 m3/s. Liquids used were water and glycerol solutions with viscosity ranging from 0.75 up to 5.0 C. P. and flowrates between 4x 10-5 and 25 x 10-5 m3/s. Void fraction and pressure drop were also measured during the heat transfer process. Flow pattern in gas-liquid mixture was investigated in a perspex tube of identical dimensions to the heat exchanger tube.

<p>A short, 30cm, test section was used to study the effect of electrohydrodynamic (EHD) forces on flow redistribution in a horizontal, shell and tube heat exchanger subject to both boiling and condensation. The use of a short test section allows for a consistent flow pattern across the test section length which provides further insight into the true effect of EHD.</p> <p>It was found that the voltage polarity of the applied voltages influences the flow distribution. For the current geometry studied, it was found that positive polarity voltages tend to pull liquid away from heat transfer surface and that negative voltages tended to repel more liquid toward the heat transfer surface. Using this knowledge we were able to show that positive voltages were more effective for convective condensation heat transfer enhancement, whereas negative voltages were more effective for convective boiling heat transfer enhancement. A twofold enhancement of convective boiling heat transfer was achieved for positive voltages and a 4fold enhancement was achieved for negative voltages. Similar pressure drop penalties were seen for both cases, approximately twice that of the no EHD case.</p> <p>Furthermore, the effect of DC level, peak to peak voltage, frequency and duty cycle waveform parameters on convective boiling enhancement were studied to explore the range of controllability for the current set of flow parameters. It was found that these various waveform parameters can induce different flow patterns and consequently different heat transfer and pressure drop configurations. In general the heat transfer is enhanced by EHD, but different pressure drop penalties can be achieved for a given enhancement ratio using different waveforms. High heat transfer for relatively low pressure drop was achieved using either negative DC signals or 50%duty cycle pulse waveforms. In some cases the enhancement is quite little compared to the pressure drop, for example the zero DC level, varying peak to peak voltage data. It is suggested that in a system where the heat exchanger pressure drop due to EHD is more dominant than the system pressure drop, it may be possible to use EHD as a method of retarding the system rather than enhancing it thereby broadening the scope of controllability.</p> <p>Finally we showed the proof of concept of using DC EHD as a rapid control mechanism for the load conditions. Using -8kVDC the water side heat flux could be varied by approximately ±3.2 kW/m² within 5 seconds. As a comparison, the same experiment was repeated using the refrigerant flow rate to control the load. Response times were similar for both experiments and although the power required for the flow rate control was less, the minimal variability in flow parameters for the EHD control make it a more attractive method of load control.</p> / Master of Applied Science (MASc)

Propõe-se o estudo do separador gravitacional de fundo de poço do tipo shroud invertido para poços direcionais e horizontais. A geometria inovadora é observada pela inclinação imposta, solução que transforma um escoamento vertical descendente, veloz e caótico, num escoamento inclinado e segregado em canal livre. Com a inclinação, minimizasse a incorporação de gás, no impacto do escoamento em superfície livre contra a interface de líquido formada pelo nível do anular interno (NAI), e a segregação é incrementada devido ao gradiente de velocidades e ao aparecimento da componente da gravidade na direção radial do poço de petróleo. O trabalho experimental tem como uma de suas metas o levantamento da eficiência de separação em função das vazões de líquido e gás, do ângulo de inclinação e o grau de interferência do escoamento no duto anular formado entre o separador e a parede do poço de petróleo, chamado neste trabalho de anular externo. Foi feito um trabalho de semelhança dimensional e foram detectados os números adimensionais pertinentes ao problema. Constatou-se que a vazão de gás e o escoamento no anular externo não interferem na eficiência de separação. Além disso, foi realizado um trabalho de caracterização dos padrões do escoamento gás-líquido em duto anular, através de visualização e análise no domínio do tempo e da frequência do sinal dinâmico da queda de pressão. Também são propostos dois modelos matemáticos, um modelo fenomenológico baseado em princípios físicos fundamentais, que foi capaz de prever com eficácia a região de máxima eficiência do separador shroud invertido, e um modelo numérico, que reproduziu a fenomenologia do processo de separação do gás. / This research project proposes the study of the inverted-shroud gravitational gas separator for directional and horizontal wells. The innovative geometry is observed by the inclination that transforms a vertical, fast and chaotic downward flow into an inclined and segregated free channel flow. Due to inclination, the incorporation of gas at the internal gasliquid interface (NAI) is minimized; the segregation is increased due to the velocity gradient and the gravitational term that arises in the radial direction of the oil well. One of the aims of the experimental work is the obtaining of new data of gas separation efficiency as a function of the flow of liquid and gas, inclination angle and the evaluation of the degree of interference of the external annular duct flow. A dimensional analysis was undertaken to identify the relevant dimensionless numbers. It was found that the gas flow and the flow pattern in the external annular duct do not interfere in the separation efficiency. A flow pattern characterization was carried out through visualization and time and frequency domain analysis of differential pressure signature signal. Two mathematical models are proposed, a phenomenological model based on fundamental physical principles, which was able to predict with good accuracy the region of maximum separation efficiency, and a numerical model, which reproduced the phenomenology of the gas separation process.

Att tillhandahålla termisk komfort är ett av de främsta kraven som ställs på byggnader i dagens samhälle. Stora delar av energianvändningen går därför åt till att styra inomhusklimatet för att upprätthålla en behaglig nivå. Det påstås att omkring 40 % av denna energi tillkommer på grund av energiförluster via öppningar och läckage genom byggnaders klimatskal. Med tanke på världens och Sveriges alltmer striktare energikrav där man bland annat vill bygga nära-nollenergibyggnader är detta någonting som bör förbättras. Det är därför viktigt att förstå hur men även varför denna luftinfiltration uppstår och vilka faktorer som har en påverkande effekt. Detta arbete innefattas av tre olika simuleringsstudier av en hög byggnad där inomhusluftens rörelsemönster samt yttre vindförhållanden har legat i fokus. En studie utfördes med hjälp av simuleringsverktyget IDA ICE där luftens infiltration undersöktes. De andra två utfördes med hjälp av CFD-programmet COMSOL Multiphysics v5.4. Den ena CFD-studien studerade termiska stigkrafter inuti byggnaden och den andra studerade vindens flödesmönster utanför byggnaden och varför infiltrationen beter sig som den gör. Resultatet av simuleringarna i IDA ICE visar att det är möjligt att minska infiltrationsmängden luft in i byggnaden från 1384 l/s till 804 l/s genom att ta hänsyn till ytterdörrens placering relativt den inkommande vinden riktning. De visar även att infiltrationens inflöde är som högst på bottenvåningen för att sedan minska och därefter övergå till ett utflöde på de högre våningsplanen.Resultatet från den första CFD-studien beskriver hur den varmare inomhusluftens rörelsemönster förändras då kallare luft tar sig in på byggnadens bottenvåning. Detta förändrade rörelsemönster resulterar i att den varmare luften stiger och därmed letar sig ut genom byggnadens högre våningsplan. Den andra CFD-studiens resultat beskriver hur den yttre vindens flödesmönster förändras då dess infallsvinkel mot byggnaden varierar. Flödesmönstrets förändring ger i sin tur upphov till en varierande tryckskillnader på utsidan samt inuti byggnaden. Detta är därför en av förklaringarna till varför infiltrationen är som högst då vinden blåser rakt mot byggnadens öppna dörr jämfört med när den kommer med en annan infallsvinkel. Slutsatsen är att ytterdörrens placering relativt den yttre vinden rörelsemönster bör tas i beaktning vid nybyggnation av höga byggnader eller renovering av redan befintliga byggnader. Detta för att minimera infiltrationen och därmed reducera den problematik som infiltrationen kan medföra. / One of the main requirements a building have is to provide thermal comfort inside it. Therefore, large parts of the energy consumptions is used to control the indoor climate in order to maintain a comfortable level in the building. It’s alleged that around 40 % of this energy is added due to energy losses through opening and leakages in the buildings enclosure. Considering the world’s increasing energy requirements, where among other things one future requirement is to build nearly-zero energy buildings, is this something that needs to be improved. It’s therefore important to understand how, and also why this air infiltration occurs and what’s affecting it. This master thesis contains of three different types of simulation studies where the air inside a high-rise building, and also the wind flow around it was analyzed. One of these three studies was performed with the simulation program IDA ICE, where the air infiltration was examined. The other two studies were performed with the CFD-software, COMSOL Multiphysics v5.4. One of these CFD-studies examined the thermal flow that occurs inside the building. The other one examined the wind’s flow pattern outside the building and why the air infiltration behavior is like it is. The results from the IDA ICE simulations shows that it’s possible to decrease the infiltration rate of air into the building from 1384 l/s to 804 l/s by taking the exterior door’s position relative the incoming wind’s direction into account. They also show that the infiltration inflow is highest on the ground floor before it starts to decrease and then change and becomes an outflow on the the higher floors. The results from the first CFD-study describes how the movements of the warmer air inside the building changes when colder air flows in on the ground floor. This changed air movement pattern makes the warmer air rise, and thus flow out through the enclosure on the higher parts of the building. The other CFD-study describes how the flow pattern of the outside wind changes around the building when the winds angle of incidence varies. The changed flow pattern causes varying pressure differences, both on the outside and the inside of the building. This is therefore the explanation to why the infiltration rate is greatest when the wind blows straight towards the opened door on the building instead of with other angles of incidence. The conclusion is that the placement of exterior doors on high-rise buildings relative to the outside wind should be taken into account when new buildings are built or when a renovation of an existing building should be made. This to minimize air infiltration through buildings and thereby reduce problems infiltration can cause.

Es wurde ein neues Zweifluidmodell entwickelt, um Nichtgleichgewichtseffekte in kritischen und nahkritischen Ein-komponenten-Zweiphasenströmungen von anfänglich unter-kühlten oder siedenden Fluiden durch Rohre und Düsen zu untersuchen. Das vorgeschlagene Sechs-Gleichungsmodell besteht aus den phasenbezogenen Erhaltungsgleichungen für Masse und Impuls, der Bilanzgleichung für die thermische Energie der flüssigen Phase sowie einer zusätzlichen Transport-gleichung für die volumetrische Blasenanzahl. Zur Lösung des Systems aus partiellen Differentialgleichungen wird ein semi-implizites Finite-Differenzen-Zeitschrittverfahren angewendet. Die Schließung des Gleichungssystems wird durch Einbindung thermodynamischer Beziehungen und konstitutiver Gleichungen, die den strömungsformabhängigen Impuls-, Wärme- und Stofftransport beschreiben, erreicht. Für Strömungssysteme mit spontaner Entspannungsverdampfung aus dem rein flüssigen Zustand (Flashing) werden verschiedene Keimbildungsmodelle eingesetzt, die den Anfangszustand der verzögerten Dampfbildung beschreiben. Auf diese Weise werden thermodynamische Nichtgleichgewichtszustände als Folge von Zuständen mit für die Aktivierung von Keimstellen benötigtem Energieüberschuß, eingeschränkt vorhandener Phasengrenzfläche sowie begrenzter Wärmeübertragung zwischen den Phasen betrachtet. Abweichungen vom fluid-dynamischen Gleichgewicht (Phasenschlupf) ergeben sich aufgrund unterschiedlicher Trägheitseigenschaften und verschieden stark ausgeprägter mechanischer Kopplung zwischen den Phasen. Die mit diesem Modell erhaltenen numerischen Ergebnisse stimmen gut mit experimentellen Werten für Zweiphasen-strömungen mit unterschiedlichen Eintrittsbedingungen und Kanalgeometrien überein. / A new two-fluid flow model has been developed in order to examine non-equilibrium effects in critical and near-critical one-component two-phase flows of initially subcooled or saturated fluids through pipes and nozzles. The six-equation model proposed consists of the phasic conservation equations of mass and momentum, the liquid thermal energy, and of an additional transport equation for the bubble number density. To solve for the unknowns of the system of partial differential equations, a semi-implicit finite difference time-marching method is utilized. The closure of the set of equations is accomplished by thermodynamic relationships and additional constitutive equations describing momentum transport, interphase heat, and mass transfer which account for different flow regimes. For fluid flow systems undergoing a sudden change of phase from the pure liquid state (flashing), distinct nucleation models are included to describe the initial state of delayed vapor generation. In this way thermal non-equilibrium states are considered to be the consequence of excessive energy states required to activate nucleation sites, of restricted interfacial area and limited heat transfer between the phases. Deviation from fluid-dynamic equilibrium (phasic slip) results from different inertial properties and from distinct strength of mechanical coupling between the phases. The numerical results obtained with this model agree quite well with experimental data for two-phase flows with various inlet conditions and channel geometries.

Propõe-se o estudo do separador gravitacional de fundo de poço do tipo shroud invertido para poços direcionais e horizontais. A geometria inovadora é observada pela inclinação imposta, solução que transforma um escoamento vertical descendente, veloz e caótico, num escoamento inclinado e segregado em canal livre. Com a inclinação, minimizasse a incorporação de gás, no impacto do escoamento em superfície livre contra a interface de líquido formada pelo nível do anular interno (NAI), e a segregação é incrementada devido ao gradiente de velocidades e ao aparecimento da componente da gravidade na direção radial do poço de petróleo. O trabalho experimental tem como uma de suas metas o levantamento da eficiência de separação em função das vazões de líquido e gás, do ângulo de inclinação e o grau de interferência do escoamento no duto anular formado entre o separador e a parede do poço de petróleo, chamado neste trabalho de anular externo. Foi feito um trabalho de semelhança dimensional e foram detectados os números adimensionais pertinentes ao problema. Constatou-se que a vazão de gás e o escoamento no anular externo não interferem na eficiência de separação. Além disso, foi realizado um trabalho de caracterização dos padrões do escoamento gás-líquido em duto anular, através de visualização e análise no domínio do tempo e da frequência do sinal dinâmico da queda de pressão. Também são propostos dois modelos matemáticos, um modelo fenomenológico baseado em princípios físicos fundamentais, que foi capaz de prever com eficácia a região de máxima eficiência do separador shroud invertido, e um modelo numérico, que reproduziu a fenomenologia do processo de separação do gás. / This research project proposes the study of the inverted-shroud gravitational gas separator for directional and horizontal wells. The innovative geometry is observed by the inclination that transforms a vertical, fast and chaotic downward flow into an inclined and segregated free channel flow. Due to inclination, the incorporation of gas at the internal gasliquid interface (NAI) is minimized; the segregation is increased due to the velocity gradient and the gravitational term that arises in the radial direction of the oil well. One of the aims of the experimental work is the obtaining of new data of gas separation efficiency as a function of the flow of liquid and gas, inclination angle and the evaluation of the degree of interference of the external annular duct flow. A dimensional analysis was undertaken to identify the relevant dimensionless numbers. It was found that the gas flow and the flow pattern in the external annular duct do not interfere in the separation efficiency. A flow pattern characterization was carried out through visualization and time and frequency domain analysis of differential pressure signature signal. Two mathematical models are proposed, a phenomenological model based on fundamental physical principles, which was able to predict with good accuracy the region of maximum separation efficiency, and a numerical model, which reproduced the phenomenology of the gas separation process.