Tesi: "Porous foam"

1

Osei-Bonsu, Kofi. "Foam-facilitated oil displacement in porous media". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/foamfacilitated-oil-displacement-in-porous-media(f2b2e93b-3a9b-41fa-a841-f81b271e8fad).html.

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Foam flow in porous media is important for many industrial operations such as enhanced oil recovery, remediation of contaminated aquifers and CO2 sequestration. The application of foam in these processes is due to its unique ability to reduce gas mobility and to divert gas to low permeability zones in porous media which otherwise would not be reached. To achieve optimum success with foam as a displacing fluid in oil recovery and remediation operations, it is essential to understand how different parameters influence foam flow in porous media. In this thesis, a variety of experimental techniques were used to study foam stability, foam rheology as well as the dynamics and patterns of oil displacement by foam under different boundary conditions such as surfactant formulation, oil type, foam quality (gas fraction) and porous media geometry. Bulk scale studies showed that foam stability was surfactant and oil dependant such that decreasing oil carbon number and viscosity decreased the stability of foam. However, no meaningful correlation was found between foam stability at bulk scale and the efficiency of oil displacement in porous media for the various surfactants studied in this work. Additionally, our results show that foams consisting of smaller bubbles do not necessarily correspond to higher apparent viscosity as the foam quality is also crucial. For the same foam quality decreasing bubble size resulted in higher apparent viscosity. Although in theory a higher apparent viscosity (i.e. higher foam quality) would be ideal for displacement purposes, increasing foam quality resulted in less stable foam in porous media due to formation of thin films which were less stable in the presence of oil. The effect of pore geometry on foam generation and oil displacement has also been investigated. Our findings provide new insights about the physics and complex dynamics of foam flow in porous media.

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2

Armitage, Paul. "Foam flow through porous media : a micromodel study". Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46650.

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3

Gabbrielli, Ruggero. "Foam geometry and structural design of porous material". Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507759.

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4

Alvarez, Martinez José Manuel. "Foam-flow behavior in porous media : effects of flow regime and porous-medium heterogeneity /". Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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5

Rodeheaver, Bret Alan. "Open-celled microcellular themoplastic foam". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/18914.

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6

Yeates, Christopher. "Multi-Scale Study of Foam Flow Dynamics in Porous Media". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS023/document.

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Pour ce travail, nous utilisons un micromodèle à haute complexité et à structure fixe pour faire une série d’expériences en variant la vitesse d’injection, la qualité de la mousse, les distributions de taille de bulles d’injection, et la méthode d’injection. Nous mettons en œuvre un suivi individuel de bulles pour associer les propriétés d’écoulement aux propriétés de taille de bulles ainsi que les caractéristiques structurelles du milieu poreux. Nous proposons de nouveaux outils pour décrire l’écoulement d’un point de vue global et local de différentes manières. Nous établissons des comportements spécifiques à chaque taille de bulle, en montrant que les bulles des mousses piégées sont plus probables d’être de taille inférieure aux tailles de bulles moyennes, alors que les mousses en mouvement accèdent elles-mêmes à différents chemins d’écoulement selon les tailles de bulles. Les bulles plus volumineuses s’écoulent en majorité dans des chemins préférentiels à haute vitesse, généralement parallèles au gradient de pression, mais les petites bulles sont transportées en supplément à l’intérieur de chemins transversaux liant les chemins préférentiels. Ailleurs, pour nos données nous démontrons l’importance supérieure de la fraction de mousse piégée vis-à-vis de la densité de bulles quant à l’explication microscopique de la viscosité apparente, malgré une contribution des deux. Nous caractérisons structurellement les zones piégées à répétition, comme étant soit des zones à faible coordination de pore, de faible taille de seuil d’entrée, d’orientation de seuil désavantageuse, ou une combinaison de ceux-ci. Les zones à fort écoulement échappent à une caractérisation en termes de paramètres de structure locale et nécessitent une considération de l’information des différents chemins traversant la totalité du modèle. À ce but, afin de décrire les zones à fort écoulement, nous développons un modèle générant des chemins, utilisant une représentation en graphe du milieux poreux, basé sur une décomposition initiale en pores et seuils, qui intègre seulement les notions de taille de seuil et d’orientation de seuil relatif au gradient de pression pour caractériser les chemins
In this work, we use of a high-complexity micromodel of fixed structure on which we perform a series of experiments with varying injection rates, foam qualities, inlet bubble size distributions and injection methods. We perform individual bubble tracking and associate flow properties with bubble size properties and structural characteristics of the medium. We propose new tools describing the local and global flow in different ways. We establish specific behaviors for different bubble sizes, demonstrating that trapped foams are more likely to have smaller than average bubble sizes, while flowing bubbles also tend to segregate in different flow paths according to bubble size. Larger bubbles tend to flow in high-velocity preferential paths that are generally more aligned with pressure gradient, but smaller bubbles tend to access in supplement transversal paths linking the different preferential paths. Furthermore, for our data we establish the pre-eminence of the trapped foam fraction over bubble density within the microscopic explanation of apparent viscosity, although both contribute to some degree. We structurally characterize consistently trapped zones as areas with either low pore coordination, low entrance throat size, unfavorable throat orientation or a combination thereof. High-flow zones however cannot be characterized in terms of local structural parameters and necessitate integration of complete path information from the entire model. In this regard, in order to capture the high-flow zones, we develop a path-proposing model that makes use of a graph representation of the model, from an initial decomposition into pores and throats, that uses only local throat size and throat orientation relative to pressure gradient to characterize paths

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7

Yeates, Christopher. "Multi-Scale Study of Foam Flow Dynamics in Porous Media". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS023.

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Pour ce travail, nous utilisons un micromodèle à haute complexité et à structure fixe pour faire une série d’expériences en variant la vitesse d’injection, la qualité de la mousse, les distributions de taille de bulles d’injection, et la méthode d’injection. Nous mettons en œuvre un suivi individuel de bulles pour associer les propriétés d’écoulement aux propriétés de taille de bulles ainsi que les caractéristiques structurelles du milieu poreux. Nous proposons de nouveaux outils pour décrire l’écoulement d’un point de vue global et local de différentes manières. Nous établissons des comportements spécifiques à chaque taille de bulle, en montrant que les bulles des mousses piégées sont plus probables d’être de taille inférieure aux tailles de bulles moyennes, alors que les mousses en mouvement accèdent elles-mêmes à différents chemins d’écoulement selon les tailles de bulles. Les bulles plus volumineuses s’écoulent en majorité dans des chemins préférentiels à haute vitesse, généralement parallèles au gradient de pression, mais les petites bulles sont transportées en supplément à l’intérieur de chemins transversaux liant les chemins préférentiels. Ailleurs, pour nos données nous démontrons l’importance supérieure de la fraction de mousse piégée vis-à-vis de la densité de bulles quant à l’explication microscopique de la viscosité apparente, malgré une contribution des deux. Nous caractérisons structurellement les zones piégées à répétition, comme étant soit des zones à faible coordination de pore, de faible taille de seuil d’entrée, d’orientation de seuil désavantageuse, ou une combinaison de ceux-ci. Les zones à fort écoulement échappent à une caractérisation en termes de paramètres de structure locale et nécessitent une considération de l’information des différents chemins traversant la totalité du modèle. À ce but, afin de décrire les zones à fort écoulement, nous développons un modèle générant des chemins, utilisant une représentation en graphe du milieux poreux, basé sur une décomposition initiale en pores et seuils, qui intègre seulement les notions de taille de seuil et d’orientation de seuil relatif au gradient de pression pour caractériser les chemins
In this work, we use of a high-complexity micromodel of fixed structure on which we perform a series of experiments with varying injection rates, foam qualities, inlet bubble size distributions and injection methods. We perform individual bubble tracking and associate flow properties with bubble size properties and structural characteristics of the medium. We propose new tools describing the local and global flow in different ways. We establish specific behaviors for different bubble sizes, demonstrating that trapped foams are more likely to have smaller than average bubble sizes, while flowing bubbles also tend to segregate in different flow paths according to bubble size. Larger bubbles tend to flow in high-velocity preferential paths that are generally more aligned with pressure gradient, but smaller bubbles tend to access in supplement transversal paths linking the different preferential paths. Furthermore, for our data we establish the pre-eminence of the trapped foam fraction over bubble density within the microscopic explanation of apparent viscosity, although both contribute to some degree. We structurally characterize consistently trapped zones as areas with either low pore coordination, low entrance throat size, unfavorable throat orientation or a combination thereof. High-flow zones however cannot be characterized in terms of local structural parameters and necessitate integration of complete path information from the entire model. In this regard, in order to capture the high-flow zones, we develop a path-proposing model that makes use of a graph representation of the model, from an initial decomposition into pores and throats, that uses only local throat size and throat orientation relative to pressure gradient to characterize paths

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8

Kim, Dae Whan. "Convection and flow boiling in microgaps and porous foam coolers". College Park, Md. : University of Maryland, 2007. http://hdl.handle.net/1903/7446.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.
Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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9

Mauray, Alexis. "Etude des propriétés de transport de mousse dans des modèles de milieux poreux". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI120/document.

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En récupération assistée du pétrole (EOR), des mousses sont injectées dans des milieu poreux pour améliorer l’efficacité de l’extraction. L’intérêt est d’éviter les digitations visqueuses, la mousse possédant une forte viscosité effective à faible nombre capillaire (Ca). Les mousses sont produites par co-injection de gaz et de solutions aqueuses de tensio-actifs. Cette thèse se propose de comprendre les mécanismes de formation et de transport de mousse en milieu poreux à travers un micromodèle hétérogène fabriqué en NOA. Les études de formation de mousse sont envisagées de deux manières. La première consiste à étudier une co-injection de deux fluides dans un milieu poreux grâce à un jet généré au centre du système. Cette expérience nous permet de constater qu’une dispersion des deux phases est visible pour des nombres capillaire d’injection plus grand que 10-5. Une deuxième expérience d’injection directe d’un train de bulle dans un milieu poreux montre que les bulles se divisent jusqu’à atteindre un diamètre proche de la taille des pores, pour des Ca suffisamment importants. Par ailleurs, nous avons étudié les propriétés de transport d’une mousse dans un milieu poreux. Des mesures directes montrent que la pression générée par l’écoulement peut être jusqu’à 3000 fois plus importante que la pression due à de l’eau à même débit d’injection pour Ca=10-6. Ce rapport diminue fortement avec le nombre capillaire. Une analyse des chemins parcourus par observation directe souligne que pour des faibles débits relatifs de gaz, seuls quelques chemins sont actifs. Il se trouve cependant qu’une augmentation de Ca ou du débit relatif de gaz conduisent à une homogénéisation du balayage de la mousse dans le milieu. A travers différents modèles de simple canaux droits à section constante ou variable, nous notons que la différence de pression créée par une seule bulle suit la loi de Bretherton en Ca^{2/3}. Cependant, la présence de constrictions conduit à l’existence d’un seuil en pression en-dessous de Ca=2.10-4, et donne lieu à des écoulements intermittents. Enfin, nous présentons des observations de formation et transport de mousse en présence d’huile. Nous constatons alors que la présence d’huile n’a pas d’impact notable pour la solution de tensio-actifs, que ce soit sur la formation ou le transport
In enhanced oil recovery (EOR), foams are injected in porous media to improve oil recovery efficiency. The objective is to limit viscous fingering thanks to the high effective viscosity of the foam at low capillary number Ca. Foam is produced by the co-injection of a gas and a solution of surfactants. This thesis focuses on foam formation and transport mechanisms in model porous media using a heterogeneous micromodel made in NOA. Foam formation is studied using two different approaches. The first one consists in studying a co-injection of two fluids thanks to a jet flowing in the center of the system. This experiment shows that the less wetting fluids is dispersed in the other one when the capillary number is higher than 10-5. A second set of experiments is conducted by injected a pre-formed train of big bubbles in model a porous media. The bubbles divide until they reach a diameter of the order of to the pore size, for high enough capillary numbers Ca. Besides, we studied the transport properties of foam in similar model porous media. Direct measurements show that the pressure drop induces by the flow can be at Ca=10-6 as high as 3000 times the pressure corresponding to water injected at the same injection flow rate. This ratio decreases with capillary number. An analysis of the preferential paths by direct observations shows that, for low relative gas flow rate, only a few paths are active. However, an increase of the capillary number or if relative gas flow rate leads to a homogenization of the flow in the medium. Thanks to different simple models of straight or wavy channels, we measure that the pressure drop induced by a single bubble is in good agreement with Bretherton’s law, and scales as Ca2/3. However, in wavy channels the pressure drop due to a single bubble deviates from this prediction and exhibits a plateau at Ca lower than 10-4. In this regime, the motion of the bubble is usually intermittent. Finally, we focus on foam formation and transport properties in presence of oil. Our observations lead to the conclusion that for our setup and surfactant formulations, oil has a negligible influence

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10

Barari, Farzad. "Metal foam regenerators : heat transfer and pressure drop in porous metals". Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/6366/.

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Open pore metal foams with moderate porosity (0.6 – 0.7) may be of interest as regenerators due to their high volumetric heat capacity and large specific surface area. Replication process is a low cost and simple foam manufacturing method which provides moderate porosity metal foams. Due to its simplicity, it provides many opportunities to investigate the effect of porosity, pore size and shape or their combination. In this study, this process was used to manufacture metal foams. A method, called vacuum-gas, was the standard method for manufacturing metal foams in the University of Sheffield Material Science and Engineering department. This method was further investigated and two new methods, gas-only and mechanical infiltration, were introduced. Based on the foams produced by these methods, the gas-only method was adopted due to its repeatability and quality. The method was further investigated by manufacturing eight more samples (1.4-1.7 mm pore size) under various infiltration pressures and the optimum infiltration pressures were found for manufacturing foams with pore size of 1-1.1 mm, 1.4-1.7 mm and 2.0-2.36 mm. A total of nine aluminium metal foams were manufactured for thermal and pressure testing. The manufactured foams had three different pore sizes, 1-1.1 mm (called Small samples), 1.4-1.7 mm (called Mid samples) and 2-2.36 mm (called Large samples). On average foams had porosity in the range of 0.62 – 0.65. Since this type of metal foams never been tested as a regenerator, two extra samples (a packed bed of 10000 2mm ball bearing and a packed bed of 100 layers of wire mesh No. 200) were made to compare with the manufactured foams and the results from other researchers. A test rig was built to test the pressure drop under steady state flow condition from 1 to 6.5 m/s (permeability based Reynolds number from 20 to 175). The extended Darcy-Forchheimer equation and a cubic velocity of Darcy-Forchheimer were used to measure the permeability and form drag of the samples. The results showed that the cubic velocity equation had a better prediction of the permeability and form drag. The Small samples had the lowest permeability and highest form drag coefficient for metal foams. The wire mesh sample had the lowest permeability and lowest form drag among the tested samples. In addition to steady state flow, samples pressure drop was also measured under oscillatory flow. A test rig was built to measure pressure drop and air instant velocity under oscillatory flow (1 to 19 Hz). The results showed that the oscillatory pressure drop was higher than steady state flow except for the Small samples which had higher pressure drop at steady state flow. The pressure drop for the wire mesh sample was measured to compare with other researchers data and a good agreement was observed with some of the published data. Moreover, the instant air velocity was measured by a hot-wire anemometer inside the connecting tube between the sample holder and the compressor. The results showed that the air velocity behaved like a turbulent flow during the acceleration and deceleration period. A single-blow test rig was designed and manufactured to measure thermal performance of the samples. To estimate the average heat transfer coefficient of the samples, several types of the single-blow models were studied and the extended Schumann-Hausen model was implemented for predicting the samples’ outlet air temperature history. Two matching techniques, maximum gradient and direct curve matching were used to match the experimental and modelled outlet temperatures history to estimate samples’ NTU and average heat transfer coefficient. The results showed that NTU increased with decreasing of pore size. Based on mass flow rate Mid samples had the highest h, however the difference between the metal foam samples were insignificant. The foam samples had higher heat transfer coefficient than the ball bearing sample but the wire mesh sample had the highest heat transfer coefficient. The heat transfer results for the wire mesh and ball bearing samples were compared with published data and good agreements were observed.

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11

Glass, Joseph. "Modelling and optimisation of metal foam integrated heat exchangers for power electronics cooling". Thesis, Université Grenoble Alpes, 2021. http://www.theses.fr/2021GRALI007.

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Il y a plusieurs décennies, l'électronique de puissance (PE) est devenue une discipline importante dans le monde de l'électrotechnique.Grâce aux progrès technologiques réguliers, à savoir l'utilisation de matériaux à "wide band gap" pour les semi-conducteurs, les dispositifs PE sont devenus plus compacts et efficaces, mais cela a malheureusement entraîné une gestion thermique réduite. Ainsi, dans le cadre d'un effort collaboratif entre G2Elab, LEGI et SIMAP, ce travail a étudié l'utilisation de la mousse métallique comme nouvel échangeur de chaleur utilisé dans un système de refroidissement à convection forcée qui peut être intégré dans des modules PE pour un refroidissement supérieur. Les mousses métalliques sont légères, ont de faibles densités, des surfaces spécifiques élevées, une structure à cellules ouvertes et de bonnes propriétés thermiques. Ils sont typiquement classés par leur porosité (ε), leur densité de pores (PPI, pores par pouce) et par le diamètre des fibres solides (df). Les avantages du transfert de chaleur proviennent de la possibilité d'une surface spécifique accrue par rapport à d'autres échangeurs de chaleur, tels que des microcanaux, et de la microstructure tortueuse qui génère des turbulences d'écoulement et améliore les transferts de convection dans le fluide de refroidissement. Les performances thermiques ont été modélisées en développant un modèle analytique qui considérait les échangeurs de chaleur comme un réseau de résistances en série. Ceci a été réalisé en simplifiant les équations LTNE qui régissent le transfert d'énergie à travers les phases solide et fluide. Le modèle a été initialement comparé aux simulations numériques et aux résultats expérimentaux de la littérature scientifique, où il a bien fonctionné. Comme niveau supplémentaire de validation, un banc d'essai expérimental a été conçu et assemblé in-house. Les performances thermiques ont été vérifiées en utilisant des thermocouples pour mesurer le profil de température des phases solide et fluide, et les propriétés hydrauliques ont été trouvées en mesurant la chute de pression à travers les échangeurs de chaleur. Les résultats analytiques et expérimentaux concordaient bien les uns avec les autres, s'écartant en moyenne de moins de 10%. Le modèle a ensuite été utilisé pour optimiser les propriétés physiques des mousses afin de produire un échangeur de chaleur qui maximise les performances thermiques tout en minimisant la puissance hydraulique requise. Les résultats montrent que pour une perte de charge de 50 kPa, la résistance thermique d'un échangeur de chaleur en mousse métallique est de 0,127 K/W. Les mousses métalliques sont donc un matériau d'échangeur de chaleur viable et le modèle proposé dans ce travail peut être utilisé comme un moyen rapide et peu coûteux d'optimisation des performances
Several decades ago, power electronics (PE) emerged as an important discipline in the world of electrical engineering. Thanks to regular technological advancements, namely the use of "wide band gap" materials for semiconductors, PE devices have become more compact and efficient, but this has unfortunately resulted in a reduced thermal management. Thus, as a collaborated effort between G2Elab, LEGI and SIMAP, this work has studied the use of metal foam as a novel heat exchanger used in a forced-convection cooling system that can be integrated into PE modules for superior cooling. Metal foams are lightweight, have low densities, high specific surface areas, an open-celled structure and good thermal properties. They are typically categorised by their porosity (ε), their pore density (PPI, pores per inch) and by the diameter of the solid fibres (df). The advantages to heat transfer arise from the possibility of an increased specific surface area over other heat exchangers, such as microchannels, and from the tortuous microstructure that generates flow turbulence and improves convective transfers within the coolant. Thermal performances were modelled by developing an analytical model that considered the heat exchangers as a network of resistances in series. This was achieved by simplifying the LTNE equations that govern energy transfer through the solid a fluid phases. The model was initially compared with numerical simulations and experimental results from the scientific literature, where it performed well. As an additional level of validation, an experimental test bench was designed and assembled in-house. Thermal performances was ascertained by using thermocouples to measure the temperature profile of the solid and fluid phases, and hydraulic properties were found by measuring the pressure drop across the heat exchangers. Analytical and experimental results agreed well with each other, deviating on average by less than 10%. The model was then used to optimise the foams physical properties in order to produce a heat exchanger that maximises thermal performances whilst minimising the required hydraulic power. The results show that for a pressure drop of 50kPa, the thermal resistance of a metal foam heat exchanger is 0.127 K/W. Metal foams are thus a viable heat exchanger material and the model proposed in this work can be used as a quick and inexpensive means of performance optimisation

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12

Clark, Laura A. "Investigation and Optimization of a Porous Sintered Ceramic Material in a Grinding Application". Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/675.

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Porous sintered ceramic foam made of 99.8% Alumina (AL2O3) was investigated for grinding applications in metallic bearings. The properties of this alumina foam were investigated and correlated to the grinding performance in an I.D. grinding application. The mechanical properties, such as density and Young's Modulus, were correlated to grinding performance. The physical properties, investigated with Scanning Electron Microscope (SEM) analysis and a CT Scan, were used to study sintering behavior and porosity size and distribution. This work found an optimal friability and sintering temperature for the alumina foam grinding wheels. This will enable the alumina foam to become a viable grinding product and compete with the conventional vitrified products. This would be significant since the alumina foam has mainly one ingredient and is manufactured with a simpler process. It can also support a higher porosity than conventional grinding wheels, which has proven to provide better grinding performance and coolant access, keeping the work piece cooler and avoiding thermal damage.

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13

Torrens, Richard. "Numerical modelling of shock wave propagation through a layer of porous medium". Thesis, Brunel University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342392.

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14

Bai, Chengying. "Highly porous geopolymer components". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3427257.

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The geopolymers, semi-crystalline three-dimensional silico-aluminate inorganic polymers, have attracted increasing attention from a wide range of scientific interests. The topic of this study deals with the synthesis, the characterization and the potential applications of porous geopolymers (PGs) or geopolymer foams (GFs, total porosity > 70 vol%), realized through different processing routes. Firstly, the processes are divided into five categories: (i) direct foaming, (ii) replica method, (iii) sacrificial template, (iv) the 3D printing, and (v) others. The microstructure, porosity, and properties of porous geopolymers also compared and discussed. Secondly, K-based porous geopolymers were produced by direct foaming using hydrogen peroxide as chemical pore-forming agent (PFA) combined with three types of stabilizing agent (SA, egg white, Tween 80, vegetable oils), and by direct foaming plus reactive emulsion templating. Furthermore, open-celled phosphate-based porous geopolymers were obtained by a simple direct foaming method (using Triton X-100 as physical pore-forming agent). The porosity, pore morphology, high temperature performance, adsorption, mechanical, and insulating properties of PGs were investigated. High strength PGs with tailored porosity and controlled macro-porous structure were fabricated by different processes. The results suggest that the porous geopolymers are promising low-cost highly porous candidates for potential applications such as catalyst or membrane supports (high open porosity and high strength), adsorption (high removal efficiency and adsorption capacity with high open porosity) and insulating (low thermal conductivity, high porosity, and acceptable strength) materials.
I geopolimeri, polimeri inorganici silicoalluminati tridimensionali semi-cristallini, hanno attirato crescente attenzione da una vasta gamma di interessi scientifici. L'argomento di questo studio riguarda la sintesi, la caratterizzazione e le potenziali applicazioni di geopolimeri porosi (PG) o schiume di geopolimeri (GF, porosità totale> 70% vol), realizzati attraverso diversi percorsi di lavorazione. In primo luogo, i processi sono suddivisi in cinque categorie: (i) schiumatura diretta, (ii) metodo di replica, (iii) modello sacrificale, (iv) stampa 3D e (v) altri. Anche la microstruttura, la porosità e le proprietà dei geopolimeri porosi sono state confrontate e discusse. In secondo luogo, i geopolimeri porosi basati su K sono stati prodotti mediante schiumatura diretta utilizzando perossido di idrogeno come agente chimico di formazione dei pori (PFA) combinato con tre tipi di agente stabilizzante (SA, bianco d'uovo, Tween 80, oli vegetali) e mediante schiumatura diretta più reattivo emulsione che modella. Inoltre, geopolimeri porosi a base di fosfato a cellule aperte sono stati ottenuti con un semplice metodo di schiumatura diretta (usando Triton X-100 come agente fisico di formazione dei pori). Sono state studiate la porosità, la morfologia dei pori, le prestazioni ad alte temperature, l'adsorbimento, le proprietà meccaniche e isolanti delle PG. I PG ad alta resistenza con porosità adattata e struttura macroporosa controllata sono stati fabbricati con diversi processi. I risultati suggeriscono che i geopolimeri porosi promettono candidati altamente porosi a basso costo per potenziali applicazioni come catalizzatori o supporti a membrana (elevata porosità aperta e alta resistenza), adsorbimento (alta efficienza di rimozione e capacità di adsorbimento con elevata porosità aperta) e isolanti (basso materiali di conducibilità termica, elevata porosità e resistenza accettabile).

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15

Kuruneru, Sahan Trushad Wickramasooriya. "Numerical modelling of particle deposition in idealized porous channels". Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/90555/1/Sahan_Kuruneru_Thesis.pdf.

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This project provides a steppingstone to comprehend the mechanisms that govern particulate fouling in metal foam heat exchangers. The method is based on development of an advanced Computational Fluid Dynamics model in addition to performing analytical validation. This novel method allows an engineer to better optimize heat exchanger designs, thereby mitigating fouling, reducing energy consumption caused by fouling, economize capital expenditure on heat exchanger maintenance, and reduce operation downtime. The robust model leads to the establishment of an alternative heat exchanger configuration that has lower pressure drop and particulate deposition propensity.

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16

Ko, Kang-Hoon. "Heat transfer enhancement in a channel with porous baffles". Texas A&M University, 2004. http://hdl.handle.net/1969.1/1519.

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An experimental and numerical investigation of heat transfer enhancement in a three dimensional channel using wall mounted porous baffles was conducted. The module average heat transfer coefficients were measured in a uniformly heated rectangular channel with staggered positioned porous baffles. A numerical procedure was implemented, in conjunction with a commercially available Navier-Stokes solver, to model the turbulent flow in porous media. The Brinkman-Forchheimer-Extended Darcy model was used for modeling fluid flow through the porous baffles. Conventional, oneequation, and two-equation models were used for heat transfer modeling. The accuracy and characteristics of each model were investigated and discussed. The results were compared with experimental data. Baffles were mounted alternatively on the top and bottom walls. Heat transfer coefficients and pressure loss for periodically fully developed flow and heat transfer were obtained for different pore densities (10, 20, and 40 pores per inch (PPI)) with two different baffle heights ( / h h B D = 1/3 and 2/3), and two baffle thicknesses ( / t h B D = 1/3 and 1/12). The Reynolds number (Re) was varied from 20,000 to 50,000. To compare the effect of foam metal baffles, the data for conventional solid-type baffles was obtained for ( / t h B D =1/3). The maximum uncertainties associated with the module Nusselt number and friction factor were 5.8% and 4.3%, respectively. The experimental procedure was validated by comparing the data for the straight channel without baffles ( / h h B D = 0) with those in the literature. The use of porous baffles resulted in heat transfer enhancement as high as 300% compared to heat transfer in straight channels without baffles. However, the heat transfer enhancement per unit increase in pumping power was less than one for the range of parameters studied in this work. Correlation equations were developed for the heat transfer enhancement ratio and the heat transfer enhancement per unit increase in pumping power in terms of Reynolds number. The conventional theoretical model, the dispersion conductivity model, and the modified two-phase model using the local thermal non-equilibrium theory were considered. The results from each model were compared against the experimental data, and compared to each other to investigate the efficiency of each model. Also, the characteristics of each model were discussed.

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17

Lundberg, Eva. "Micro-Structure Modelling of Acoustics of Open Porous Material". Licentiate thesis, KTH, Farkost och flyg, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-187322.

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Transportation is a large and growing part of the world’s energy consumption. This drives a need for reduced weight of rail vehicles, just as it does for road vehicles. In spite of weight reductions, the vehicle still has to provide the same level of acoustic comfort for the passengers. Porous materials, with more than 90% air, are often included in multi-layer vehicle panels, contributing to acoustic performance without adding much weight. Here the acoustic performance of open cell porous materials, with focus on flow resistivity, is evaluated based on simplified micro-structure models to investigate the effect of anisotropy on the performance In order to evaluate how the redistribution of material affects the flow resistivity, the porosity of the material is kept constant. Two micro-geometries are analysed and compared: the hexahedral model and the tetrakaidecahedron (Kelvin cell). For flow resistivity calculations the solid frame is assumed to be rigid. The models are elongated in one direction to study the influence of micro-structural anisotropy on the macro level flow resistivity. To keep porosity constant, two different approaches are investigated. The first approach is to let strut thickness be uniform and adjust the volume of the cell to a constant ratio compared to the isotropic case. The second approach is to let the strut volume, and cell volume, be constant. For an anisotropic hexahedral cell with uniform strut thickness, the flow resistivity increases substantially with increasing height to width ratio for the hexahedral model, while the flow resistivity for the tetrakaidecahedron model with uniform strut thickness decreases with increasing height to width ratio. For both geometries and constant strut volume, the average flow resistivity is close to the same constant value. For uniform strut thickness the relative volume of anisotropic to isotropic volume is very important.

The work has been carried out within the Centre for ECO² Vehicle Design.

QC 20160523

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18

Echard, Dalton. "Drying Methods for the Fabrication of Polymer Foam Material". VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4096.

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This is a report on the study of the drying of nanoporous polymer foam material fabricated by photolithogtaphic methods. Three drying methods were employed, which were air drying, supercritical drying and freeze drying. After fabrication and drying, physical properties of the polymer foams were measured. These measurements included density of the material, Young’s modulus, surface area, and the shape of the skeletal particles. The measurements determined the effect of the polymer concentration and the effect of drying methods. It was determined that polymer concentration had a much larger effect on the properties of the materials than the drying method.

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19

Lind, Eleonora. "Predicting and optimising acoustical and vibrational performance of open porous foams". Licentiate thesis, Stockholm : Department of Aeronautics and Vehicle Engineering, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4820.

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20

Li, Yuan. "Synthesis and mechanical characterization of transversely isotropic nanoporous platinum". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42927.

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Nanoporous (NP) metal foams combine desirable characteristics of metals with unique nanoarchitectural features to yield weight normalized properties far superior than either dense metals or bulk metal foams. Due to their high surface to volume ratios these structures show great promise as components of fuel cells, as sensors and have been suggested for use in biological applications, for example as antimicrobial scaffolds or as platforms on which to explore biological material behavior. While most NP metal foams are isotropic, structures with anisotropic features spanning different length scales can further extend applications. This work examines the parameters controlling the synthesis of transversely isotropic NP Platinum foam by dealloying an amorphous Pt-Si alloy. The structure that is examined in this work is hierarchical with Voronoi polyhedra that form on the free surface and under each polyhedral hyper-structure, nanocrystalline NP Pt foam forms with radial struts of length ~60 nm and grain size of 5 nm. The size of the polyhedra can be tailored by changing the dealloying potential. In turn, the mechanical properties of these structures as assessed by nanoindentation can range from 1 to 3GPa depending on the geometric arrangement of the struts. Finally, the initiation location of these structures and the relationship between electrochemical parameters and dealloying front evolution is examined.

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21

Esen, Ziya. "Production And Characterization Of Porous Titanium Alloys". Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608964/index.pdf.

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In the present study, production of titanium and Ti6Al4V alloy foams has been investigated using powder metallurgical space holder technique in which magnesium powder were utilized to generate porosities in the range 30 to 90 vol. %. Also, sintering of titanium and Ti-6Al-4V alloy powders in loose and compacted condition at various temperatures (850-1250oC) and compaction pressures (120-1125 MPa), respectively, were investigated to elucidate the structure and mechanical properties of the porous cell walls present due to partial sintering of powders in the specimens prepared by space holder technique. In addition, microstructure and mechanical response of the porous alloys were compared with the furnace cooled bulk samples of Ti-6Al-4V-ELI alloy subsequent to betatizing. It has been observed that the magnesium also acts as a deoxidizer during foaming experiments, and its content and removal temperature is critical in determining the sample collapse. Stress-strain curves of the foams exhibited a linear elastic region
a long plateau stage
and a densification stage. Whereas, curves of loose powder sintered samples were similar to that of bulk alloy. Shearing failure in foam samples occurred as series of deformation bands formed in the direction normal to the applied load and cell collapsing occured in discrete bands. Average neck size of samples sintered in loose or compacted condition were found to be different even when they had the same porosity, and the strength was observed to change linearly with the square of neck size ratio. The relation between mechanical properties of the foam and its relative density, which is calculated considering the micro porous cell wall, was observed to obey power law. The proportionality constant and the exponent reflect the structure and properties of cell walls and edges and macro pore character.

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22

Geiger, Derek M. "AN EXPERIMENT ON INTEGRATED THERMAL MANAGEMENT USING METALLIC FOAM". DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/75.

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This report details an approach to using metal foam heat exchangers inside an integrated thermal management system on a variable cycle engine. The propulsion system of interest is a variable cycle engine with an auxiliary, variable flow rate fan. The feasibility of utilizing an open-celled metallic foam heat exchanger in the ducting between the constant and variable-fans on this variable cycle engine to cool the avionics was explored using an experimental approach. Two heat exchangers, 6.3 inch width by 6.3 inch length by 0.5 inch thickness, were constructed from 20 and 40 pores per inch (PPI) metal foam and tested. Both were constructed using 6061-T6 aluminum open-cell metal foam with a relative density of 8% and brazed using 4047 aluminum braze to 0.02 inch thick sheet metal made of 6061-T6 aluminum. Both models were subjected to internal forced convection using heated air with flow rates of 4, 8, 12, 16, and 20 standard cubic feet per minute (SCFM). They were also subjected to external forced convection using blowers to supply cooling air to simulate the variable cycle engine’s fans. One duct was supplied with a constant 34 ft/s cooling flow, while the other cooling flow velocity was varied between 0% and 100% of this 34 ft/s, in 25% increments. The temperature and pressure of the flow internal to the metal foam, as well as the heat exchanger external surface and cold flow temperatures, were recorded. A hot-flow Reynolds number range of 1,300 to 6,400 was tested. Results showed expected trends for the hydraulic performance of both heat exchangers. The form factors were 50.4 and 54.8 ft^-1 and the permeabilities were 9.11E-7 and 6.32E-7 ft^2 for the 20 and 40 PPI heat exchangers, respectively. Due to a defect on one side of the 40 PPI heat exchanger, the thermal results are based only on the 20 PPI heat exchanger. While the present study examines a different metal foam heat transfer configuration than most other studies, the metal foam Nusselt numbers were comparable to past studies. In addition, the pumping power required was not excessive and would allow the thermal management system to be realized without an unreasonable energy input. Therefore, a metal foam heat exchanger integrated within the ducting of a variable cycle engine is deemed feasible. The pumping power and thermal resistance were used to create a performance predicting model of the 20 PPI heat exchanger. From this model, the optimized 20 PPI heat exchanger has a hot-flow rate of 10.5 SCFM. The resulting pumping power and thermal resistance are estimated to be 6.7 BTU/hr and 0.036 °R/(BTU/hr), respectively.

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23

Arjmandi-Tash, Omid. "Interaction of droplets and foams with solid/porous substrates". Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/24889.

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Current problems on the interaction of complex liquids (i.e. droplets or foams) with complex surfaces (i.e. soft deformable or porous surfaces) are addressed in the following areas: (1) wetting of deformable substrates and surface forces, (2) kinetics of wetting and spreading of non-Newtonian liquids over porous substrates, (3) kinetics of spreading of non-Newtonian solutions over hair, (4) free drainage of foams produced from non-Newtonian solutions, and (5) foam drainage placed on porous substrates. Equilibrium of liquid droplets on deformable substrates was investigated and the effect of disjoining pressure action in the vicinity of the apparent three phase contact line was taken into account. It was proven that the deformation of soft solids is determined by the action of surface forces inside the transition zone. Spreading/imbibition of blood, which is a power law shear thinning non-Newtonian liquid, over a dry porous layer was investigated from both theoretical and experimental points of view. It was found that blood droplet spreading/imbibition over porous substrates shows two different behaviours: (i) partial wetting case with three subsequent stages: initial fast spreading, constant maximum droplet base and the shrinkage of the droplet base; (ii) complete wetting case with only two stages: initial fast spreading and the shrinkage of the droplet base. The wetting of hair tresses by aqueous solutions of two commercially available polymers, AculynTM 22 (A22) and AculynTM 33 (A33) was investigated experimentally. Both A22 and A33 solutions demonstrate well pronounced shear thinning behaviour. Initial contact angle of the A22 and A33 solutions on hair tresses was about 100o. The A22 droplets remained on the hair tress after spreading for at least half an hour. However, a fast penetration of the A33 droplets inside the hair tresses was observed when advancing contact angle in the course of spreading reached a critical value of about 60o. This could be explained by Cassie-Wenzel wetting transition which is caused by filling the pores inside the porous media by liquid. The influence of non-Newtonian rheology of A22 and A33 solutions on foam drainage was also investigated experimentally and a new theory of foam drainage was presented for the case of free drainage. For lowly viscous polymeric solutions and under the assumption of rigid surface of the Plateau border, the predicted values of the time evolution of the foam height and liquid content were in good agreement with the experimental data. However, in the case of highly viscous solutions an interfacial mobility at the surface of the Plateau border has to be taken into account. A completely new theory of foam drainage placed on porous substrate was developed. It was found that there are three different regimes of the process: (i) a rapid imbibition, the imbibition into the porous substrate dominates as compared with the foam drainage; (ii) an intermediate imbibition, that is, the imbibition into the porous substrate and the rate of drainage are comparable; (iii) a slow imbibition, the rate of drainage inside the foam is higher than the imbibition into the porous substrate for a period of time and a free liquid layer is formed over the porous substrate.

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24

Aydogmus, Tarik. "Processing And Characterization Of Porous Titanium Nickel Shape Memory Alloys". Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612232/index.pdf.

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Porous TiNi alloys (Ti-50.4 at. %Ni and Ti-50.6 at. %Ni) with porosities in the range 21%-81% were prepared successfully applying a new powder metallurgy fabrication route in which magnesium was used as space holder resulting in either single austenite phase or a mixture of austenite and martensite phases dictated by the composition of the starting prealloyed powders but entirely free from secondary brittle intermetallics, oxides, nitrides and carbonitrides. Magnesium vapor do not only prevents secondary phase formation and contamination but also provides higher temperature sintering opportunity preventing liquid phase formation at the eutectic temperature, 1118 °
C resulting from Ni enrichment due to oxidation. By two step sintering processing (holding the sample at 1100 °
C for 30 minutes and subsequently sintering at temperatures higher than the eutectic temperature, 1118 °
C) magnesium may allow sintering probably up to the melting point of TiNi. The processed alloys exhibited interconnected (partially or completely depending on porosity content) open macro-pores spherical in shape and irregular micro-pores in the cell walls resulting from incomplete sintering. It has been found that porosity content of the foams have no influence on the phase transformation temperatures while deformation and oxidation are severely influential. Porous TiNi alloys displayed excellent superelasticity and shape memory behavior. Space holder technique seems to be a promising method for production of porous TiNi alloys. Desired porosity level, pore shape and accordingly mechanical properties were found to be easily adjustable.

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25

Anghelescu, Mihnea S. "Thermal and Mechanical Analysis of Carbon Foam". View abstract, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3353337.

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26

Mines, Levi Walden Dyer. "Porous polyurethane foam for use as a particle collection substrate in a Nanoparticle Respiratory Deposition Sampler". Thesis, University of Iowa, 2015. https://ir.uiowa.edu/etd/1701.

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Abstract (sommario):

Porous polyurethane foam was evaluated as a potential replacement substrate for the eight nylon meshes currently being used in the diffusion stage of the Nanoparticle Respiratory Deposition (NRD) Sampler. A semi-empirical particle deposition model and preliminary tests were used to select the dimensions of foam substrate needed to match the collection of the NRD sampler at recommended sampling conditions. The foam substrate consisted of a cylinder nominally 25-mm diameter by 40 mm in depth, housed in a conductive plastic cassette cowl (internal diameter of 23 mm) compatible with the existing NRD sampler. Pristine foam was evaluated for metals content via acid-assisted microwave digestion and inductively coupled plasma-optical emissions spectroscopy (ICP-OES) chemical analysis. Foam collection efficiency was evaluated using salt (NaCl) and metal fume test aerosols in independent tests. Foam collection efficiency was compared to the nanoparticulate matter (NPM) criterion (established to reflect the total deposition in the human respiratory system for particles smaller than 300 nm) and theoretical modeling. The collection efficiency of NaCl particles was similar to the NPM criterion (R2 = 0.98) and the model underestimated the experimental efficiency (R2 = 0.38). Increased collection efficiency of metal fume was observed for particles larger than 70 nm presumably due to increased interception effects of fractal shaped particles. The pressure drop across the pristine foam was 1/12th that of the nylon meshes. Foam and nylon meshes were loaded with metal fume particles to evaluate performance under simulated field conditions. Changes in collection efficiency and pressure drop were used as measures of performance. Foam had substantially lower changes in collection efficiency and pressure drop with ~ 19 mg metal fume loaded compared to the nylon meshes with ~ 3 mg metal fume loaded.

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27

Moussa, Nadine. "Multi scale modelling and numerical simulation of metal foam manufacturing process via casting". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC021/document.

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L'objectif est d'élaborer un nouveau procédé de fabrication de mousses métalliques par voie de fonderie en modélisant l'infiltration et la solidification d'un métal liquide dans un milieu poreux. La modélisation est faite en deux étapes.Tout d'abord, à l'échelle locale un brin de la mousse métallique est considéré comme un tube capillaire et l'infiltration et solidification d'un métal liquide dans un moule cylindrique est étudiée. Deuxièmement,le modèle macroscopique de la solidification diffusive d'un métal liquide dans un milieu poreux est obtenu par prise de moyenne volumique. Le modèle local est codée dans un outil CFD opensource et trois études paramétriques ont été faites permettant la détermination des relations de la longueur et le temps d'infiltration en fonction de paramètres de fonctionnement. La modélisation de la solidification d’un métal liquide dans un milieu poreux est simplifié en considérant que le moule est complètement saturé par un métal liquide au repos,par suite la solidification se produit par diffusion pure (pas de convection). L'équilibre thermique local (LTE) est considéré entre les phases solide et liquide du métal tandis qu'un non équilibre thermique local (LTNE) est retenue entre la phase métallique et le moule. Les problèmes de fermeture associés ainsi que le problème macroscopique ont été résolus numériquement
The objective of this work is to elaborate a new manufacturing process of metal foams via casting by modelling the infiltration and solidification of liquid metal inside a porous medium.However, due to the complexity of this problem the study is divided into two steps. First, at local scale one strut of the metal foam is considered as a capillary tube and the infiltration and solidification of liquid metal inside a cylindrical mould is studied. Second, a macroscopic model of diffusive solidification is derived using the volume average method. The local model is coded in an open source CFD tool and three parametric studies were done where the relations between the infiltration length and time as function of the operating parameters are determined. The modelling of the solidification of liquid metal inside a porous medium is simplified by considering that the mould is fully saturated by liquid metal at rest, solidification occurs by pure diffusion. Local thermal equilibrium (LTE) is considered between the solid and liquid phases of the metal while local thermal non equilibrium (LTNE) is retained between the metallic mixture and the mould. The associated closure problems as well as the macroscopic problem were numerically solved

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28

Nakas, Gul Ipek. "The Processing Of Porous Ni-rich Tini Alloys Via Powder Metallurgy And Their Characterization". Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615032/index.pdf.

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In the scope of this study, TiNi foams with porosities in the range of 39-64 vol% were processed from prealloyed powders by Mg space holder technique. Porous TiNi alloys displayed homogeneously distributed spherical pores with interconnections, which is suitable for bone ingrowth. Porous Ti-50.8 at%Ni alloys were processed by sintering at 1200 °
C for 2 h to analyze the microstructure as well as mechanical behavior. SEM, TEM and XRD studies were conducted for the characterization of microstructure and phase analyses in addition to the mechanical characterization performed by monotonic and superelasticity compression tests as well as compressive fatigue tests. It was observed that stress required to trigger martensitic transformation was decreased via increasing porosity. The monotonic compression test results also indicated that altering the porosity content of TiNi foams leads to different monotonic compression behaviors. It was observed that the foams display more bulk deformation like behavior as a composite structure composed of TiNi and macropores when the porosity content was low. As the porosity content has increased, the struts became more effective and deformation proceeds by the collapse of favorable struts. On the other hand, cyclic superelasticity tests results indicated that maximum achieved and recovered strain values at the end of fifth cycle increase while the fraction of strain recovered at the end of fifth cycle decreases with decreasing porosity content. Furthermore, the fatigue lives of the processed foams were observed to vary within a band which has a width decreasing with decreasing &sigma
max / &sigma
y yielding an endurance limit ranging in between 26-89 MPa or 0.5-0.6 &sigma
y. Fractography studies on the failed foams after fatigue testing revealed that the failure occurs by the coalescence of micro-cracks initiated from pore walls leading to macro-cracks aligned at 45o with respect to the loading axis. In addition to the mentioned characterization studies, the effects of sintering temperature and time on TiNi foams with 58 vol% porosity as well as heat treatment on the microstructure and the mechanical behavior of TiNi foams with 49 vol% porosity were analyzed with SEM and compression tests. Aging of TiNi foams with 49 vol% porosity at 450 °
C for 1.5 h has shown that the presence of Ti3Ni4 precipitates improve the superelastic response.

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29

Thomas, Tony. "Fabrication techniques to produce micro and macro porous MAX-phase Ti2AlC ceramic". Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669028.

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MAX-phase ceramics are a class of ductile ceramic material group with the general molecular formula Mn+1AXn (n = 1, 2, 3….), where M is an early transition element, A is an element from the ‘A’ group of the periodic table and X is either nitride or carbide. One advantage of these materials is that they maintain their strength at high temperatures. In addition these ceramic materials possess the best properties of both ceramics and metals. Some of their important characteristics are low density, high stiffness, machinability, excellent thermal and electrical conductivity and they even exhibit some plasticity at elevated temperature. These amazing combinations of properties have made researchers foresee the technological importance of these materials as a structural ceramic for high temperature application. Since this ceramic is relatively new to the market, only a handful of work has been undertaken on this material and its applications are limited to heating elements. In addition, analysis of the thermodynamic data on this material is incomplete. This PhD work addresses this issue and conducts a complete thermodynamic analysis involved in the formation mechanism of the ternary titanium carbide MAX-phase Ti2AlC ceramic, using Self-propagating High temperature Synthesis (SHS) form of combustion synthesis process, based on the following exothermic reaction: (2+x) Ti + (y) Al + C → Ti2AlC + (x) Ti + (y) Al (i) Where x and y = 0.1. 0.2, 0.3… A thermodynamic model has been formulated to predict the temperature evolution during the reaction (i), for the formation of Ti2AlC using SHS process. In addition the effect of particle size in the elemental reaction has been studied on the formation mechanism of Ti2AlC and methods to control the porosity by fine tuning the particle size has been recognized. Manufacturing processes such as Self-propagating High temperature Synthesis (SHS), foam replication and freeze casting have been developed in this thesis to produce micro and macro porous Ti2AlC ceramic mainly for electrode applications. A systematic material development technique to produce macro porous Ti2AlC ceramic, using a foam replication technique has been established in this research work. The material fabricated by this technique has a uniform pore size (up to 5mm), with open interconnected pores and is ideal for a flow battery application which requires a multifunctional electrode material which is highly porous to allow the flow of electrolyte through it, is corrosion resistant and at the same time being electrically conductive. The mechanical properties of the ceramic produced by this method has been characterised and steps to mitigate the cracks and defects formed during the fabrication process to obtain structurally stable macro porous Ti2AlC ceramic has been reported in this work. This research demonstrates that one of the applications of macro porous Ti2AlC ceramic formed using foam replication technique is as an electrode material in a photo-Microbial Fuel Cell (p-MFC). Graded porosity micro porous Ti2AlC ceramics have also been fabricated using a freeze casting technique, with camphene as the freezing vehicle. A systematic material development process has been tailored for this particular material. A ceramic material with gradient pore size ranging from 27-305µm has been fabricated using this technique. This type of ceramic is a good candidate as an electrode material in micro-redox battery and for sensing applications. A variety of processing parameters such as solid loading (amount of ceramic content in the material), freezing temperature and mould material which affect the pore formation and pore size have been studied in this PhD and the range of porosities achieved by controlling these parameters have been reported.

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30

Mensire, Rémy. "Hydrodynamics of oil in contact with an aqueous foam : wetting, imbibition dynamics and flow in rough confined media". Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1137/document.

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L’extraction de matières premières du sol à des fins énergétiques (récupération assistée d’huile) et environnementales (dépollution des sols) fait l’objet de recherches intensives en lien avec des thématiques telles que la séquestration du carbone ou la fracturation hydraulique. L’objectif est de trouver des méthodes moins destructives, moins gourmandes en matériel et en énergie, mais aussi plus efficaces et moins coûteuses. Nous proposons d’étudier une méthode alternative aux moyens conventionnels avec l’utilisation de mousses aqueuses comme agent extracteur d’huile. Les mousses aqueuses sont souvent utilisées en présence d'huile : dans des applications quotidiennes comme la cosmétique et la détergence, mais aussi dans des domaines moins connus comme la décontamination des centrales nucléaires ou l’industrie pétrolière. Ainsi, des tensioactifs et du gaz sont couramment injectés dans le sol afin d'améliorer les procédés de récupération de pétrole. Nous explicitons deux mécanismes d'extraction que nous quantifions en termes d'efficacité et de stabilité. Tout d'abord, la mousse peut aspirer de l'huile en son sein, comme le ferait une éponge. Ensuite, lorsque celle-ci est mise en écoulement, elle peut entraîner de l'huile confinée dans la rugosité d'une surface par cisaillement. Notre étude s’appuie en particulier sur une analyse théorique et expérimentale, à la fois multi-échelle, statique et dynamique pour laquelle nous avons systématiquement fait varier les paramètres géométriques (configuration de l'huile, taille des bulles et fraction volumique de liquide dans la mousse) et physico-chimiques (tensions interfaciales, rigidité des interfaces entre bulles et viscosité)
The extraction of raw materials from the soil for energetical (enhanced oil recovery) and environmental purposes (soil remediation) is the subject of intense fundamental and applied research. This field is related to other important topics, such as carbon sequestration and hydraulic fracturing. The goal is to find fewer destructive, as well as energy and material-saving methods. These techniques should also be cost-effective and more efficient. To find a substitution to conventional means, we study an alternative method that puts aqueous foams on the map as the extraction material. Aqueous foams are often used in numerous daily applications, such as cosmetics and detergency, but also in less known fields, such as the decommissioning of nuclear power plants and the oil industry. Thus, surfactants and gas are commonly injected into the soil to improve the recovery processes of oil. We explain two extraction mechanisms that we quantify in terms of efficiency and stability. On one hand, the foam is able to absorb oil, similarly to a solid sponge. On the other hand, when a flow of foam is induced, the foam can entrain oil confined in the roughness of a surface by shearing the oil-water interface. Our work especially lies on a theoretical and experimental analysis, which is multiscale, static and dynamic. We systematically vary the geometrical parameters (oil configuration, bubble size and liquid fraction in the foam) and the physical and chemical parameters (interfacial tensions, interfacial rigidity and viscosity)

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31

Marangoni, Mauro. "Dense and porous glass and glass ceramics from natural and waste raw materials". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424468.

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Abstract (sommario):

The main goal of the herewith presented research activities was to develop innovative processes and materials for building applications adapted to the needs of Saudi Arabia according to the information exchanged with the partners from KACST (King Abdulaziz City of Science and Technology). The research activity focused on the development of a wide range of ceramic components via sinter-crystallization of glasses produced from waste (fly ash, slag, sludge) with or without the addition of vitrification aids, such as cullet or silicates. The raw materials have been mixed in the appropriate ratios to yield ceramic compositions that could be used in the building industry (e.g glass ceramic tiles, porous panels, lightweight aggregates). Monolithic, porous or dense, sintered glass ceramics and ceramics were manufactured as substitutes for natural stones or traditional ceramics. Dense glass ceramics have outstanding properties (hardness, mechanical strength, durability), while porous glass ceramics provide low density and thermal conductivity. Furthermore highly reflective glazes, also matching the whiteness of Thassos marble, were manufacture sintering glass frits. All the developed materials are based on the use of natural resources or waste materials from Saudi Arabia. Moreover, several techniques for direct foaming of glass ceramics have been developed, leading to highly porous ceramics with mainly closed cells. Alternative techniques have been developed for the production of open-celled ceramics.
Il principale obiettivo delle attività di ricerca qui presentate riguardano lo sviluppo di nuovi processi e materiali per applicazioni in edilizia adattate alle esigenze dell'Arabia Saudita in base alle informazioni scambiate con i partner di KACST (King Abdulaziz City of Science and Technology). L'attività di ricerca è stata focalizzata sullo sviluppo di una vasta gamma di componenti ceramici mediante sintercristallizzazione di vetri prodotti da rifiuti (ceneri volanti e scorie) con o senza l'aggiunta di fondenti come rottame di vetro o silicati. Le materie prime sono state miscelate in rapporti adeguati alla produzione di composizioni ceramiche adatte all’utilizzo in edilizia; ad esempio piastrelle vetroceramiche, pannelli alleggeriti e aggregati leggeri. Vetroceramiche e ceramiche, dense e porose, sono state realizzate come sostituti alle pietre naturali e ai ceramici tradizionali. Vetroceramici densi presentano proprietà eccezionali (durezza, resistenza meccanica, durabilità), mentre vetroceramiche porose presentano ridotte densità e conducibilità termica. Inoltre sinterizzando fritte vetrose sono stati ottenuti smalti altamente riflettenti con bianchezza corrispondente al marmo di Thassos. Tutti i materiali sviluppati sono basati sull'utilizzo di risorse naturali o materiali di scarto provenienti dall’Arabia Saudita. Inoltre, sono state sviluppate diverse tecniche per la schiumatura diretta di vetroceramiche, portando alla realizzazione di materiali altamente porosi con celle principalmente chiuse. Utilizzando tecniche alternative sono state invece sviluppate vetroceramiche con una prevalenza di celle aperte.

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32

Wöckel, L., A. Seifert, C. Mende, I. Roth-Panke, L. Kroll e S. Spange. "Resin and carbon foam production by cationic step-growth polymerization of organic carbonates". Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-220096.

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Acid induced step-growth polymerizations of bis(p-methoxybenzyl) carbonate (pMBC), bis(m-methoxybenzyl) carbonate (mMBC) and difurfuryl carbonate (DFC) have been performed to produce resin-foams, because controlled release of carbon dioxide takes place during polymerization of those organic carbonates. The monomers are polymerized in bulk using p-toluene sulfonic acid (pTS) as a catalyst. The volume development of the foams is assisted by use of an appropriate surfactant and the crosslinking agent 1,3,5-trioxane as co-components. A portion of carbon dioxide release is a function of the carbenium stability of the reactive intermediate derived from the monomer; DFC > pMBC ≫ mMBC. Resins derived from mMBC can be post-treated to release carbon dioxide after polymerization. The molecular structures of the resulting materials are investigated by solid state 13C-NMR spectroscopy and IR spectroscopy. Scanning electron microscopy was used to study foam morphology. The carbon dioxide release was monitored with TG-MS analysis. Finally, the polymer foams have been converted into carbon foams and investigated by means of mercury porosimetry
Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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33

Van, Zyl Willem Heber. "Investigation into the production and application of porous titanium within the biomedical field". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96097.

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Thesis (MScEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: In this study, commercially pure titanium foam was produced using space holder powder metallurgy techniques. Titanium foam is attractive as a scaffolding material for bone replacement and implants in the body. The porous morphology of the foam promotes osteogenesis, while the mechanical behaviour of the foam is closer to that of bone, which has an elastic moduli range of 5 - 40 GPa. Titanium foam was manufactured from powder mixtures of commercially pure titanium (CPTi) powder mixed with 41.4 wt% ammonium bicarbonate (ABC) powder and 1.45 wt% polyethyl glycol (PEG) powder. In this study, two CPTi powders with different particle size distributions, < 75 μm (-200 mesh, designated TiAA) and < 200 μm (-100 mesh, designated TiG), were mixed with the space holder ABC powder, that had been sieved into specified particle size ranges. The size ranges of space holder material studied were: 0 - 710, 250 - 425, 425 - 560, and 560 - 710 μm. This allowed foams with different large or macropore distributions to be produced from the different mixtures. The mixtures were uniaxially compacted at 100 MPa into transverse rupture bars. The ABC and PEG was then removed by thermal debinding in air for 5 hours at 100 °C and 1 hour at 330 °C each, consecutively. The debound samples are then sintered under high (10-6 mbar) vacuum on yttria-stabilised zirconia substrates, heating at 5 °C/min to 1200 °C, with a 2 hour hold at temperature. The microstructures of the different foams were evaluated by examining the polished samples using light optical microscopy. Three point bend tests were conducted on the sintered bars in order to determine the flexural strength and flexural modulus of the different foams. The produced foams had a relative density range between 37.5 - 62.5 % and average macro pore size range between 300 - 500 μm. The foams were found to have an elastic modulus similar to that of bone, 2 - 7 GPa. Finally, the mechanical properties of the foams were compared to known open foam mechanical models and other research projects. It was found that: (i) changes in either metal or space holder powder influences the sintering behaviour of metal foams, (ii) sintered titanium foams with similar densities but different macro/micropore size distributions have different mechanical responses to stress and (iii) the Ashby-Gibson model, based on foam density alone, gives a rough estimate of mechanical properties for the titanium foams studied, but does not capture variations due to pore size distribution.
AFRIKAANSE OPSOMMING: In hierdie studie is kommersiële suiwer titaanskuim geproduseer met behulp van ruimtehouer poeier metallurgie tegnieke. Titaanskuim is aantreklik as 'n raamwerkmateriaal vir beenvervanging en -inplantings in die liggaam. Die poreuse morfologie van die skuim bevorder osteogenese, terwyl die meganiese gedrag van die skuim naby aan dié van been is, met ‘n elasticiteitsmodulus tussen 5 - 40 GPa. Titaanskuim is vervaardig van ‘n poeier mengsel van kommersiële suiwer titaan (CPTi) poeier gemeng met 41,4 gew% ammonium bikarbonaat (ABC) poeier en 1.45 gew% poli-etileenglikol (PEG) poeier. In hierdie studie is twee tipes CPTi poeiers met verskillende deeltjiegrootteverspreiding, < 75 μm (-200 stofdigtheid, TiAA genoem) en <200 μm (-100 stofdigtheid, TiG genoem), met die ruimtehouer ABC-poeier, wat in bepaalde deeltjiegroottereekse gesif is, gemeng. Die wisselende groottes van ruimtehouer wat bestudeer is, was: 0 - 710, 250 - 425, 425 - 560, 560 - 710 μm. Dit het die vervaardiging van skuim met verskillende groot of macroporeuse vanaf die verskillende mengsels toegelaat. Die mengsel is teen 100 MPa in een rigting gekompakteer. Die ABC en PEG is dan verwyder word deur termiese ontbinding in lug vir 5 uur by 100 °C en 1 uur by 330 °C elk, onderskeidelik. Die ontbinde monsters is dan onder hoë (10-6 mbar) leemte op yttrium-gestabiliseer zirconia-substraat, met verwarming teen 5 °C/min tot 1200 °C met 'n verdere 2 uur by 1200 °C, gesinterd. Die mikrostrukture van die verskillende skuim is geëvalueer deur gepoleerde monsters met behulp van ‘n ligmikroskopie te ondersoek . Driepunt draaitoetse is op die gesinterd stawe uitgevoer om die buigsterkte en buigmodulus van die verskillende skuime te bepaal. Die vervaardigde skuime se relatiewe digtheid het tussen 37,5 - 62,5 % gewissel en die gemiddelde makroporiegrootte tussen 300 - 500 μm gewissel. Die skuim het 'n elastisiteitsmodulus soortgelyk aan dié van been getoon, 2 – 7 GPa. Ten slotte is die meganiese eienskappe van die skuim met bekende oop skuim meganiese modelle en ander navorsingsprojekte vergelyk. Daar is bevind dat: (i) veranderinge in óf metaal of ruimtehouer poeier beïnvloed die sinteringgedrag van metaalskuime, (ii) gesinterd titaniumskuim met soortgelyke digthede, maar verskillende makro / mikroporeuse verdelings, toon verskillende meganiese reaksies op stres en die Ashby-Gibson model, gebaseer op die skuimdigtheid alleen, (iii) wat 'n rowwe skatting van die meganiese eienskappe vir die bestudeerde titaniumskuime gee, maar nie die variasies ingrootteverspreiding van porieë ondervang nie.

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34

Rožėnas, Paulius. "Putų cementbetonio savybių tyrimas". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080722_132553-98463.

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Šio magistrantūros studijų baigiamojo darbo tikslas yra išnagrinėti autoklavinio poringojo betono savybes į kurio mišinio sudėtį dedama akytojo betono gamybos atliekų. Akyta cementbetonio struktūra sudaryta naudojant putas. Darbas susideda iš teorinės ir eksperimentinės dalių. Teorinėje dalyje atlikta literatūros analizė, pateiktos bendrosios žinios apie akytuosius betonus, jų žaliavas, klasifikaciją bei kai kurias fizikines ir mechanines savybes. Autoklavinis putų cementbetonis nagrinėjamas kaip viena iš akytojo betono atmainų. Nagrinėjami putokšliai, lyginamos iš jų išplaktų putų savybės. Aptariamas akyto betono atliekų panaudojimas gaminant putų cementbetonį. Šiuo tikslu buvo nagrinėjami įvairūs literatūros šaltiniai, lyginamos įvairių autorių sukauptos žinios ir tyrimų rezultatai. Eksperimentinėje dalyje tiriamos putokšlių ir iš jų išplaktų putų savybės. Nagrinėjamas akytojo betono gamybos atliekų panaudojimas. Aprašoma putų ir betono atliekų kiekio įtaka putų cementbetonio tankiui, gniuždomajam stipriui ir gaminių struktūrai.
The point of this postgraduate studies final work is research the autoclaved porous concrete characteristics, in whose composition is waste of porous concreat. The porous structure is make by foam. This work consists of theoretical and experimental parts. The teoretical part of this work consist of literature analysis, there are given general knowledge about porous concrete, materials, classifications, physical and mechanical characteristics. The autoclaved foam cement concrete was researched like one of the active concrete species. There were analysed foamers, comparables internals of foams. Considerating the waste of porous concreat utilization maiking foam cement concrete. For this purpose were researched various information publikations, compared the cumulated knowledges and experimental results of various authors. In experimental part are described foamers and from their mades foams characteristics. Reserching the waste of porous concreat utilization. Described quantity of foams and concrete wastes influence to density, strength and composition of foam cement concrete.

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35

Haffner, Benjamin. "Stabilité des suspensions fortement aérées". Thesis, Paris Est, 2015. http://www.theses.fr/2015PEST1095/document.

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Nous étudions le drainage des mousses de suspension granulaire. Nos paramètres de contrôle sont : la fraction en gaz, la taille des bulles, celle des particules et la fraction volumique de celles-ci dans la phase interstitielle. En premier lieu, nous mesurons la proportion de liquide et de particules retenus dans le réseau de la mousse en fonction des paramètres cités précédemment. Ces mesures réalisées une fois le drainage terminé apportent des éléments de compréhension indispensables à la description des vitesses de drainage. Nous montrons également que certaines combinaisons de nos paramètres d'étude conduisent au blocage du système gaz, liquide, solide. Dans un second temps, nous avons identifié différents régimes de cinétique de drainage, nous montrons qu'ils sont contrôlés par deux paramètres : (i) le rapport lambda de la taille des particules et de la taille des constrictions du réseau, (ii) la fraction en particules dans la phase interstitielle phi. Le point clé pour comprendre ces régimes est le piégeage des particules dans la mousse qui peut avoir deux origines : (i) par piégeage collectif (jamming) qui peut survenir pour des fractions étonnamment basses à cause de la géométrie du réseau interstitiel, (ii) la capture individuelle des particules par la mousse lorsque leur taille devient supérieure à celle des constrictions du réseau interstitiel. Des particules encore plus grosses sont exclues du réseau et participent à une remontée de la vitesse de drainage, faisant apparaître un minimum pour le régime correspondant à la capture individuelle. La fraction granulaire de la phase interstitielle est aussi essentielle, le drainage pouvant être stoppé pour des fractions suffisamment élevées lorsque lambda est judicieusement choisi. Ce travail propose des pistes prometteuses pour la stabilité des matériaux triphasiques
We study the drainage of granular suspensions foams. Our control parameters are the gas fraction, the bubble size, the particles size and the interstitial particle fraction. First, we measure the proportion of liquid and particles retained in the foam network as function of the above mentioned parameters. These measurements are performed when the drainage is over, they are essential for the description of drainage velocity. We show that certain combinations of our study parameters lead to the jamming of the three-phase system : gas, liquid, solid. Secondly, we highlight different regimes of drainage velocity, we show that is controlled by two parameters : (i) lambda, the ratio of the particle size and constriction size, (ii) the fraction of particles in the interstitial network : phi. The key to understand these regimes is the trapping of particles in the foam : (i) the jamming, which may occur for surprisingly low fractions due to the geometry of the pore network, (ii) the particles captured by the foam network when they become larger than the constrictions network. Finally, larger particles excluded from the network increase the drainage velocity, as a consequence the minimum for the velocity corresponds to the individual capture. The granular fraction of the suspension in the foam network is the other key parameter. Especially, the drainage can be stopped for sufficiently high fractions for certain values of lambda. This work offers promising outlook for the stability of three-phase materials

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36

Medvescek, James. "Experimental investigation of fully developed flows of a Newtonian fluid in straight rectangular ducts with adjacent open and porous-metal-foam domains". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119474.

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Over the last two decades, porous metal foams (which have very high values of surface-area-to-volume ratio, of the order of 10,000 square meters per cubic meter; and values of porosity in the range 0.85-0.98) have been increasingly used in devices for heat transfer (ultra-compact heat exchangers and heat sinks; heat pipes; and loop heat pipes), filtration, catalytic conversion, and acoustical control. In computational methods for thermofluid optimization of such devices, cost-effective modeling of fluid flows in adjacent open and porous-metal-foam domains is done using two different, but compatible, sets of volume-averaged governing equations; and at the interface between these domains, the intrinsic-phase-averaged pressure, phase-averaged fluid velocity, and normal stress are assumed to be continuous, and a tangential stress-jump condition, with two adjustable coefficients, is imposed. Accurate experimental data for determining these adjustable coefficients and establishing possible laminar-turbulent transition criteria for the aforementioned flows are urgently needed. In the present work, an experimental investigation of fully developed flows of air in a straight, uniform, rectangular duct of high cross-sectional aspect ratio and containing open and porous-metal-foam domains was undertaken. These flows are akin to those studied in the classical Beavers-Joseph problem. Four different porous metal foams (with nominal pores per inch designations of 20, 40, 60; nominal thickness of 12.7 mm; and porosity in the range 0.85-0.94) were considered. An experimental facility was specially designed and constructed to allow test-section configurations of nominal open-domain heights of 0 (completely filled with porous metal foams), 3.175 mm, 6.35 mm, and 12.7 mm. The nominal width and length of the test section was fixed at 152.4 mm and 457.2 mm, respectively. The top wall of the test section had 64 wall-static-pressure taps and also a wall-shear-stress sensor, which was redesigned (improved) from an earlier version. The airflow rates were measured using a Venturi tube (specially designed, constructed, and calibrated for this work) and a bank of laminar flow elements. An analytical solution for laminar fluid flows in the problems of interest was adapted from other works in the published literature. The results obtained from experiments undertaken for benchmarking tasks, characterization of the porous metal foams (photomicrographs; ligament, pore, and cell effective diameters; and porosity), and calibration of the wall-shear-stress sensor are presented and discussed. Data from experiments undertaken to determine the permeability and dimensionless form-drag coefficient of the porous metal foams were processed using four different approaches, and the results are presented and comparatively discussed. Comprehensive sets of experimental data collected for airflows in adjacent open and porous-metal-foam domains (in the laminar, transitional, and turbulent regimes) are presented and discussed. These experimental data, the analytical solution for such problems with laminar flows, power-spectral-density (PSD) plots of the instantaneous wall-shear-stress measurements, and the requirements for physically tenable values for the laminar-flow results were collectively used to obtain guidance regarding laminar-turbulent transition, and then deduce the two coefficients in the interfacial jump condition on the shear stress. For flows through test sections completely filled with the porous metal foams, the data collected were used to obtain a Darcy friction factor as a function of a Reynolds number (both based on the superficial velocity of the air and the effective diameter of the metal-foam ligaments). The data collected in the experiments on flows in test sections with adjacent open and porous domains were used to obtain the open-domain Darcy friction factor as a function of the corresponding Reynolds number. These results are presented and discussed.
Au cours des deux dernières décennies, les mousses métalliques poreuses, MMP, (ayant des valeurs très élevées de superficie d'échange thermique volumétrique, de l'ordre de 10 000 mètres carrés par mètre cube, et valeurs de la porosité de 0,85 à 0,98) sont devenues de plus en plus commun dans plusieurs domaines: le transfert thermique (échangeurs de chaleur ultracompacts, dissipateurs de chaleur, caloducs et des caloducs en boucle), la filtration; la conversion catalytique; et l'acoustique. Les simulations numériques d'écoulements en domaines ouvert / de MMP adjacents se font en résolvant deux équations différentes (moyennées volumétriquement), correspondant aux deux domaines différents. À l'interface de ceux-ci, la pression intrinsèque (moyennée), la vélocité du fluide (moyenné), et la contrainte normale sont supposées être continues, et une discontinuité de la contrainte tangentielle à l'interface, avec deux coefficients réglables, est imposée. La connaissance de ces coefficients réglables, et l'établissement de critères de transition laminaire-turbulent pour ces types d'écoulements nécessitent urgemment des données expérimentales précises. Le travail ci-inclus comprend une étude expérimentale d'écoulements d'air pleinement développés, en canal rectangulaire et uniforme, de rapport largeur/hauteur élevé, et contenant des domaines ouvert / de MMP adjacents. De tels écoulements ressemblent à ceux étudiés dans le problème Beavers-Joseph. Quatre MMP différentes (ayant des pores de tailles nominaux de 20, 40, 60 pores par pouce, une épaisseur nominale de 12,7 mm, et des porosités allant de 0,85 à 0,94) furent examinées. Un dispositif expérimental fut conçu et construit pour permettre des configurations d'hauteurs du domaine ouvert dans la section de mesure de 0 (complètement rempli de MMP), 3,175 mm, 6,35 mm, et 12,7 mm. La largeur nominale et la longueur de la section de mesure furent fixées à 152,4 mm et 457,2 mm, respectivement. La paroi supérieure de la section de mesure possède 64 prises de pression statique et un capteur de contrainte de cisaillement à la paroi. Les débits d'air furent mesurés en utilisant un tube de Venturi (spécialement conçu, construit, et étalonné pour ce travail) et une banque d'éléments laminaires. Les résultats obtenus des expériences menées pour i) des tâches d'analyse comparative; ii) la caractérisation des mousses métalliques (microphotographes; diamètres effectifs des ligaments, des pores et des cellules; porosité); et iii) l'étalonnage du capteur de contrainte de cisaillement sont présentés et interprétés. Les données provenant des expériences mesurant la perméabilité et le coefficient adimensionnel de traînée de forme des MMP furent déterminées selon quatre approches différentes, et comparées. Des ensembles de données expérimentales recueillies en écoulements d'air en domaines ouvert / poreux adjacents (dans les régimes laminaire, de transition, et turbulent) furent présentés et analysés. Ces données, la solution analytique de tels écoulements laminaires, les densités spectrales de puissance des mesures instantanées de la contrainte de cisaillement à la paroi, et les conditions nécessaires correspondantes au régime laminaire furent collectivement utilisées pour obtenir des indicateurs concernant la transition laminaire-turbulent, et pour déduire les deux coefficients dans la condition de discontinuité de la contrainte de cisaillement à l'interface. Les données provenant des mesures dans lesquelles le canal était complètement rempli de MMP furent utilisées pour calculer un coefficient de frottement de Darcy en fonction du nombre de Reynolds (basé sur la vélocité superficielle de l'air et le diamètre effectif des ligaments de la MMP). Les données recueillies dans les expériences en domaines ouverts / poreux adjacents furent utilisées pour obtenir le coefficient de frottement de Darcy (du domaine ouvert) en fonction du nombre de Reynolds correspondant. Ces résultats sont présentés et interprétés.

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37

Delbos, Aline. "Imprégnation forcée de fluides dans des milieux poreux". Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00542832.

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Cette thèse porte sur les capacités d'extraction d'une mousse déposée sur un support poreux dans le but d'y déloger un contaminant ayant imprégné la porosité. Nous avons donc considéré l'imprégnation forcée de fluides dans un pore unique, étudiée pour deux cas particuliers : (i) lors de l'impact d'une goutte de liquide à l'aplomb d'un pore unique vertical cette situation visant à modéliser l'imprégnation du poreux par le contaminant, et (ii) lors de l'aspiration d'une mou sse liquide à travers le pore qui illustre la compétition d'aspiration entre la mousse et le poreux. Dans chaque cas, le diamètre du pore est inférieur à celui des gouttes ou des bulles.Pour le premier cas, nous nous sommes intéressés au volume et à la profondeur d'imprégnation pour des surfaces hydrophiles et hydrophobes. Nous établissons les diagrammes d'imprégnation en fonction du diamètre du pore et de la vitesse d'impact et un travail de modélisation nous permet de déterminer les limites entre les différentes régions de ces digrammes.Pour le second cas, nous montrons que lors de l'aspiration, la mousse entre dans le pore uniquement dans un domaine bien déterminé dans le diagramme fraction liquide, rapport de taille pore/bulle et débit d'aspiration. En dehors de ce domaine, l'aspiration peut faire entrer soit le gaz seul, soit le liquide seul. La encore, un travail de modélisation nous permet de prédire les limites des différentes zones du diagramme. Dans une dernière partie, nous revenons à un problème pratique d'imprégnation sur support textile et quantifions les capacités d'extraction d'une mousse dans cette configuration dans le but d'y déloger un contaminant

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Del, Campo Estrada Estefania. "Ecoulements de mousse pour la dépollution d'aquifères". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0101/document.

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La pollution d’aquifères par des hydrocarbures est très persistante et difficile à traiter, devenant un enjeu majeur pour l’environnement en raison de l’effet négatif sur la santé humaine. La génération de mousse in situ combinée au lavage de sols est une technique de dépollution innovante, permettant un meilleur contrôle de la mobilité des fluides dans des formations hétérogènes. Le but de cette méthode est de bloquer l’écoulement dans les couches à forte perméabilité pour améliorer l’efficacité de balayage des strates peu perméables.Le mémoire se divise en deux parties principales décrivant une étude expérimentale et une étude numérique.Une sélection préalable de tensioactifs respectueux de l’environnement à été réalisée sur la base de leur moussabilité. Le sucrose laurate (émulsifiant alimentaire) a été retenu et comparé avec un tensioactif dit classique. Des tests sur colonnes 1-D ont permis d’étudier l’influence de la perméabilité, du type de tensioactif et de la qualité de la mousse sur le facteur de résistance à la mobilité du gaz. Les résultats, interprétés à l’aide de la pression capillaire, révèlent deux régimes d’écoulement, correspondants aux deux textures de mousse : « weak » et « strong ». Des expériences sur pilotes 2-D hétérogènes ont permis de visualiser les différentes phases du processus de remédiation et de comparer l’efficacité de balayage avec et sans une région bloquée par de la mousse.La partie modélisation comprend une simulation numérique des tests sur colonne 1-D en utilisant le code UTCHEM et une étude de sensibilité des paramètres les plus importants du modèle, ainsi qu’une modélisation des tests de traçage sur pilote 2-D avec le code MODFLOW
Aquifer pollution with hydrocarbons is very persistent and difficult to treat, becoming a major issue for the environment because of the negative effect on human health. In situ foam generation combined with soil washing is an innovative remediation technology that allows a better fluid mobility control in heterogeneous formations. The purpose of this method is to block the flow through the high permeability layers in order to improve the sweep efficiency of low permeability strata.The thesis is divided into two main parts describing an experimental study and a numerical study.A preliminary selection of environmentally-friendly surfactants was carried out on the basis of their foamability. Sucrose laurate (emulsifier from food industry) was selected and compared with a conventional surfactant. 1-D column tests were performed to study the influence of permeability, surfactant type and foam quality on the resistance factor. The results, interpreted using the capillary pressure, show two flow regimes, corresponding to the two foam textures: "weak" and "strong". Experiments on 2-D heterogeneous pilot allowed visualizing the different steps of the remediation process and comparing the sweep efficiency with and without a region blocked by foam.The numerical part includes modeling 1-D column tests using UTCHEM, a sensitivity study of the most important parameters of the model, and a simulation of tracer tests on 2-D pilot using MODFLOW

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Mühlbauer, Sebastian J. [Verfasser], Thorsten [Akademischer Betreuer] Pöschel, Thorsten [Gutachter] Pöschel e Jens [Gutachter] Harting. "Multiscale modeling of heterogeneous catalysis in porous metal foam structures using particle-based simulation methods / Sebastian Josef Mühlbauer ; Gutachter: Thorsten Pöschel, Jens Harting ; Betreuer: Thorsten Pöschel". Erlangen : FAU University Press, 2019. http://nbn-resolving.de/urn:nbn:de:bvb:29-opus4-126488.

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40

Mühlbauer, Sebastian Josef [Verfasser], Thorsten [Akademischer Betreuer] Pöschel, Thorsten [Gutachter] Pöschel e Jens [Gutachter] Harting. "Multiscale modeling of heterogeneous catalysis in porous metal foam structures using particle-based simulation methods / Sebastian Josef Mühlbauer ; Gutachter: Thorsten Pöschel, Jens Harting ; Betreuer: Thorsten Pöschel". Erlangen : FAU University Press, 2019. http://d-nb.info/1203375018/34.

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41

Lacoste, Clément. "Mousses rigides de tannins de type procyanidine : formulation et caractérisation". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0259/document.

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Abstract (sommario):

Les mousses rigides constituent une classe très importante de matériaux de par leur large champ d’applications et de leur poids économique considérable. Le développement de mousses à base de tannins a permis d’obtenir des matériaux issus à 90% de produits naturels. Dans ce travail, un type de tannins très réactif dit « procyanidine », a été employé. Les formulations et la technologie de fabrication de mousses rigides ont été développées à partir de tannins extraits d’écorce de pin et d’épicéa. Dans un premier temps, la composition et la réactivité des tannins ont été étudiées. Ensuite, l’étude du processus de moussage des résines à base de ces tannins a permis l’élaboration d’une large gamme de mousses rigides tannin-furanique. Leur excellente résistance au feu, leur résistance mécanique et leur haute performance thermique en font des matériaux d’isolation de haute qualité. Ces mousses peuvent également être employées comme absorbeurs acoustiques. De plus, de nouveaux solides cellulaires à base de tannins et de protéine ont également été développés, proposant ainsi un nouveau type de matériaux issu de produits naturels
Rigid foams contitute a very important class of materials considering their wide application range and their considerable economic impact. The development of tannin-based foams provided materials made from 90% natural products.In this work, a type of tannins highly reactive, namely « procyanidin », was used. First, tannins composition and reactivity were studied. Then, the foaming process investigation of tannin-based resins leads to a wide pannel of tannin-furanic rigid foams. Their excellent fire resistance, mechanical resistance and high thermal performance make them high quality insulation materials. These foams are also suitable for other applications such acoustic absorption. Thus, new cellular solids from tannin and protein were also developped, offering a new type of materials derived from natural products

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42

Clerget, Mattéo. "Formation et destruction de mousse en écoulement dans un milieu confiné". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS493.

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Abstract (sommario):

L'injection de mousse en milieu poreux est une technique très prometteuse pour de nombreuses applications comme le stockage de dioxyde de carbone, la dépollution des sols ou la récupération assistée du pétrole. L'écoulement de cette mousse en milieu confiné met en jeu différents processus de formation ou de destruction des bulles qui la composent. La compréhension des mécanismes physiques de ces processus est nécessaire à l’amélioration du procédé, notamment au travers de l'optimisation de la formulation de la phase liquide.Notre approche consiste à découpler ces différents phénomènes, grâce à des dispositifs modèles d’écoulement à deux dimensions, à l’échelle de la micro- ou milli-fluidique. Leur transparence nous permet de visualiser la structure de la mousse en écoulement et de faire le lien avec ses propriétés macroscopiques. Différents tensioactifs et additifs sont systématiquement testés afin d’étudier la capacité de nos dispositifs à les discriminer, et les résultats obtenus sont systématiquement comparés aux résultats obtenus en milieu poreux.Notre première expérience, qui étudie la formation de bulles lors du passage du co-écoulement gaz/liquide dans un pore microfluidique, met en évidence un phénomène d’hystérèse de formation expliqué par un processus de rétroaction hydrodynamique amorcé par l'écoulement en aval. Nous mettons également en évidence grâce à des simulations numériques l'existence d'une limite à la qualité de la mousse pouvant être formée, liée uniquement à la géométrie du pore. Différents tensioactifs sont étudiés, et ces résultats sont comparés à des mesures à la fois en volume et en milieu poreux à trois dimensions.Notre seconde expérience étudie l’influence de l’ajout d’un additif sur cette formation, notamment au travers des effets Marangoni que celui-ci génère. Un modèle théorique simple est développé pour prendre en compte ces effets.Nous décrivons enfin un montage de millifluidique permettant d’observer et d’étudier la destruction de mousse par coalescence de bulles. Nous montrons que les résultats diffèrent drastiquement en fonction des tensioactifs et additifs utilisés
Foam injection into porous media is a highly promising technique for a wide range of applications, including carbon dioxide storage, soil remediation, and enhanced oil recovery. The flow of this foam in a confined environment brings into play different processes of formation or destruction of the bubbles of which it is composed. Understanding the physical mechanisms of these processes is essential to improve this technique, in particular by optimizing the formulation of the liquid phase.Our approach is to decouple these different phenomena, using two-dimensional flow model devices, at the micro- or milli-fluidic scale. Their transparency allows us to visualize the structure of the flowing foam and to relate it to its macroscopic properties. Various surfactants and additives are systematically tested to investigate the ability of our devices to screen them, and the results obtained are systematically compared with those obtained in porous media.Our first experiment, which studies the formation of bubbles during the passage of a gas/liquid co-flow in a microfluidic pore, highlights a formation hysteresis phenomenon explained by a hydrodynamic feedback process initiated by the downstream flow. Using numerical simulations, we also demonstrate the existence of a limit to the quality of foam that can be formed, linked solely to the pore geometry. Different surfactants are investigated, and these results are compared with measurements both in volume and in three-dimensional porous media.Our second experiment studies the influence of an additive on this formation, in particular through the Marangoni effects it generates. A simple theoretical model is developed to account for these effects.Finally, we describe a millifluidic setup for observing and studying foam destruction by bubble coalescence. We show that the results vary drastically depending on the surfactants and additives used

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43

Hourtané, Virginie. "Écoulement de mousse dans des modèles de milieux poreux". Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0330/document.

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Abstract (sommario):

Pour augmenter le taux de récupération du pétrole, une des solutions chimiques utilisées consiste à injecter des mousses dans les milieux poreux. En effet, les mousses permettent sous certaines conditions de diminuer la mobilité et ainsi d’améliorer le balayage du réservoir. Cependant, les mécanismes contrôlant la mobilité des mousses ne sont pas bien compris. Nous proposons une approche microfluidique permettant une observation directe de l’écoulement des bulles dans un micromodèle de milieux poreux. Nous observons que l’écoulement n’est pas homogène dans le milieu poreux: il se fait uniquement dans quelques chemins. Le nombre de chemins préférentiels dépend de la qualité de la mousse et du nombre capillaire. Si nous simplifions le milieu poreux à une boucle, nous montrons que la formation des chemins préférentiels dépend de la taille de la boucle. En effet, les bulles sont bloquées dans la boucle uniquement quand la taille de la boucle est de l’ordre de grandeur de la taille des bulles
Crude oil is already usually trapped into heterogeneous porous media. In order to increase the recovery efficiency, one of the chemical solutions consists in injecting foams in porous media to expel oil from the rock. Foam is indeed able in some cases to greatly decrease the mobility, leading to a better sweeping of the reservoir. However, the mechanisms controlling the foam mobility are not well known. We propose a microfluidic approach allowing a direct observation of the flow of bubbles in a model of porous media. We observe that the flow is not homogeneous in the porous medium: it is concentrated in some paths. The number of these preferential paths depends of the foam quality and the capillary number. If we simplify the geometry of the porous medium to a loop, we prove that the formation of preferential paths depends of the size of the loop. Indeed we can only immobilize the bubbles if the size of the loop is around the size of the bubbles

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44

Ouali, Chakib. "Caractérisation multi-échelle de l’écoulement de mousses en milieux poreux en contexte EOR". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS001/document.

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Abstract (sommario):

L’utilisation de la mousse en récupération assistée du pétrole (Enhanced Oil Recovery, EOR) présente un avantage indéniable par rapport à l’injection du gaz seul pour pallier les problèmes de ségrégation gravitaire et de digitations visqueuses. Son utilisation systématique en ingénierie du réservoir nécessite des connaissances plus approfondies sur son comportement en milieu poreux. La littérature montre deux types d’approches expérimentales basées soit sur des études pétrophysiques effectuées sur des systèmes poreux 3D et basées sur des mesures de pressions intégrées sur l’ensemble du milieu poreux, soit sur des études micro-fluidiques qui permettent une visualisation directe de l’écoulement mais qui sont limitées à des systèmes modèles dans des géométries à 1 ou 2 dimensions. L’objectif de cette thèse est de faire le pont entre ces deux approches. La stratégie proposée consiste à caractériser in situ l’écoulement de la mousse dans des milieux poreux 3D à différentes échelles, en utilisant des techniques complémentaires permettant d’accéder à une large gamme de résolutions spatiale et temporelle. Un environnement instrumenté donnant accès aux mesures pétro-physiques classiques a été développé puis couplé à différentes cellules d’observation conçues spécifiquement pour chaque instrument de caractérisation. Dans un premier temps, un scanner X a été utilisé pour décrire et visualiser les écoulements de la mousse à l’échelle de la carotte. La rhéologie de la mousse à cette échelle a pu être étudiée en fonction des conditions d’injections comme la vitesse interstitielle du gaz et la qualité de mousse. Dans un deuxième temps, la technique de diffusion des neutrons aux petits angles (SANS) a permis de sonder la texture de la mousse en écoulement sur trois ordres de grandeurs en taille. Des informations in situ sur la texture de la mousse en écoulement (taille et densité des bulles et des lamelles) ont pu être mesurées pour différentes qualités de mousse puis en fonction de la distance au point d’injection. Une comparaison avec les caractéristiques géométriques du milieu poreux a également été effectuée. Dans un troisième temps, la micro-tomographie X rapide haute résolution sur Synchrotron a été utilisée pour visualiser la mousse en écoulement à l’échelle du pore. Cette technique a permis de confirmer de visu certaines caractéristiques de la mousse mesurées par SANS et de décrire en sus les effets d’intermittence du piégeage de la mousse. Cette étude constitue une étape importante de la caractérisation multi-échelle de l’écoulement des mousses en milieux poreux 3D et apporte des éléments de réponse à certaines hypothèses admises
Foam has long been used as a mobility control agent in Enhanced Oil Recovery (EOR) processes to enhance sweep efficiency and overcome gravity segregation, viscous fingering and gas channeling, which are gas-related problems when the latter is injected alone in the reservoir. However, the systematic use of foam in reservoir engineering requires more in-depth knowledge of its dynamics in porous media. The literature shows two types of experimental approaches based either on petrophysical studies carried out on 3D porous systems and based on pressure measurements, or on microfluidic studies that allow direct visualization of foam flow but are limited to 1D or 2D model systems. The research investigated in this thesis aims to bridge the gap between these two approaches. The proposed strategy is to characterize in situ the foam flow in 3D porous media with techniques providing a wide range of temporal and spatial resolutions. A coreflood setup giving access to classical petro-physical measurements was developed and then coupled to different observation cells designed specifically for each characterization instrument. First, an X-ray CT scanner was used to describe and visualize the foam flow at the core scale. The rheological behavior of foam on this scale was studied as a function of the injection conditions such as gas velocity and foam quality. Secondly, Small Angle Neutron Scattering (SANS) was used to probe the foam structure in situ during the flow, on a wide length scale, up to three orders of magnitude in size. In situ foam texture (size and density of bubbles and lamellae) was measured for different foam qualities and at different propagation distances from the injection point. A comparison to the geometric characteristics of the porous medium was also realized. Thirdly, High Resolution Fast X-ray Micro-tomography on a Synchrotron was used to visualize the foam flow at the pore scale. This allowed to confirm visually some foam characteristics measured with SANS and to investigate on local intermittent gas trapping and mobilization. This study is an important step in the multi-scale characterization of foam flow in 3D porous media and provides some answers to certain generally accepted assumptions

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45

Omirbekov, Sagyn. "Remédiation des sols pollués par injection des mousses tensioactifs : expériences et changement d’échelle". Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAE025.

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Abstract (sommario):

L'injection de mousse dans des milieux poreux a été étudiée pour une variété d'applications dans l'industrie pétrolière et récemment pour des procédés de dépollution des sols afin d’éliminer les contaminants. Cependant, l'injection de mousse pour la remédiation des sols n'est toujours pas répandue en raison de la nature complexe de la mousse et des aquifères. Afin d'étudier l'application de la mousse pour la remédiation des sols, nous avons étudié expérimentalement le comportement de la mousse à l'échelle du laboratoire. Le but final de la recherche était d'étudier l'écoulement de mousse pour détourner l'écoulement des eaux souterraines des zones de sols contaminés en tenant compte des caractéristiques de l'écoulement de mousse en milieux poreux hautement perméables. Ainsi, la rhéologie de la mousse pré-générée a été étudiée dans des milieux poreux hautement perméables, dans des tubes capillaires, ainsi qu'à l'aide d'un rhéomètre. De plus, une étude numérique a été menée pour examiner l’écoulement de mousse à plus grande échelle sur la base des résultats de la rhéologie de la mousse hors milieu poreux. En conséquence, il a été démontré que l'écoulement de mousse présente un comportement non newtonien. Nous avons constaté que le comportement d'écoulement de la mousse en milieu poreux très perméables et dans les tubes capillaires est cohérent avec le comportement rhéologique de la mousse hors milieu poreux, si les bulles de mousse sont beaucoup plus petites que la taille des pores des milieux poreux. Ces résultats peuvent guider l'étude de la mousse pré-générée en milieux poreux très perméables
Foam injection in porous media has been investigated for a variety of applications in the oil industry and recently for soil remediation processes to remove contaminants. However, foam injection for soil remediation is still not widespread because of the complex nature of foam and aquifers. In order to investigate application in soil remediation processes, we experimentally studied the behavior of foam on a laboratory scale. The final goal of the research was to study foam flow for diverting the flow of groundwater from contaminated soil areas considering the features of foam flow in highly permeable porous media. Thus, the rheology of pre-generated foam was studied in highly permeable porous media, in capillary tubes, as well as using a rheometer. Moreover, a numerical study was conducted to examine foam flow in a bigger scale based on bulk foam rheology results. As a result, foam flow was showed to feature non-Newtonian behavior. We found that the foam flow behavior in high permeable porous media and in capillary tubes are consistent with the rheology behavior of bulk foam if bubbles are much smaller than the pore size of porous media. Hence, these findings can guide the study of pre-generated foam in very highly permeable porous media

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46

Forey, Natacha. "Mousses renforcées en polymère ou particules : application à la remédiation des sols pollués". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0311.

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Abstract (sommario):

Pour des raisons environnementales et de santé publique, la remédiation des sites et sols pollués est impérative. Une des techniques in-situ utilisées pour dépolluer des sols présentant une pollution aux hydrocarbures, est l’utilisation de mousse liquide. Grâce à son effet bloquant, la mousse crée une barrière entre l’eau et le polluant, et facilite le pompage de celui-ci. La principale problématique de cette technique est la stabilité de la mousse face à l’huile. Des techniques de renforcement de la mousse en présence d’huile sont développées, notamment grâce à l’ajout de polymère ou de particules solides.Ce travail portera donc sur la formulation d’une mousse résistante à l’huile en milieu poreux, et ce grâce à l’utilisation de polymère ou de particules colloïdales.La première partie de ce travail présente les tests de moussabilité et de stabilité effectués hors milieu poreux, ayant permis de présélectionner les produits nécessaires à l’obtention de telles mousses. Dans une seconde partie, des essais en colonne de milieu poreux ont mené à l’optimisation des conditions d’injection, ainsi qu’au choix final des produits à utiliser. Ils ont montré comment l’ajout de polymère permet d’augmenter la résistance à l’écoulement sans augmenter la force de la mousse, et comment l’ajout de particules renforce la résistance de la mousse face à l’huile. Des essais en pilote 2D ont ensuite été réalisés dans le but de comprendre le déplacement de la mousse en milieu poreux 2D vertical. Grâce aux formulations trouvées en colonne 1D, les expériences 2D effectuées en présence d’huile ont permis de tester le renforcement face à l’huile en deux dimensions. Pour finir, la méthodologie et les contraintes à prendre en compte pour réaliser un essai de pompage 3D sont présentées en perspectives
Given the possible environmental and health issues occurring when facing a hydrocarbon polluted site, soil remediation is necessary. One of the in-situ technique to remediate a Light Non Aqueous Phase Liquid pollution is the use of foam. Because of its blocking effect, foam is able to create a water blocking barrier, to confine water beneath the floating pollutant. However, the main issue with this technique is the stability of foam facing the oily pollutant. Several options are currently under review to reinforce foam against oil, which includes polymer or particles addition.The present study thus describes the work performed to obtain an oil-resistant foam in porous media, with the use of polymer or solid colloidal particles.In the first part of the study, foamability and stability tests were performed in bulk to select a broad range of products used to formulate such foams. Then, sandpacks experiments were realized in 1D columns in order to optimize the foam injection parameters and finalize the choice of surfactant and additives. Column experiments showed how additives impacted foam strength. Polymer addition led to an increased flow resistance without improving foam strength while particles addition proved to reinforce foam resistance against oil. Those results were then applied to carry out 2D-tank experiments to study foam displacement in a vertical two dimensions’ porous medium. The 2D tank also helped to simulate a foam injection below an oily layer and observe foam behaviour. Finally, the methodology and constrains to take into account to perform a pumping test in a 3D-pilot, were presented in the outlook section

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47

Ouali, Chakib. "Caractérisation multi-échelle de l’écoulement de mousses en milieux poreux en contexte EOR". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS001.

Testo completo

Abstract (sommario):

L’utilisation de la mousse en récupération assistée du pétrole (Enhanced Oil Recovery, EOR) présente un avantage indéniable par rapport à l’injection du gaz seul pour pallier les problèmes de ségrégation gravitaire et de digitations visqueuses. Son utilisation systématique en ingénierie du réservoir nécessite des connaissances plus approfondies sur son comportement en milieu poreux. La littérature montre deux types d’approches expérimentales basées soit sur des études pétrophysiques effectuées sur des systèmes poreux 3D et basées sur des mesures de pressions intégrées sur l’ensemble du milieu poreux, soit sur des études micro-fluidiques qui permettent une visualisation directe de l’écoulement mais qui sont limitées à des systèmes modèles dans des géométries à 1 ou 2 dimensions. L’objectif de cette thèse est de faire le pont entre ces deux approches. La stratégie proposée consiste à caractériser in situ l’écoulement de la mousse dans des milieux poreux 3D à différentes échelles, en utilisant des techniques complémentaires permettant d’accéder à une large gamme de résolutions spatiale et temporelle. Un environnement instrumenté donnant accès aux mesures pétro-physiques classiques a été développé puis couplé à différentes cellules d’observation conçues spécifiquement pour chaque instrument de caractérisation. Dans un premier temps, un scanner X a été utilisé pour décrire et visualiser les écoulements de la mousse à l’échelle de la carotte. La rhéologie de la mousse à cette échelle a pu être étudiée en fonction des conditions d’injections comme la vitesse interstitielle du gaz et la qualité de mousse. Dans un deuxième temps, la technique de diffusion des neutrons aux petits angles (SANS) a permis de sonder la texture de la mousse en écoulement sur trois ordres de grandeurs en taille. Des informations in situ sur la texture de la mousse en écoulement (taille et densité des bulles et des lamelles) ont pu être mesurées pour différentes qualités de mousse puis en fonction de la distance au point d’injection. Une comparaison avec les caractéristiques géométriques du milieu poreux a également été effectuée. Dans un troisième temps, la micro-tomographie X rapide haute résolution sur Synchrotron a été utilisée pour visualiser la mousse en écoulement à l’échelle du pore. Cette technique a permis de confirmer de visu certaines caractéristiques de la mousse mesurées par SANS et de décrire en sus les effets d’intermittence du piégeage de la mousse. Cette étude constitue une étape importante de la caractérisation multi-échelle de l’écoulement des mousses en milieux poreux 3D et apporte des éléments de réponse à certaines hypothèses admises
Foam has long been used as a mobility control agent in Enhanced Oil Recovery (EOR) processes to enhance sweep efficiency and overcome gravity segregation, viscous fingering and gas channeling, which are gas-related problems when the latter is injected alone in the reservoir. However, the systematic use of foam in reservoir engineering requires more in-depth knowledge of its dynamics in porous media. The literature shows two types of experimental approaches based either on petrophysical studies carried out on 3D porous systems and based on pressure measurements, or on microfluidic studies that allow direct visualization of foam flow but are limited to 1D or 2D model systems. The research investigated in this thesis aims to bridge the gap between these two approaches. The proposed strategy is to characterize in situ the foam flow in 3D porous media with techniques providing a wide range of temporal and spatial resolutions. A coreflood setup giving access to classical petro-physical measurements was developed and then coupled to different observation cells designed specifically for each characterization instrument. First, an X-ray CT scanner was used to describe and visualize the foam flow at the core scale. The rheological behavior of foam on this scale was studied as a function of the injection conditions such as gas velocity and foam quality. Secondly, Small Angle Neutron Scattering (SANS) was used to probe the foam structure in situ during the flow, on a wide length scale, up to three orders of magnitude in size. In situ foam texture (size and density of bubbles and lamellae) was measured for different foam qualities and at different propagation distances from the injection point. A comparison to the geometric characteristics of the porous medium was also realized. Thirdly, High Resolution Fast X-ray Micro-tomography on a Synchrotron was used to visualize the foam flow at the pore scale. This allowed to confirm visually some foam characteristics measured with SANS and to investigate on local intermittent gas trapping and mobilization. This study is an important step in the multi-scale characterization of foam flow in 3D porous media and provides some answers to certain generally accepted assumptions

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48

Gassara, Omar. "Modélisation des écoulements de mousse dans les milieux poreux en récupération assistée du pétrole". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066588/document.

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Abstract (sommario):

Depuis les années 60, la mousse présente un grand potentiel pour améliorer le balayage volumétrique par le gaz dans un réservoir pétrolier : des travaux de laboratoire et des essais sur champs montrent l’intérêt technique et économique de ce procédé. En effet, ses caractéristiques uniques, qui résultent de la dispersion du gaz dans un volume de liquide contenant des tensioactifs, en font un bon agent de réduction de mobilité du gaz, et par conséquent, ce qui conduit à la réduction des instabilités visqueuses issues du contraste de mobilité entre le gaz et l'huile en place. Par ailleurs, la mousse atténue les effets préjudiciables des hétérogénéités et de la ségrégation gravitaire sur la récupération, grâce à son comportement différent entres les faciès du réservoir. Dans la pratique industrielle, les simulateurs de réservoir s’attachent à ne modéliser que les effets de la mousse sur les déplacements en régime permanent, sans chercher à prédire son comportement dynamique régi par la génération, destruction et transport des lamelles (films minces) de mousse dans les milieux poreux. Suivant cette approche, la mousse est modélisée comme une réduction de mobilité du gaz, en particulier par le biais des perméabilités relatives, en utilisant des lois d'interpolations de paramètres impactant sa rhéologie, à savoir la vitesse et la qualité de la mousse, la saturation en huile, la concentration en tensioactif et la perméabilité du milieu poreux. Un tel modèle a l’avantage de la simplicité conceptuelle fondée sur l'extension des modèles de Darcy polyphasiques en n’utilisant que les paramètres d'écoulement mesurés au laboratoire, sans y intégrer le nouveau paramètre caractéristique de la mousse qui est la texture (densité des lamelles). Cependant, ces lois empiriques manquent de généralité et doivent être calibrées/ajustées à partir d’essais de laboratoire afin d'assurer la fiabilité des prévisions. Un modèle calibré à partir d’un nombre limité d’expériences comporte un degré d'incertitude et d’indétermination. L’ingénieur de réservoir a néanmoins recours à un tel modèle pour prédire et guider l’exploitation du gisement sur la base de ce procédé. D’où l’objectif principal de cette thèse qui consiste à améliorer le paramétrage des modèles de mousse empiriques via des lois mieux formulées et calibrées afin d’accroitre leur prédictivité. Dans cette thèse, nous avons établi les fondements physiques nécessaires pour valider les modèles empiriques en développant leur équivalence avec les modèles en texture assurée par des relations d’interdépendance entre les paramètres des deux approches. Cette équivalence a été montrée et étudiée en utilisant un modèle à lamelles pré-calibré de la littérature aux mesures de déplacements de mousse en régime permanent. Par ailleurs, ce parallèle avec les modèles en texture nous a permis de mettre au point une nouvelle procédure pour calibrer d'une manière fiable et déterministe les modèles empiriques. Cette procédure a été testée à partir des résultats d'expériences menées à IFPEN traduits en termes de texture en régime permanent. Enfin, nous avons proposé et interprété des lois d'échelle des paramètres du modèle de mousse en fonction de la perméabilité du milieu poreux, en analysant les paramètres des modèles calibrés sur des carottes de différentes perméabilités. L'importance de ces lois a été mise en évidence à travers des simulations sur une coupe de réservoir bi-couche. Les résultats de la simulation indiquent que les prévisions de performance d'un procédé à base de mousse, appliqué à un réservoir hétérogène, nécessitent une bonne connaissance des lois d'échelle des paramètres empiriques avec la perméabilité
Conventional techniques of oil recovery consist in injecting water and/or gas into the geological formation to force out the oil. These methods may reveal ineffective because of high permeability contrasts, unfavorable mobility ratio between the driving fluid and the oil in place which generally generates viscous fingering, and gravity segregation. In this context, foam has shown a great potential to overcome all these detrimental effects, and thereafter, to improve the volumetric sweep efficiency. Still some key points need to be addressed regarding the predictive calculation of multiphase foam flow in porous media. Methods for modeling foam flow in porous media fall into two categories: population balance (PB) models and (semi)-empirical (SE) models. On the one hand, PB models describe foam lamellas transport in porous media and predict the evolution of foam microstructure as the result of pore-scale mechanisms of lamellas generation and destruction. Within this framework, the modeling of foam effects on gas mobility is directly related to foam texture (lamellas density) along with the effects of other parameters impacting its rheology such as foam quality and velocity, permeability of the porous media, surfactant concentration, etc. On the other hand, SE models are based on the extension of multiphase classical Darcy's model to describe foam flow in porous media, such that the foam texture effects are described indirectly through a multi-parameter interpolation function of parameters measured/observed in laboratory. Such formulation has to be calibrated from foam flow experimental data on a case-by-case basis, which can turn to be a cumbersome task. Furthermore, SE models involve uncertainty because they are not based on mechanistic laws driving lamellas transport in porous media, and their predictive capacity remains low as too few laboratory data are generally available for their calibration. Nonetheless, the reservoir engineer needs a reliable foam model in order to design, assess and optimize foam enhanced oil recovery processes for field application. Accordingly, this thesis aims at providing further insights into the topics related to the parameterization of (semi)-empirical models through better formulated and calibrated laws in order to improve their predictivity. In this work, we have established the physical basis necessary to validate the (semi)-empirical models. Indeed, we developed the equivalence between SE and PB models achieved through relationships between the parameters of these two modeling approaches (industrial and physical). The equivalence has been established and studied using a pre-calibrated PB model of the literature to fit steady-state foam measurements. In addition, this equivalence allowed us to develop a new procedure to calibrate the (semi)-empirical models in a reliable and deterministic way. This procedure was tested and validated using results from IFPEN core-flood experiments by translating them into steady-state texture measurements. Finally, we proposed scaling laws for empirical model parameters with the permeability of the porous media, by analyzing the fitted parameters on cores of different permeabilities. Different interpretations of the scaling laws are herein provided using theoretical models for lamellas stability. Then, their importance has been demonstrated through simulations on a two layer reservoir cross-section. The simulation results indicate that the predictions of foam flow in a heterogeneous reservoir require a good knowledge of the scaling laws of SE model parameters with permeability

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49

Petit, Clémence. "Etude des propriétés mécaniques de matériaux cellulaires par la tomographie aux rayons X et par modélisation par éléments finis". Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0130/document.

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Abstract (sommario):

Les matériaux cellulaires sont des échantillons à très forte porosité qui peuvent être décrits à deux échelles : la mésostructure et la microstructure. Le lien entre l'architecture des matériaux et les propriétés mécaniques a été largement étudié dans la littérature. Les caractéristiques microstructurales peuvent avoir une influence importante sur les propriétés macroscopiques. Le but de ce travail est de relier les caractéristiques architecturales et microstructurales des matériaux cellulaires à leurs propriétés mécaniques grâce notamment à la tomographie aux rayons X. Une nouvelle approche combinant l'imagerie 3D à plusieurs résolutions, le traitement d'images et la modélisation éléments finis a permis de prendre en compte la microstructure de la phase solide. Quatre matériaux cellulaires modèles ont ainsi été étudiés : des mousses d'aluminium, des structures cellulaires périodiques en alliage de cobalt-chrome, des échantillons de β-TCP et des composites hydroxyapatite/β-TCP. Les matériaux métalliques ont été fournis par des collègues d'autres laboratoires, tandis que les matériaux céramiques ont été fabriqués dans le cadre de cette étude. Pour chaque type de matériaux (métaux et céramiques), une structure régulière et une stochastique ont été comparées. Pour utiliser la méthode multi-échelle développée dans ce travail, les échantillons ont d'abord été scannés grâce à la tomographie locale dans laquelle l'échantillon est placé près de la source de rayons X. La tomographie locale permet de scanner la petite partie irradiée de l'échantillon et d'obtenir une image agrandie par rapport aux images à plus basse résolution. Ces images permettent d'observer certains détails de la phase solide non visibles à plus basse résolution. Différentes étapes de traitement d'images ont ensuite été mises en œuvre pour obtenir une image à basse résolution incluant les informations provenant des images à haute résolution. Ceci a été réalisé grâce à une série d'opération de seuillage et sous-résolution des images à haute résolution. Le résultat de ces différentes étapes de traitement d'images donne une image de l'échantillon initial à basse résolution mais qui inclut l'information supplémentaire décelée à haute résolution. Ensuite, des essais mécaniques in situ ont été réalisés dans le tomographe pour suivre à basse résolution l'évolution des échantillons pendant la déformation. Les images initiales citées plus haut ont été utilisées pour produire des maillages éléments finis. Des programmes Java ont été adaptés pour créer des fichiers d'entrée pour les modèles éléments finis à partir des images initiales et des maillages. Les images initiales contenant les informations à propos de la phase solide, les images des essais mécaniques et les modèles éléments finis ont permis d'expliquer le comportement mécanique des échantillons en reliant les sites d'endommagement expérimentaux et les lieux de concentrations de contraintes calculés
Cellular materials are highly porous systems for which two scales are mainly important: the mesostructure and the microstructure. The mesostructure corresponds to the architecture of the materials: distribution of solid phase “walls” and macroporosity and can be characterized by X-ray tomographic low resolution images. The link between the architecture of the materials and the mechanical properties has been frequently studied. The microstructure refers to the characteristics of the solid phase. Its microstructural features (presence of a secondary phase or of defects due to the sintering) can have a strong influence on the macroscopic properties. The aim of this work is to link the morphological and microstructural features of metallic and ceramic based cellular materials and their mechanical properties thanks to X-ray tomography and finite element modelling. A new method combining X-ray tomography at different resolutions, image processing and creation of finite element modelling enabled to take into account some microstuctural features of the cellular samples. Four different cellular materials were studied as model materials: aluminium foam fabricated by a liquid state process, cobalt periodic structures made by additive manufacturing, β-TCP porous samples fabricated by conventional sacrificial template processing route and hydroxyapatite/β-TCP composites made by additive manufacturing (robocasting). The metal based materials were provided by colleagues while the ceramic based porous materials were fabricated in the frame of the current study. For each type (metals or ceramics), a stochastic and a regular structure have been compared. For implementing the multiscale method developed in this work, the samples were firstly scanned in a so called “local” tomography mode, in which the specimen is placed close to the X-ray source. This allowed to reconstruct only the small irradiated part of the sample and to obtain a magnified image of a subregion. These images enable to observe some details which are not visible in lower resolution. Different image processing steps were performed to generate low resolution images including microstructural features imaged at high resolution. This was done by a series of thresholding and scaling of the high resolution images. The result of these processing steps was an image of the initial sample. Then, in situ mechanical tests were performed in the tomograph to follow the deformation of the sample at low resolution. The above mentioned initial images were used to produce finite element meshes. Special Java programs were adapted to create finite element input files from initial images and meshes. The initial images containing information about the solid phase, the images from the mechanical tests and the finite element models were combined to explain the mechanical behaviour of the sample by linking the experimental damage locations in the sample and the simulated stress concentration sites

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50

Simone, Anthony E. (Anthony Eugene) 1970. "Porous metals and metallic foams". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10190.

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