Bibliografie tematiche / Two-Phase Reactive Flow

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Letteratura scientifica selezionata sul tema "Two-Phase Reactive Flow"

Autore: Grafiati
Pubblicato: 2 novembre 2024

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Articoli di riviste sul tema "Two-Phase Reactive Flow"

1

Cheng, Cheng, e Xiaobing Zhang. "Numerical simulation of two-phase reactive flow with moving boundary". International Journal of Numerical Methods for Heat & Fluid Flow 23, n. 8 (28 ottobre 2013): 1277–90. http://dx.doi.org/10.1108/hff-11-2011-0242.

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2

Geiss, S., A. Dreizler, Z. Stojanovic, M. Chrigui, A. Sadiki e J. Janicka. "Investigation of turbulence modification in a non-reactive two-phase flow". Experiments in Fluids 36, n. 2 (1 febbraio 2004): 344–54. http://dx.doi.org/10.1007/s00348-003-0729-3.

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3

Rai, Nirmal K., e Tariq D. Aslam. "Evaluation of thermodynamic closure models for partially reacted two-phase mixture of condensed phase explosives". Journal of Applied Physics 131, n. 18 (14 maggio 2022): 185902. http://dx.doi.org/10.1063/5.0085208.

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Abstract (sommario):
One of the key fundamental issues that is crucial in the continuum modeling of reactive flow phenomena is the thermodynamically consistent description of reaction mixture properties. To define the mixture properties, thermodynamic closure rules that relate the properties of the individual reaction components to the mixture properties are required. In the context of reactive two-phase modeling approaches, various strategies to define the thermodynamic closures have been adopted such as pressure temperature (PT) equilibrium between the individual reaction components, pressure (specific) volume (PV) equilibrium, etc. The choice of closure rules determines the relative distribution of specific volume and energy across the reaction components that comprise the mixture. Therefore, depending on the choice of the closure, the mixture thermodynamic behavior can vary. The present work examines the effect of different closure approaches on the thermodynamic properties of the reaction mixture. The analysis is performed for a condensed phase HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) based plastic bonded explosive (PBX) 9501 explosive using four different thermodynamic closures, viz., PT equilibrium, PV equilibrium, volume temperature (VT) equilibrium, and pressure (P) equilibrium with reactants on an isentrope. The relative variations in the thermodynamic properties of the mixture are analyzed and compared under both compression and expansion loading regimes. It is shown that out of the four closure models, only PT equilibrium and P equilibrium closures lead to a thermodynamically accurate description of the mixture under both compression and expansion.
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4

Sengupta, Rajarshi, Mukul D. Tikekar, James V. Raj, Kris T. Delaney, Michael C. Villet e Glenn H. Fredrickson. "Phase-field simulations of morphology development in reactive polymer blending". Journal of Rheology 67, n. 1 (gennaio 2023): 1–14. http://dx.doi.org/10.1122/8.0000523.

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Reactive blending is an efficient method for synthesizing polymer blends. Industrially, this process is carried out in extruders, where the reacting polymers and the generated copolymer are subjected to high shear stresses. The dynamics of the process, and the resulting morphology is dictated by a coupling of the hydrodynamic forces in the extruder, the thermodynamic interactions between species, and the reaction kinetics on a complex interfacial manifold. We use phase-field simulations to quantify the evolution of the reactive blending process under an external shear flow. Specifically, we consider a model system of two homopolymers of equal length, which react via an end-coupling reaction to form a diblock copolymer of double the length. We compare the morphology development in two different initial geometries of the homopolymers—a cylindrical thread and a drop of one homopolymer in a matrix of the second. We investigate the effect of flow strength, measured by the shear rate, and reaction kinetics, quantified by a Damkohler number, on the progress of the reaction and morphology development. Cylindrical threads are susceptible to breakup via the Rayleigh capillary instability. We demonstrate that this instability can be suppressed by imposing shear along the direction of the thread and increasing the extent of the reaction. The reaction rate in this geometry is unaffected by shear imposed along the cylinder axis. Drops deform significantly under an imposed flow, eventually stretching to long cylindrical threads for sufficient shear rates. In the case of drops, shear stresses enhance the reaction rate by deforming the drop, enabling more homopolymers to come in contact at the expanded interface. We show that shear stresses significantly impact the morphology development and reaction dynamics in reactive polymer blending.
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5

Xue, She Sheng. "Modeling and Numerical Simulation of a Gas/Drop Flow". Applied Mechanics and Materials 444-445 (ottobre 2013): 1503–7. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1503.

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To investigate the mechanism of TUSOG(Transverse Uniform Singlet Oxygen Generator), a two-phase, chemistry reactive flows model is established to describe the physical and chemical performances of Cl2/He mixed gases which transversely travels through a falling BHP(KOH,H2O2,H2O) droplets field, and the relevant numerical simulation is carried out. In the gas-phase model equations, the mass source term is determined by drop-absorbed chlorine and released singlet oxygen due to chemical reaction between drops and chlorine. An assumption is made that the BHP drops have equal sizes and fall vertically in equal speeds. The set of gas-phase control equations is solved by SIMPLEC scheme. The computational results agree well with the test results provided by relevant reference. It is found, that chlorine utility and singlet oxygen yield decreases with increasement of gas inflow speed, and increases with increasement of the speeds of falling drops, and the absorption of chlorine mainly takes place in the upstream reactive region.
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6

Cheng, Cheng, e Xiaobing Zhang. "Numerical investigation of two-phase reactive flow with two moving boundaries in a two-stage combustion system". Applied Thermal Engineering 156 (giugno 2019): 422–31. http://dx.doi.org/10.1016/j.applthermaleng.2019.04.061.

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7

Oliver, J. M. "Thin-film theories for two-phase reactive flow models of active cell motion". Mathematical Medicine and Biology 22, n. 1 (1 marzo 2005): 53–98. http://dx.doi.org/10.1093/imammb/dqh022.

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8

Hannebique, Gregory, Patricia Sierra, Eleonore Riber e Bénédicte Cuenot. "Large Eddy Simulation of Reactive Two-Phase Flow in an Aeronautical Multipoint Burner". Flow, Turbulence and Combustion 90, n. 2 (9 ottobre 2012): 449–69. http://dx.doi.org/10.1007/s10494-012-9416-x.

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9

Sin, Irina, Vincent Lagneau e Jérôme Corvisier. "Integrating a compressible multicomponent two-phase flow into an existing reactive transport simulator". Advances in Water Resources 100 (febbraio 2017): 62–77. http://dx.doi.org/10.1016/j.advwatres.2016.11.014.

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10

Keller, Tobias, e Jenny Suckale. "A continuum model of multi-phase reactive transport in igneous systems". Geophysical Journal International 219, n. 1 (25 giugno 2019): 185–222. http://dx.doi.org/10.1093/gji/ggz287.

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SUMMARY Multiphase reactive transport processes are ubiquitous in igneous systems. A challenging aspect of modelling igneous phenomena is that they range from solid-dominated porous to liquid-dominated suspension flows and therefore entail a wide spectrum of rheological conditions, flow speeds and length scales. Most previous models have been restricted to the two-phase limits of porous melt transport in deforming, partially molten rock and crystal settling in convecting magma bodies. The goal of this paper is to develop a framework that can capture igneous system from source to surface at all phase proportions including not only rock and melt but also an exsolved volatile phase. Here, we derive an n-phase reactive transport model building on the concepts of Mixture Theory, along with principles of Rational Thermodynamics and procedures of Non-equilibrium Thermodynamics. Our model operates at the macroscopic system scale and requires constitutive relations for fluxes within and transfers between phases, which are the processes that together give rise to reactive transport phenomena. We introduce a phase- and process-wise symmetrical formulation for fluxes and transfers of entropy, mass, momentum and volume, and propose phenomenological coefficient closures that determine how fluxes and transfers respond to mechanical and thermodynamic forces. Finally, we demonstrate that the known limits of two-phase porous and suspension flow emerge as special cases of our general model and discuss some ramifications for modelling pertinent two- and three-phase flow problems in igneous systems.
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Più fonti

Tesi sul tema "Two-Phase Reactive Flow"

1

Lundberg, Matthew James. "Two-phase reactive flow within variable aperture fractures". Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p1427766.

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2

Lettieri, Claudio. "Large eddy simulation of two-phase reacting flows". Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/11285.

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3

Shao, N. "Gas-liquid two-phase flow and reaction in microstructured reactors". Thesis, University College London (University of London), 2010. http://discovery.ucl.ac.uk/19893/.

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Abstract (sommario):
The thesis presents investigations on two-phase gas-liquid microstructured reactors operating in Taylor flow and the dependence of reactor performance on design parameters. Literature review revealed that flow patterns in microchannels are affected not only by channel dimension, fluids flowrates and surface tension, but also by wall wettability and gas inlet size. A universal flow regime map does not seem to exist. The hydrodynamic parameters of Taylor flow were investigated both by Computational Fluid Dynamics simulations and experiments in microstructures with sizes 0.3mm – 1mm and various inlet configurations such as T- and Y- junctions fabricated in-house. The same parameters that influence flow patterns and their transitions were also found to affect Taylor bubble sizes. To account for the effect of inlet conditions, correlations were developed for predicting bubble/slug size in the T- and Y- inlet geometries that were used subsequently. Mass transfer with and without chemical reaction was investigated numerically in Taylor flow microreactors using CO2 physical absorption into water or chemical absorption into NaOH aqueous solution. Chemical absorption was enhanced by a factor of 3-18 over physical absorption. With reaction present, the reactor performance depended mainly on the gas-liquid interfacial area, while mixing within the phases was only important in physical absorption. This agreed with the experimental results of a similar reaction system, which showed that bifurcating main channels, where new interfaces are generated, significantly improved reaction conversion while meandering channels that enhance liquid mixing had little impact. Finally, the performance of a Taylor flow microreactor was evaluated for an industrial fast gas-liquid reaction of CO2 absorption from fuel gas into amine solutions. The Taylor flow microreactor offered the largest specific area and the smallest reactor volume compared to other microreactor types. However, in order to meet absorption specifications for the case considered multistage absorption would have been necessary.
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4

Hare, John Andrew. "The venting of a runaway esterification reaction on both the laboratory and pilot scales". Thesis, London South Bank University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245039.

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5

Pannala, Sreekanth. "On large eddy simulations of reacting two-phase flows". Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/11978.

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6

Sin, Irina. "Modélisation numérique d’écoulement diphasique compressible et transport réactif en milieux poreux - Applications à l'étude de stockage de CO2 et de réservoir de gaz naturel". Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0058/document.

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Abstract (sommario):
Les activités humaines dans la subsurface se développent rapidement (stockage de déchets,nouvelles techniques minières, stockage à haute fréquence de l’énergie), alors que dans le même temps les attentes du public et des autorités s’intensifient. L’évaluation de chaque étape de ces opérations souterraines repose sur des études détaillées de la sûreté et des impacts environnementaux.Elles reposent sur des simulateurs élaborés et sur de la modélisation multiphysique. Avec leur approche orientée processus, les simulations en transport réactifs proposent une méthode efficace pour comprendre et prévoir le comportement de ces systèmes complexes, à différentes échelles de temps et d’espace.Le but de ce travail est d’intégrer la résolution de l’écoulement diphasique compressible dans le cadre de codes de transport réactifs à l’aide d’une méthode de séparation d’opérateurs. Un module multiphasique a été créé dans le code de transport réactif HYTEC. Une nouvelle approche a ensuite été développée pour coupler écoulement multicomposant multiphasique compressible, description de propriétés thermo-dynamiques complexes pour les fluides, avec des codes de transport réactif. La méthode a été intégrée dans HYTEC. Des cas de validation sont proposés, puis des exemples d’application pour la simulation du stockage souterrain de CO2 et des impuretés associées
Human activity in the subsurface has rapidly been expanding and diversifying (waste disposal, new mining technologies, high-frequency storage of energy), while the public and regulatory expectations keep growing. The assessment of each step of underground operations requires careful safety and environmental impact evaluations. They rely on elaborate simulators and multiphysics modeling. With its process-based approach, reactive transport simulation provides an effective way to understand and predict the behavior of such complex systems at different time and spatial scale.This work aims at incorporating a compressible multiphase flow into conventional reactive transport framework by an operator splitting approach. A multiphase flow module is developed in the HYTEC reactive transport software. A new approach is then developed to fully couple multiphase multicomponent compressible flow, the complex thermodynamic description of the fluid properties, with existing reactive transport codes. The method is implemented in HYTEC. Some validation is provided, before application to the simulation of underground storage of CO2 and associated impurities
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7

Eyssartier, Alexandre. "LES of two-phase reacting flows : stationary and transient operating conditions". Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0011/document.

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L'allumage et le réallumage de haute altitude présentent de grandes difficultés dans le cadre des chambres de combustion aéronautiques. Le succès d'un allumage dépend de multiples facteurs, des caractéristiques de l'allumeur à la taille des gouttes du spray en passant par le niveau de turbulence au point d'allumage. Déterminer la position optimale de l'allumeur ou le potentiel d'allumage d'une source d'énergie donnée à une position donnée sont ainsi des paramètres essentiels lors du design de chambre de combustion. Le but de ces travaux de thèse est d'étudier l'allumage forcé des chambres de combustion aéronautiques. Pour cela, des Simulation numériques aux Grandes Echelles (SGE) d'écoulements diphasiques réactifs sont utilisées et analysées. Afin de les valider, des données expérimentales issues du banc MERCATO installé à l'ONERA Fauga-Mauzac sont utilisées. Cela permet dans un premier temps de valider la méthodologie ainsi que les modèles utilisés pour les SGE diphasiques évaporantes avant leur utilisation dans d'autres conditions d'écoulement. Le cas diphasique réactif statistiquement stationnaire est ensuite comparé aux données disponibles pour évaluer les modèles en condition réactives. Ce cas est étudié plus en détail à travers l'analyse de caractéristiques de la flamme. Celle-ci semble être le théâtre de régimes de combustion très différents. On note aussi que la détermination de la méthode numérique la plus appropriée pour le calcul d'écoulements diphasiques n'est pas évidente. De plus, deux méthodes numériques différentes peuvent donner des résultats en bon accord avec l'expérience et pourtant avoir des modes de combustion différents. Les capacités de la SGE à correctement calculer un écoulement diphasique réactif étant validé, des SGE du phénomène transitoire d'allumage sont effectuées. La sensibilité observée expérimentalement de l'allumage aux conditions initiales, i.e. à l'instant de claquage, est retrouvé par les SGE. L'analyse met en évidence le rôle prépondérant de la dispersion du spray dans le développement initial du noyau de flamme. L'utilisation des SGE pour calculer les séquences d'allumage fournie de nombreuses informations sur le phénomène d'allumage, cependant d'un point de vue industriel, cela ne donne pas de résultat optimal, à moins de ne tester toutes les positions, ce qui rendrait le coût CPU déraisonnable. Des alternatives sont donc nécessaires et font l'objet de la dernière partie de ces travaux. On propose de dériver un critère local d'allumage, donnant la probabilité d'allumage à partir d'un écoulement diphasique (air et carburant) non réactif instationnaire. Ce modèle est basé sur des critères liés aux différentes phases menant à un allumage réussi, de la formation d'un premier noyau à la propagation de la flamme vers l'injecteur. Enfin, des comparaisons avec des données expérimentales sur des chambres aéronautiques sont présentées et sont en bon accord, indiquant que le critère d'allumage proposé, couplé avec une SGE d'écoulement diphasique non réactif, peut être utilisé pour optimiser la puissance et la position du système d'allumage
Ignition and altitude reignition are critical issues for aeronautical combustion chambers. The success of ignition depends on multiple factors, from the characteristics of the igniter to the spray droplet size or the level of turbulence at the ignition site. Finding the optimal location of the igniter or the potential of ignition success of a given energy source at a given location are therefore parameters of primary importance in the design of combustion chambers. The purpose of this thesis is to study forced ignition of aeronautical combustion chambers. To do so, Large Eddy Simulations (LES) of two-phase reacting flows are performed and analyzed. First, the equations of the Eulerian formalism used to describe the dispersed phase are presented. To validate the successive LES, experimental data from the MERCATO bench installed at ONERA Fauga-Mauzac are used. It allows to validate the two-phase evaporating flow LES methodology and models prior to its use to other flow conditions. The statistically stationary two-phase flow reacting case is then compared to available data to evaluate the model in reacting conditions. This case is more deeply studied through the analysis of the characteristics of the flame. This last one appears to experience very different combustion regimes. It is also seen that the determination of the most appropriate methodology to compute two-phase flow flame is not obvious. Furthermore, two different methodologies may both agree with the data and still have different burning modes. The ability of the LES to correctly compute burning two-phase flow being validated, LES of the transient ignition phenomena are performed. The experimentally observed sensitivity of ignition to initial conditions, i.e. to sparking time, is recovered with LES. The analysis highlights the major role played by the spray dispersion in the development of the initial flame kernel. The use of LES to compute ignition sequences provides a lot of information about the ignition phenomena, however from an industrial point of view, it does not give an optimal result, unless all locations are tested, which brings the CPU cost to unreasonable values. Alternatives are hence needed and are the objective of the last part of this work. It is proposed to derive a local ignition criterion, giving the probability of ignition from the knowledge of the unsteady non-reacting two-phase (air and fuel) flow. This model is based on criteria for the phases of a successful ignition process, from the first kernel formation to the flame propagation towards the injector. Then, comparisons with experimental data on aeronautical chambers are done and show good agreement, indicating that the proposed ignition criterion, coupled to a Large Eddy Simulation of the stationary evaporating two-phase non-reacting flow, can be used to optimize the igniter location and power
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8

Blanch, Ojea Roland. "Numerical and experimental analyses of single and two-phase microfluidic flows with implications in microreactors". Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/63824.

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Aquesta tesi centra els seus esforços en l'àmbit de la microfluídica, un camp relativament recent dins de la Mecànica de Fluids, amb un futur prometedor i amb un ritme d'investigació intens en les seves diferents especialitzacions. En aquest sentit, la tesi presenta dos aportacions científiques principals. Primer, aporta una eina numèrica d'elaboració pròpia per realitzar simulacions de fluxos reactius en microcanals. Eina que s'aplica satisfactòriament a la identificació dels principals processos de transport involucrats en la oxidació parcial del metà per a produir gas de síntesi, i a l'estudi de l'efecte que tenen alguns paràmetres d'operació en aquest procés reactiu. Segon, estén el coneixement dels fluxos multifàsics en microunions en T, estudiant experimentalment fluxos de dues fases amb fluids principalment miscibles i en condicions supercrítiques, que son portats al seu equilibri vapor-líquid. Durant aquest estudi, a més, reporta un succés inesperat que presenta futurs reptes en l'aplicació d'aquest tipus de fluxos multifàsics.
The present thesis focuses on microfluidics, a relatively recent field of Fluid Mechanics with promising expectations and with an intense scientific interest on its different areas. In this regard, the thesis aims to provide two main scientific contributions. First, it presents an in-house numerical tool to carry out simulations of reactive flows within microchannels. The tool is successfully applied to the identification of the main transport phenomena involved on the partial oxidation of methane to produce synthesis gas, and to the analysis of the effect of several operating parameters on this reactive process. Second, it extends the knowledge on multiphase flows in microfluidic T-junctions with an experimental study of two-phase flows of mixtures of potentially miscible fluids, in supercritical conditions and in vapour-liquid equilibrium. In this study it is also reported an unexpected phenomenon, which brings new challenges to the application of these kind of multiphase flows.
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9

Stock, Antoine. "Simulatiοn exaflοpique de la cοmbustiοn de sprays". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMIR18.

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Abstract (sommario):
La simulation numérique des grandes échelles (LES, pour Large Eddy Simulation) s'est imposée comme un outil numérique puissant pour la conception et l'analyse des brûleurs de sprays, permettant de capturer avec une grande précision les interactions complexes entre l'écoulement turbulent, la combustion et la dynamique des sprays. Cependant, cette précision accrue de la LES s'accompagne d'un coût CPU élevé. Ces simulations nécessitent souvent l'utilisation de maillages de grande taille afin de résoudre les turbulences à petite échelle et les fronts de flamme nets, ainsi que la gestion de nombreuses espèces chimiques et réactions. Ces exigences posent des défis importants en termes de ressources informatiques et de temps de calcul, ce qui peut freiner l'application pratique de la LES dans les processus de conception industrielle. Cette thèse s'attaque aux défis numériques associés à la LES des brûleurs de sprays en explorant et développant des approches numériques visant à réduire coût de calcul sans compromettre la précision des simulations. Trois stratégies principales sont étudiées : l'équilibrage de charge Euler-Lagrange, l'adaptation dynamique de maillage, et le clustering dynamique des termes source
Large Eddy Simulation (LES) has emerged as a powerful computational tool for the design and analysis of spray burners, offering the ability to capture the complex interactions between turbulent flow, combustion, and spray dynamics with high fidelity. However, the high accuracy of LES comes at a significant computational cost. The simulation of these systems often requires the use of large meshes in order to resolve fine-scale turbulence and sharp flame front as well as the handling of numerous species and chemical reactions. These demands pose substantial challenges in terms of the required computational resources and the time required for the simulation process, which can hinder the practical application of LES in industrial design processes. This thesis addresses the computational challenges associated with LES of spray burners by exploring and developing numerical approaches aimed at reducing the computational burden without compromising the accuracy of the simulations. Three primary strategies are investigated: Euler-Lagrange load balancing, Adaptive Mesh Refinement, and Dynamic Cell Clustering
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10

Sin, Irina. "Modélisation numérique d’écoulement diphasique compressible et transport réactif en milieux poreux - Applications à l'étude de stockage de CO2 et de réservoir de gaz naturel". Electronic Thesis or Diss., Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0058.

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Abstract (sommario):
Les activités humaines dans la subsurface se développent rapidement (stockage de déchets,nouvelles techniques minières, stockage à haute fréquence de l’énergie), alors que dans le même temps les attentes du public et des autorités s’intensifient. L’évaluation de chaque étape de ces opérations souterraines repose sur des études détaillées de la sûreté et des impacts environnementaux.Elles reposent sur des simulateurs élaborés et sur de la modélisation multiphysique. Avec leur approche orientée processus, les simulations en transport réactifs proposent une méthode efficace pour comprendre et prévoir le comportement de ces systèmes complexes, à différentes échelles de temps et d’espace.Le but de ce travail est d’intégrer la résolution de l’écoulement diphasique compressible dans le cadre de codes de transport réactifs à l’aide d’une méthode de séparation d’opérateurs. Un module multiphasique a été créé dans le code de transport réactif HYTEC. Une nouvelle approche a ensuite été développée pour coupler écoulement multicomposant multiphasique compressible, description de propriétés thermo-dynamiques complexes pour les fluides, avec des codes de transport réactif. La méthode a été intégrée dans HYTEC. Des cas de validation sont proposés, puis des exemples d’application pour la simulation du stockage souterrain de CO2 et des impuretés associées
Human activity in the subsurface has rapidly been expanding and diversifying (waste disposal, new mining technologies, high-frequency storage of energy), while the public and regulatory expectations keep growing. The assessment of each step of underground operations requires careful safety and environmental impact evaluations. They rely on elaborate simulators and multiphysics modeling. With its process-based approach, reactive transport simulation provides an effective way to understand and predict the behavior of such complex systems at different time and spatial scale.This work aims at incorporating a compressible multiphase flow into conventional reactive transport framework by an operator splitting approach. A multiphase flow module is developed in the HYTEC reactive transport software. A new approach is then developed to fully couple multiphase multicomponent compressible flow, the complex thermodynamic description of the fluid properties, with existing reactive transport codes. The method is implemented in HYTEC. Some validation is provided, before application to the simulation of underground storage of CO2 and associated impurities
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Più fonti

Libri sul tema "Two-Phase Reactive Flow"

1

Pannala, Sreekanth. Computational gas-solids flows and reacting systems: Theory, methods and practice. Hershey, PA: Engineering Science Reference, 2011.

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2

Pannala, Sreekanth. Computational gas-solids flows and reacting systems: Theory, methods and practice. Hershey, PA: Engineering Science Reference, 2011.

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3

Nguyen, Hung Lee. Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1989.

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4

Center, Lewis Research, a cura di. Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1989.

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5

Center, Lewis Research, a cura di. Two-dimensional analysis of two-phase reacting flow in a firing direct-injection diesel engine. [Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1989.

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6

1971-, Pannala Sreekanth, Syamial Madhave e O'Brien Thomas J. 1941-, a cura di. Computational gas-solids flows and reacting systems: Theory, methods and practice. Hershey, PA: Engineering Science Reference, 2010.

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Capitoli di libri sul tema "Two-Phase Reactive Flow"

1

Embid, Pedro F., e Melvin R. Baer. "Modeling Two-Phase Flow of Reactive Granular Materials". In Multidimensional Hyperbolic Problems and Computations, 58–67. New York, NY: Springer New York, 1991. http://dx.doi.org/10.1007/978-1-4613-9121-0_5.

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Neumann, Sebastian, Amjad Asad e Rüdiger Schwarze. "Numerical Simulation of Continuous Steel Casting Regarding the Enhancement of the Cleanliness of Molten Steel". In Multifunctional Ceramic Filter Systems for Metal Melt Filtration, 769–85. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-40930-1_30.

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AbstractResearch results of this chapter show a great potential to improve inclusion removal from steel melts using active and reactive exchangeable filtration systems in steelmaking. This contribution investigates numerically the performance and the efficiency of the reactive cleaning and active filtration in continuous casting tundishes. For this purpose, a Euler–Lagrange model of the disperse two-phase flow of steel melt and non-metallic inclusions has been developed. Here, implicit large eddy simulations have been employed to resolve the large-scale turbulent structures in the tundish flows. By means of multiphase flow simulations, two prototype tundish configurations (laboratory one-strand tundish, industrial-scale two-strand tundish) were researched with alumina-coated, carbon-bonded ceramic foam hybrid filters. The research aimed the investigation of the effect of the filtration system, e.g. filter position, filter shapes and filter size on inclusion removal. The results of the numerical simulations indicated the high cleaning efficiencies obtained by using a reactive filter system, where reactively generated carbon monoxide bubbles carried a high amount of inclusions to the slag. Moreover, it was concluded from the results that the contribution of active filtration to inclusion removal by the deposition of inclusions on filter surfaces was neglectable compared to the contributions of reactive cleaning.
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Ahusborde, E., B. Amaziane e M. El Ossmani. "Finite Volume Scheme for Coupling Two–Phase Flow with Reactive Transport in Porous Media". In Springer Proceedings in Mathematics & Statistics, 407–15. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-57394-6_43.

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Poinsot, Thierry. "Two-Phase Flow Combustion". In Instabilities of Flows: With and Without Heat Transfer and Chemical Reaction, 267–85. Vienna: Springer Vienna, 2010. http://dx.doi.org/10.1007/978-3-7091-0127-8_10.

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Borghi, Roland, e Fabien Anselmet. "Fluctuations of the Gas Phase in Reactive Two-Phase Media". In Turbulent Multiphase Flows with Heat and Mass Transfer, 379–97. Hoboken, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118790052.ch16.

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Biagini, Carlo, Alberto Aglietti e Andrea Bongini. "A BIM-Based Approach to the Management of Historic Bridges". In CONVR 2023 - Proceedings of the 23rd International Conference on Construction Applications of Virtual Reality, 1105–16. Florence: Firenze University Press, 2023. http://dx.doi.org/10.36253/10.36253/979-12-215-0289-3.110.

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Building Information Modelling applied to civil infrastructure has opened up interesting scenarios for integrated management of existing infrastructural works. In the last few years Bridge Management System (BMS) have been increasingly used by infrastructure owners, based on different control systems: from stochastic methods, which make it possible to define a condition ratio (CR) starting from periodic inspections of bridges, to sensors for structural monitoring, which can originate a flow of information exchange between real artifacts and the digital model capable of activating effective reactive or planned responses in the operation and maintenance phase of the asset. The paper intends to outline a BIM-oriented process workflow, which from the creation of parametric objects for infrastructural works using Scan-to-BIM acquisition techniques and procedures, arrives at the implementation of information bridge models to manage both static data from scheduled inspections of technicians of defects and their severity according to specific guidelines, and dynamic data from incoming and outgoing sensors placed in the physical asset for real time monitoring towards analysis, supervision and control systems of the facilities owner. The defined process workflow will be applied to some case studies, related to bridges of different characteristics, outlining some directions for future developments. In detail the research showcases the tasks undertaken and the outcomes achieved on four selected bridge case studies, which are real and situated within the geographical area of the Tuscany region, Italy. The studied bridges are all still in use and hold historical significance, as they were constructed between two hundred and one hundred years ago
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Biagini, Carlo, Alberto Aglietti e Andrea Bongini. "A BIM-Based Approach to the Management of Historic Bridges". In CONVR 2023 - Proceedings of the 23rd International Conference on Construction Applications of Virtual Reality, 1105–16. Florence: Firenze University Press, 2023. http://dx.doi.org/10.36253/979-12-215-0289-3.110.

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Abstract (sommario):
Building Information Modelling applied to civil infrastructure has opened up interesting scenarios for integrated management of existing infrastructural works. In the last few years Bridge Management System (BMS) have been increasingly used by infrastructure owners, based on different control systems: from stochastic methods, which make it possible to define a condition ratio (CR) starting from periodic inspections of bridges, to sensors for structural monitoring, which can originate a flow of information exchange between real artifacts and the digital model capable of activating effective reactive or planned responses in the operation and maintenance phase of the asset. The paper intends to outline a BIM-oriented process workflow, which from the creation of parametric objects for infrastructural works using Scan-to-BIM acquisition techniques and procedures, arrives at the implementation of information bridge models to manage both static data from scheduled inspections of technicians of defects and their severity according to specific guidelines, and dynamic data from incoming and outgoing sensors placed in the physical asset for real time monitoring towards analysis, supervision and control systems of the facilities owner. The defined process workflow will be applied to some case studies, related to bridges of different characteristics, outlining some directions for future developments. In detail the research showcases the tasks undertaken and the outcomes achieved on four selected bridge case studies, which are real and situated within the geographical area of the Tuscany region, Italy. The studied bridges are all still in use and hold historical significance, as they were constructed between two hundred and one hundred years ago
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Fuhrmann, J., e K. Gärtner. "Modeling of Two-Phase Flow and Catalytic Reaction Kinetics for DMFCs". In Topics in Applied Physics, 297–316. New York, NY: Springer New York, 2009. http://dx.doi.org/10.1007/978-0-387-78691-9_9.

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Speares, W., e E. F. Toro. "An Adaptive Gridding Approach to the Computation of Reactive Two-Phase Flows in Two Dimensions". In Shock Waves @ Marseille III, 155–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-78835-2_26.

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Sanjosé, M., E. Riber, L. Gicquel, B. Cuenot e T. Poinsot. "Large Eddy Simulation of a Two-Phase Reacting Flow in an Experimental Burner". In Direct and Large-Eddy Simulation VII, 345–51. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-90-481-3652-0_51.

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Atti di convegni sul tema "Two-Phase Reactive Flow"

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Zhang, F., e H. Gröning. "Detonation study of two-phase flow (reactive particles-gas)". In Current topics in shock waves 17th international symposium on shock waves and shock tubes Bethlehem, Pennsylvania (USA). AIP, 1990. http://dx.doi.org/10.1063/1.39503.

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Deng, Hang, Sergi Molins, Pei Li e Xin Wang. "Multiphase reactive transport modeling – the impacts of two-phase flow on mineral reaction rate". In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.16078.

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Ciriaco, H. M., H. M. Nick e A. A. Eftekhari. "Estimating two-phase reactive flow model parameters from single- and two-phase modified-salinity core flooding data". In IOR 2021. European Association of Geoscientists & Engineers, 2021. http://dx.doi.org/10.3997/2214-4609.202133091.

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Castelijns, Henricus Jozef, Leo Pel, Henk Huinink e Pacelli Lidio Jose Zitha. "Investigation of reactive transport phenomena for modification of two-phase flow using NMR". In SPE European Formation Damage Conference. Society of Petroleum Engineers, 2005. http://dx.doi.org/10.2118/94559-ms.

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Simoes, Marine, Patrick Della Pieta, Franck Godfroy e Olivier Simonin. "Modeling of Particulate Pressure in the Frame of Eulerian Approach for Compressible Reactive Dispersed Two-Phase Flows". In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77159.

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In solid rocket motors (SRM) used for space propulsion, such as Ariane 5, aluminum is frequently used as a propellant additive to increase specific impulse. However, its combustion produces aluminum oxide residues that are carried away by the flow field. Thus, physical modeling of aerodynamic flows in SRM should account for this condensed phase. In the frame of full Eulerian approach, unsteady compressible Navier-Stokes equations are solved for both phases. However, numerical simulations performed on a simple axisymmetric motor have pointed out a flaw of the basic Eulerian approach. Indeed, the variance of the particle velocity distribution is not accounted for, leading to unrealistic accumulations of particles in some specific flow region. Hence, we have developed an advanced Eulerian model to correct this shortcoming, which is presented in this paper.
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Allen, Mark G., e R. K. Hanson. "Simultaneous imaging of species distributions in two-phase reacting flowfields". In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.thl57.

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Hydrodynamic interactions between an evaporating fuel spray and a turbulent reacting flowfield pose a considerable challenge for combustion modelers and experimentalists. Simultaneous imaging of critical species concentrations provides an opportunity for more detailed observation of these interactions than was previously possible. We report here on our work to obtain simultaneous images of reactive intermediates (OH or CH), based on planar laser-induced fluorescence, and fuel vapor, based on planar multiphoton dissociation. Earlier work1 with single species imaging suggested that CH and OH images served to mark the instantaneous reaction zone and postcombustion zones, respectively, in a turbulent heptane-air spray flame. Photodissociation of C2H2 (a dominant pyrolysis product of the evaporating droplets) and imaging of the resultant CH fragment fluorescence enables tracking of the distribution of precombustion zones in the flow field. Using a tunable dye laser (Quanta Ray DCR-1 Nd:YAG pumped PDL) and an ArF excimer laser (Lambda Physik EMG 203 MSC), simultaneous images of pairs of these species distributions have been obtained. The laser radiation is formed into a thin sheet and focused into the flame. The resulting fluorescence is imaged onto an intensified photodiode array. The signal on the array is digitized and stored on an LSI 11/23 computer for processing and display. Near shot-noise-limited performance is often obtained, and molecular species detection limits are typically of the order of 10 ppm. In addition, we hope to infer droplet size fields from images of the Mie scattered light from a spectrally broad illumination source.
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Simoes, M., e O. Simonin. "Modeling of Particulate Pressure in the Frame of Mesoscopic Eulerian Formalism for Compressible Reactive Dispersed Two-Phase Flows". In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98201.

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In space propulsion, compressible reactive dispersed two-phase flows are investigated in order to predict the behavior of solid or liquid rocket motors. In the frame of full Eulerian approach, physical modeling of aerodynamic flows in such motors is performed resolving unsteady compressible Navier-Stokes equations for both phases. However, numerical simulations performed on a simple axisymmetric motor have pointed out a flaw of this basic Eulerian approach. Indeed, the variance of the particle velocity distribution is not accounted for, leading to unrealistic accumulations of particles in some specific flow region. To correct this shortcoming, we have developed an advanced Eulerian model based on a statistical approach in the framework of the Mesoscopic Eulerian Formalism (MEF).
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Lecourt, Renaud, Guillaume Linassier e Ge´rard Lavergne. "Detailed Characterisation of a Swirled Air/Kerosene Spray in Reactive and Non-Reactive Conditions Downstream From an Actual Turbojet Injection System". In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45173.

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As part of the investigations of the ignition of jet-engines under altitude conditions, a detailed data base was built with the results of experiments on the two-phase flow produced by an actual swirl air/kerosene turbojet injection system. The injection system had a fairly simple geometry. It was used with liquid kerosene injected through a pressure-swirl fuel atomiser. In this case the measurements were carried out at atmospheric pressure in a windowed combustion chamber, with air at ambient temperature. The tested equivalence ratio was 0.95 which corresponds to an air mass flow rate of 0.035 kg/s. For this operating point, we obtained the velocity field of the gas phase under non-reactive conditions by LDA. The axial velocity component of the gas phase was also measured in the burning spray using an original method with a phase Doppler device. The data recorded with the PDA were also processed to obtain the kerosene droplet sizes and velocities under reactive conditions. The same phase Doppler device was used in non-reactive conditions to measure the size and velocity distributions of the kerosene droplets in a section close to the injection system exit in order to complete the data base with the boundary conditions for the liquid phase. In addition the flame was visualised qualitatively. The picture of the stabilized flame was processed with an Abel transform to compare the LDA/PDA measurements with the flame structure, obtained under the reactive conditions. Finally, unsteady pressure measurements were taken under non-reactive conditions and the LDA measurements processed, close to the injection system exit, to get the PVC (Precessing Vortex Core) frequency. The data were analysed to determine the influence of the spray combustion on the two-phase flow. The geometry of the whole experimental setup and the data base are available to other researchers for testing and validating spray combustion models and unsteady two-phase flow numerical simulations.
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Lipchitz, A., Lilian Laurent e G. D. Harvel. "Suitability of Eutectic Field’s Metal for Use in an Electromagnetohydrodynamically-Enhanced Experimental Two-Phase Flow Loop". In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54103.

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Several Generation IV nuclear reactors, such as sodium fast reactors and lead-bismuth fast reactors, use liquid metal as a coolant. In order to better understand and improve the thermal hydraulics of liquid metal cooled GEN IV nuclear reactors liquid metal flow needs to be studied in experimental circulation loops. Experimental circulation loops are often located in a laboratory setting. However, studying liquid metal two phase flow in laboratory settings can be difficult due to the high temperatures and safety hazards involved with traditional liquid metals such as sodium and lead-bismuth. One solution is to use a low melt metal alloy that is as benign as reasonably achievable. Field’s metal is a eutectic alloy of 51% Indium, 32.5% Bismuth and 16.5% Tin by weight and has a melting point of 335K making it ideal for use in a laboratory setting. A study is undertaken to determine its suitability to use in a two-phase experimental flow loop enhanced by magnetohydrodynamic forces. The study investigated its reactivity with air and water, its ability to be influenced by magnetic fields, its ability to flow, and its ease of manufacture. The experiments melted reference samples of Field’s metal and observed its behaviour in a glass beaker, submerged in water and an inclined stainless steel pipe. Then Field’s metal was manufactured in the laboratory and compared to the sample using the same set of experiments and standards. To determine Field’s metal degree of magnetism permanent neodymium magnets were used. Their strength was determined using a Gaussmeter. All experiments were recorded using a COHU digital camera. Image analysis was then performed on the video to determine any movements initiated by the magnetic field forces. In conclusion, Field’s metal is more than suitable for use in experimental settings as it is non-reactive, non-toxic, simple to manufacture, easy to use, and responds to a magnetic force.
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Bastidas, Manuela, Sohely Sharmin, Carina Bringedal e Sorin Pop. "A numerical scheme for two-scale phase-field models in porous media". In VI ECCOMAS Young Investigators Conference. València: Editorial Universitat Politècnica de València, 2021. http://dx.doi.org/10.4995/yic2021.2021.12571.

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A porous medium is a highly complex domain, in which various processes can take place at different scales. Examples in this sense are the multi-phase flow and reactive transport. Here, due to processes like dissolution or precipitation, or chemical deposition, which are encountered at the scale of pores (the micro-scale), the local structure and geometry of the pores may change, impacting the fluid flow. Since these micro-scale processes depend on the model unknowns (e.g., the solute concentration), free boundaries are encountered, separating the space available for flow from the solid, impermeable part in the medium. Here we consider a phase-field approach to model the evolution of the evolving interfaces at the micro-scale. For mineral precipitation and dissolution, we have evolving fluid-solid interfaces. If considering multi-phase flow, evolving fluid-fluid interfaces are also present. After applying a formal homogenization procedure, a two-scale phase-field model is derived, describing the averaged behavior of the system at the Darcy scale (the macro-scale). In this two-scale model, the micro and the macro scale are coupled through the calculation of the effective parameters. Although the resulting two-scale model is less complex than the original, the numerical strategies based on the homogenization theory remain computationally expensive as they require the computation of several problems over different scales, and in each mesh element. Here, we propose an adaptive two-scale scheme involving different techniques to reduce the computational effort without affecting the accuracy of the simulations. These strategies include iterations between scales, an adaptive selection of the elements wherein effective parameters are computed, adaptive mesh refinement, and efficient non-linear solvers.
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Rapporti di organizzazioni sul tema "Two-Phase Reactive Flow"

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Longaker, Benjamin, e Mikael Toye. Evolution of Two-Phase High Explosive Reactive Flow. Office of Scientific and Technical Information (OSTI), agosto 2023. http://dx.doi.org/10.2172/1996147.

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Klingenberg, G. Investigation of Highly Pressurized Two-Phase, Reacting Flow. Fort Belvoir, VA: Defense Technical Information Center, febbraio 1988. http://dx.doi.org/10.21236/ada192472.

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Lahav, Ori, Albert Heber e David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, marzo 2008. http://dx.doi.org/10.32747/2008.7695589.bard.

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The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.
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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz e Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, febbraio 2001. http://dx.doi.org/10.32747/2001.7573998.bard.

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The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.
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