Dissertations / Theses on the topic 'Réacteurs chimiques – Simulation, Méthodes de'
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Louleh, Ziad. "Modélisation et conduite des réacteurs discontinus par analyse des flux thermiques." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT037G.
Foucher, Laurent. "Utilisation de la méthode des éléments finis pour la simulation des réacteurs à termes sources distribués : application aux réacteurs électrochimiques et au chauffage par induction électromagnétique." Toulouse, INPT, 1994. http://www.theses.fr/1994INPT029G.
Roger, Thierry. "Modélisation du comportement de réacteurs chimiques semi-fermés à double enveloppe et à fluide unique." Rouen, 1993. http://www.theses.fr/1993ROUES036.
Touré, Inza. "Contribution à la simulation numérique par éléments finis de l'hydrodynamique des cuves agitées : application à l'étude des bioréacteurs." Châtenay-Malabry, Ecole centrale de Paris, 1993. http://www.theses.fr/1993ECAP0296.
Simon, Muriel. "Etude des performances d'un système de mélange-agitation fluidique : cas des jets multiples et instationnaires." Toulouse, INSA, 1992. http://www.theses.fr/1992ISAT0033.
Sklaveniti, Sofia. "Développement et déploiement sur le terrain d’un analyseur pour la mesure de la vitesse de formation d’ozone dans la troposphère." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10121/document.
Ground level ozone (O3) is a major environmental concern due to its detrimental impacts on human health, vegetation and climate. The photochemical formation of ozone follows a complex nonlinear chemistry that makes strategies for ozone reduction difficult to implement. Governments rely on atmospheric chemistry models to develop emission regulations, but there are still uncertainties associated with the chemical mechanisms used in these models. Direct measurements of ozone production rates, P(O3), is a new technique that can help validating current atmospheric chemical mechanisms and provide real-time data for emission regulations of ozone precursors. The main objective of this thesis was (i) to advance the understanding of P(O3) measurements and (ii) to investigate the ozone production chemistry in ambient air. In this context, an instrument capable of P(O3) measurements was developed, characterized in the laboratory and deployed in the field. The principle of the instrument is based on differential Ox (=O3+NO2) measurements between two sampling reactors, one acting as a “reference” reactor with no O3 production, and the other one reproducing the same O3 production chemistry than in ambient air. The characterization of this instrument was performed through laboratory and modelling experiments to assess the accuracy of P(O3) measurements. Finally, the instrument was deployed during the IRRONIC campaign to investigate the P(O3) sensitivity to NO in a forested area. Comparison between measured and modeled P(O3) values allowed to assess the performances and limitations of this new instrument and evaluate the feasibility of direct P(O3) measurements
Garzón, Losik Germán Alexander. "Étude et modélisation d’un procédé de dissolution poussée en réacteur continu – application aux oxydes (U, Pu)O₂." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0050.
Plutonium multirecycling aims to stabilise the plutonium inventory and eventually close the fuel cycle in France. This action involves the reprocessing and recycling of plutonium-rich Mixed OXide (MOX) spent fuel, which implies the adaptation of current technologies, in particular dissolution. Therefore, an experimental study of the reaction between uranium-plutonium mixed oxides and nitric acid coupled with chemical reactor modelling is required. In this context, a study of the dissolution of three mixed oxides (30, 40, and 65% Pu/(U+Pu)) and plutonium dioxide in nitric acid is carried out using an optical setup. It can be highlighted that the mixed oxide dissolves according to a similar mechanism as plutonium dioxide when the plutonium content in the solid exceeds 30%. Moreover, only the mixed oxide with the highest uranium content undergoes an autocatalytic reaction mechanism similar to that identified for uranium dioxide. A dissolution model describing the size evolution of a single particle against time was developed. Such model considers the description of particles surface by a fractal geometry approach as well as the surface where the reaction actually takes place. Model was validated by comparison of experimental data from this work and from literature. In addition, a second model was developed, taking into account the single particlemodel, based on population balance equations. The model allows to describe the behaviour of a fluidised bed dissolver, which presents interesting advantages for solid-fluid type reactions. Finally, by implementing the developed model, simulations were performed showing a first estimation of the feasibility of a new dissolution process for current and upcoming MOX fuels
Matamoros, Marin Fatima. "Modélisation et optimisation des fours de cémentation gazeuse basse pression." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0288.
This PhD work deals with the development of an optimization methodology for low-pressure gas carburizing furnaces. The objective is to determine the optimal operating conditions allowing operators exposed to the toxic by-products generated (polycyclic aromatic hydrocarbons (PAHs) and soot in this case) to work in safer conditions. A first-principles model of the process based on mass balance equations as well as equations derived from a detailed kinetic mechanism of gas-phase acetylene pyrolysis is first developed. The kinetic model is then reduced in order to reduce the size of the differential system; then completed by a model of soot formation, a pyrolytic carbon formation reaction and heterogeneous phenomena occurring on the surface of the steel parts to be cemented which are described by means of Langmuir-Hinshelwood-Hougen-Watson model. Experiments conducted on a laboratory scale tubular reactor and a jet stirred reactor are carried out without steel parts. The results are then compared to the results of simulations of acetylene pyrolysis, soot and pyrolytic carbon formation in a plug flow reactor and in a perfectly stirred tank reactor. The results show the importance of the role played by the formation of pyrolytic carbon and soot on the formation of PAH. Experiments on an industrial low-pressure gas-carburizing furnace are conducted as well; they consist in the carburization of steel parts using an industrial "recipe", i.e. predetermined operating conditions obtained by trial-and-error basis in order to meet the desired carburizing depth. The experimental results are used to estimate the parameters of the heterogeneous surface reaction by assuming a complete model of low-pressure gas carburizing in a perfectly stirred tank reactor. The model is then used in the formulation of the dynamic constrained optimization problem which aims to minimize the production of toxic compounds while ensuring the industrial quality of the carburized steel parts. Optimal operating conditions allowing to obtain steel parts of the same quality as those obtained with the industrial recipe are then determined by solving the optimization problem and experiments using the new operating conditions are conducted in the industrial furnace. The results corroborate that the optimized recipe leads to steel parts of the same quality as the industrial recipe, while reducing the process toxicity
Elia, Marc. "Etude de la stabilité thermique dans les réacteurs chimiques." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4707/document.
In refining and petrochemistry process safety is a major issue. For highly exothermic processes it is necessary to ensure in a rigorous way the safe that the process operates in safe conditions, hence avoiding thermal runaway. The objective of this thesis was to develop a methodology to determine the operating conditions of reliable operation of chemical reactors. The methodology relies on stationary and dynamic analysis. The stationary stability analysis based on the Van Heerden criterion was generalized to complex chemical systems. The dynamic analysis applies the perturbation theory to definitely determine if a stationary point is stable according to eigenvalue analysis.The methodology was applied to ebullated-bed technology for residue hydroconversion at pilot and industrial scale. Two comprehensive dynamic models that accurately represent the ebullated-bed pilot plant and industrial process were developed for the study. The models take into account a detailed description of the reactive system and the configuration of the pilot and industrial plants: three phases, kinetics and flow characterization. A stationary and dynamic thermal stability analysis was carried out for both configurations and stable/unstable operating regions were identified. The study showed that the pilot plant reactor can operate in a larger domain of operating conditions compared to the industrial reactor while the parameters have the same effect on both reactors. The resulting reactor operation diagrams are a essential guide for engineers in the reactor design and operation practice
Crouslé, Olivier. "Analyse, mise au point et méthodes d'exploitation d'un réacteur chimique pilote pour calorimétrie de réaction." Lyon 1, 1996. http://www.theses.fr/1996LYO10191.
Belgacem, Mayouf. "Étude de réacteurs équipés de turbines autoaspirantes : modélisation et simulation pour le cas d'une turbine Rushton." Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL131N.
Cuille, Pierre. "Approche de la simulation dynamique : application aux procédés discontinus." Toulouse, INPT, 1986. http://www.theses.fr/1986INPT013G.
Swaels, Philippe. "Modélisation et simulation dynamique de réacteurs chimiques discontinus : application à la synthèse des polyesters insaturés." Rouen, 1995. http://www.theses.fr/1995ROUES036.
Hassnaoui, El Hassan. "Etude mathématique, simulation et contribution à la modélisation d'un réacteur de craquage catalytique." Saint-Etienne, 1992. http://www.theses.fr/1992STET4020.
Rafalimanana, Célestin Alexis. "Contribution à la modélisation des cinétiques réactionnelles, à la simulation et à la conduite thermique des réacteurs de chimie fine." Toulouse, INPT, 1990. http://www.theses.fr/1990INPT039G.
Ait-Amer, Slimane. "Elaboration d'un logiciel général de simulation de réacteurs de CVD." Toulouse, INPT, 1994. http://www.theses.fr/1994INPT004G.
Arab, Sofiane. "Développement d'un procédé de synthèse de méthanol à partir de CO2 et H2." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0240/document.
As the result of fossil resources increasing scarcity, and geopolitical tensions due to energy supply securing, some countries are gradually moving to renewable and low carbon energy resources to reduce significantly their energy dependency. The electricity production from solar and wind energy are intrinsically responsible for intermittency issues that periodically lead to a gap between production and consumption. Transforming the unused excess of electricity production to chemicals may be an interesting solution for optimal exploitation of these resources. This thesis aims at investigating some means of developing new methanol process synthesis from CO2 stemming from industrial sources and H2 produced by the excess of electricity through water electrolysis. The envisioned methanol unit should be able to operate under variable regime. Initially, heat and mass transfer for two reactor technologies of methanol synthesis have been studied by using criteria described in literature. Then, a heterogeneous reactor model has been grounded in the results of heat and mass transfer analysis obtained previously. The reactor model was used to carry out a large parametric analysis of the reactor. In a second step, the reactor survey has been extended to the methanol loop to learn about the effect on the global reactor performances after its integration in the methanol loop. Once the phenomena involved in methanol process have been understood in steady regime, a transient model of the methanol loop has been developed and used to investigate the process dynamics such as the required time to start the process or to move from an operating state to another. The current and medium term electricity availability has been assessed in order to estimate the number of transitions per year undergone by the methanol unit. Based on these observations, reactor designs and operating strategies have been suggested so that they lower the impact of transitions on methanol unit. A whole chapter has been dedicated to evaluate some alternatives to develop and to improve the process of methanol synthesis. Some reactor designs have been suggested and their ability to convert hydrogen to methanol has been simulated. Although the reactor design proposals are only at the concept stage, some of them arouse more interest, and merit further evaluation. Finally, a decision support tool has been presented and used to choose the most appropriate reactor technology for the process of methanol synthesis
Lucas, Philippe. "Modélisation et simulation du régime transitoire d'unités de séparation d'un procédé chimique avec leur système de régulation : Application à la conduite d'un atelier industriel." Châtenay-Malabry, Ecole centrale de Paris, 1988. http://www.theses.fr/1988ECAP0083.
Chalmet, Stéphanie. "Simulation de processus chimiques en phase liquide par des méthodes hybrides DFT/MM." Nancy 1, 2000. http://www.theses.fr/2000NAN10175.
Crignon, Anne-Marie. "Modélisation et simulation d'un réacteur discontinu : application à une polymérisation en émulsion." Lyon 1, 1992. http://www.theses.fr/1992LYO10066.
Genty, Joël. "Modélisation et simulation dynamique du couplage bioréaction-filtration : application aux fermentations alcoolique et lactique." Châtenay-Malabry, Ecole centrale de Paris, 1992. http://www.theses.fr/1992ECAP0262.
Baba-Aissa, Chafik. "Modélisation et simulation numérique des écoulements diphasiques, turbulents au sein des réacteurs chimiques : application aux colonnes à bulles." Vandoeuvre-les-Nancy, INPL, 1998. http://www.theses.fr/1998INPL129N.
Fillon, Manuel. "Développement d'une méthodologie pour la modélisation et la simulation des réacteurs discontinus. Application à la fermentation brassicole." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT026G.
Pfeil, Jörg. "Contribution a la commande adaptative des réacteurs discontinus." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL141N.
Wiss, Jacques. "Contribution à l'étude de la sécurité des réacteurs chimiques au point d'ébullition par utilisation du refroidissement par évaporation : techniques d'évaluation des risques, méthodes de conception d'installations sûres." Mulhouse, 1992. http://www.theses.fr/1992MULH0250.
Monge, Thierry. "Modélisation et commande multivariable non linéaire robuste des réacteurs chimiques discontinus - application à un procédé industriel." Rouen, 1996. http://www.theses.fr/1996ROUES069.
Azoumah, Yao Kétowoglo. "Conception optimale, par approche constructale, de réseaux arborescents de transferts couples pour réacteurs thermochimiques." Perpignan, 2005. http://www.theses.fr/2005PERP0646.
Heat and mass transfer and chemical reaction improvements in thermochemical reactors strongly increase their performance in power and / or in energy. The reactor geometry plays an important role in these improvements. This work developed original methods combining constructal approach and two thermodynamics optimization criteria: the entropy generation minimization (for steady state modelling) and the ratio of the power over the entropy generation (for dynamic modelling). These methods enabled to optimize the design of the coupled heat and mass transfer networks in the thermochemical reactors. This study showed that for every reactor there exists its optimal shape regardless to the reactive material that filled it. Analytical and numerical models, coupling heat and mass transfer, and chemical reaction, enabled to demonstrate the constructal tree-network architecture efficiency in the thermochemical reactors design. An experimental approach was started in order to valid the analytical and numerical models
Bisch, Christophe. "Etude d'un réacteur destiné à caractériser par effet Raman spontané la phase gazeuse dans le procédé de dépôt chimique en phase vapeur." Perpignan, 1996. http://www.theses.fr/1996PERP0235.
Gaudy, Anne-Marie. "Conduite automatique et simulation d'un réacteur discontinu de développement industriel à système de chauffage-refroidissement par monofluide." Toulouse, INPT, 1992. http://www.theses.fr/1992INPT034G.
Vérant, Jean-Luc. "Etude de méthodes numériques et de modèles physico-chimiques pour des écoulements hypersoniques réactifs : application aux véhicules spatiaux." Aix-Marseille 1, 1990. http://www.theses.fr/1990AIX11314.
Vial, Christophe. "Apport des méthodes de la mécanique des fluides à l'étude des contacteurs gaz/liquide : expérience et simulation numérique." Vandoeuvre-les-Nancy, INPL, 2000. http://docnum.univ-lorraine.fr/public/INPL_T_2000_VIAL_C.pdf.
This work is devoted to the experimental study, the modelling and the numerical simulation of the hydrodynamics of a bubble column and an external loop airlift reactor. It includes three parts. First, measuring techniques have been developed to study the local and global hydrodynamic parameters of the bubbly flow. In this section, several treatments of the fluctuating wall pressure signal have been developed to identify the prevailing flow regime; three measuring techniques have been adapted to bubbly flows in order to measure the local velocity of the continuous phase: the "Pavlov" tube, an electrochemical method and Laser Doppler Velocimetry. These techniques have completed the methods already available to study the dynamics of the gas phase: local optical probes and an ultrasound Doppler technique. Then, this set of measuring techniques has been used to characterise the hydrodynamics in both reactors. Regime transitions have been deterrnined. The local and global parameters which have been measured are: the gas hold-up; the velocity, the size and the morphology of the bubbles; the liquid velocity and its local fluctuations. The Reynolds shear stress, which could not be measured, has been estimated using a simple model. The evolution of these parameters has been related to the gas flow rate, the gas distribution and the hydrodynamic regime. The whole experimental data are finally compared to the predicted values obtained using a commercial CFD code. Several models of drag, additional forces and turbulence have been used to obtain the best agreement between calculations and experiments. The ability of this commercial code to predict correctly the flow and its current limits have been highlighted
Laganier, Frank S. "Simulation dynamique de procédés : méthodes itératives dynamiques pour la résolution de systèmes algébro-différentiels." Toulouse, INPT, 1993. http://www.theses.fr/1993INPT038G.
Mbaye, Cheikh Tidiane. "Contribution à la simulation dynamique des procédés agro-alimentaires : application au procédé d'extraction de l'huile d'arachide." Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0470.
Marmillot, Philippe. "Études théoriques et expérimentales de structurations spatiales apparaissant dans un système biocatalytique compartimenté." Compiègne, 1990. http://www.theses.fr/1990COMPD303.
Behloul, Chakib Rafik. "Méthodes de conception de réacteurs multifonctionnels (réacteur-échangeur-séparateur) : application à la synthèse directe de DME à partir de CO₂ et d’H₂." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0249.
The depletion of resources and the accumulation of pollutant gases in the atmosphere are nowadays of growing concern. The current energy transition requires that certain material and energy transformation processes be partially modified or profoundly reconsidered to fit more sustainable operating conditions. Low-carbon electricity and hydrogen can substitute fossil fuels, leading to an energy mix with a low greenhouse gas (GHG) footprint. In addition to hydrogen, the production of alternative fuels and high value-added products is another way to support the energy transition.Looking for optimal, sustainable and economical processes is therefore a major challenge that process engineers are facing. The present work has thus focused on the intensification of mass and energy transformation processes, through multifunctional units, which take advantage of the synergies between elementary functions of transformation (reaction, transfer, separation, etc.) within an intensive equipment. The concept of multifunctional reactors, coupling several elementary functions, has been a real success when historical demonstrators were created (Eastman-Kodak process, etc.), but their implementation has not been generalized, due to a lack of practical design methodology.This work focuses on the implementation of some intensification methodologies to understand and improve the performance of a process involving balanced exothermic reactions. The dimethyl ether (DME) direct synthesis from CO₂ and H₂ is considered as a case study. Different exploratory ways for the DME direct synthesis process development have been investigated based on modeling and simulation. Reactor- Heat exchanger, multifunctional reactor (reactor-heat exchanger-membrane separator), hybrid elementary block processes and a process involving the cooled reactor in a conventional process environment in the presence of additional unit operations and recycle loop are studied from different angles. Different optimization cases and strategies have been addressed which differ by the decision variables and the solving method. The different methodologies applied have demonstrated the relevance of the solutions obtained and the opening towards process innovation.At the equipment level, the profiles optimization represents the heart of the methodology. The results demonstrate the potential of multifunctional reactors: a CO₂ conversion per pass of 98%, a DME yield of 95% and the possibility to remove a distillation column are obtained. In order to assess the maximum achievable performance in a multifunctional reactor, a hybrid process of elementary blocks has been optimized. At the process scale, the reactor behavior has been studied to further understand the impact of the reactor integration in a recycle loop and to estimate the local and global effects on the multiple performance criteria. Based on various criteria (overall DME yield, overall CO₂ conversion, TRL, etc.), the comparison of the different designs revealed that a reduction of the equipment number by a factor of 11 is possible in the case of a multi-functional reactor choice
Chakroun, Ihab. "Contribution de la simulation à l'évaluation de l'instrumentation des procédés alimentaires : application au raffinage des huiles végétales." Châtenay-Malabry, Ecole centrale de Paris, 1995. http://www.theses.fr/1995ECAP0430.
Salimi, Fariba. "Approche comparative de la simulation dynamique des colonnes de distillation à plateaux et à garnissage." Châtenay-Malabry, Ecole centrale de Paris, 1996. http://www.theses.fr/1996ECAP0474.
Pioch, Magali. "Contribution à l'étude du devenir, en milieu urbain, pendant le ruissellement des eaux pluviales, des produits de fission émis en cas d'accident nucléaire." Montpellier 2, 1993. http://www.theses.fr/1993MON20068.
Lebrun, Michel. "Conception d'un pilote de pompe à chaleur chimique solide-gaz : simulation et dimensionnement à partir de résultats de maquette." Perpignan, 1988. http://www.theses.fr/1988PERP0065.
Pages, Anne. "Identification de paramètres et réconciliation de données simultanées dans l'environnement d'un simulateur." Toulouse, INPT, 1993. http://www.theses.fr/1993INPT047G.
Chaumat, Hélène. "Hydrodynamique locale et globale d'une colonne à bulles en conditions industrielles." Toulouse, INPT, 2004. http://www.theses.fr/2004INPT017G.
In order to extend the present knowledge of gas-liquid contactor to industrial applications, this study deals with global and local characterization of the complex flow encountered in bubble colurnn working with solvents, at high flow rates and with partition plates. The measurement of local hydrodynamic needs first the elaboration and the validation of a methodology which allows the use of an optical bi-probe in complex flows. The related experimental study provides on the first hand data on axial and radial evolutions of local characteristics in solvent (gas hold-up, velocity and diameter) and on the other hand effects of media, liquid throughput and partition plates. As the knowledge of gas-liquid dispersion isn’t sufficient to anticipate the efficiency of an industrial reactor, the gas-liquid mass transfer is estimated. For this purpose, an original approach, based on a steady state study of nitrogen desorption with carbon dioxide, is proposed
Guillemin, Perrine. "Recherche de la haute conversion en cycle thorium dans les réacteurs CANDU et REP : Développement des méthodes de simulation associées et étude de scénarios symbiotiques." Grenoble INPG, 2009. http://www.theses.fr/2009INPG0176.
In the frame of a sustainable nuclear energy, this study assesses Thorium-fueled CANDU and PWR competitiveness to reduce access difficulties to cheap uranium resources and Gen. IV cost and availability problems. It focuses on neutronic analysis of two thorium fuel management options : 233U production from Th/Pu fuels and 233U conversion in these reactors. In particular, breeding in multirecycled Th/U CANDU has been established. Before this work, simulation methods and nuclear data have been validated by cross-checking two different types of codes (probabilistic and deterministic). Symbiotic scenarios, with various reactor and fuel combinations have been evaluated and compared. Resources savings have been quantified through core slight modifications. Deeper modifications towards breeding in PWR have been proposed and preliminarily studied
Motamed, Dashliborun Amir. "Performance of multiphase packed-bed reactors and scrubbers on offshore floating platforms: hydrodynamics, chemical reaction, CFD modeling and simulation." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30439.
Floating production storage and offloading (FPSO) systems have been introduced to offshore hydrocarbon exploitation sectors as readily movable tools for development of small or remote oil and gas fields in deeper water. These systems are increasingly contemplated for onboard treatment and refining operations of hydrocarbons extracted from undersea reservoirs near extraction sites using embarked packed-bed scrubbers and reactors. Numerous efforts in the literature to uncover the hydrodynamics of multiphase flow in packed beds have disclosed that such reactors continue to challenge us either in their design/scale-up or their operation. Furthermore, when such reactors are subjected to marine conditions, the interaction of phases becomes even more complex, resulting in further challenges for design and scale-up. The proposed research aims at providing important insights into the performance of two-phase flow packed-bed reactors in the context of floating industrial applications. To achieve this aim, a hexapod ship motion simulator with six-degree-of-freedom motions was employed to emulate FPSO movements while capacitance wire mesh sensors (WMS) and electrical capacitance tomography (ECT) coupled with the packed bed scrutinized on-line and locally the two-phase flow dynamic features. The effect of column tilts and oscillations on the hydrodynamic behavior of multiphase packed beds was investigated and then the results were compared with their corresponding onshore analogs. Moreover, potential operational strategies were proposed to diminish fluid maldistribution resulting from bed oscillations as well as for process intensification of heterogeneous catalytic reactions in packed-bed reactors. In parallel with the experiment studies, a 3D transient Eulerian CFD model was developed to simulate the hydrodynamic behavior of multiphase packed beds under column tilts and oscillations. Ultimately, a systematic experimental study was performed to address the amine-based CO2 capture performance of packed-bed scrubbers on board offshore floating vessels/platforms. Apart from gaining a comprehensive knowledge on the influence of translational and rotational movements on multiphase flows in porous media, oil and gas sectors and ship industry would benefit from the results of this work for design and scale-up of industrial reactors and scrubbers.
Unité flottante de production, de stockage et de déchargement
Saberi, Shadi. "Modélisation des systèmes à écoulement gaz-solide : application aux cas des réacteurs à lit fluidisé circulant." Compiègne, 1996. http://www.theses.fr/1996COMPD945.
Lei, Minghai. "Modélisation, simulation et optimisation des réacteurs de production d'acroléine à partir du propylène ou du glycérol." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0088/document.
In this work, modeling, simulation and optimization of multitubular gas/solid fixed bed catalytic reactors for acrolein production from propylene or from glycerol are investigated. The first part of the work deals with the catalytic oxidation of propylene to acrolein. Different kinetic and reactor models are developed and the unknown parameters involved are identified from experimental measurements. A set of operating variables that maximize the yield of key products then determined using the validated reactor model. The second part of the work is devoted to the production of acrolein from glycerol. This part consists of two steps: a glycerol dehydration step and a catalyst regeneration step. A two-dimensional heterogeneous model is developed. In the catalyst regeneration step, a kinetic model enabling the identification of the concentration and initial compositions of the coke and the prediction of its combustion process is developed and identified using experimental measurements. The optimization of the operating conditions of the regeneration step is then carried out. In the dehydration step, a kinetic model that allows the simultaneous simulation of glycerol dehydration, coke formation and catalyst activity variation is developed and identified by means of experimental measurements
Kadi, Mohamed El Amine. "Contribution à l'étude de l'influence des biocarburants et de leurs propriétés sur le fonctionnement des moteurs à combustion interne." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0207.
Global warming, mainly due to greenhouse gases, and the increasing of global demand for fossil fuels and their rapid depletion, represent strong environmental and economic challenges, which have prompted the global community to turn to alternative and renewable energy. This thesis falls within this perspective of developing renewable energies. The research work can be summed up in two main areas,where the first includes the development of the process of continuous biodiesel production with different raw materials through two reactions (transesterification and esterification). This axis consists of a simulation under ANSYS Fluent of the flow of fluids inside a chaotic mixer, a synthesis and purification of biodiesel, a kinetic study of the biodiesel production system, followed by an investigation on the effects of operating conditions on biodiesel’s yield and properties. The results obtained showed the effectiveness of this process in intensifying the continuous production of biodiesel. The second axis was devoted to the study of the effect of the physicochemical properties of biodiesels on the internal combustion engine operation. In this part, several biodiesels having a wide range of physicochemical characteristics were used in a direct injection (DI) and naturally aspirated diesel engine, with a rated electric power of 30.4 kW at 1500 rpm. Engine performance (specific consumption, efficiency) and pollutant emissions (unburnt hydrocarbons, NOx, CO2, CO, PM) were studied for the various biodiesels, used alone or as a mixture. The results showed a small deviation between the various biodiesels tested in the engine with the exception of HC and particulate emissions
Jiang, Wenbiao. "Simulation du bullage dans un photobioréacteur." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC086/document.
The working principle of a typical photobioreactor is to inject gas bubbles into the culture medium, providing CO2 to the cells and also stirring the liquid. Subsequently, the cells convert inorganic carbon into organic carbon through photosynthesis under illumination. Therefore, physical phenomena, e.g. bubbly flow, mass transfer, radiative transfer, and biological phenomena, e.g. photosynthesis, cell growth and death, coexist in a photobioreactor. More importantly, all the basic phenomena are not completely independent to each other. For example, bubble volume and bubble shape can influence gas-liquid mass transfer according to Young-Laplace equation and Henry's law. Moreover, some recent research revealed that bubble behaviors also directly affect the biological process. In view of the important impact of bubble behaviors on productivity of a phototbioreactor, the bubbly flow was investigated in this thesis by both experimental and numerical methods.In the experimental study, we first manufactured a new photobioreactor in order to study the bubbles and other phenomena. Subsequently, the bubbles were captured by high speed camera by virtue of a shadowgraphy technique and bubble behaviors were obtained by processing and analyzing the images. From the experimental results, we found that both averaged bubble volume and bubbling frequency increased with gas flow rate. Furthermore, we also discovered that the distribution of bubble volume was almost monodisperse at low flow rate, and it became more and more polydisperse with increasing flow rate. Regarding bubble shape evolution, we used two shape factors, viz. aspect ration and circularity, to quantitatively study it. We found that both shape factors dropped rapidly during bubble rising (within the limit of the field of view of our video camera), which implied that bubbles were flattened in the course of rising. Nonetheless, bubbles became more vertically elongated at higher flow rate, partially due to the more frequent bubble coalescence at higher flow rate.In the numerical study, we adopted VOF method and OpenFOAM, an open source CFD library, as our numerical tool to represent bubbly flow. First of all, the robustness of OpenFOAM in simulating two-phase flow was validated by literature survey. Subsequently, 2D simulations were carried out for seeking the appropriate and not very time-consuming numerical parameters, i.e. maximum Courant number and mesh size. We found that mesh size should somehow be smaller than the nozzle diameter to have meaningful results. On the other hand, maximum Courant number had no particular importance in the simulations (as long as between 0 and 1). Furthermore, 3D simulations were in good agreement with the experiments in terms of bubble volume and bubble shape evolution. However, 3D simulations were not able to represent the polydispersity of bubble volume due to the limited computing power. In addition, several hydrodynamic characteristics were also explored by the proposed numerical tool, which gave reasonable results.To conclude, bubble behaviors were successfully captured by experimental methods and represented by numerical methods in this thesis, which will help us go further in understanding the complicated physical-biological phenomena of a photobioreactor
Michau, Alexandre. "Dépôts chimiques en phase vapeur de revêtements à base de chrome sur surfaces complexes pour environnements extrêmes : expérimental et simulation." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0088/document.
Nuclear fuel cladding tubes resistance against high temperature oxidation during accident conditions is crucial because it means protecting the first containment barrier. This can be done by coating the inner wall of the cladding tube with CVD processes, which are most likely to do so. More specifically, we used DLI-MOCVD to grow chromium based (Cr(S), metallic crystalline chromium) and chromium carbides based (amorphous chromium carbides CrxCy, recycled CrxCy, silicon doped CrxSizCy) coatings, known for their good oxidation resistance. The coating process was optimized using numerical modelling to improve coatings performance. A reaction kinetics model of the deposition process of amorphous CrxCy coatings was adjusted and validated after the identification of the chemical mechanism. It was also shown that the liquid solution containing organometallic precursor (bis(arene)chromium) and solvent (toluene) could be directly recycled, thereby increasing the industrialization potential of such process. Physical, chemical and structural properties of coatings deposited with this process were characterized. A study of the coatings mechanical properties has also been undertaken. It shows that compared to related coatings grown with other processes, those deposited by DLI-MOCVD exhibit a particularly high hardness (up to 30 GPa), compressive residual stresses, good adhesion with the substrate and finally a different abrasive wear resistance depending on the temperature. The assessment of their oxidation resistance at 1200 °C revealed excellent performances of amorphous chromium carbides coatings, which can delay catastrophic oxidation up to two hours with only a 10 µm thickness. All the other coatings only increase the thermal resistance of zircaloy substrates
Aslan, Lina. "Dégradation atmosphérique de composés organiques multifonctionnels : les hydroxycétones et les aldéhydes insaturés." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10120/document.
This work was carried out with the objective of providing relevant information on the atmospheric fate of two families of multifunctional oxygenated volatile organic compounds (OVOCs), hydroxyketones and unsaturated aldehydes, to complement atmospheric models for air quality forecasts and for the drafting of regulations. The reactivity of the selected compounds was carried out in a flexible atmospheric simulation chamber equipped with various analytical techniques. The present work provides the first kinetic and mechanistic study of 4-hydroxy-4-methyl-2-pentanone (4H4M2P) photolysis and the first determination of the relative rate coefficient for the reaction of Cl atoms with 4H4M2P. The photolysis frequencies of 4-hydroxy-3-hexanone (4H3H) and 5-hydroxy-2-pentanone (5H2P) were also determined. These measurements enable estimating the atmospheric lifetimes of the three compounds by photolysis which ranged from 7 to 28 days. The main photolysis products of 4H4M2P were acetone (121±4)% and formaldehyde (20±1)%. These results allowed us to propose a mechanistic scheme for photolysis including a Norrish II intramolecular rearrangement process. In a second part, the preliminary study of photolysis kinetics of two unsaturated aldehydes, trans-2-hexenal (T2H) and trans-2-pentenal (T2P) was carried out. The estimated rate constant for photolysis of T2H ((1.2±0.6)´10-3 h-1) indicates that the photodissociation of T2H is negligible in the atmosphere. All the data obtained show that the photolytic reactivity of OVOCs is strongly linked to their structure
Codaccioni, Marc. "Évaluation de l’exposition fœtale aux substances chimiques grâce à la modélisation pharmacocinétique basée sur la physiologie (PBPK) et son application aux données d’imprégnation des populations." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2020. http://www.theses.fr/2020IAVF0019.
Numerous biomonitoring studies have shown the exposure of pregnant women to synthetic substances. In parallel, several epidemiological studies have highlighted associations between maternal blood concentrations measured during pregnancy or cord blood concentrations measured at birth and adverse effects in the offspring at birth or later in life. However, this type of measurements does not guarantee being representative of in utero exposures throughout pregnancy. Furthermore, it is not possible to measure longitudinally fetal concentrations due to obvious ethical reasons. Pregnancy physiologically-based pharmacokinetic (pPBPK) models allow the simulation of xenobiotic internal exposures in different maternal and fetal organs during gestation. Therefore, they offer an opportunity to better estimate the relationship between the dose and the risk of a toxic effect by considering tissue dosimetry. Although pPBPK models often incorporate physiological changes associated with pregnancy, some processes are still poorly known such as placental transfer (PT). The aim of the thesis is to improve the integration of PT in pPBPK modelling in order to predict fetal internal exposures from biomonitoring data.First, a scientific literature review of the published pPBPK models was conducted with a focus on the various model structures used to describe PT. It allowed the identification of 12 structures among 50 original models which corresponded to 4 types of kinetic profiles according to the number of transfer constants. Animal in vivo data were identified as the main source to support their parameterization although they cannot be directly extrapolated to humans and imply the killing of numerous animals. From this basis, we developed a pPBPK model which integrated four transfer models calibrated using non-animal methods so as to assess their performance to predict the fetal dosimetry on a set of ten substances. Our results show that the performance varied among models and substances, preventing the identification of a reference predictive model. Monte-Carlo simulations showed that one of the transfer models differed from the others in terms of fetal exposure variation across trimesters. Finally, a global sensitivity analysis shed light on a great extent of influence of the transfer constants as well as the metabolic clearance and fraction unbound, to a lesser extent, on simulated fetal exposure. The last part of the thesis consisted in applying the developed pPBPK model to estimate the internal fetal concentrations of two PCB and two PBDE substances from observed maternal plasma concentrations taken from the French ELFE cohort. To that end, we selected a specific PT model for each compound based on the prediction of fetal to maternal concentrations ratio at term. The ranking of chemicals based on the simulated exposure indicators varied between mother and fetus at term, as between the first and the other two trimesters in fetal plasma.In conclusion, this work highlights the potential of pPBPK modelling in the prenatal exposures assessment. It demonstrates the ability of a model to simulate adequate internal exposure indicators from a mechanistic and temporal points of view, notably from biomonitoring data. Furthermore, in light of strong ethical and regulatory constraints, this work indicates the role of alternative methods in the parameterization of key processes of the internal fetal dose such as the transplacental passage. This work could be used for the assessment of the prenatal exposome as well as in the developmental toxicity risk assessment of a substance