Rozprawy doktorskie na temat „Combustion hétérogène”
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Glorian, Julien. "Cinétique hétérogène pour la combustion de l’aluminium". Palaiseau, École nationale supérieure de techniques avancées, 2015. http://www.theses.fr/2014ESTA0014.
Pełny tekst źródłaThe aim of this study is to evaluate the importance of the surface chemistry involved in aluminum particle combustion. During the burning, aluminum particles add more energy to the system and significantly increase the specific impulse of solid rocket motors. This work provides a surface chemistry section to the simulation of single particle combustion. Multi-scale modeling is employed for the building of a detailed heterogeneous mechanism solving the chemistry on an aluminum surface. Quantum chemistry calculations are performed in order to establish a valuable thermodynamic and kinetic database for the building of the surface mechanism. Different assumptions are made to build the surface mechanism. Preliminary tendencies from zero dimensional calculation are satisfying and consistent with some literature observations. A surface kinetic solver has been added to a CFD code (CPS) that enables the simulation of single particle combustion. The numerical results are directly compared with experimental results from the literature. Estimated burning times and alumina residue show a decent agreement with experimental measurements from the literature. The atmosphere composition and the decreasing size of the particles make the surface chemistry more important
Malheiro, Salvador. "Etude expérimentale de la combustion d'un mélange méthane-air hétérogène globalement pauvre". Poitiers, 2002. http://www.theses.fr/2002POIT2253.
Pełny tekst źródłaDégé, Philippe. "Elimination de composés organiques volatils (COV) ; oxydation catalytique de l'o-xylène sur catalyseurs palladium et platine/zéolithes". Poitiers, 1999. http://www.theses.fr/1999POIT2298.
Pełny tekst źródłaMichel, Jean-Baptiste. "Modélisation de la combustion turbulente d'un mélange hétérogène en vue de l'application à la simulation des moteurs diesel". Châtenay-Malabry, Ecole centrale de Paris, 2008. http://www.theses.fr/2008ECAP1102.
Pełny tekst źródłaNowadays, due to more and more stringent regulations, internal combustion engines have to become more efficient and cleaner. For this purpose, three dimensional numerical simulations of the internal flows and specifically RANS simulations are frequently used by engineer during the engine conception. The aim of this work is the development of a turbulent combustion model dedicated to RANS simulations which should be able to represent auto-ignition as well as diffusion flames in physical conditions corresponding to Diesel engines. The fir~ part of this work aims at showing that laminar diffusion flames can be approximated by flamelets in which the chemical terms are extracte from a look-up table based on perfectly stirred reactors calculations. These flamelets can be calculated very fast and are then used to generate a turbulent look-up table, leading to the ADF-PCM model (Approximated Diffusion Fame Presumed Conditional Moment). This model is first validated in terms of auto-ignition delays predictions by simulating the hydrogen/air auto-ignition experiments developed at Cambridge University. Furthermore, an improved model which accounts for variable scalar dissipation rate is introduced. Then, the experiment of Cabra et al. Is used to quantify the ability of ADF-PCM to predict the lift-off height and the chemical composition of a methane/air lifted jet flame. The next part of this work concerns the prediction of the NO concentration. An approach based on characteristic times is retained and validated on the Cabra experiment simulation. To conclude this work, the application of ADF-PCM to large eddy simulations and to engine simulations is investigated
Net-David-Buytaert, Sopheak. "Etude de la réactivité hétérogène des composés organiques issus de la combustion de la biomasse". Aix-Marseille 1, 2010. http://theses.univ-amu.fr.lama.univ-amu.fr/2010AIX11034.pdf.
Pełny tekst źródłaBiomass combustion is one of the major sources of fine organic materials (<2. 5μm), which contribution has been estimated at more than 70% of the total organic fraction of aerosols and more than 50% of the mass PM2. 5 in urban areas. The transformation of this ultrafine particulate matter and its impact on climate, environment and health, yet remains an intriguing question. Moreover, the heterogeneous interactions between the gas-phase oxidants and aerosol particles in the atmosphere are not completely resolved. One of the primary goals of this thesis was to develop new knowledge towards chemical and photochemical heterogeneous chemistry of the organic compounds produced from wood combustion processes. To this end, the heterogeneous reactions between gaseous ozone and 12 of the most representative wood combustion products adsorbed on the silica particles were carried out at various experimental conditions of atmospheric relevance. The results obtained in this work show the importance of heterogeneous reactivities at the interface gas/particles. This type of reactions gives secondary products with a range of physico-chemical properties, i. E. Variable volatiliy, polarity and molecular masses (sometimes even oligomers). Such secondary products may interact with the gas, aqueous and solid phase in the atmosphere. In this thesis, the kinetic constants of chemical and photochemical reactions were determined as well. The reaction products were identified and the major products were confirmed and quantified by their corresponding standards
Artizzu, Paola. "Combustion catalytique du méthane à haute température : application dans les turbines à gaz". Lyon 1, 1996. http://www.theses.fr/1996LYO10261.
Pełny tekst źródłaAkil, Joudia. "Purification catalytique du CO₂ issu de l'oxycombustion". Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0471/document.
Pełny tekst źródłaGlobal warming, mainly due to high CO₂ emissions, reference greenhouse gas, motivates researchers to find solutions to combat this phenomenon. The techniques of capturing and storing or reuse of CO₂ are revelant solutions, but which require a CO₂ as pure as possible. Among these techniques, oxyfuel combustion seems promising enough to produce CO₂ in high concentration. However, depending on the nature of the fuel and the oxygen purity, some pollutants may appear such as CO and NOx. To carry out this purification, catalysis is an effective means for simultaneously converting NO and CO respectively into N₂ and CO₂. The objective of this study is to develop active catalysts for NOx reduction in N₂ by CO, in oxidizing conditions and presence of water. Two types of catalysts were chosen : supported noble metals (Pd, Pt, Rh) and transition metal oxides (Co, Cu, Al). The results obtained show that the Pt-based catalysts were more efficient and that their catalytic activity increases for the samples supported on a neutral support (SiO₂) or reducible (TiO₂) whether in the presence or absence of water. The mixed oxides of transition metals, obtained by hydrotalcite, show that the nature of the bivalent cation plays an important role. Co-Cu mixed oxides showed better activity than materials composed of only one of these two elements. However, the addition of water to the reaction flow led to a decrease in activity of the Cu-containing catalysts
Bonne, Magali. "Optimisation de la synthèse de matériaux poreux de haute surface, composés d'oxydes simples (SiO2, TiO2, Al2O3) et d'oxydes mixtes (perovskites), pour des applications en catalyse hétérogène". Poitiers, 2010. http://theses.edel.univ-poitiers.fr/theses/2010/Bonne-Magali/2010-Bonne-Magali-These.pdf.
Pełny tekst źródłaFirst of all the study of the synthesis of mixed oxides of ABO, perovskite in the pores of a silica host is studied. A novel method of autoignition developed within the PhD has yielded mixed oxide nanoparticles of small size (<4 nm) homogeneously dispersed in the pores of the support while sizes of the order of 15-30 nm for this type of mixed oxide are generally observed. The mobility of oxygen in these materials is much higher than that measured for bulk perovskites. In second part, the synthesis, structural and textural properties, and the activity of SiO2-TiO2 nanocomposites are presented. Anatase nanocrystals of 4 nm or less, accessible in the pores of a mesoporous support are obtained. High amounts of titania were deposited without clogging the pores of the support or alter the physical properties of the final composite. These nanoparticles exhibit high oxygen mobility. Reactivity tests showed that control of particle size allowed to adjust the metal – support interaction (effect SMSI) where the noble metal was deposited on its surface. The last part of the PhD was on the synthesis of alumina by different routes of mesostructuration. The interest of these procedures of obtaining solids with high surface area and large pores has been shown. Preliminary results also showed the flexibility of these synthetic routes for the functionalization of the surface of alumina by incorporation of a noble metal of transition metal during synthesis
Bernigaud, Pierre. "Modélisation de la combustion des matériaux énergétiques nouvelle génération". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAE017.
Pełny tekst źródłaUsed in civil and military rocket engines, composite propellants are characterized by a heterogeneous structure at the microscopic level. They consist mainly of oxidizer particles embedded in a polymer matrix known as the binder. The binder maintains the structural integrity of the propellant, and produces via its pyrolysis gases whose combustion is responsible for most of the heat release within the flame. The combustion products of the oxdizer particles oxidize the fuel generated by the binder.Ammonium perchlorate (AP) is a widely used oxidizing agent in composite propellants, mainly in association with a polymer binder such as hydroxytelechelic polybutadiene (HTPB). Next-generation propellants could include nitramines in their composition, such as hexogen (RDX), as a partial replacement for AP for certain specific purposes. In particular, reducing the amount of AP contained in the propellant can limit the formation of a visible trail at the engine exhaust, reducing the vehicle's signature.In this thesis, we propose to revisit the studies carried out on the combustion of conventional AP/HTPB propellants, and to characterize the effect of RDX inclusion in their composition.To this end, the first part of the thesis is dedicated to the development of combustion models for the ingredients under consideration: AP, homogenized AP/HTPB blend, and RDX.A chemical kinetics mechanism is assembled, capable of representing the chemical processes characteristic of the combustion of all these energetic materials. For each ingredient, a condensed-phase decomposition model is also formulated, to be associated with the kinetic mechanism. One-dimensional simulations are then carried out using a coupled flame/solid approach, in order to validate the whole on available experimental data.Due to their heterogeneous structure, the study of composite propellant combustion requires the use of multidimensional numerical methods. A second part of the thesis is therefore dedicated to the development and validation of a 2D calculation code, enabling the simulation of the combustion of an oxidizer particle surrounded by a layer of binder, in an axisymmetric configuration.In a final section, the combustion models and the computational code are used in conjunction to study the effect of RDX inclusion in a conventional AP/HTPB propellant. For the first time, the flame structure produced by such AP/HTPB/RDX propellant is obtained and characterized. The effect of pressure and RDX particle size on propellant regression is investigated, demonstrating the existence of different combustion regimes. Recommendations are made for optimizing the performance of this type of composition
Yagoubi, Mouadh. "Optimisation évolutionnaire multi-objectif parallèle : application à la combustion Diesel". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00734108.
Pełny tekst źródłaTéphany, Hervé. "Modèles expérimentaux de combustion sur milieux hétérogènes aléatoires". Poitiers, 1997. http://www.theses.fr/1997POIT2309.
Pełny tekst źródłaPopp, Patrick. "Simulation numérique des réactions homogènes/hétérogènes, des transferts de chaleur, et de la formation de polluants pendant l'intéraction flamme-paroi". Toulouse, INPT, 1996. http://www.theses.fr/1996INPT035H.
Pełny tekst źródłaGrégoire, Yann. "Etude expérimentale et numérique de la dispersion explosive et de la combustion de particules métalliques". Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2009. http://www.theses.fr/2009ESMA0018.
Pełny tekst źródłaThe explosive dispersion of particles and their inflammation in air along with the blast wave effects were investigated experimentally and numerically. The experimental configuration consisted in studying the free-field explosion of spherical charges made of a central booster of solid explosive surrounded by a loose-packed density shell of inert (glass spheres) or reactive (atomized and flaked aluminium) particles. The high speed cinematography of the explosions coupled with image processing by a "Background Oriented Schlieren" method, and the pressure records by piezoelectric gauges permit to plot the x-t diagrams of the explosions. A technique has been developed to capture samples of dispersed particles and to make their post-analysis. The experimental results are confronted with numerical simulations performed with LCD’s reactive multiphase flows code EFAE. The boundary of the dispersed cloud is not uniform but has a spiky shape with dendrites due to the formation of particle agglomerates of several millimetres. After 1m of propagation, some of those agglomerates overcome the leading shock front due to a ballistic effect. Glass particles are disintegrated by the shock. They have a mitigating effect, making the shock propagation slower and decreasing its amplitude. The effect of aluminium particles depends on their size: with the finer ones, after an initial slowdown phase, a re-acceleration of the leading shock and an increase of the pressure impulse are observed. With coarser particles, the shock is weakened but particle combustion raises the pressure level behind the shock front and slightly increases its impulse. An analysis of the collected agglomerates reveals that, in all cases, the combustion of aluminium particles is incomplete. Numerical simulations are in reasonable agreement with experimental results in the farfield domain
Pinto, Teixeira de Lemos Luis Eugénio. "Contribution à l'étude de la combustion, en chambre sphérique, des mélanges hétérogènes particules solides-gaz : cas des mélanges amidon-air". Poitiers, 1989. http://www.theses.fr/1989POIT2316.
Pełny tekst źródłaMacé, Olivier. "Etude des champs de températures dans des écoulements hétérogènes : applications aux flammes de charbon pulverisé et aux lits fluidisés circulants". Rouen, 1989. http://www.theses.fr/1989ROUES032.
Pełny tekst źródłaPeigney, Benjamin-Edouard. "Contribution à l'analyse de problèmes multi-échelles : application à des processus de diffusion et de combustion". Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC096.
Pełny tekst źródłaThe results established in this thesis deal with some multi-scale problems for which we design specially taylored techniques in order to tackle a specific physical problem, in which the multi-scale aspect plays a crucial role. We also try to justify, as rigorously as possible, the different methods we propose. The first considered multi-scale problem deals with the heat equation inside a cracked medium. In particular, following a homogeneization approach, we show that the crack effects can be modeled by a volume source term in the homogenized heat equation. The second multi-scale problem is related to the modeling of fusion plasma, in the Inertial Confinement Fusion (ICF) context. We derive an accurate kinetic modeling of the combustion process of hydrogen. The multi-scale aspect of the problem comes from the coexistence of two energy scales that are required to describe the different ion populations. A multiscale analysis of the Fokker-Planck operator leads to an original and efficient strategy to solve the kinetic modeling of ICF target combustion
Hamidouche, Ziad. "Modeling and numerical simulation of coupled reactive fluidized beds in a Chemical Looping Combustion system". Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/17921/1/hamidouche.pdf.
Pełny tekst źródłaBriand, Arnaud. "Contribution à l'étude de la structure des détonations dans les milieux biphasiques". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2009. http://tel.archives-ouvertes.fr/tel-00460888.
Pełny tekst źródłaFaccinetto, Alessandro. "High sensitivity detection of Polycyclic Aromatic Hydrocarbons desorbed from soot particles using Laser Desorption/Laser Ionisation/Time-Of-Flight Mass Spectrometry : an approach for studying the soot growth process in flames". Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10096/document.
Pełny tekst źródłaPolycyclic Aromatic Hydrocarbons (PAH) are important precursors of carbonaceous soot particles, thus influence the quantity and morphology of particulate emission of combustion processes. Furthermore the PAH adsorbed on the surface of the soot particles contribute to the carcinogenicity of the particles, so there is scientific interest in characterising and quantifying those species to provide key information on the mechanism of soot formation and to understand their impact on environment and human health. An original setup based on the coupling of Laser Desorption, Laser Ionisation and Time-Of-Flight Mass Spectrometry techniques has been dedicated to the analysis of PAH desorbed from soot. Briefly, soot is sampled from flames using an extractive vacuum probe and deposed on porous filters. The samples are irradiated with a 532 nm laser beam to promote the desorption of neutral molecules. The ejecta are then ionised with a 266 nm laser beam, and the positive ions produced this way are mass analysed in a TOF-MS. The complete characterisation of the desorption and ionisation process has been the first goal of this work. The acquired expertise allowed investigations on different flames in which the PAH have been identified and studied at different level of their formation. Particularly, relevant differences in the mass spectra have been detected in the soot inception region. A new method based on the deposition of soot on different substrates is proposed in order to distinguish the PAH belonging to the gas-phase during the sampling from those adsorbed on soot particles, hence the role of the heterogeneous reactions between gaseous PAH and soot particles has been highlighted