Dissertations / Theses on the topic 'Oxygène et méthane liquides'
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Lechner, Valentin. "Experimental study of LOX/CH4 flames in rocket engines." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST040.
Using methane as a fuel in rocket engines would have many advantages but the combustion with pure oxygen at high pressure remains poorly understood. From a thermodynamic point of view, methane and oxygen share very similar critical point values, making it challenging to predict propellant mixing, flame anchoring, stability and structure. Moreover, when methane is injected in excess, aerosols can be produced, which can clog the lines, damage the turbine, and reduce the efficiency.Therefore, a thorough update of the knowledge of LOX/CH4 combustion is necessary. These challenges are tackled within the consortium composed of EM2C laboratory, ONERA, CNES, and ArianeGroup. Two test campaigns are carried out at the MASCOTTE facility from ONERA, aiming to study three central topics: the flame structure, wall heat transfers, and aerosol production. To this end, various experimental diagnostics are implemented simultaneously during high-pressure hot-fire tests.Various imaging diagnostics are implemented to analyze the flame structure and the dense liquid jets. Despite the acquisition difficulties encountered in these extreme conditions, the analyses reveal a complex flame structure. In the subcritical regime, atomization and evaporation mechanisms dominate. The flame is much more opened and longer than at higher pressures, where diffusive mixing mechanisms prevail. Characterizing flame anchoring remains a challenge. A water ice ring surrounding, and masking, the flame foot has been identified. Formation mechanisms are proposed, and a growth/destruction temporal cycle is highlighted. Its presence strongly affects flame visualizations, and may lead to misinterpretations of its topology.Laser-induced phosphorescence (LIP) is implemented for the first time at MASCOTTE. Various LIP methods exist, but they are not well suited to the MASCOTTE conditions: wide temperature range, thermal transients, and two-phase flow environment favoring laser absorption/diffusion. Therefore, a specific method, the Full Spectrum Fitting method (FSF method), has been developed. It exploits the spectral dependence on temperature, enabling instantaneous measurements from 100 to 900 K with a precision of 17 K, with no dependence on the laser excitation energy. A detailed data analysis highlights the predominant wall heat transfer modes, studies the influence of the operating points, and compares the experimental data with a wall heat transfer model, which is particularly well suited for deducing the convective properties of the flow.Three diagnostics are used to characterize aerosols. An intrusive probe samples particles and burnt gases downstream of the flame. The particles are sampled on TEM grids and analyzed by Transmission Electron Microscopy. Detailed images of the aerosol morphology reveal that the particles are soot. Combustion products are analyzed by gas chromatography. This makes it possible to identify soot precursor molecules such as benzene and acetylene. Soot are quantified temporally by laser extinction. A dedicated post-processing method is developed and various hypotheses are discussed to explain the spatial variations of the soot production downstream of the flame
De, Stefani Vania. "Etude de la solubilité de solides à pression modérée, liée au domaine de la cryogénie : mesures et modélisation." Paris, ENMP, 2003. http://www.theses.fr/2003ENMP1125.
Jacquemin, Johan. "Etude thermodynamique de liquides ioniques non aqueux." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00693921.
Gispert, Camille. "Conception et développement d’un microcapteur stérilisable pour la mesure de traces et d’ultratraces d’oxygène dissous." Toulouse 3, 2010. http://www.theses.fr/2010TOU30179.
The intensification of industrial processes and the development of new compounds in biotechnologies and pharmacy need to use new parameters and increase the performance of current sensors. The on line dissolved oxygen monitoring is essential in many industrial processes. Sensors are placed in harsh environments. The design of a sterilizable dissolved oxygen micro sensor requires news electrolytes materials and a new MEMS design. This multidisciplinary approach has permit to get prototypes running on a temperature wide range
Xia, Meng. "Etudes expérimentales et numériques de la pyrolyse et l’oxydation du charbon pulvérisé dans les flammes étirées de méthane/oxygène/azote." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLC060/document.
In the present work, a laboratory-scale laminar strained configuration is used to investigate the characteristics of pulverized coal devolatilization and oxidation in a mixture of CH4/O2/N2 reactive flow both in conventional air conditions and in oxygen-enriched combustion conditions. Two optical diagnostics, Flame Emission Spectroscopy and measurement of spontaneous emission, are employed for the characterization of flame structure. The spatial concentration evolution of three excited radicals, OH*, CH*and C*2 , are measured and analyzed.1-D simulations using detailed gas-phase kinetics including OH*, CH*, and C*2 sub-mechanisms and coal combustion submodels are performed and compared with experimental data. Qualitative comparison with experiments showed that the current numerical configuration was suitable for the prediction of OH*, CH* and C*2 emission. The predicted results differed with changes to the coal sub-models and kinetic parameters. The devolatilization model and volatile matters seem to play more important roles
APPORA, GNEKINDY IRMA. "Etude experimentale du fractionnement isotopique du carbone et de l'oxygene dans les systemes co 2-carbonates liquides : application au contexte carbonatitique." Paris 7, 1998. http://www.theses.fr/1998PA077170.
De, Sant'ana Hosibero Batista. "Mesure et modélisation des propriétés volumétriques et de la viscosité d'hydrocarbures liquides et de gaz à haute pression." Clermont-Ferrand 2, 2000. http://www.theses.fr/2000CLF2A002.
Humbert, Franck. "Solubilité de l'azote dans les silicates liquides influence de la fugacité d'oxygène et de la composition." Nancy 1, 1998. http://www.theses.fr/1998NAN10250.
Jorat, Luc. "Propriétés électriques et diélectriques des liquides organiques refroidis jusqu'à leur température de transition vitreuse." Saint-Etienne, 1987. http://www.theses.fr/1987STET4015.
Gontharet, Swanne. "Les suintements hydrothermaux froids et leur impact sur l'écosystème benthique." Paris 6, 2006. http://www.theses.fr/2006PA066364.
Gomez, ruiz Braulio. "Prédiction de la dégradation de la vitamine C en conditions de traitement thermique : étude en milieu modèle liquide entre 50 et 90 °C." Thesis, Paris, AgroParisTech, 2016. http://www.theses.fr/2016AGPT0002.
Vitamin C is often used as an indicator of labile nutrient retention in processed products because of its sensitivity to processing and conservation conditions. Understanding the behavior of vitamin C in complex matrices transformation processes is difficult, due to the importance of several parameters that affect its degradation (temperature, pH, exposure to light, the presence of oxygen and metal catalysts). Studying reactivity in a simple environment of known composition, under controlled conditions, is necessary for a better understanding of the mechanisms and for modelling in order to predict the impact of process parameters on the residual vitamin content. The present research aims at contributing to this goal for temperatures of a transformation process (50 - 90 °C), while decoupling the effect of concentration of dissolved oxygen (between 0 and 30%). To achieve this, a simple and rapid method of quantification of ascorbic acid (AA) and dehydroascorbic (DHAA) was first developed and validated. It allowed obtaining a reaction database for different couples of temperature and oxygen concentration, in a buffered and perfectly stirred medium. Two kinetic models were developed: a simple reaction model to predict the degradation of AA, and a more complex model taking into consideration both oxidative and thermal degradation pathways on the degradation kinetics of AA and DHAA. Both models show a good fit to experimental data and a strong correlation between k1 reaction rate of the oxidation reaction and the stoichiometric coefficient β relative to oxygen. A linear relationship between β and temperature was also proposed
Nasri, Ridha. "Conception et réalisation d'un adaptateur haute impédance programmable : epplication à la caractérisation de liquides magnétiques." Saint-Etienne, 1994. http://www.theses.fr/1994STET4014.
André, Laura. "Étude de verrous scientifiques et technologiques pour la compréhension et l’optimisation du procédé de méthanisation voie sèche discontinu de sous-produits d’origine agricole." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2279/document.
The dry anaerobic digestion (AD) process is an opportunity to develop the methanization in France. Agricultural waste is abundant in France. However, many scientific and technical locks are complex and must be solved to develop the dry anaerobic digestion process in France. In this work, the chemical oxygen demand (COD) method was adapted for solid waste no implying waste dilution or a high quantity of reagent. This COD method was available to monitor and manage the dry AD process. The study of acidification phase, a major lock of the dry AD process, showed that the storage condition and the origin of inoculum influence the capacity to manage this phase. The inoculum is a major parameter of the dry AD process. But, the inoculum is few studied.On another part of experiments concerned the water transfers studied on agricultural waste with a tracing method. The modeling of the elution curves to determine the diffusion and the convective transfers was made with a model with two Mobile-Immobile regions. The evolution of water transfers was studied during the AD cycle showing a decrease about the permeability of solid phase after the second peak of methane production. Thus, the inoculum passes on the board of solid phase. Two recirculations were tested allowing to obtain an improvement the methane production about 20 % after the AD cycle. The water transfers of these two recirculations modalities were identical after the AD cycle. The improvement of methane production occurred after the second peak of the methane production. Water and mass balances made showing that 36 % of organic matter was find in the digestat. Consequently, the process was not optimized. Others experiments modulating the immerged part of solid phase showed an improvement of the methane production about 13 % with the increasing of immerged part. This methane improvement was induced by the development of Methanosarcinaceae. The methanogens dynamics were studied in the liquid and solid phases during the AD process showing (i) a population transfer between the liquid phase to the solid phase, (ii) a hierarchy of hydrogenotrophs methanogens in the media, and (iii) a strong development of acetotrophs methanogens in the solid phase. In the final part, the electrical tomography was implemented in a dry AD batch at full scale (30 m3). This method was adapted to localize the liquid phase, the zones of methane potential and the degraded zones according to filling and the emptying protocols. This method can detect the “dead” zones of process in dry AD process.Though, experiments carried out at different scales and with different problematic and several methodologies were adapted to understand the dry AD process. Moreover, the optimization of dry AD process was finding to increase the methane production
Kennel, Claire. "Mesures expérimentales et modélisation de la formation des oxydes d'azote dans les flammes d'hydrocarbures dopées à l'amoniac." Rouen, 1989. http://www.theses.fr/1989ROUES001.
Joly, Jean-Pierre. "Synthèse d'éthers-couronnes osidiques et leur fixation sur support chromatographique en vue de la séparation d'énantiomères." Nancy 1, 1989. http://www.theses.fr/1989NAN10019.