Dissertationen zum Thema „Plasma non thermique (PNT)“
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Korichi, Noussaiba. „Epuration d'effluents pharmaceutiques par plasmas non thermiques couplés à des procédés catalytiques“. Electronic Thesis or Diss., Orléans, 2023. http://www.theses.fr/2023ORLE1057.
Der volle Inhalt der QuelleThe work of this PhD thesis aims at studying a hybrid process for the treatment of organic molecules in water. It consists of the Non Thermal Plasma (NTP) process coupled with heterogeneous catalysis (Fenton-like type). Paracetamol is used as the target molecule for this study. Two different configurations of Dielectric Barrier Discharge (DBD) plasma reactor were used: (i) a multi-needles-to-plane reactor in static mode; (ii) a coaxial tubular reactor with flow of the solution to be treated. In order to evaluate the synergy between the two processes (plasma and catalysis), the treatments were applied separately and then coupled. The synergistic effects of the coupled plasma-catalysis process were demonstrated in terms of degradation rate, energy yield, and also in terms of pollutant mineralization, corresponding to a decrease of the organic molecules load in the solution with the conversion of organic carbon into inorganic carbon. The first part of the work carried out with the multi-needles-to-plane reactor allowed to establish the effective role of the plasma-catalysis coupling in comparison with the plasma process alone. Indeed, in coupling, a mineralization of 54% was reached after the 60 minutes of treatment and the energy yield was increased by a factor of two, thus reducing the cost of treatment. The work carried out on the coaxial reactor allowed us to study the effect of many parameters on plasma-catalysis coupling efficiency such as the composition of the injected gas, the gas and liquid flow rate, the position of the catalyst in relation to the plasma discharge, etc. We were thus able to show the interest of working in an oxygen-rich gas on kinetics of degradation and mineralization as well as the role of applied electrical power on the oxidation mechanisms. As an example, it was possible to obtain a mineralization of 70 % after 90 minutes under air, whereas under O₂/N₂ (80/20 sccm), the mineralization reached 95 %. The stability of the catalyst was also studied in terms of mineralization after several reuses of the catalyst. We also demonstrated the role of the hydroxyl radical (·OH) on the treatment with the use of radical scavengers. Indeed, the presence of methanol, known as a scavenger of hydroxyl radicals, a decrease of the degradation of nearly 50% was obtained and no mineralization was observed
Delaux, Joakim. „Activation de biopolymères par plasma atmosphérique non thermique“. Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2310.
Der volle Inhalt der QuelleFrançois Jerome's team developed new processes for the pretreatment of lignocellulosic biomass. This fundamental work is based on the use of non-thermal atmospheric plasma for the deplolymerization of biopolymers (cellulose, inuline) selectively. The advantage of this physical pretreatment is the non-using of catalysis or solvent and so it's resolve the dilution problem or the purifying problem usually met. A low consummation of energy can be cited too. This pretreatment could be increase the reactivity of biopolymers (hydrolysis for example) and get a better yield than the chemical or enzymes processes.The goal of the thesis is to understand what are the good conditions to obtain a cellulose more reactive for the chemical reactions and what the mechanism for the plasma treatment are. What kind of species react with the surface of the polymers and how they enter in the bulk ? What is the role of the nature and constitution (crystallinity, different polymer, kind of link…) ? Then, a study on the reactivity of the plasma cellulose was performed and the focus was put on the yield of glucose after acid hydrolysis. Like this, we can see the influence of the physical pretreatment (plasma, milling or both) on the cellulose. At the end, a mechanism is proposed by using all the information recovered in particularly with the structural analysis
Baudin, François. „Catalyse de NOx assistée par plasma "non thermique"“. Paris 6, 2004. http://www.theses.fr/2004PA066416.
Der volle Inhalt der QuelleOuni, Fakhreddine. „Production d'hydrogène et valorisation des alcanes par plasma non thermique“. Orléans, 2006. http://www.theses.fr/2006ORLE2055.
Der volle Inhalt der QuelleRodrigues, Anthony. „Caractérisation des interactions entre un plasma non-thermique et des matériaux“. Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2288.
Der volle Inhalt der QuelleThe interactions between the active species generated by a non thermal plasma and various material surfaces have been studied in this work. In a first part, biopolymers coming from biomass have been the subject of our investigations as they offer a great reservoir for a platform molecule, glucose, from which valuable chemicals can be generated. More specifically, the effects of a dielectric barrier discharge plasma on the structure and depolymerization of inulin, cellulose and starch were evaluated. For that purpose, the electrical and chemical characteristics of the plasma discharge were varied and their effects on the biopolymers evaluated in order to understand the reaction mechanisms. Our results showed that a plasma pre-treatment increased considerably the final monomer yield (in glucose and fructose) compared to the untreated starting material (84 and 54 % yield in glucose from plasma treated starch and cellulose, instead of 65 and 1 % for the same untreated samples). This effect could be partly explained by the depolymerization of the amorphous areas of the polymers by and acid attack within the plasma discharge.In a second part, the study focused on the removal of VOCs by coupling non-thermal plasma and inorganic materials. For this purpose, we designed and implemented an innovative apparatus. It consists of a plasma-catalyst reactor with controlled atmosphere that allows the analysis of the catalyst surface by IR spectroscopy (DRIFT). The decomposition of four VOCs (isopropanol, acetone, ethanol and toluene) adsorbed on different metallic oxides (y-Al2O3, CeO2 and TiO2) placed within the discharge area have been studied in situ using this method. The first results have enlightened the decomposition pathways of the different VOCs
Bouchoul, Nassim. „Valorisation du dioxyde de carbone par couplage plasma non-thermique et catalyse“. Thesis, Poitiers, 2019. http://theses.univ-poitiers.fr/62720/2019-Bouchoul-Nassim-These.
Der volle Inhalt der QuelleThe two main greenhouse gases emitted by human activities are carbon dioxide and methane. Within the context of the current environmental crisis, it has become vital to find a method to valorise these gases. Therefore, this thesis has been conducted to be a part of this process: CO2 and CH4 valorisation. To this end, dry reforming of methane was carried out by coupling non-thermal plasma and catalysts. Metal-based catalysts, such as Ni/Al2O3, are usually used for plasma-catalyst. However, the results are often dissimilar, and even contradictory, as far as conversions and selectivities are concerned. In order to better understand the reasons behind this heterogeneity, the influence of the nature of the solid was studied. For this purpose, metal oxides, such as γ-Al2O3, α-Al2O3, MgO, CaO, La2O3, ZnO, CeO2, SiO2, BaO, TiO2, and a zeolite, were selected because of their respective physicochemical properties (permittivity, acidity, basicity, specific surface). These oxides were submitted to identical tests with identical operational conditions, e.g. a dielectric barrier discharge reactor (DBD), 8W power (800 Hz frequency, 13 and 16 kV tension), a total output of 40 mL.min-1 and a CH4/CO2=0,5 ratio.The study of the physical characteristics of catalysts highlighted the impact of the material’s permittivity or of the size of its grains on the discharge. A high dielectric constant hindered the reaction. When TiO2 (εr=2903) was found in the discharge, it led to a decline in CH4 and CO2 conversions, as they decreased from respectively 20 and 9% without catalyst, to 5 and 2% with TiO2. Furthermore, when grains were too large, there was less surface accessible to plasma, which led to a fall in the reagents’ conversions. Indeed, they dropped from respectively 30 and 15% for CH4 and CO2 for small-sized grains (250-355µm), to 24 and 11% for the largest grains (800-1000µm). In addition to this, the study of the catalysts’ chemical properties showed how basicity influenced the conversions of carbon dioxide. It seemed that when there was a great number of basic sites in a solid, CO2 adsorption was likely to be better. Furthermore, a more detailed study was carried out by coupling calcium oxide with non-thermal plasma. Indeed, the former does not only have a low permittivity, but also a high number of basic sites. Structural and textural modifications appeared after plasma. This was shown by examining the influence of the CH4/CO2 ratio and of the temperature on CaO. When there was a CH4/CO2 = 2 ratio, for a temperature of 300°C, the production of water (reverse water-gas shift reaction) tended to result in the formation of Ca(OH)2 and CaCO3.When water (0,1g.h-1) was added to the reaction mixture, CaO hydroxylation and Ca(OH)2 carbonatation were observed. Furthermore, hydrated calcium hydroxide (Ca(OH)2+ 18% H2O) carbonatation is more likely to occur under plasma. The analysis of gases at the outlet by a mass spectrometer revealed an oscillatory phenomenon associated with CO2 adsorption. A reaction pathway, during which CO2 and H2O adsorption and elimination occur successively, was therefore put forward. A low-energy plasma (4W) is likely to cause carbonatation, as the solid is originally composed of 0,9Ca(OH)2, 0,9 H2O, 0,1 CaCO3, and is made of 0,1Ca(OH)2, 0,9CaCO3 after plasma. Thus, applying a non-thermal plasma seems to encourage CO2 diffusion at the core of Ca(OH)2+ 18% H2O. Carbonatation is a method to store CO2 but it is a slow process, which is often hindered by CO2 diffusion. In this study, plasma was proved to be a highly interesting process, provided that its efficiency could be increased
Arabi, Khadija. „Traitement par plasma non thermique d'alcools et produits issus de la pyrolyse ou de la gazéification de la biomasse“. Phd thesis, Université d'Orléans, 2011. http://tel.archives-ouvertes.fr/tel-00705856.
Der volle Inhalt der QuelleYao, Yijun. „Exploration d’un équipement d'observation non intrusif pour la compréhension des processus de projection thermique“. Electronic Thesis or Diss., Bourgogne Franche-Comté, 2023. http://www.theses.fr/2023UBFCA025.
Der volle Inhalt der QuelleThe fourth industrial revolution ushered in a new technological era characterized by digitalization and intelligence. In this context, there is a growing tendency to combine traditional technologies with more modern information technologies. This approach is opening up a new avenue of interpretation for scientific research.In the context of this study, which is specific to thermal spraying, the work involved using a non-invasive display device to collect on-line images of a jet seeded with powder particles. Processing these images using a specially developed algorithm resulted in the extraction of relevant and reliable data on the construction processes of a spray coating.Indeed, thermal spraying, as a traditional technology in the field of surface treatments, is also a very promising technique in the field of additive manufacturing. The coatings produced by this method have excellent properties and are widely applied in a variety of sectors. It therefore seems important to change the paradigm by incorporating computer technologies.The experiments carried out enabled us to observe the phenomena/processes involved in the plasma spraying of alumina particles, and an algorithm was developed to extract the interesting data contained in the images observed (size distribution of the flying particles, growth pattern of the coating on the substrate, deposition efficiency, etc.). In this way, it was possible to study the particle velocity and flight angle distributions throughout the plasma spraying process.Subsequently, validation of the observation technique and the algorithm applied to plasma spraying made it possible to study the existing cold spraying process. In situ observation of copper particles was therefore carried out to identify the stacking process of cold-sprayed layers and to quantify the size and dispersion of the particles forming the deposit. The study also combined different characterization methods to understand the process of layer stacking during cold spraying
FRESNET, FRANCOIS. „Traitement par plasma non-thermique des effluents issus d'un moteur fonctionnant dans des conditions d'exces d'air“. Paris 11, 2001. http://www.theses.fr/2001PA112229.
Der volle Inhalt der QuelleNastase, Raluca-Andreea. „Préparation de nanocelluloses aux propriétés interfaciales innovantes fonctionnalisées par traitement plasma non thermique à pression atmosphérique“. Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4006/document.
Der volle Inhalt der QuelleAs an alternative to fossil source, cellulose is ideally placed to obtain sustainable and available materials. In order to respect the environmental constraints, the economic efficiency and to be less detrimental to human health, non-thermal plasma technology is proposed as a method for the nanocellulose functionalization and valorisation. This technology that requires no or few reagents, needs only an energy supply and a gas flow to lead to the modification of nanocellulose by generating highly reactive species at room temperature. The implementation of the reactions by plasma has been carried out in liquid media, using several aqueous solvents and gases (N₂, O₂, air, NHᴣ), their chemical nature allowing access to specific functionalizations such as oxidation, amination, etc. The high reactivity of plasma allows the activation of molecules without using polluting or expensive methods. Because of its efficiency, its ease of implementation and its low energy consumption, the modification of nanocellulose by non-thermal plasma at atmospheric pressure will open new ways to innovative chemical modification of biomass
Dolmaire, Alice. „Développement de barrières thermiques anti-CMAS et non mouillantes par projection thermique de suspensions“. Thesis, Limoges, 2020. http://www.theses.fr/2020LIMO0039.
Der volle Inhalt der QuelleThis PhD work is involved in the development of new technologies capable of withstanding harshenvironmental constraints demanded to the aeronautical industry on new turbojets. A new architecture of thermal barrier coating, exposed to temperatures higher than 1200°C and meant to protect highpressure turbine blades, is suggested in this work. This architecture is a bilayer coating comprising a columnar layer made of yttria-partially stabilised zirconia (YSZ) and a superficial dense layer containing gadolinium zirconate (GZ) and one non-oxide ceramic. It is produced by an emerging process called suspensions plasma spraying (SPS). This bilayer has to be resistant to atmospheric siliceous particles (CMAS) and has to exhibit thermomechanical properties compliant with the thermal barrier coating application. One part of the studies highlights the potential for a CMAS corrosion barrier from the composite coating GZ – SiC, due to the existence of an in situ reservoir of gadolinium oxyapatite and disilicate. Surface carbide is also likely limiting the spreading of the model CMAS glass tested. The coating displays a partially wetting behaviour up to 1300°C. This could result in a higher lifetime of the superficial coating during service. Bilayer coating YSZ – GZ/SiC shows similar properties to thermal aging and CMAS infiltration resistance. Characterisation in the plasma jet of the submicronic particles kinetic behaviour upon impact on diverse surfaces and the evaluation of plasma thermophysical properties on particles’ thermokinetic treatment refined current knowledges on coating columnar growth produced by SPS on intricate surfaces. A judicious choice of plasma conditions led to the production of a bilayer coating showing similar thermomechanical properties to current EB-PVD thermal barrier coatings used on high-pressure turbine blades
Gadonna, Katell. „Torche à plasma micro-onde à la pression atmosphérique : Transfert thermique“. Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00699619.
Der volle Inhalt der QuelleChollet, Alexis. „Étude expérimentale et théorique de la fragmentation de Composés Organiques Volatils pour des applications environnementales“. Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112029/document.
Der volle Inhalt der QuelleThis thesis is an experimental and theoretical study of organic compounds fragmentation. For this purpose, we had to built a new non-thermal plasma reactor and modify a statistical model used for nuclear fragmentation (Microcanonical Metropolis Monte Carlo or MMMC) to describe the fragmentation of CnHm types species. The non-thermal plasma is created by a nanosecond high-voltage (100 kV) pulse with a steep rise front (15-20 kV.ns-1). This pulse allows to have a large volume of diffuse plasma and to create important quantities of reactive species (radicals, metastables, etc.), which could react with organic molecules. In the case of propane fragmentation, the non-equilibrium discharge used allows to product as major by-products methane, ethane and propene. The energetic efficiency of the conversion by this discharge is twice more efficient than the one obtained with a dielectric barrier discharge or a pre-ionised discharge. The MMMC model describes, for a given energy, the accessible phase space for the system. All static (discrepancy, internal excitation, position, etc.) and dynamic (translation and rotation) degrees of freedom for every fragment of the initial molecule are taken into account. The physical properties (dissociation energies, geometry, vibrational frequencies, etc.) of each fragment are needed to perform calculations and are obtained by using an ab-initio code. Different computation methods (composite or DFT) and different levels of calculation (with or without hydrogen polarisation) have been compared to experimental values. We have shown that the hydrogen polarisation has an important influence on the properties. Probabilities of fragmentation paths are slightly identical between the two methods. The main differences are explained by the existence of a variation between the ground energy of some fragments. Comparison between theoretical and experimental results is indirect because the MMMC model only described the fragmentation phase. By-products will react between them and with their environment during and after the excitation phase. The complex kinetic evolution of the by-products must be taken into account. Moreover, the energetic distribution injected in the initial molecule by metastable states of nitrogen and electronic collisions must be determined. These two steps are require to obtain theoretical results, which could be compared to experimental ones. This study should be the following work after our study. Experimental results seem to suggest that the model overestimates the number of C-H bonds, that are broken. Probably, because the first step of the model, the construction of fragments, works only by breaking bonds in the initial molecule of propane and propene. Les fragments H2 and CH4 are not allowed, but their production in one reaction is possible (C3H6 and C2H4 are experimentally measured). Non-used energy by their production is reported to break CH bonds
Djakaou, Iya-Sou. „Elimination de solutés organiques polluants d'effluents liquides par plasma non thermique : comparaison des processus mis en jeu à l'interface liquide-plasma dans les procédés Glidarc et DBD“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00831334.
Der volle Inhalt der QuelleIya-Sou, Djakaou. „Elimination de solutés organiques polluants d'effluents liquides par plasma non thermique : comparaison des processus mis en jeu à l'interface liquide-plasma dans les procédés Glidarc et DBD“. Paris 6, 2012. http://www.theses.fr/2012PA066213.
Der volle Inhalt der QuelleThe role of oxidant species created in the gas phase has been investigated in two non-thermal plasma processes applied for the water treatment: Gliding Arc and falling film Dielectric Barrier Discharge (DBD) processes. Three different model organic pollutants have been treated in the two discharge reactors. The obtained results, from easier to more difficult to remove, are as follows: phenol>> Heptanol> pCBA> for the Glidarc reactor and 1-Heptanol >> Phenol> pCBA for DBD falling film reactor. The differences between the two reactors are not only due to the quality and quantity of active species generated in each case but also to the mass transfer at the gas-liquid interface. The removal mechanisms also differ depending on the characteristics of the pollutant treated. Phenol reacts strongly with °NO2 radicals produced by the dissociation of N2O4 in the liquid phase. For 1-Heptanol, the degradation is proceeded by desorption assisted by the gas phase reactions with the short-lived species. For this type of pollutant, the DBD reactor is the most competitive, partly due to the efficient mass transfer owing to the convective movements generated in the liquid by the discharge. In the case of pCBA, the removal rate is weak in the two processes because of the insufficient production of OH° radicals in the solution. Finally, a numerical simulation allowed us to validate the proposed elimination mechanisms
Tarkwa, Jean-Baptiste. „Elimination des polluants organiques des effluents industriels aqueux par plasma non-thermique de type glidarc et le procédé photo-Fenton : optimisation des procédés et mécanisme d’oxydation des polluants“. Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2020/document.
Der volle Inhalt der QuelleThis work focused on the application of two photochemical advanced oxidation processes (humid air gliding arc plasma and photo-Fenton) for the treatment of aqueous solutions of 4-Chlorophenol and the azo dye (Orange G). UV-vis spectroscopy and high performance liquid chromatography were used to follow pollutants degradation while the degree of mineralisation of their aqueous solution was estimated using TOC-meter (SHIMADZU). Ionic chromatography was performed to measure the concentration of inorganic ions released to the solution. The solid catalyst (laterite) was characterized by atomic absorption spectroscopy, N2 adsorption/desorption BET method, X-ray diffraction (XRD), Fourier transform infrared and RAMAN spectroscopies. The oxidation of 4-chlorophenol and Orange G by photo-Fenton process was devoted to the optimization of degradation and mineralization operating conditions. Thus, complete (100%) degradation of 0.2 mM 4-chlorophenol is reached at only 4 min of treatment under the established optimum conditions (pH =3, 0.1 mM Fe3+ and 6 mM H2O2) corresponding to the R = [H2O2]/ [Fe3+] of 60. In contrast, R = 20 with (0.1 mM Fe3+), is the optimum ratio allowing 81 % of mineralization, after 180 min of treatment. During Orange G degradation by Photo-Fenton process, the optimization was focused on the use apparent rate constants of degradation. Thus, it was established a ratio R = [H2O2] / [Fe3+] = 13.8; either 6 mM H2O2 and 0.435 mM Fe3+. Under these conditions, a complete degradation (100%) of the Orange G was obtained at 5 min and 93% TOC removal at 180 min of treatment. From the identified organic intermediates (aromatic and carboxylic acids) and leached inorganic ions products, we proposed a plausible mechanism for oxidation of each pollutant by hydroxyl radicals. The degradation of Orange G by gliding arc plasma aimed to improve the performance of glidarc by optimizing the operating conditions in order to reduce energy cost. Therefore, two catalysts (Fe3+ and laterite) were comparatively tested during the treatment of 0.1 mM Orange G aqueous solution. Under optimal conditions, degradation (decays and mineralization) of (17 and 6); (74 and 25); (100 and 57) and (100 and 82%) were recorded respectively using glidarc alone; glidarc/Fe3+(0.2 mM); glidarc/Fe3+(0.2 mM)/H2O2(4 mM) and glidarc/laterite (3 g L-1) systems after 60 min of treatment. Finally, the comparative analysis of the overall cost of each process under optimal operating conditions and for a required time of at least 90% of mineralization of 0.1 mM Orange G aqueous solution, gave the following cost classification : plasma/laterite
Bouamra, Kahina. „Physico-chimie d'une décharge électrique impulsionnelle dans un mélange air iso-octane : application au reformage par association plasma-catalyseur“. Paris 11, 2004. http://www.theses.fr/2004PA112320.
Der volle Inhalt der QuelleThis thesis deals with the hydrogen production (reforming), for use in a fuel-cell vehicle, from a hydrocarbon: iso-octane, using a non-equilibrium plasma coupled to a catalyst. This work is part of a PSA Peugeot Citroen and LPGP program. A Dielectric Barrier Discharge is used as a non-equilibrium plasma, with or without a reforming catalyst of iso-octane. The experiments show that characteristics of the electric discharge (voltage, current, energy) are dependent on the flowing gas temperature and the presence of water vapour. Plasma chemical decomposition of iso-octane is higher and increased with temperature: 80 % at ambient temperature and 280 J/l energy, 100 % at 600°C and 30 J/l. The conversion by-products are analysed outlet discharge and post-discharge, namely H₂, CO, CO₂, hydrocarbons, ketones and olefins. . . The formation of these molecules is explained using kinetic schemes for the oxidation of iso-octane. From 1000 ppm of iso-octane in 1 l/min of air, a few hundred ppm of hydrogen are measured. Lt's insufficient for an industrial application. In order to improve the plasma efficiency, a reforming rhodium-catalyst of iso-octane is coupled to the discharge. We showed that a plasma pretreatment of the gas at 80 J/l and 250°C induced a catalyst activation at a temperature below its normal minimal operating temperature
Braci, Lamia. „Traitement d'effluents gazeux pollués par des mercaptans par procédé plasma non-thermique à pression atmosphérique : étude des mécanismes d'oxydation partielle en post-décharge“. Paris 6, 2010. http://www.theses.fr/2010PA066268.
Der volle Inhalt der QuelleLeray, Alexis. „Identification des mécanismes physico-chimiques impliqués dans le post-traitement plasma des gaz d'échappement et études comparatives des différentes technologies plasma“. Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2049.
Der volle Inhalt der QuelleThe new HCCI combustion mode is well adapted to improve nitrogen oxide and particulate matter reduction from Diesel engine in order to meet future emission regulations adopted in the Euro zone. However, HCCI engines emit relatively high amounts of unburned hydrocarbons and carbon monoxide due to lower engine exhaust temperature increasing the catalyst light-off time and decreasing the average efficiency of the Diesel oxidation catalyst (DOC). In this environmental and economic context, the combination of plasma with DOC has been considered especially for intermittent use during the cold start. The thesis presents the combination of nonthermal plasma upstream Diesel oxidation catalyst (Pt-Pd/Al2O3) applied to the treatment of simulating Diesel HCCI exhaust gas (O2-NO-H2O-CO-CO2-CH4-C3H6-C7H8-C10H22-N2). The studies were conducted at atmospheric pressure with a pilot-scale dielectric barrier discharge reactor (DBD) on two experimental devices. The first is a laboratory scale set-up (low flow rate : 20 Lmin−1) used to understand the physico-chemical involving the plasma and the catalyst by focusing on the by-products reactions. The second is an industrial scale (gas flow rate up to 260 Lmin−1) used to study the feasibility and the efficiency of the plasma-DOC system under conditions similar to those encountered in Diesel exhaust engine. The effects of the plasma, the DOC and the plasma-DOC systems on the exhaust gas have been investigated under various conditions. The main contribution of the plasma was to give a « thermal » and a chemical « push » to the DOC resulting in the decrease of light-off temperature for CO and HC oxidation. These improvements were shown to depend on the treatment conditions (injected energy i.e. energy density, space velocity, gas temperature and nature of the driving cycle). It is shown that for a simulated European Driving Cycle (NEDC), the combination of plasma upstream DOC reduces the cumulative mass of CO and hydrocarbons by about 68% and 42%, respectively, in accordance with the Euro 6 standard (2014). The efficiency of plasma for hydrocarbons and NO oxidation at low temperature in high flow conditions (up to 900 Lmin−1 on the NEDC) has been confirmed and the main reaction products identified and quantified
JAFFREZIC, XAVIER. „Etude de l'amorcage de la combustion dans un melange air-propane par un plasma non thermique. Application a l'optimisation de l'allumage sur un moteur“. Paris 11, 1995. http://www.theses.fr/1995PA112353.
Der volle Inhalt der QuelleKassir, Abdel Majid. „Spectres radiatifs de plasmas d'air, N2, Ar-N2-H2 à l'équilibre et en déséquilibre thermique : étude théorique et caractérisation d'une décharge micro-ondes“. Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30140.
Der volle Inhalt der QuellePlasma radiation plays an important role in many applications, ranging from surface modification to aerospace sciences. In a medium constituted of atoms and molecules, such as a plasma, the spectral emission analysis of these species allows one to calculate the medium's characteristic temperatures and electron number density. This study aims to characterize a plasma through its radiation in both thermal equilibrium and weak non-equilibrium conditions. To achieve this goal, a radiative spectra simulation code was developed to study the plasma radiation as a function of the medium's characteristic temperature(s). Additionally, a microwave plasma torch experimental setup was assembled allowing the generation of a weak non-equilibrium plasma, which was then characterized by means of optical emission spectroscopy. First, the context of this study will be positioned in respect to the literature and scientific project of the team. The physical laws governing equilibrium and non-equilibrium plasma will be detailed, and optical emission spectroscopy diagnostic methods normally used to probe these plasmas will be presented. In addition, radiative spectra simulation software, such as LIFBASE, SPECAIR, and SPARTAN, will be described at the end of the first chapter; spectra calculated via these software serve as a reference and comparison basis for the code developed for this work. The second part of this study focuses on the radiative spectra simulation of equilibrium and non-equilibrium plasmas. The theory of molecular radiation will be thoroughly reviewed, as will the diatomic molecules energy levels calculation. The selection rules allowing the radiative transitions between these states and leading to the particular structure of molecular spectra will be discussed, and the spectra simulated by our code will be compared to the reference spectra for the molecular systems of an air plasma and an argon-nitrogen-hydrogen plasma. The agreements and discrepancies noted during these comparisons will be underlined, as well as the necessity to compare the calculated spectra with experimental spectra in order to judge the validity of our model and those implemented in the software used as references. The third part of this work presents the experimental study that was led at the LAPLACE laboratory on the characterization of the radiation emitted by a microwave plasma torch operating at atmospheric pressure. The theory of microwaves propagation along a waveguide and the energy coupling efficiency between the microwaves and the plasma will be briefly reviewed. The experimental setup will then be detailed, and the physical conditions for generating and sustaining the discharge will be discussed. [...]
Vanhulle, Gabriel. „Étude de la cinétique chimique et des propriétés de transport d'un plasma d'arc SF6-C2F4 en déséquilibre thermique : application à l'étude des disjoncteurs haute tension“. Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30330/document.
Der volle Inhalt der QuelleModelling a high voltage circuit breaker using a MHD model needs plasma properties databanks to simulate the electric arc behavior. The local thermodynamic equilibrium hypothesis is often used to calculate these properties. However, the equilibrium conditions are not satisfied near the walls or the electrodes, or during the zero crossing of the current. The thermal nonequilibrium considerably modify the chemistry and properties of the plasma. The study of these properties for a 2t plasma is the subject of this thesis. The first part of this thesis presents the industrial context at the origin of this study. Basics assumptions for the 2t hypothesis are then explained. In this section, special attention is given to the temperatures characteristic of the internal energy modes. Two sets of hypotheses concerning these temperatures are used in this work, and the choice of these hypotheses is discussed. The second part of this work is dedicated to the calculation of sf6-c2f4 plasma composition at 2t. This calculation will be done with two different methods: the first is based on the mass action law extended to 2t, and the second on a collisional-radiative calculation. Examples of compositions obtained with these two methods are presented. The hypotheses concerning the temperatures of populating of the internal energy levels are discussed in the light of these results. The third chapter of this thesis deals with the calculation of the thermodynamic properties at 2t of the plasma. The theoretical formulations of each of these properties are first recalled, and the results from these expressions are then presented and discussed, for the two methods of calculating the composition. The fourth chapter is dedicated to calculating the transport coefficients of a sf6-c2f4 plasma at 2t. This part is based on a bibliographic study of the already existing methods of calculation and the essential data to obtain these properties (collision integrals). For each property (viscosity, electrical conductivity and thermal conductivity) the various calculation methods identified in the literature are compared. The choice of the most appropriate calculation technique is made by comparing the results to the ETL. Particular attention is paid to the calculation of the reactive part of the thermal conductivity, and a formulation adapted to the needs of this work is proposed. The results from these expressions are presented and discussed following the same logic when in the previous chapter
Baloul, Yasmine. „Contribution à l’étude du traitement de résidus médicamenteux dans les milieux aqueux par plasmas non thermiques. Application au paracétamol et à l’ésoméprazole“. Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2008/document.
Der volle Inhalt der QuelleMany drug molecules are not effectively treated by conventional techniques used in wastewater treatment plants and accumulate in natural environments. The objective of this thesis was to develop an advanced oxidation process using a non-thermal plasma generated by electric discharge for the treatment of drug molecules (paracetamol and esomeprazole). The NTP treatments were carried out using two reactors: a multiple needle-to-plate reactor with the plasma in direct contact with the liquid to be treated and a wire-cylinder reactor with the plasma up stream of the liquid to be treated. Conversion rates higher than 80% have been obtained with energy yields, which can reach 8 g/kWh and 39 g/kWh for paracetamol and esomeprazole, respectively. The electrical discharge created between the need leand the liquid has been characterized by optical emission spectroscopy to observe the presence of the oxidative species produced by the plasma and to estimate the temperature of the ionized medium. The species produced in the liquid during the degradation of paracetamol and esomeprazole have been identified by the HRMS technique. The produced species, are mainly carboxylic acids as well as nitrogen products. The identification of production pathways for the formation of the main products has been studied particularly using numerous chemical methods such as HPLC/MS, MS/MS, and different labelling of paracetamol. It has been proven that the main carboxylic acids produced come from the breaking of the aromatic ring. In conclusion, this study allowed us to obtain energy efficiencies of treatment of the two study molecules comparable to those found in literature, and especially to establish a pathways of degradation of paracetamol
Baumann, Xavier. „Étude de la composition chimique et des propriétés thermodynamiques et radiatives d'un plasma de SF6-C2F4 en condition de déséquilibre thermique“. Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30032.
Der volle Inhalt der QuelleTo transport the electrical current on large distances, we have to use high voltage to minimize the energy losses. However, if an electrical fault occurs in the distribution network, we should be able to turn off the electrical current. For this purpose, we use specific devices: the high voltage circuit breakers that should to shut off the electrical arc formed when the electrical contacts are separated. To design and to upgrade the high voltage circuit breakers, the manufacturers are increasingly using numerical modelisations that simulate the electrical arc and the plasma behaviors. Nevertheless, the physics phenomena in the plasma are complex. To describe them, a specific expertise, available in the public research laboratories, is necessary. This thesis is in a partnership between the Siemens company and the AEPPT group in LAPLACE to create a databank to study the extinction phase of electrical arc. This data bank includes thermodynamic and radiative properties of plasma. The transport coefficients have been studied in another thesis conducted in parallel by G. Vanhulle. The calculation of these properties is relatively well known if the plasma is in local thermodynamic equilibrium. But, during the extinction of arc, the free electrons and the heavy particles (molecules, atoms and ions) are not necessary in thermal equilibrium and are describe by different temperatures (the plasma is referred to as 2T plasma). The originality of this thesis is in the extension of the calculation of properties for a SF_6-C_2 F_4 plasma out of thermal equilibrium. First, we discuss the calculation of internal temperatures of heavy particles (excitation temperatures of electronic, vibrational and rotational levels). Then, we report the calculation of partition functions that are essential to get the others properties. To get the 2T chemical composition of the plasma, we developed an approach based on a set of balance equations. In this method, the physical approximations are limited but it is not adapted for the massive calculation of a databank. Therefore, we opted for a method based on two multi-temperature laws of mass action. With the chemical compositions, we calculated the thermodynamic and radiative properties. The thermodynamic properties (mass density, enthalpy and heat capacity) are described and the results are discussed. The radiative properties are complex. We describe in details the radiative processes and the broadening phenomena of atomic lines to get the emission and absorption coefficients. Finally, we discuss the transfer of radiation across the plasma. We show our results resulting of the net emission coefficient method to get the divergence of radiation flux used in magneto-hydrodynamic model
Khacef, Ahmed. „Plasmas hors équilibre thermodynamique et applications : développement de sources UV-X, dépollution (DéNOx, DéCOV), et production de gaz de synthèse“. Habilitation à diriger des recherches, Université d'Orléans, 2007. http://tel.archives-ouvertes.fr/tel-00198361.
Der volle Inhalt der QuelleLe spectre des thèmes abordés est assez large et regroupe les études sur :
la cinétique réactionnelle du milieu actif du laser à excimère XeCl,
le développement de sources flash de rayonnement X,
les différents continua d'excimères de gaz rares à très haute pression (30 bars) excités par flash de rayonnement X,
la réduction des oxydes d'azote (deNOx) par association plasma-catalyse et oxydation des Composés Organiques Volatils (deCOV),
la production de gaz de synthèse et d'hydrogène à partir d'hydrocarbures, l'aide à la combustion des moteurs automobiles, et l'initiation de la réaction dite de "Water Gas Shift" pour la réduction du monoxyde de carbone par décharge à barrière diélectrique.
Rollier, Jean-Damien. „Étude théorique et expérimentale du reformage d'essence assisté par plasma hors équilibre“. Phd thesis, École Nationale Supérieure des Mines de Paris, 2006. http://pastel.archives-ouvertes.fr/pastel-00678639.
Der volle Inhalt der QuelleDaviot, Ronan. „Etude des champs de flux thermique sur les composants faisant face au plasma dans un tokamak à partir de mesures de température par thermographie infrarouge“. Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00534809.
Der volle Inhalt der QuelleFayeulle, Dominique. „Elaboration et étude de révêtements céramiques à sous-couche d'accrochage cellulaire pour la protection chimique et thermique de composants de turbomachines“. Paris, ENMP, 1989. http://www.theses.fr/1989ENMP0149.
Der volle Inhalt der QuelleJarrige, Julien. „Etude expérimentale des décharges électriques impulsionnelles nanoseconde à pression atmosphérique. Application au traitement des effluents gazeux et à la décontamination de surface“. Rouen, 2008. http://www.theses.fr/2008ROUES010.
Der volle Inhalt der QuelleThis work deals with the study of filamentary electrical discharges and their applications for environmental purposes. The first part concerns the study of a corona discharge driven by ultra-short positive high voltage pulses (Marx generator). Electrical signals are analyzed in order to identify the typical steps of the discharge : initiation, propagation and conduction. The influence of pulse parameters (amplitude, width, rise time) on streamers characteristics is studied. The production efficiency of active species in air is especially improved when reducing the amount of energy dissipated after cathode junction. The removal of three volatile organic compounds (propane, isopropyl alcohol and propene) shows that the kinetic mechanism is complex and that several undesirable byproducts can be formed. When coupling the discharge with a MnO2-based catalyst, the process efficiency is improved and the byproducts are partly removed. In a second part, a coplanar dielectric barrier discharge is developed for chemical and biological decontamination of surfaces. The decomposition of a simulant of neurotoxic agent VX shows that reactive oxygen species and initial contamination rate have an effect on the decontamination efficiency. The process is very effective for the sterilization of bacteria Escherichia coli. The main inactivation processes are highlighted : chemical erosion by oxidizing species, membrane rupture due to charged species
Gaspar, Jonathan. „Fluxmétrie et caractérisation thermiques instationnaires des dépôts des composants face au plasma du Tokamak JET par techniques inverses“. Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4739/document.
Der volle Inhalt der QuelleThis work deals with the successive resolution of two inverse heat transfer problems: the estimation of surface heat flux on a material and equivalent thermal conductivity of a surface layer on that material. The direct formulation is bidimensional, orthotropic (real geometry of a composite material), unsteady, non-linear and solved by finite elements. The studied materials are plasma facing components (carbon-carbon composite tiles) from Tokamak JET. The searched heat flux density varies with time and one dimension in space. The surface layers conductivity varies spatially and can vary with time during the experiment (the other thermophysical properties are temperature dependent). The two inverse problems are solved by the conjugate gradient method with the adjoint state method for the exact gradient calculation. The experimental data used for the first inverse problem resolution (surface heat flux estimation) is the thermogram provided by an embedded thermocouple. The second inverse problem uses the space and time variations of the surface temperature of the unknown surface layer (infrared thermography) for the conductivity identification. The confidence calculations associated to the estimated values are done by the Monte Carlo approach. The method developed during this thesis helps to the understanding of the plasma-wall interaction dynamic, as well as the kinetic of the surface carbon layer formation on the plasma facing components, and will be helpful to the design of the components of the future machines (WEST, ITER)
Hameurlaine, Kheira. „Contribution à l'étude d'un arc électrique de faible puissance“. Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00821030.
Der volle Inhalt der QuellePham, Huu Thien. „Contribution à l'étude de la dépollution de l'air chargé en composés organiques volatils par un procédé associant un plasma de décharge à barrière diélectrique impulsionnelle et des catalyseurs“. Thesis, Orléans, 2014. http://www.theses.fr/2014ORLE2022/document.
Der volle Inhalt der QuelleThe focus of this thesis is the application of non-thermal plasma and catalysis in chemical processing, in particular for the removal of Volatile Organic Compounds (VOC) diluted in air. In a first part, the oxidation of three pollutants (methane, propene, and toluene) is studied experimentally in a pulsed dielectric barrier discharge (DBD) reactor and in a catalyst reactor working independently. In a second part, a hybrid plasma-catalyst reactor either in a single-stage or in a two-stages configuration, in which the catalyst is located inside or downstream from the plasma reactor, respectively. Catalyst materials based on Pd, Mn, Cu, and Co supported on alumina beads were tested and characterized by ICP-OES, TEM/EDX, XRD, XPS, and DRIFTS. Products were analyzed and quantified by infrared spectroscopy. Achieved VOCs removal efficiencies and CO/CO2 selectivity, as well as nature and concentrations of the formed products, were evaluated as function of many factors, particularly the specific input energy, the gas temperature, the initial VOCs concentration, the nature of catalyst (size support, metal loading), and the hourly space velocity. It has been successfully demonstrated that the combination of plasma and catalyst in the both configurations has many benefits compared to traditional thermal-catalysis and plasma alone treatment including a lowering of the catalyst operating temperature, an improvement of the conversion of VOCs at similar temperatures, and a better end-products selectivity and energy efficiency. The mutual interaction lead to a synergistic effect in plasma-catalysis especially when the discharge is in direct contact with the catalyst whatever the VOCs studied
Brisset, Alexandra. „Physique des décharges nanosecondes diffuses générées sous champs électriques extrêmes“. Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS456.
Der volle Inhalt der QuelleNon-thermal high-pressure plasmas are extensively studied to understand in detail the development mechanisms of the discharges that create them and the kinetic processes induced. They activate a specific non-equilibrium chemistry that is very interesting for many applications. High concentrations of highly reactive species are thus generated with a relatively low energy consumption. At atmospheric pressure, the discharge is generally filamentary and unstable. In recent years, studies have identified new types of stable and diffuse discharges, in the sense of the spatial extension which can extend over centimetre scales. These discharges are very interesting because they combine both a large plasma volume and very high electric fields. However, the physics of these discharges is not well known.The work carried out in this thesis will addressfirst of all, physical mechanisms of triggering of the discharge. Different discharge regimes will be presented through rapid imaging measurements and the study of electrical signals. In particular, they will determine the influence of voltage on propagation rates and light intensity profiles. We will then measure the spatial and temporal distribution of the electric field and study its specificities. Then we will study how the injected energy contributes to the chemical reactivity of the discharge. In particular, the temperature and absolute densities of the majority of reactive species (O, O3, N2(B,C)) are measured. Finally, we will look at the mechanisms of energetic relaxation in post-discharge. Many diagnostics, often complementary, will make it possible to link the succession of physico-chemical processes during the temporal development of the discharge from its initiation to its complete relaxation
Lisnyak, Marina. „Theoretical, numerical and experimental study of DC and AC electric arcs“. Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2013/document.
Der volle Inhalt der QuelleThe ignition of an electric arc in the electric distribution system of an aircraft can be a serious problem for flight safety. The amount of information on this topic is limited, however. Therefore,the aim of this work is to investigate the electric arc behavior by means of experiment and numerical simulations.The MHD model of the LTE arc column was used and resolved numerically using the commercial software comsol Multiphysics. In order to describe plasma-electride interaction, the model had to be extended to include non-equilibrium effects near the electrodes. These zones were taken into account by means of current and energy conservation in the non-equilibrium layer. The correct matching conditions were developed and are described in the work. Validation of the model in the case of a free burning arc showed excellent agreement between comprehensive models and the experiment.This model was then extended to the case of the electric arc between rail electrodes in a 3D geometry. Due to electromagnetic forces the electric arc displaces along the electrodes. A self-consistent description of this phenomenon was established. The calculation was performed for DC, pulsed and AC current conditions at atmospheric and lower pressures. The main characteristics of the arc were analyzed and discussed. The results obtained were compared with the experimental measurements and showed good agreement.The model of electric arcs between busbar electrodes is able to predict the behavior of a fault arc in aeronautical conditions. Further improvements of the model are discussed as an outlook of the research
Zadeh, Massiel. „Étude d’une pompe active EHD basée sur la mise en œuvre de décharges de surface pour le traitement des effluents gazeux d’origine industrielle“. Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0059/document.
Der volle Inhalt der QuelleThe Volatile Organic Compounds (VOC) emitted in the atmosphere by various forms is considered as principal atmospheric pollutant. In order to treat a high flow of gaz with a low concentration, few efficient methods exist like the non-thermal plasma. Its low power consumption and compactness make the non-thermal plasma treatment a promising candidate. My thesis deals with the development and study of a VOC treatment device based on the surface dielectric barrier discharges which have the characteristic of producing an oriented electric wind. To do this, we have designed and optimized a chemically active plasma pump, composed of an assembly of active surfaces, capable of drawing and treating simultaneously the air polluted in VOC. At first, we had to work on the optimization of the following parameters: electrical, geometric and material of an elementary active surface. And then conceive an active channel consisting of two optimal active surfaces disposed in a mirror effect, eventually leading to the construction of a prototype plasma pump having a flow rate approximately equal to 10 Nm3/h. This original pump by its capacity of chemical treatment consists on the physical and chemical prototype of the thesis. It allowed testing the conversion of 5 different VOCs injected into air which are: ketone, methyl ethyl ketone, butyraldehyde, methyl penatanoate, methyl butyrate and evaluate the respective abatement rates, but also identifying the main by-products of degradation, using the gas chromatography coupled to the mass spectrometry
Redolfi, Michaël. „Etude de l' Oxydation de différents types d'hydrocarbures par des procédés utilisant des techniques de déharges électriques non- thermiques à pression atmosphérique: application à la problématique du démarrage à froid“. Phd thesis, Université Paris-Nord - Paris XIII, 2007. http://tel.archives-ouvertes.fr/tel-00358147.
Der volle Inhalt der QuelleRenaud, Nicolas. „Modelisation des jets relativistes et de l'émission haute énergie des blazars et des microquasars galactiques“. Grenoble 1, 1999. http://www.theses.fr/1999GRE10239.
Der volle Inhalt der QuelleRenaud, Nicolas. „Modélisation des jets relativistes et de l'émission haute énergie des blazars et des microquasars galactiques“. Phd thesis, Université Joseph Fourier (Grenoble), 1999. http://tel.archives-ouvertes.fr/tel-00724425.
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