Dissertations / Theses on the topic 'Discharges in liquids'
To see the other types of publications on this topic, follow the link: Discharges in liquids.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Discharges in liquids.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Grav, Torstein. "Mechanisms Governing the occurrence of Partial Discharges in Insulation Liquids." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22385.
Abstract:
Breakdown of electrical equipment is unwanted and the use of reliable methods of insulation are therefore necessary. Liquid insulation is one preferred material for electrical devices used in subsea installations due to outstanding qualities related to insulation, heat transfer, safety and incompressibility properties. To ensure that the selected insulating liquid is suitable for the specific equipment it will be necessary to test its insulating quality. This is verified by stressing the liquid with voltages higher than the partial discharge inception voltage (PDIV). While there are existing tests for these properties, such as use of partial discharge measurements, this thesis examines an experimental approach to testing the properties of different liquids in a point-plane gap through the use of high AC voltage.Charges, like ions, in an electrical field creates a current flow. In a liquid, dissociative ionization under applied voltage is the mechanism that generates the most charges. Field emission originating from the negative polarity contributes in some liquids. Moving charges in the liquids results in measurable currents of the order 10 - 80 nA under applied AC voltage of 20 kV$_{peak}$ in a 20 mm point-plane gap in different liquids. Space charges are also found to affect the partial discharge (PD) behaviour in liquids. Different liquids have different chemical and physical properties and therefore different PD behaviour. It has been observed that PDs are stochastic, and in some sense correlated to earlier stress due to residual ions from previous half periods and permanently change of the chemical structure of some liquid molecules after a PD. The PD rate increases exponentially with increasing voltage, while the maximum charge per half period tends to increase linearly. This observed behaviour is in agreement with what is found in earlier reports.The presence of free electrons is important. A significant increase in the rate of PD at low magnitudes in both polarities occurred when the test cell was exposed to X-rays. PDs start under the influence of a strong field or an electron avalanche. It is essential to be able to test different liquids in laboratory conditions, for economical reasons, in order to identify the most suitable insulating media. Power electronics utilizing quality insulation is more reliable with a lower probability of downtime. The test setup and methods used in this thesis may easily be adapted for test of electrical components and equipment instead of the simple point-plane gap method.Different liquids have different PD phase patterns. This thesis intends to describe the reasons to explain this difference. It is found to be the result of different properties in the liquids for charge creation and differences in their electrical field threshold for PD initiation. PDs of a certain size are rarely occurring events and are strongly dependent on the prehistory of the stressed liquid gap. We do not know whether PDs in itself is harmful to insulating properties or not. It is therefore uncertain whether the IEC 61294 test method, based on PDs, provides any useful information or not. More research is therefore needed in order to fully understand the PD phenomenon.
2
Sadeghzadeh-Araghi, Mohsen. "The initiation and development of negative discharges in dielectric liquids : a computer aided investigation." Thesis, University of Salford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258230.
3
Nominé, Anna V. "Synthesis of Bi₂O₂CO₃ nanosheets by electrical discharges in liquids for photocatalytic and nanoelectronic applications." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0357.
Abstract:
Ce travail fournit des informations sur la synthèse de feuillets nanométriques ultrafins composés de Bi₂O₂CO₃, ci-après dénommé BOC. La synthèse est réalisée par une technique rapide et simple connue sous le signe EDDL correspondant au procédé de décharges électriques dans les liquides diélectriques. Pour assurer la reproductibilité de la synthèse, une méthode de prétraitement impliquant la gravure d'électrodes de bismuth avec du Nital a été employée. Le processus choisi consiste à initier des décharges électriques entre ces électrodes alors qu'elles sont immergées soit dans l'azote liquide, soit dans l'eau. Fait remarquable, les deux liquides conduisent à des nanostructures identiques, une similitude validée par spectroscopie d'émission optique, technique qui a permis de confirmer la nature métallique de la décharge dans les deux milieux. Après cette étape, les nanofeuillets subissent une oxydation et une carbonatation rapides lorsqu'ils sont exposés à l'air. Le mécanisme de croissance proposé est étroitement lié au mécanisme connu sous le nom de « ledge mechanism », en raison de la présence de « kinks » et de « jogs » clairement visibles le long des bords des nanofeuillets. Ces nanostructures bidimensionnelles émergent d'abord à la surface de la cathode et croissent ensuite verticalement. Cette croissance anisotrope est rendue possible par l'assistance ionique dans les régions qui ressemblent à des motifs en forme de peigne formés pendant l'étape de gravure chimique, condition préalable nécessaire à une forte reproductibilité du processus de croissance. La caractérisation cristallographique détaillée des nanofeuillets de BOC a été réalisée à l'aide d'une série de techniques, notamment la microscopie électronique en transmission (TEM), la microscopie électronique en transmission à balayage (STEM), la microscopie électronique en transmission à haute résolution (HRTEM), la spectroscopie de rayons X à dispersion d'énergie (EDX), la diffraction d'électrons en aire sélectionnée (SAED), la diffraction d'électrons en faisceau convergent (CBED), la microscopie électronique en transmission filtrée en énergie (EFTEM) et la spectroscopie de perte d'énergie des électrons (EELS). L'étude révèle que la structure cristallographique du BOC est conforme au groupe spatial I4/mmm, avec des paramètres de réseau a=3,91 Å et c=13,77 Å, une détermination qui a été confirmée par diffraction des rayons X (DRX). L'étude clarifie également l'origine potentielle des taches satellites qui sont régulièrement observées dans les motifs SAED le long de l'axe de zone [001]. Dans cette étude, ces taches ont été principalement attribuées à deux phénomènes : la diffraction multiple et les transformations locales ordre-désordre qui se produisent dans la structure cristalline du BOC. Cette transformation implique une transition d'une structure quadratique centrée vers un réseau primitif de Bravais. Afin d'évaluer leur utilité pratique, nous avons mesuré la performance photocatalytique des nanofeuillets de BOC synthétisés à l'aide de la méthode EDDL et nous avons constaté qu'elle était comparable à elle de BOCs obtenus par d'autres méthodes. En outre, nous avons évalué la performance électronique des BOC dans le but de découvrir leur potentiel dans les applications liées à des nanodispositifsThis work provides information on the synthesis of ultrathin nanosheets composed of Bi₂O₂CO₃, hereafter referred to as BOC. The synthesis is achieved through the rapid and straightforward technique known as Electrical Discharges in Dielectric Liquids (EDDL). To ensure the reproducibility of the synthesis, a pre-treatment method involving the etching of bismuth electrodes with Nital was employed. The chosen process entails initiating electrical discharges between these electrodes while submerged in either liquid nitrogen or water. Remarkably, both liquids produced identical nanostructures, a similarity validated by optical emission spectroscopy, which confirmed the metallic nature of the discharge in both environments. Following this stage, the nanosheets undergo rapid oxidation and carbonation upon exposure to air. The proposed growth mechanism is closely linked to the ledge mechanism, considering the presence of clearly visible kinks and jogs along the edges of the nanosheets. These two-dimensional nanostructures first emerge on the cathode's surface and then grow vertically. This anisotropic growth is made possible by ion assistance in regions that exhibit comb-like patterns formed during the chemical etching step, which is a necessary precondition for high reproducibility of the discharge process. Detailed crystallographic characterization of BOC nanosheets was achieved through a range of techniques, including Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM), High-Resolution TEM Transmission Electron Microscopy (HRTEM), Energy-Dispersive X-ray Spectroscopy (EDX), Selected Area Electron Diffraction (SAED), Convergent Beam Electron Diffraction (CBED), Energy Filtered Transmission Electron Microscopy (EFTEM), and Electron Energy-Loss Spectroscopy (EELS). The investigation reveals that the crystallographic structure of BOC conforms to the space group I4/mmm, with lattice parameters a=3.91 Å and c=13.77 Å, a determination that was confirmed by X-ray Diffraction (XRD). The study also clarifies the potential origin of satellite spots that are consistently observed in SAED patterns along the [001] zone axis. In this research, these spots were primarily attributed to two phenomena: multiple diffraction and local disorder-to-order transformations occurring within the BOC crystal structure. This transformation entails a transition from a body-centered tetragonal structure to a primitive Bravais lattice. To gauge their practical usefulness, we assessed the photocatalytic performance of BOC nanosheets synthesized using the EDDL method and found it to be consistent with BOC obtained through alternative methods. Furthermore, we explored the electronic performance of BOC with the goal of uncovering their potential in nanodevice applications
4
Okubo, H., H. Kojima, F. Endo, K. Sahara, R. Yamaguchi, and N. Hayakawa. "Partial Discharge Activity in Electrical Insulation for High Temperature Superconducting (HTS) Cables." IEEE, 2008. http://hdl.handle.net/2237/12061.
5
Hernandez, Avila José Luis. "Etude des decharges couronne dans l'argon et l'azote, du gaz au liquide." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10173.
Abstract:
Ce memoire resume les travaux sur les phenomenes de conduction electrique et des mecanismes de transport que nous avons effectue pour l'argon et l'azote en fonction de la densite du fluide. Par des mesures electriques et optiques nous avons caracterise la decharge couronne en fonction de divers parametres tels que: la tension d'apparition de la decharge, les impulsions de courant, l'analyse spectroscopique de la lumiere emise. L'etude ete effectue pour des pointes de petit rayon de courbure, allant de 1 a 10 micrometres, les phenomenes dependent beaucoup de la polarite de la pointe, ainsi que de la nature du gaz. Les caracteristiques courant-tension pour l'azote presentent trois regions differents pour un seuil de tension caracteristique qui dependant de la densite du milieu. Deux regions d'entre elles sont liees a la presence d'impuretes, leur influence se manifeste par une reduction de la mobilite des porteurs de charge ainsi comme la presence des impulsions similaires a celles observees dans les gaz electronegatifs (impulsions de trichel). La troisieme region corresponde a une transition ou le courant atteint des valeurs de l'ordre du milliampere, sans la presence d'impulsions. Pour l'argon gazeux les impuretes presentent un effet notable sur les conditions d'apparition de la decharge, elle presente une transition nette, pour une tension seuil, vers des courants de l'ordre de la microampere. Une analogie de la loi de paschen pour une configuration d'electrodes planes et paralleles, nous a permis d'etablir une relation entre la tension seuil et le produit de la densite du fluide et le rayon de courbure nous a permis de caracteriser les decharges couronne dans le gaz et le liquide sur une region definie par le produit nr#p. La validation de cette relation est fondee sur mecanismes d'avalanches et des coefficients d'ionisation pour le gaz et le liquide
6
Pajurková, Jana. "Diafragmový výboj v roztocích organických barviv." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216665.
Abstract:
This Diploma thesis was focused on the degradation of dyes Saturn Red L4B (Direct Red 79) and Saturn Blue LB (Direct Blue 106) by DC diaphragm discharge (DC-DD). Supplied power was between 160 and 180 W. Conductivity and pH were changing at each electrode area during the DC diaphragm discharge, therefore the effect of pH and conductivity changes on the dye solution itself were examined. All samples were measured by UV-VIS spectrometer in the wavelength range of 300–800 nm. No significant dependence of dye absorption spectra on conductivity was observed, while pH significantly affected the absorption curves of dyes. Ageing of dye spectra showed significant changes of Saturn Red L4B. Next task was the comparison of dyes destruction efficiency by DC-DD, audiofrequency diaphragm discharge (AF-DD) and electrolysis. Dye decomposition by AF-DD was not observed at set conditions (voltage of 80–120 V, current of 2.2 A and frequency of 2 kHz). In the case of DC diaphragm discharge the electrolysis played an important role. Decomposition efficiency of the dyes by electrolysis was up to 15 %. The pumping effect in the DC diaphragm discharge was also investigated. Although the individual electrode areas were linked only by a small pinhole in a nonconductive barrier (the pinhole diameter of 0.3 mm), solutions of the anode and cathode compartment interacted with each other up to 10 %. Finally, the degradation products of Saturn Red L4B treated by DC-DD in two electrodes parts are also described. Decomposition products were determined by high performance liquid chromatography (HPLC) combined with the mass spectrometer.
7
Zhou, Rusen. "Low-temperature discharge plasmas in liquids assisted biomass conversion." Thesis, Queensland University of Technology, 2021.
Abstract:
This project contributed to the establishment of the plasma-based, sustainable, and energy-efficient biorefinery platform. By introducing in-liquid discharge plasmas and understanding plasma-liquid interactions, this thesis explored the engineering and scientific basis of using such plasmas for bioresource conversion, and developed a “plasma-assisted reforming” process for fast biomass liquefaction and selective ethanol conversion into higher-value products at near-ambient conditions.
8
Qureshi, Mohammad Iqbal. "Relationship between current pulses and discharges in liquid dielectrics." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315303.
9
Prior, Alison D. "Towards achieving Zero Liquid Discharge in process industry." Thesis, Prior, Alison D. (2008) Towards achieving Zero Liquid Discharge in process industry. Honours thesis, Murdoch University, 2008. https://researchrepository.murdoch.edu.au/id/eprint/38933/.
Abstract:
Fresh water is invaluable in supporting life on Earth. It is scarce, cheap, and exploited. A number of initiatives have been taken to reduce the consumption of fresh water, particularly in agricultural and residential situations. In industry, much focus has been placed on pollution control and wastewater minimisation, however attention to source protection and water minimisation is nominal. The ultimate goal of any water management program is achieving Zero Liquid Discharge (ZLD). This research argues that with a current focus on pollution control and wastewater minimisation, ZLD is not attainable. Protection of water sources has recently been identified as the most critical issue preventing sustainability of industrial water management. It is also given the least attention. This thesis argues that incorporating water auditing and water conservation programs into industrial water management programs is a crucial step towards achieving water source protection and ultimately in achieving zero liquid discharge. A water audit of key water using operations at the BP Refinery in Kwinana has been undertaken to test this hypothesis.
The BP Oil Refinery in Kwinana is an example of an industry which has received much attention for its
excellent practice in water management. BP has almost halved its total water consumption from 7ML/day in 1996 to 4ML/day in 2007. It has developed employee awareness-raising programs, on-site recycling and reuse of wastewater and is now in the final stages of using recycled domestic wastewater as a key water source, expected to minimise fresh water consumption even further.
Despite this, detailed analysis of the major water uses at the refinery show a number of poor management
practices and severe wastages of water. In assessing the whole of refinery water use in Chapter 2, we see that poor record keeping and meter reading is commonplace. Major leaks are left unattended and information about major water-loss incidents is often unavailable. In Chapters 3-5 we look more closely at specific water using operations within the refinery. The refinery steam system is one of the largest fresh water users on site and has been commended for its steam trap survey program and the development of condensate return infrastructure, increasing the percentage of condensate returned from 32% in 1998 to a condensate return target of 50% in 2007. Despite this, major losses still occur in the steam system and turnaround time for fixing major leaks can take years. Simple measures can improve the condensate return rate from 50%-75% quite easily, but there are few incentives for the refinery to invest in such a program which offers diminishing returns. The use of water in process units is enormous, particularly the use of scheme water in the Residue Cracking Unit. A number of available tools and techniques, particularly water pinch and water optimisation tools, are widely recognised to reduce water use on such units but have not been investigated at BP. Many water losses on process units occur because of poor operator management and a focus on increasing efficiency of feed throughput which offers the refinery the greatest financial return. Another inefficient water user in the process category is the Waste Management Area Land Farm. The land farm is irrigated to keep the moisture content of waste high. The exceptionally large volumes of water used in this area can be easily reduced, however costs are considered too high. Finally we assess other uses of water at the refinery. Other uses include commercial and domestic uses, safety showers and the staff carwash. Because of the extraordinary volumes of water used in the refining process, these other uses are considered comparatively insignificant. Practically no water efficiency measures have been taken at this level, and enormous wastages of high quality water are witnessed through our case study of the staff carwash. The carwash is an enormous water waste which uses scheme water once before it is discharged to the sewer.
Each of these case studies shows major inefficiencies in current water management at a number of levels at the BP Refinery in Kwinana. It is important not to forget that this refinery has been recognised for its excellence as a leader in water management not only in the Kwinana Industrial Area but also in the global oil refining industry. This reflects the inherent flaws in water management throughout industry. Chapter 6 assesses management implications associated with reducing water use on site and applies these principles and concepts to industry in general. The most significant barriers to closing industrial water loops were found to be neglect of protection of water sources and larger focus on pollution prevention and wastewater minimisation; misconceptions about the true value of water; and poor regulatory drivers to reduce water use. A paradigm shift in industrial water management to incorporate a more holistic approach is required if water scarcity is to be seriously addressed by industry.
10
Davidová, Jaroslava. "Diafragmový výboj v roztocích organických barviv z hlediska elektrolytického rozkladu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216664.
Abstract:
This Diploma thesis is focused on physical and chemical effects which contribute to the decomposition of organic dyes by diaphragm discharge generated in water solutions. Due to the application of DC high voltage source in continuous regime, there is an effect of electrolysis contributing to the dye decomposition by diaphragm discharge. The aim of this work was to find out when the electrolysis is running (or when is the moment of discharge breakdown) and which factors influence the breakdown. The other goal was decomposition of selected textile and food organic dyes by electrolysis itself. In the theoretical part, theory about creation of electrical discharges in aqueous solutions is noted and various types of underwater discharges are described. Background researches about underwater electrical discharges used in the world are mentioned as well as the use of diaphragm discharges and various ways how to remove organic dyes from wastewater. Finally, theories of electrolysis, UV-VIS spectroscopy and basis of other analytical methods useful for detection of organic molecules are described. Experimental part is oriented to experiment procedure which was carried out in a reactor with separated electrode areas. Separation was made by dielectric diaphragm with a pinhole in the centre. Its initial diameter was 0.4 mm. Used chemicals and course of experiments are described in this part, too. First, the breakdown moment in the reactor was investigated (i. e. determination, when only electrolysis was operating) by formation of hydrogen peroxide and measurement of dynamic (time resolved) electrical characteristics. Next, decomposition of selected dyes by electrolysis was carried out. As the decomposition was related to decolorization of the solution, UV-VIS spectroscopy in the range of 350–700 nm was used for determination of dye concentration. Next part focused on results presents various factors which had an effect on breakdown of diaphragm discharge. These factors are kind of used electrolyte, initial conductivity of solution, kind of dye, temperature of solution and type of reactor (or solution volume). From the result, the most important factor is initial solution conductivity. After the determination of the breakdown moment, the electrolysis of organic dyes was performed. The applied current was 10 mA, initial conductivity was 500 µS/cm and used electrolyte was NaCl. Moreover comparison of dye decomposition in dependence on the different applied power was realized. From this comparison one can assume, there is no significant contribution of electrolysis (the efficiency is approximately 15 %) to the diaphragm discharge in aqueous solution.
11
Faderani, Shokrollah dabbaghi Varnos. "Discharge and transport of nearly-buoyant coarse granular solids in liquids." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336751.
12
Liu, Zhao. "Partial discharge and streamer characteristics of transformer liquids under AC stress." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/partial-discharge-and-streamer-characteristics-of-transformer-liquids-under-ac-stress(82628a33-9bc3-467f-899a-7240307d7601).html.
Abstract:
Pre-breakdown phenomena in transformer liquids have been extensively investigated. The published work can be broadly categorised into streamer and partial discharge (PD) studies, with the former focusing on physical nature and the latter being more relevant to industrial applications. Mineral oil, as the dominant candidate, has been used in power transformers for over a century. In the past decade, there has been an increasing interest in filling power transformers with alternative liquids, e.g. esters and gas-to-liquids (GTL) based oils. This work aims to correlate the PD and streamer characteristics of three transformer liquids under AC stress. The liquids include a conventional mineral oil (Gemini X), a GTL oil (Diala S4 ZX-I) and a synthetic ester (MIDEL 7131). A circuit arrangement in compliance with the IEC 60270 was used, which allowed PD measurements, wide-band current measurements and streamer shadowgraphs to be obtained simultaneously. To simulate the quasi-uniform electric fields in transformers, a plane-to-plane electrode system incorporating an adjustable needle protrusion (PNP) was employed. A needle-to-plane electrode system (NP), which is widely used in the field, was also employed to provide reference results. Based on the PD measurement results, the PD inception fields (PDIFs) of the three liquids were found to be independent of electrode geometry for the investigated tip radius. The PDIF of the synthetic ester is about 13% lower than that of the mineral oil or the GTL oil. Compared with the PD magnitude, the pulse repetition rate is more sensitive to liquid type. At the same voltage under both the NP and PNP configurations, the synthetic ester has the highest pulse repetition rate, followed by the GTL oil, and then the mineral oil. In divergent electric fields (provided by the NP electrode system), it was found that the streamers in the three liquids have a similar stopping length at the same voltage, even though the apparent charge readings are not the same. The correlations between PD and streamer characteristics indicated that the synthetic ester has the highest branching tendency, and has therefore the smallest stopping length per unit of apparent charge among the three liquids. In quasi-uniform electric fields (provided by the PNP electrode system), the streamer branching tendencies of the three liquids were largely suppressed. The change from a propagation-induced breakdown in divergent fields to an initiation-induced breakdown in quasi-uniform fields was explained. The correlations between PD and streamer characteristics revealed that the same apparent charge can indicate different levels of streamer development in the insulation, depending on the uniformity of the electric field. Overall, interpreting PD measurement results needs to take the electric field uniformity (PD location) as well as liquid type into consideration.
13
Smith, Gordon V. "A study of electrode erosion by discharges in a dielectric liquid." Thesis, University of Surrey, 1991. http://epubs.surrey.ac.uk/843078/.
Abstract:
Samples of copper, iron and graphite, commonly used as tool and workpiece electrodes in the electro-discharge machining process are subjected to single electrical discharges by breakdown of the paraffin liquid in which they are immersed. The discharge currents and durations used are typical of the repetitive discharges used in EDM. The electrode morphologies, resulting from the erosive action of the discharges, are examined using both optical and electron microscopy. The results of these examinations are related to single discharge erosion data derived from performance figures of commercial EDM equipment. It is concluded that the anode is heated by a plasma discharge which expands with time. During the discharge cathode material is evaporated by cathode spots which differ in character for thermionic and nonthermionic materials. Molten anode and cathode material is evacuated after the discharge by a fall in pressure within a bubble of vapour which surrounds the electrodes during the discharge. Graphite electrodes are eroded by sublimation during the discharge. A novel proposal for the relation between micro-cratering of iron cathodes and the plasma diameter is proposed and tested.
14
Lamptey, Benjamin Odarkwei Mills. "The discharge of solid-liquid mixtures from storage vessels." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335132.
15
Harper, Grant. "Biomass-powered zero liquid discharge desalination of brackish water." Thesis, Harper, Grant (2018) Biomass-powered zero liquid discharge desalination of brackish water. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/44867/.
Abstract:
Desalination is accepted as being a necessary technology to support the livelihood of communities. However, to prevent the harmful environmental impacts of brine, desalination needs to be designed with zero liquid discharge being the process rather than an afterthought. Existing approaches are often found to be inadequate and significant amounts of research into ways to prevent liquid waste are currently in place. The challenge is that the technology must be able to treat post-RO salinities (usually with high amounts of thermal energy) to be able to overcome the low heat capacities and high boiling points of saline solutions >70,000 mg/L.
This research honours project investigates a proposal developed by Enerbi Pty Ltd that incorporates heat, mechanical and electrical energy into a desalination unit that is powered by Biomass and produces a Zero Liquid Discharge product. The system was modeled in Excel and ChemCad and found to successfully produce a dry product with moderate quantities of biomass. The proposal was then modelled to treat 60ML per year under various scenarios using two particular types of Biomass, Plantation Waste, and Oil Mallee crops. These scenarios included high-value agricultural and horticultural crop scenarios using desalinated water for irrigation and salinity, with salinity problems on site being amended via saline water uptake and intervention crop planting.
The design was carried further to a Pilot Plant configuration specified using ‘off the shelf’ products, and the Pilot Plant design included upgrading the power configuration to allow for additional equipment. The Pilot Plant configuration was tested up to salinities of 85,000mg/L. It was found to successfully cope with this salinity, the most likely upper limit due to heat requirements of evaporation of hyper-saline solutions. A final concept 3D model was created to assist with placement and configuration.
16
Wang, Xin. "Partial discharge behaviours and breakdown mechanisms of ester transformer liquids under AC stress." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/partial-discharge-behaviours-and-breakdown-mechanisms-of-ester-transformer-liquids-under-ac-stress(43a16189-379b-4645-870c-ccc5cb03bf06).html.
Abstract:
Mineral oil has been widely used in liquid insulation of power transformers. However, it is poorly biodegradable and could cause serious contamination to the environment if a spill occurs. With increasingly strict environmental rules and regulations, there is considerable interest from the Utilities to apply esters in power transformers as substitutions to mineral oil. In order to use esters in large power transformers, their dielectric properties should be thoroughly investigated. This PhD thesis covers the experimental studies on the dielectric properties of a type of synthetic ester (Midel 7131) and a type of natural ester (FR3) in both uniform and divergent electric fields, using a mineral oil (Gemini X) as the benchmark. The dielectric properties of transformer liquids in uniform fields were investigated using breakdown voltage tests. The breakdown voltages of esters should be at least similar to that of mineral oil to allow a replacement in transformers. To obtain a fair comparison, the AC breakdown voltages of well-processed transformer liquids were tested, and their distributions were statistically analyzed. Since the breakdowns of transformer liquids in uniform fields are caused by the weakest-links, conditions representative of in-service transformer liquids were also considered by testing the effects of extraneous factors, such as particles, water and electrode area. The divergent fields were produced by sharp needle electrodes with tip curvatures of a few micrometers. The dielectric properties of transformer liquids in such fields were studied using several methods. A traditional PD detector was used to study the partial discharge characteristics of insulating liquids, such as the inception voltages and the repetition rates. A high speed camera was utilized to identify the streamer generation, propagation and breakdown phenomena. An oscilloscope was used to investigate the current signals associated with these phenomena. The breakdown voltages of transformer liquids were also determined in the divergent field at various gaps. Furthermore, the fault gases in transformer liquids under partial discharge faults were determined and analyzed. The following findings and conclusions can be made from the research in this thesis: * The AC dielectric strengths of esters in uniform fields are similar to that of mineral oil when they are in a well-processed condition. When practical liquid conditions are considered, the AC dielectric strengths of esters are higher than that of mineral oil. * The partial discharge behaviours at overstressed voltages can be used to differentiate various transformer liquids. Esters are relatively inferior to mineral oil in terms of higher discharge amplitude, higher discharge repetition rate and more negative partial discharges.* Mineral oil possesses a higher ability to suppress the propagation of negative streamers. Thus, the AC dielectric strength of mineral oil in the divergent field is relatively higher than those of esters. * Esters generate the same types of fault gases due to electrical discharge as mineral oil, but in relatively larger amounts.
17
Yi, Xiao. "Characteristics of creepage discharges along ester-pressboard interfaces under AC stress." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/characteristics-of-creepage-discharges-along-esterpressboard-interfaces-under-ac-stress(73749539-3231-467e-b5ee-1c7aa6eaabe8).html.
Abstract:
Ester liquids including natural ester and synthetic ester are considered as potential substitutes for mineral oil, due to their good biodegradability and high fire points. Although these liquids have been widely used in distribution and traction transformers, research efforts are required for the purposes of design and manufacture of high voltage and large power transformers which are filled by esters. Indeed, it would be risky to apply esters in large power transformers without thorough understandings of their behaviours in large gaps and/or when combined with pressboard insulation. Therefore, investigations of creepage discharges along the surface of pressboard in esters are vitally important and their behaviours should be compared with those of mineral oils. This thesis is aimed to investigate the creepage discharges along pressboard in esters and mineral oil under ac divergent electric field. Apparent charges, current signals and images of streamer channels were obtained synchronously to identify whether and how the introduction of pressboard surface would influence the inception and propagation of discharges as compared to tests in open gap. When over-stressed by higher voltages, the surface tracking along the pressboard-ester interface, triggered by sustaining creepage discharges, was studied and the evolutions of accompanying creepage discharge patterns were investigated. In these experiments, both esters and mineral oil impregnated pressboards were comparatively studied. The test results indicated that at the inception stage, the presence of pressboard or any other solid types in different liquids under test do not influence the PD inception voltages; in the propagation stage, solid surface tends to promote the development of discharges, especially those occurring in negative half cycles, and shifts more discharges towards the zero-crossing phase angles. This discharge promotion effect is much more evident in esters than in mineral oil, probably because of higher discharge intensity in esters and higher viscosity of esters. The space charge effect and the residual low density channel effect are proved as the mechanisms best explaining the influences of solids on creepage discharges. Under higher voltages, it was found that the impregnated pressboard is susceptible to discharge erosion characterized by “white and carbonized tree-shaped marks”, due to intense discharges occurring on or near the pressboard surface. The “white mark” appears at a lower voltage and propagates more easily on ester impregnated pressboard. The gaseous “white mark” channels will attract the subsequent discharges to follow the same discharge routes; the accumulative energy dissipation in these channels will then result in the carbonization of the channels. Once formed, the surface tree-shaped mark can continue to grow even under reduced voltage levels until it bridges the gap and causes the final flashover.
18
Invernizzi, Laurent. "Développement, caractérisation et optimisation d'une source plasma pour le traitement de liquides." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30231.
Abstract:
Depuis quelques dizaines d'années, un intérêt grandissant dans la caractérisation et l'optimisation des jets de plasma à pression atmosphérique a vu le jour grâce à la variété d'applications possibles. L'une d'entre elle concerne la décontamination de liquides contenant des polluants. En effet, le plasma est capable de créer des agents oxydants tels que des espèces réactives de l'oxygène et de l'azote (RONS), des champs électriques, des radiations UV/VUV et des espèces chargées. En particulier, la variété et le nombre de RONS qui sont créés et déposés en phase liquide sont deux paramètres clés dont la compréhension et l'optimisation sont fondamentales pour pouvoir développer une source plasma efficace en terme de décontamination de liquides. La création de RONS est possible par une cascade de transferts d'énergie entre les espèces issues du plasma, l'air qui les entourent et la cible liquide placée en contact avec le jet de plasma. Il est donc nécessaire d'étudier les espèces qui donnent naissance aux RONS, à savoir les atomes d'hélium métastable He(23S). Ces espèces ont la particularité de posséder une énergie relativement conséquente (19.8 eV), en plus de pouvoir la conserver pendant plusieurs dizaines de nanosecondes dans le cas où un mélange He + 0.2% O2 est utilisé. La collision entre ces métastables et les espèces de l'air est à l'origine de la création d'espèces réactives en phase gazeuse qui se déposent ensuite en phase liquide, permettant de réduire voire de détruire le polluant présent dans l'eau. Dans ce travail, l'étude est séparée en trois parties : le plasma, le liquide et l'efficacité biocide du jet de plasma. Dans ce travail de thèse, l'étude de l'influence de la géométrie de la source, du débit ou encore du mélange gazeux sur la quantité des atomes d'hélium métastable dans le jet de plasma est réalisée par spectroscopie d'absorption laser lors de son interaction avec une cible liquide. L'utilisation de l'inversion d'Abel permet de déterminer la densité et la durée de vie de ces espèces localement dans le jet de plasma. La spectroscopie d'émission optique est utilisée pour obtenir une cartographie de toutes les espèces excitées entre 200 et 1000 nm présentes dans le jet. Ces espèces en phase gazeuse sont également étudiées grâce à l'utilisation d'une caméra intensifiée permettant de suivre l'évolution spatio-temporelle du jet de plasma au cours de sa propagation dans l'air jusqu'à son contact avec le liquide.[...]In recent decades, a growing interest in the characterization and optimization of atmospheric pressure plasma jets has emerged due to the variety of possible applications. One of them concerns the decontamination of liquids containing pollutants. Indeed, plasma jets are capable of creating oxidizing agents such as reactive oxygen and nitrogen species (RONS), electric fields, UV/VUV radiation and charged species. In particular, the variety and number of RONS that are created and deposited in the liquid phase are two key parameters. Understanding and optimizing them is fundamental to the development of an effective plasma source for liquid decontamination. The creation of RONS is possible by a cascade of energy transfers between the species in the plasma, the surrounding air and the liquid target placed in contact with the plasma jet. Therefore, it is necessary to study the species providing these RONS, namely the metastable helium atoms He(23S). These species have the particularity of storing a relatively high energy (19.8 eV), and can release it several tens of nanoseconds after, in the case of plasma in He + 0.2% O2 mixture. The collision between these metastables and air species causes the creation of reactive species in the gas and liquid phase. These reactive species can then reduce or destroy the pollutant present in the water. In this work, the study is separated in three parts: the plasma, the liquid, and the biocidal efficiency of the plasma jet. The study of the source geometry influence, the flow rate or the gas mixture on the quantity of metastable helium atoms in the plasma jet is performed by laser absorption spectroscopy. The use of Abel inversion allows the density and lifetime of these species to be determined locally in the plasma jet during its interaction with a liquid target. Optical emission spectroscopy is used to map all excited species between 200 and 1000 nm present in the plasma jet. These excited species in the plasma are also studied using an intensified camera to monitor the spatial and temporal evolution of the plasma jet during its propagation in the air. The asymmetric source, whose mass electrode has a larger surface than a conventional source (symmetric source), produces more metastable helium atoms and excited species. The quantities of the main RONS (hydrogen peroxides, nitrites and nitrates) were measured in the liquid. The complex molecule targeted in this study to model water pollutant is methylene blue.[...]
19
Lokajová, Aneta. "Analýza produktů elektrického výboje ve směsích vody a etanolu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401875.
Abstract:
The thesis is focused on electrical discharge in liquid solutions, in particular in ethanol solutions. In the theoretical section, the plasma is defined along with its important parameters, types of plasma generation and usage of plasma technologies. Main part is focused on the discharges in water solutions. Electric discharges in liquid solutions enable physical processes (shock waves, UV radiaton, electric current) as well as chemical ones (generation of radicals and ions). Both types of the processes are used in many fields – medicine (tool sterilization, destruction of pathogens), consumer technologies (surface adjustemen, processing of the textiles, surface clearing) of environmental protection (clearing water, decomposition of organic compounds). Goal of the thesis was to analyze discharge products on ethanol solution. Multiple samples were measured and concentration od selected products was monitored during the measurement – ethanol, acetone and acetaldehyde. PTR-TOF-MS method was used to collect and analyze the data. This method is well used thanks to quick response and immediate measurement. It produce the reset accurate enough for our purpose. It would be more efficient to use this method in combination with another analytical metohod in the future research, e.g. gas chromatography.
20
Hayakawa, N., M. Nagino, H. Kojima, M. Goto, T. Takahashi, K. Yasuda, and H. Okubo. "Dielectric characteristics of HTS cables based on partial discharge measurement." IEEE, 2005. http://hdl.handle.net/2237/6772.
21
Koch, Benedikt. "Greening or greenwashing dirty laundry? Tracing sustainability in the Tirupur textile cluster." Thesis, Linköpings universitet, Tema Miljöförändring, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129924.
Abstract:
The contemporary world landscape is epitomised by a highly globalised world economy, where neo-liberal agendas push for ultimate competitiveness and much of the manufacturing and production processes have been relocated from core to semi-peripheral countries. To be able to compete in the global arena, many developing nations and newly emerging economies have sacrificed an approach to sustainable development by neglecting social and ecological aspects. A showcase of such unsustainable growth in recent years can be observed in Tirupur, South India. Tirupur’s heavy export orientation of ready-knitted garments transformed it into a major textiles cluster for fashion retailers and buyer groups worldwide. However, the substantial pollution of water resources due to the discharge of raw effluents by processing units into the Noyyal river and the overexploitation of groundwater cast a shadow on the city’s economic expansion. In order to tackle these challenges, a number of regulatory directives were issued from the mid 1990’s onwards, leading to the enforcement of strict Zero Liquid Discharge norms in the cluster. This study investigates whether intervention efforts directed at Tirupur’s textiles sector have been able to address inherent challenges impacting the local environment and population. The findings gathered from an extensive literature review and a field study to Tirupur suggest that while some problems of the past have been attended to, major sustainability issues remain. Serious concerns such as a shift in pollution and economical uncertainty in the cluster have been identified as consequences from the policy interventions.
22
Sully, Vicky Ann. "Characterisation of the discharge flowrate and dispersion of non-flashing liquid releases through failed pipe flanges." Thesis, London South Bank University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369883.
23
Marinov, Ilya. "Plasmas in liquids and at the interfaces." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00998381.
Abstract:
Growing interest in biomedical applications of nonthermal plasmas inspires the development of new plasmas sources. Dielectric barrier (DBD) and corona discharges produced in ambient air or in noble gas flow are typically applied. Direct production of plasma in liquids has a great potential for sterilization of liquid substances and extracorporeal blood treatment. The physical mechanisms of discharge formation in liquid medium are not fully understood.The first part of this thesis deals with the initiation and development of the nanosecond discharge in liquid dielectrics (deionized water, ethanol and n-pentane). Time-resolved shadowgraph visualization, optical emission spectroscopy and electrical diagnostics are applied to investigate the discharge formation on point anode.We have shown that depending on the applied voltage amplitude three different scenario can occur in the polar dielectric, namely, cavitation of a bubble, discharge development in the gaseous cavity (bush-like mode) and initiation of the filamentary discharge (tree-like mode) propagating in bulk liquid. Formation of the bush-like and the tree-like discharges is governed by distinct physical mechanisms, resulting in strongly different plasma parameters.In the second part of this work we address the question of how cold atmospheric plasma interacts with living cells in-vitro and in-vivo, and what is the mechanism of plasma induced cell death. Flowcytometry based cell viability assay with two markers AnnexinV (AV) and Propidium iodide (PI), demonstrates a dose dependent induction of the apoptosis for human T lymphocyte (Jurkat) and epithelial (HMEC) cells treated with DBD plasma. In nude mice model, induction of apoptosis and necrosis in dose dependant manner is observed by electron microscopy in thin epidermis sections. Histological analysis shows significant lesions appeared in epidermis, dermis, hypodermis and muscle as a function of treatment duration. Production of hydrogen peroxide in culture medium (PBS) exposed to DBD plasma is measured using selective fluorescent probe (Amplex® Red). Cell viability of human thyroid epithelial (HTori-3) and melanoma (1205Lu) cells demonstrates nonmonotonous dependence on H2O2 concentration. The major role of plasma produced hydrogen peroxide and DBD electric field is suggested.
24
Dahlgren, Maja. "Breaking the silos: Bridging the resource nexus in the textile industry when adapting to Zero Liquid Discharge." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295909.
Abstract:
The concept of resource nexus is an acknowledgement of the interconnections between the uses of natural resources. This research will further the work done on the resource nexus by examining the multiple effects of measures taken in the Indian textile industry to lower the costs incurred due to the implementation of Zero Liquid Discharge (ZLD). ZLD combines a variety of technologies to cease the discharge of untreated water from production processes to the surrounding area. The paper will, based on surveys answered by an IKEA supplier and four of IKEA’s sub-suppliers of textile in India, present a multiple case study of possible multiple effects of projects undertaken to lower the increased cost of manufacturing with ZLD. Building on the multiple case study, and marrying it with the knowledge of the multiple benefits of energy efficiency improvements, the Value Added Water (VAW) tool, and the rebound effect, this paper constructs and offers a Multiple Effects Framework (MEF) for measures taken in factories as a response to the increased cost of manufacturing with ZLD. The framework handles both quantifiable and non-quantifiable multiple effects of measures taken, such as changes in resource use (water, energy, chemicals, materials), productivity and work environment. The MEF aggregates a more comprehensive picture of the overall effects of measures taken to adapt to the increased costs associated with ZLD in the textile supply chain, and can to a certain extent be applied to other factories facing a future mandate for ZLD. When changed accordingly, the framework can also be applied to other situations and industries as a decision-making and evaluation tool. In order to deepen the understanding of customer expectations and future trends, interviews were made with IKEA co-workers and a consultant involved with the factories investigated. Lessons learnt by IKEA and the consultant regarding ZLD implementation and the resource nexus are presented for internalization by factories, customers and authorities.
25
Lewis, Christopher James. "Development of a Methodology for Numerical Simulation of a D C ARC Discharge in a Liquid Dielectric." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2394.
Abstract:
The majority of literature regarding the numerical simulation of arc discharges in gaseous environments has used a plasma physics approach. Virtually all simulations treat the discharge as an idealized gaseous plasma, which can be described by temperature, pressure, and electric field. This approach can work well if the media is a shielding gas such as Argon; however, the approach does not work well for processes such as underwater welding, EDM, and underwater discharges used to generate high purity particles. The reason these discharges do not have many extensive simulation efforts as described in the literature is because they occur in liquid dielectric media (Oil and water) which complicates the simulation efforts. Most research efforts in these areas describe experimental methods to evaluate discharge properties In this research a new method to investigate discharges in a dielectric media using an electrostatic and particle physics approach is proposed and validated. A commercial code that has been developed to simulate charged particle beams, dielectric materials, and perform multi-physics analyses, is the Vector Fields suite of solvers from Cobham Technical Services. This research demonstrates a simulation methodology that can be used to simulate a DC electric arc discharge in a lossy dielectric media using the Vector Fields environment. This simulation is the first of its kind to simulate this type of a discharge with a commercial FEA code. As such there are some limitations to the simulation. However, the simulation can be used to investigate the following:
1.Any metal, electrode geometry, discharge gap, or dielectric media can be studied
2.Primary Beam Physics
– Electron velocity/acceleration (direct calculation of electron temperature)
– Energy deposition on the anode from all emission sources
– Effect of dielectric media on beam physics (trajectories, velocity, constriction, beam induced magnetic fields, space chare, and secondary emission)
– Beam current
– Particle trajectories (including relativistic effects)
3. Secondary Particle Generation and physics
– Atomic species (neutral particles or ions) and secondary electron emission
– Particle trajectories
– Back ion bombardment on the cathode
26
Chvátalová, Barbora. "Kapalné výpusti 14C v českých jaderných elektrárnách a odhad jejich radiologických dopadů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295644.
Abstract:
This thesis deals with the determination of 14C activity in liquid discharges from the Czech nuclear power plants and with the estimation of their radiological impacts on the vicinity of nuclear power plants. This work summarizes the issue of 14C liquid discharges of several nuclear power plants in the world and Czech nuclear power plants are compared to them. The sewage routs of liquid discharges from control tanks to waste water station are described in this thesis for both power plants - Dukovany and Temelín. Measured values of the 14C activity in liquid discharges from nuclear power plants Temelín and Dukovany are presented in this work. The procedure for calculating the exposure of representative persons as a result of liquid discharge of 14C activity is described in this thesis. The resulting values of annual commited effective dose for each age category of representative persons are presented in this work.
27
Bagiante, Salvatore. "Carbon Nanotubes: Synthesis, Characterization and Integration." Thesis, Universita' degli Studi di Catania, 2011. http://hdl.handle.net/10761/107.
Abstract:
Today many different techniques are used for CNT synthesis, and the main issues concern the production yield/cost ratio and the determination and control of the produced material and its properties. Moreover, still a lot of improvement on the CNT synthesis remains to be achieved in order to have CNT grown on selected areas, with a given diameter and chirality, thereby enabling the production of well defined devices.
The main aim of this work is the study of CNT synthesis by one of the techniques that allows high yield/cost ratio: arc discharge in liquid nitrogen. This method still needs to be fully understood in order to achieve a good control of the produced nanomaterials and their properties by the use of suitable experimental parameters. This thesis work gives a contribution towards the comprehension of the arcing process for CNT production. The second aspect that has been considered in this work is the use of CNTs for the fabrication of new and innovative devices. The unconventional approach considered here is the use of ultra-clean nanotubes, grown by chemical vapor deposition (CVD) in the last fabrication step, after all the device structure has already been completed.
In summary, the outline of the thesis is the following: after an introductive chapter on the basic properties of CNTs, with a discussion of theoretical concepts as well as fundamental experimental results (chapter 2), the next chapter (chapter 3) is devoted to the study of MWCNTs produced by arc-discharge in liquid nitrogen (LN2). In this technique, liquid nitrogen substitutes both vacuum and cooled systems. A morphological and structural characterization of the C nanostructures obtained as the experimental parameters are varied, has been performed, by electron microscopy techniques (SEM, TEM) and Raman spectroscopy. MWCNTs produced by this technique, have a high-quality, small innermost tube diameter and, for particular synthesis conditions, hybrid system, formed by linear C chains inserted in MWCNT (LCC@MWCNTs), can be produced. LCCs have attracted considerable fundamental and practical interest in material science and astrophysics. Two different kinds of linear carbon chains exist: polyyne, with alternate single-triple bonds on the chain, and cumulene, with double bonds only. Polynnes, in particular, can be considered as precursors for carbon materials such as carbine, fullerenes and nanotubes; they are candidates for molecular wires, molecular devices for electron transport through bonds or electronic communication, and the interpretation of some IR bands from the interstellar powder could be related to the presence of sp-coordinated carbon. In the last chapter (chapter 4), we present the fabrication steps of a device based on ultra-clean suspended nanotubes and preliminary results obtained by electrical and optical measurements. The use of ultra-clean carbon nanotubes gives many advantages such as: (i) nanotube not exposed to electron beam, (ii) in the optical measurement the brightness is 10-100 times higher of the conventional device, (iii) using suspended nanotubes we remove all possible interaction with the substrate, and (iv) in the electrical measurement the signal/noise ratio is very high. The resistance of different conductive materials (metals or alloys) during the CVD growth of CNTs (T=900à à à ºC with Ar, H2 and CH4 gasses) has been evaluated, in order to choose the most suitable ones to create the contacts with the nanotube. Moreover, we have demonstrated that not only it is possible to have electrostatic doping of a CNT by using different gates, but even that it is possible to have an extremely precise control of the spatial electrostatic doping and therefore the p-n junction position along the CNT, by changing the voltage applied to each gate.
28
Němcová, Lucie. "Interakce plazmatu s kapalnou fází." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-233370.
Abstract:
Disertační práce se zabývá detailním studiem vlastností různých elektrických výbojů generovaných ve vodných roztocích. Tyto výboje se staly v posledním desetiletí velmi populárním tématem, a to zejména díky mnoha praktickým využitím jako například v biomedicíně, čištění odpadních vod, ekologii nebo nanoinženýrství. Studium je zaměřeno na generaci peroxidu vodíku, jakožto jednu z nejvýznamnějších částic generovaných právě elektrickými výboji v kapalinách. Pro první část této práce byla využita speciální výbojová komora zkonstruovaná na Fakultě chemické Vysokého Učení Technického v Brně. Komora byla rozdělena tenkou diafragmovou přepážkou na dvě poloviny, přičemž uvnitř přepážky se nacházela malá dírka. V každé části komory se nacházela jedna elektroda, a obě dvě části komory byly vyplněny kapalinou. Ze zdroje bylo do kapaliny aplikováno vysokofrekvenční napětí (1 a 2 kHz), které tak vlastně upravovalo roztok chloridu sodného (1.5 l). Bylo zjištěno, že tento druh napětí, v porovnání s DC, nezpůsobuje nežádoucí přehřívání roztoku (počáteční vodivost 100 - 800 S/cm) během jeho úpravy při zachování účinnosti produkce peroxidu. Experimentální aparatura pro druhou část práce byla sestavena na Gentské Univerzitě v Belgii. Stejnosměrný výboj byl generován v bublinách plynů (He, Ar, N2, vzduch) v prostředí vodných roztoků. Byla studována generace peroxidu vodíku a odbourávání organických barviv přítomných ve zkoumaném roztoku. Ke generaci peroxidu vodíku byl použit roztok NaH2PO4 . 2H2O (5 microS/cm, V= 750 ml), ke zkoumání rozkladu barviv byly použity roztoky organických barviv Direct Red 79 (20 mg/l) a Direct Blue 106 (20 mg/l, V= 750 ml). Minimální koncentrace peroxidu vodíku byla naměřena při aplikaci proudu 10 mA, zatímco maximální koncentrace peroxidu vodíku byla zaznamenána při použití proudu 30 mA. Rozklad organických barviv vykazoval stejné vlastnosti. Čím vyšší byla dodávaná energie, tím více barviva se odbouralo. Třetí část práce probíhala ve spolupráci s Queen's University of Belfast, Centrum for Plasma Physics, UK. K realizaci experimentů bylo využito vysokofrekvenčního plazmového skalpelu (Arthrocar). Bylo zjištěno, že hodnota koncentrace peroxidu vodíku dosahovala maxima v roztocích s nepatrným přídavkem alkoholu (0.25 %). Celkem byly studovány čtyři 0.15 M roztoky BaCl2, Na2CO3, KCl a NaCl (V= 20 ml), jejichž počáteční vodivost se pohybovala kolem 13 mS/cm. Z výsledků bylo patrné, že největší rozdíl hodnot pH byl zaznamenán u roztoků s přídavkem ethanolu. V optických emisních spektrech byly identifikovány především radikály OH, které jsou prekurzory peroxidu vodíku. Výsledky ukázaly, že plazma v takovémto roztoku je stále tvořeno, což může být považováno za první krok generace plazmatu v organických sloučeninách. Poslední část práce byla zaměřena na tzv. mikroplazmatický jet v přímém kontaktu s kapalnou fází. Tato experimentální práce byla realizována na pracovišti Nanotechnology & Integrated Bio-Engineering Centre (NIBEC), University of Ulster, UK během studijní stáže. Jako vodivé médium byl použit roztok trihydrátu kyseliny chlorozlatité s různou počáteční vodivostí. Zajímavým zjištěním je fakt, že při tomto druhu měření bylo generováno stabilní plazma i při velmi malém výbojovém proudu (0.05 a 0.2 mA), a tedy i peroxid vodíku vznikal při velmi malé vstupní energii, což může být považováno za velmi dobrý výsledek.
29
Okubo, H., M. Hazeyama, N. Hayakawa, S. Honjo, and T. Masuda. "V-t characteristics of partial discharge inception in liquid nitrogen/ PPLP/sup /spl reg// composite insulation system for HTS cable." IEEE, 2002. http://hdl.handle.net/2237/6762.
30
Muslim, Joko. "Study of dielectric liquids as alternative encapsulant for high temperature electronics power modules applications." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAT109.
Abstract:
La recherche et le développement sur les matériaux semi-conducteurs ont permis de transformer la technologie des dispositifs électroniques de puissance, avec une densité de puissance, des performances thermiques et un dimensionnement plus compacts. Ils permettent aux appareils de fonctionner à des tensions, températures et fréquences de commutation plus élevées dans les modules de puissance. Pourtant, ces développements ne sont pas suivis de la même manière par d’autres éléments, tels que les encapsulants.Avec un matériau d'encapsulation récent, à savoir un gel de silicone, la température maximale de fonctionnement ne peut pas dépasser 200 ° C alors que les dispositifs à semi-conducteurs WBG sont très supérieurs (par exemple, du SiC à 500 ° C). Il s’agit là d’un obstacle majeur car il joue un rôle important dans la protection mécanique et électrique d’un module de puissance. Dans ce travail, nous proposons des liquides diélectriques comme agent d’encapsulation alternatif pouvant avoir une performance thermique supérieure au gel de silicone. Les caractérisations diélectriques de plusieurs candidats ont été effectuées dans le cadre d’une cellule d’essai spécialement conçue, capable de chauffer à haute température dans un environnement contenant de l’azote afin d’éviter les risques d’incendie et d’oxydation. Nous avons mesuré la conductivité de liquides soumis à une variation de température en appliquant une spectroscopie de champ alternatif dans une large plage de mobilité fréquentielle et ionique sous une variation de polarité inverse en courant continu. Nous étudions l'influence de la température et de la pression sur les pannes avec des champs quasi uniformes et divergents, ainsi que des décharges partielles, aussi bien dans les liquides que dans les substrats céramiques noyés dans des liquides, afin de démontrer leurs applications dans les modules de puissance. Des modèles numériques ont également été développés par simplification à partir des résultats de spectroscopie diélectrique afin d'estimer et d'observer la distribution de champ à un point triple critique.Enfin, nous présentons une comparaison de candidats liquides et de gel de silicone pour montrer leurs avantages et leurs inconvénients pour les applications d’électronique de puissance à haute température. Néanmoins, ces travaux ne couvrent pas tous les aspects fondamentaux et d’applications tels que le vieillissement thermique, la capacité de refroidissement des liquides, etc., ces résultats ont établi une bonne base pour les liquides diélectriques dans les applications à haute températureTodays, power electronics cover wide range of applications in our daily life, starting from household appliances, communications, transportation systems up to harsh and extreme environment as in oil and gas exploration and the deep space missions. The main deliveries of power electronics are energy efficiency, compact size, reliability, long durability. Improving power electronics will surely mean to deal with materials, the packaging system, switching technologies, heat dissipation, dielectric properties, thermal stability etc. It was since the first arc-mercury rectifying in traction system, and then reshaped by the discovery of classical semiconductor (Si based) and ultimately the wide bandgap semiconductor materials, such as SiC, GaN and carbon based (diamond). They have superior thermal and dielectric properties compared to previous classical semiconductor technologies (Ge, Si and GaAs), and allow devices to operate at higher voltage, temperature and switching frequency in power modules. Unfortunately, these developments are not equally followed by other parts within, such as encapsulant.Despite their key roles to provide mechanical and electrical protection inside a power module, silicone gel as major encapsulant is limited to 200°C, which is far below devices (e.g. SiC at 500°C). Encapsulant came from polymerization and curing process of silicone liquids mixture and transforms into gel. They worked very well when assembly with classical SC devices, but not with WBG SC. Thus, it is necessary to solve this thermal related issue by improving silicone gel or start looking for other type of encapsulant with better thermal performance such as dielectric liquid or gas.Dielectric liquids have been used as insulating medium for high voltage (HV) applications for decades. Their excellent self-healing and arc quenching properties were used in the HV circuit breaker applications even though nowadays replaced by gas. Their low viscosity allow the fluid flow to exchange heat from internal source yielding effective cooling system as in power transformers. Other industries use dielectric liquids as heat transfer liquid at much higher temperature range compare to those in HV applications. Of course as heat transfer liquids, their dielectric properties are out of considerations. Nevertheless, having this wide range of applications spectrum, dielectric liquids seem rather promising and potential as alternative encapsulant. Some questions then aroused such as how are their electrical properties at high temperature (HT) approx. 400°C, are their dielectric properties stable at HT and can they contribute to cooling of devices inside power module.This work presents the initial study of dielectric liquids for HT power electronics module applications. We demonstrated the electrical characterization of several dielectric liquids under influence of temperature such as dielectric spectroscopy and ion mobility measurement, partial discharge, streamers and breakdown. Interesting physical phenomena such as liquid motions due to EHD and natural thermal convection were observed during experiments. Comparison among liquids are showed to indicate the most convenient. In term of application, conditions were adapted and simplified to replicate as those in power module when we performed characterizations to actual ceramic substrates under quasi-uniform to highly divergent electric field with AC, DC and impulse voltage. Many fundamental behaviours of liquids have been confirmed and evidenced at HT range. Governing parameters for electrical properties such as breakdown, charge injection etc. were affirmed.While not all aspects of encapsulant requirement in term of HT are covered, this work has established essential basis for electrical properties of dielectric liquids. Further works are required to fully assess their compatibility as alternative encapsulant, such as thermal ageing process, cooling contribution, complete modelling, etc
31
Kabbara, Hiba. "Élaboration de nanoparticules par décharges spark nanosecondes dans des liquides diélectriques : compréhension des mécanismes élémentaires et synthèse de composites." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0038/document.
Abstract:
La production de nanoparticules (NPs) par des décharges spark en phase liquide permet d’atteindre des rendements jusqu’à présent inégalés de l’ordre de quelques centièmes de milligramme par joule. Même si l’essentiel de l’énergie est dissipé dans la formation de la décharge, l’érosion des électrodes métalliques permet la production efficace de NPs. La nature des NPs formées est largement tributaire du liquide diélectrique dans lequel la décharge est réalisée. Il est ainsi possible de contrôler les nanoparticules produites en choisissant de manière ad hoc les électrodes et le liquide. Nous cherchons dans ce travail à comprendre les mécanismes qui ont lieu durant la décharge en étudiant différents cas d’élaboration de NPs soit d’alliages soit de composites. Les NPs synthétisées auront des applications dans divers domaines selon le(s) matériau(x) choisi(s). À l’aide d’un générateur d’impulsions nanosecondes, les décharges ont été créées en appliquant une impulsion de haute tension (10 kV- 200ns- 10 Hz) entre deux électrodes immergées dans de l’azote liquide. Trois systèmes principaux ont été étudiés : Si-Sn, Cu-Zn et Cu-Ag. Les tests ont été réalisés avec des électrodes pures ou avec des alliages contenant les 2 éléments en proportions variables pour améliorer notre compréhension sur la manière dont les nanoparticules sont formées. Des analyses en microscopie électronique en transmission à haute résolution (HRTEM), en spectroscopie des rayons X à dispersion d'énergie (EDX), en spectroscopie de perte d'énergie des électrons (EELS) et des analyses de micro-diffraction ont été menées pour caractériser les NPs synthétisées (morphologie, cristallinité, composition chimique, etc.). Enfin, des mesures de spectroscopie d’émission optique résolues dans le temps ont été réalisées pour disposer d’informations sur l’évolution temporelle des raies émises au cours de la décharge et ainsi sur les conditions qui prévalent dans le plasmaDischarges in liquids offer a simple way to synthesize nanoparticles at high rate and low cost. When spark discharges are ignited in a dielectric liquid, a strong heating of the electrode material occurs, producing a metallic vapor from which nanoparticles grow by condensation. Even if most of the energy is dissipated in the formation of the discharge, the erosion of the metal electrodes allows the efficient production of NPs. The nature of the NPs formed is largely dependent on the dielectric liquid in which the discharge is performed. It is thus possible to control the nanoparticles produced by choosing the electrodes and the liquid in an appropriate manner. We seek in this work to understand the mechanisms that take place during the discharge by studying different cases of elaboration of NPs either alloys or composites. The synthesized NPs will have applications in various fields depending on the material(s) chosen. Using a nanosecond pulse generator, the discharges were created by applying a high voltage pulse (10 kV-200ns-10 Hz) between two electrodes immersed in liquid nitrogen. Three main systems have been studied: Si-Sn, Cu-Zn and Cu-Ag. The tests were performed with pure electrodes or alloys containing the 2 elements in varying proportions to improve our understanding of how nanoparticles are formed. High resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), electron energy loss spectroscopy (EELS) and micro-diffraction analyzes were carried out to characterize the synthesized NPs (morphology, crystallinity, chemical composition, etc.). Finally, time-resolved optical emission spectroscopy measurements were performed to obtain information on the temporal evolution of the lines emitted during the discharge and thus on the conditions that prevail in the plasma
32
Klímová, Edita. "Elektrické výboje ve vodných a organických roztocích." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216930.
Abstract:
This work is focused on study of electrical discharges in liquids, especially in water solutions. Generation of the discharge in water solutions leads to simultaneous effect of UV radiation, shock waves, electrical field and most importantly, chemically reactive species. This can be utilized in many applications such as sterilization, degradation of organic waste products, lithotripsy or other medical applications. The experimental part is concentrated on a diaphragm arrangement of the reaction system. This means that the reactor is divided into two electrode reservoirs connected only through a small orifice in a dielectric barrier. This barrier is made of Macor® non-porous ceramics with thickness of 1 mm, with the diameter of the orifice 0.6 mm, in the first part of work. In the second part, ShapalTM-M ceramics of thickness 1.0 mm and orifice diameter 0.6 mm was used. The experimental part is divided into two sections. For both, NaCl is chosen as an electrolyte to set the initial conductivity of the tested solutions to the value of 400 S/cm. Supplied direct voltage is regulated to attain power of 100 W in the system. In the first part, effect of addition of chosen alcohols (ethanol, isopropylalcohol and glycerol) on the efficiency of the discharge in their water solutions is studied. For this purpose, a special glass reactor was designed and constructed. The efficiency of the discharge is measured by a spectroscopic determination of concentration of complex formed by a titanium reagent and hydrogen peroxide, which is generated during the discharge. The results show no positive effect of addition of extra OH group to the reaction through the alcohols. The use of isopropylalcohol causes even a significant decrease in the amount of hydrogen peroxide generated. The subject of the second part is a comparison of effect of different electrode materials on the discharge. The efficiency is measured by the same method as in the first part. Materials chosen were stainless steel, platinum, aluminium, copper and carbon. Each material shows different hydrogen peroxide production rate under the same parameters. The most perspective material seems to be carbon, as an inert material, that can be expected not to initiate any decomposition of hydrogen peroxide. The least favourable appears to be copper. When used, no production of hydrogen peroxide was observed in one of the electrode parts of the reactor.
33
Adámková, Barbora. "Diagnostika plazmatu generovaného ve směsích vody a alkoholů." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414082.
Abstract:
This diploma thesis is aimed to the corona-like discharge in solutions of alcohols, specifically in ethanol, methanol, glycerol, butanol and isopropyl alcohol. The electric discharge was diagnosed by two methods. The first method was the measuring of electrical characteristics. Current-voltage characteristics were constructed from the measured average values of voltage and current. The breakdown voltages were determined from the current-voltage characteristics. The breakdown voltages of the individual alcohol solutions were dependent on the alcohol concentration, polarity of the electrodes in the reactor and solution conductivity. The breakdown voltage was determined for solutions of butanol, glycerol and isopropyl alcohol with a concentration of 20 vol. % and conductivity of 200 µS. The highest value of the breakdown voltage was determined for solution of glycerol at 580 V. The lowest voltage at which the discharge was observed was estimated for butanol (320 V), but due to the limited miscibility with water this value is inaccurate, and therefore in the second part of experiment butanol was not used. Alcohol series was supplemented with methanol. The second diagnostic method was the proton ionization mass spectrometry with the time of flight analyzer. The products formed in the reactor due to the plasma discharge were identified from the mass spectrum. Mostly, aliphatic hydrocarbons and their radicals were detected. The amount of products was observed in the dependence on the changing experimental conditions: alcohol concentration in the solution, the polarity of the electrodes in the reactor and the duration of the discharge. Only a small amount of compounds were detected in methanol. However, more molecules were formed with the increasing carbon chain in the alcohol molecule. More compounds were also detected with the increasing alcohol concentration and in case of the negative polarity of the main electrode. The formation of acetaldehyde as a typical discharge product was studied in details. Its production in time was observed and the reaction pathways of its formation in the ethanol solution were suggested.
34
Kogelheide, Friederike [Verfasser], Peter [Gutachter] Awakowicz, and Katharina [Gutachter] Stapelmann. "Characterisation of a dielectric barrier discharge and its impact on liquids and biological systems / Friederike Kogelheide ; Gutachter: Peter Awakowicz, Katharina Stapelmann ; Fakultät für Elektrotechnik und Informationstechnik." Bochum : Ruhr-Universität Bochum, 2021. http://d-nb.info/1226428630/34.
35
Procházková, Michaela. "Studium působení plazmatu na roztoky chininu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-414084.
Abstract:
This diploma thesis focuses on quinine solutions and quality of these solutions after applying plasma discharge. These electric discharges can be used to destroy some substances from the water. The theoretical part is focused on description of electric discharges in liquids and on the properties of quinine. In the experimental part, the properties of quinine solutions containing different electrolytes were analysed by UV-VIS spectrophotometer and fluorescence spectroscopy. Two different types of configurations of plasma discharges in liquids were used. Solutions were compared on the base of different concentration of quinine, different electrolytes, different configurations of plasma discharges and pH values of the solutions. Furthermore, the experimental work focuses on quinine solutions with the sodium nitrate. The time instability of the solutions was analysed. Also, the influence of the solution age and different types of the plasma discharge on the excitation and emission spectra of quinine were investigated.
36
Iost, Caroline. "Produção de sedimentos e qualidade da água de uma microbacia hidrográfica rural." Universidade Estadual do Oeste do Parana, 2008. http://tede.unioeste.br:8080/tede/handle/tede/285.
Abstract:
Made available in DSpace on 2017-05-12T14:47:46Z (GMT). No. of bitstreams: 1
Caroline Iost.pdf: 1234608 bytes, checksum: d5a0ddd1cd06d5366dc84b88a138a1dc (MD5)
Previous issue date: 2008-02-12Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The objective of this work was to evaluate the influence of land use in the production of sediment and water quality of the micro basin of river Mandarina micro basin, located in the city of Cascavel-PR. The liquid discharge, the suspended sediment and the physic-chemical parameters dissolved oxygen (DO), electrical conductivity, pH, temperature of the water, turbidity, color, nitrate, nitrite, total nitrogen, total phosphorus was monitoring between the months January and August 2007 at the river's main. It was determined the curve-key of the liquid discharge and discharge of suspended solid, which showed good correlation (R2 equal to 0.98 and 0.93, respectively). The results indicated a low production of sediment, average of 0,27 t dia-1 and good water quality, because the parameters have not gone beyond the limits praised by Resolution 345/05 of CONAMA for rivers, Class 2, with the exception of dissolved oxygen in some collections was below 5 mg L-1, color and total phosphorus which also exceeded the limits stipulated. Agriculture is the predominant activity in the micro basin (88%) and water courses have about 79% of the area of riparian forest required by law. It is believed that the soil management in the area of agriculture with practices such as tillage and system of terraces, as well as the presence of riparian forest in rivers, influenced for the good quality water and low production sediment on the water.
O objetivo deste trabalho foi verificar a influência do uso do solo na produção de sedimento e na qualidade da água da microbacia hidrográfica da sanga Mandarina, localizada no município de Cascavel-PR. A vazão, o sedimento em suspensão e os parâmetros físico-químicos da água, oxigênio dissolvido (OD), condutividade elétrica, pH, temperatura da água, turbidez, cor, nitrato, nitrito, nitrogênio total e fósforo total foram monitorados entre os meses de janeiro e agosto de 2007, no principal rio da microbacia. Determinou-se a curva-chave da vazão e da descarga sólida em suspensão, as quais apresentaram boa correlação (R2 igual a 0,98 e 0,93, respectivamente). Os resultados indicaram uma baixa produção, média de 0,27 t dia-1 de sedimento e uma boa qualidade da água, pois os parâmetros não ultrapassaram os limites regidos pela Resolução 345/05 do CONAMA para rios de Classe 2, com exceção do oxigênio dissolvido que em algumas coletas esteve abaixo de 5 mg L-1, cor e fósforo total que também ultrapassaram os limites estipulados. A agricultura é a atividade predominante na microbacia (88%) e os cursos d água apresentam cerca de 79% da área de mata ciliar exigida por lei. Acredita-se que o manejo do solo na área agricultável com práticas como o plantio direto e sistema de terraços, assim como a presença de mata ciliar nos rios influenciaram para o boa qualidade da água e baixa produção de sedimento no curso d água.
37
Nguyen, Thi Hai Van. "Spectroscopie d'émission d'un plasma crée par des décharge couronne dans l'hélium." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT002/document.
Abstract:
La spectroscopie d’émission est un outil puissant pour obtenir des informations sur lesprocessus microscopiques dans un plasma de décharge hors-équilibre (décharge couronne)dans des milieux denses tels que le gaz supercritique à haute pression et les liquides. Lesobservations spectroscopiques de la lumière émise à partir d'une zone d'ionisation créée parune décharge entre une pointe fine et un plan sont utilisées pour caractériser l'environnementlocal des atomes ou des molécules émettrices. Les caractéristiques spectrales observablesétant sensibles à l'environnement immédiat de l'espèce émettrice, rend la spectroscopieoptique très utile pour l'étude du plasma hors-équilibre en fonction des paramètres du milieu(pression et température).Dans ce travail, nous avons étudié les caractéristiques courant-tension et lacomposition spectrale d’un cryoplasma initié par une décharge couronne dans l'hélium liquideet gazeux à des températures cryogéniques. Ces expériences ont été effectuées pour un certainnombre de températures fixes de 300 K à 4,2 K dans une plage de pression de 0,1 à 10 MPa.Ces conditions couvrent une large région des états thermodynamiques de la matière avec unedensité d'environ 1019 cm-3 pour le gaz à une densité de 2*1022 cm-3 pour le liquideFluorescence spectroscopy is a powerful tool to obtain information on microscopicprocesses in non-equilibrium discharge plasma (corona) in dense media such as high pressuresupercritical gas and even liquids. Spectroscopic observations of the light emitted from anionization zone near a tip electrode can be used to determine structural information of thelocal environment of the emitting atoms or molecules. The spectral features observable aresensitive to the immediate surroundings of the emitting species, which makes emissionspectroscopy very useful for study of the cold nonequilibrium plasma varying the pressureand the temperature.In this work, we have studied the current-voltage characteristics and spectralcomposition of helium cryoplasma initiated with a corona discharge in gaseous and liquidhelium. A cryoplasma has been realized in laboratory conditions using corona discharge ingaseous and liquid Helium at cryogenic temperatures of the matter. Experiments were carriedout at a number of fixed temperatures from 300 K down to 4.2 K within the pressure range0.1÷10 MPa. The conditions covered a wide region of thermodynamic states of the mattersuch as from a gas with density of ~1019 cm-3 up to liquid Helium with density of 2*1022cm-3
38
Maier, Marcus R. "Onsets of liquid and gas entrainment during discharge from a stratified air-water region through two horizontal side branches with centerlines falling in an inclined plane." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ32176.pdf.
39
Haidara, Modibo. "Impulsions de Trichel dans le cyclohexane liquide et les gaz comprimés." Grenoble 1, 1988. http://www.theses.fr/1988GRE10160.
Abstract:
Resultats d'etude de la conduction electrique de liquides non polaires tres purs (cyclohexane, n-propane) en geometrie pointe-plan, en fonction du rayon de courbure de la pointe et de la pression hydrostatique (p<->10**(7)pa)
40
Sumonsiri, Nutsuda. "Effect of Powder and Target Properties on Food Powder Coating and Comparison of Solid-liquid Separation (SLS) and Vacuum Concentration of Tomato Juice." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1336625577.
41
Scheiber, Julia [Verfasser], and H. G. [Akademischer Betreuer] Stosch. "Formation of Precipitates in a Desalination Plant with Zero Liquid Discharge : Identification of the main Processes by Mineralogical-Geochemical Methods and Modelling / Julia Scheiber. Betreuer: H.-G. Stosch." Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1020663537/34.
42
Tmenova, Tetiana. "Étude expérimentale de la décharge électrique pulsée dans l'eau." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30248.
Abstract:
Bien que le procède de dispersion par arc électrique soit connu depuis un certain temps, le plasma formé durant ce procédé est encore peu étudié et compris. La complexité des phénomènes se produisant durant les décharges immergées génèrent de nouveaux obstacles à la caractérisation de tels plasmas, du fait de la faible taille et de la durée souvent très courte, les difficultés liées à l'environnement de la décharge, leur nature stochastique et la faible reproductibilité. Le principal objectif de cette thèse est l'étude du plasma se formant lors de la synthèse de colloïdes métalliques par un générateur de dispersion par étincelle électrique. Le premier résultat concluant de ce travail a été de démontrer la faisabilité de la spectroscopie optique d'émission pour le diagnostic de telles décharges. Les efforts réalisés pour le développement d'une approche expérimentale ont permis d'atteindre les objectifs de recherche. Les résultats obtenus au cours de ce travail permettent de tirer des conclusions intéressantes sur les propriétés physiques des plasmas de décharge électrique pulsée dans la configuration étudiée. La décharge est créée à partir d'un court-circuit et d'un amorçage par pont fondu. L'allumage de l'arc est caractérisé par la formation d'une bulle causée par une onde de choc de pression. L'imagerie rapide a permis de distinguer deux phases dans la durée de vie de la décharge : d'abord un plasma dans l'eau, puis un plasma à l'intérieur d'une bulle de gaz formée par la suite. Du point de vue de la condensation de la matière vaporisée, on peut s'attendre à ce que ces deux phases conduisent à des conditions de trempe différentes, et en conséquence des conditions de synthèse différentes. Dans le cas d'une décharge générée entre des électrodes en molybdène, une émission de lumière décroissant lentement après la fin de la décharge se produit, ce qui peut être attribué à l'éjection de particules métalliques érodées. La dissipation de l'énergie aux électrodes s'est avérée être différente pour le cuivre et le molybdène : du fait d'une conductivité thermique plus faible pour le molybdène, une part plus faible de l'énergie transférée aux électrodes conduit à une part plus importante de l'énergie fournie à la colonne d'arc. Les mesure par spectroscopie optique d'émission ont permis d'établir que la densité (~ 10 17 cm-3) et la température modérée (0.6 - 0.95 eV) du plasma correspondent à une pression supérieure à 1 bar. Il présente donc quelques effets non-idéaux, tels que l'élargissement et la forme asymétrique de la raie Ha et l'absence de la raie Hß. En général, les paramètres du plasma se sont avérés être relativement insensibles à la plupart des paramètres de la décharge, tels que le courant de décharge ou le type d'eau, les principales différences étant liées aux matériaux des électrodes utiliséesAlthough electric spark dispersion processes have been known for a while, the plasma created during this process is not well-studied and understood. The complexity of the phenomena occurring during the underwater electric discharges brings additional obstacles to experimental characterization of such plasmas imposed by as small sizes of plasma and their often-short duration, difficult environment of the discharge, its stochastic nature and poor reproducibility. The main objective of this thesis was set on the investigation of the plasma occurring during the synthesis of metal colloids by an electrospark dispersion generator. The first success of this work was simply to show the applicability of optical emission spectroscopy diagnostics to such discharges. The efforts made for the development of the effective experimental approach in order to meet this research objective have been well rewarded. The results obtained in this work allow to draw interesting conclusions about the physical properties of the underwater pulsed electric discharge plasma of the considered configuration. Discharge ignites from the short circuit and molten bridge mechanism. Ignition of the arc is characterized by formation of bubble resulting from a pressure shockwave. High-speed imaging allowed to distinguish two phases in the discharge lifetime: plasma in water, and plasma in bubble formed afterwards. From the vapor condensation point of view, these two phases presumably lead to different quenching conditions, and, consequently, to the different synthesis conditions. In the case of discharge generated between molybdenum electrodes, there is a slowly-decaying light emission after the end of the discharge which can be attributed to the ejection of eroded metallic particles. The energy dissipation on the electrodes was found to be different for copper and molybdenum: due to the lower thermal conductivity of molybdenum, smaller portion of energy transferred to the electrodes results in higher energy input into the arc column. Spectroscopic measurements allowed to establish that plasma density (~ 10 17 cm-3) and moderate temperature (0.6 - 0.95 eV) correspond to a pressure greater than 1 bar. Moreover, plasma presents several non-ideal effects, such as broadening and the asymmetrical shape of the Ha line and absence of Hß line. In general, plasma properties were found to be relatively insensitive to most of the discharge parameters, such as the discharge current or the type of liquid with the main differences being associated to the used electrodes material
43
Holíková, Lenka. "Diagnostika plazmatu výboje ve vodných roztocích a jeho aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216715.
Abstract:
This thesis deals with the study of parameters of diaphragm discharge in liquids. NaCl solution of different conductivity was used as a conductive medium. Conductivities were adjusted in the range from 220 to 1000 µS cm-1. Two diagnostic methods were used for the study of plasma parameters. The first one was employed in the laboratory of plasma chemistry at Faculty of Chemistry, Brno University of Technology, namely the optical emission spectroscopy. The second method used for plasma diagnostics was the time resolved ICCD camera at the Laboratoire de Physique des Plasmas at the École Polytechnique in Paris. The reactor for the diagnostics by optical emission spectroscopy had the volume of 4 l, and it was made of polycarbonate. PET diaphragm was placed in the barrier separating the cathode and the anode space. Electrodes were made of titanium coated with platinum. Electric power source supplied a constant DC voltage of maximum 5 kV and electric current up to 300 mA. Spectrometer Jobin Yvon TRIAX 550 with CCD detector was used during the experiments in order to measure overview spectra within the range from 200 to 900 nm as well as OH molecular spectra and Hß line spectra. All spectra were scanned in both discharge polarities, i.e. at the cathode and the anode part of reactor. The basic parameters of the discharge plasma were calculated from the spectra, that means rotational and electron temperature and electron density. Another part of experiment consisted of measurements by the ICCD camera iStar 734. Two types of reactors were used. The first one was the same as the reactor for the measurements by the optical emission spectroscopy. The second one was also made of polycarbonate, but the volume of conductive solution was 110 ml, only. HV electrodes made of stainless steel were placed in this reactor. Ceramic diaphragm (Shapal-MTM) was used in both reactors. Diaphragms had different thickness and diameter of holes. ICCD camera acquired photographs with details of processes of the bubbles generation and discharge operation (propagation of plasma channels), depending on solution conductivity, dimensions of the diaphragm, and with respect to the electrode part of the reactor.
44
Massala, Gaston. "Propagation et propriétés électriques des streamers positifs à grande distance dans l'huile minérale sous très haute tension impulsionnelle." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0112.
Abstract:
L'objectif de ce travail est d'étudier la propagation des précurseurs du claquage ("streamers" en anglais) et leurs propriétés électriques dans l'huile minérale à grande distance sous tension impulsionnelle (jusqu'à 480 kV) dans diverses conditions de tension appliquée (de la tension minimum de propagation jusqu'aux fortes surtensions), de distance inter¬électrode (de 2,5 à 35 cm), de géométrie des électrodes (pointe-plan, semi-uniforme, sphère-plan) et en présence de solides isolants. Ce travail apporte une contribution sur la caractérisation des phénomènes de claquage et des mécanismes mis en jeu dans les streamers positifs. Pour des tensions inférieures à la tension de claquage, l'arrêt, la transition au claquage et la conductibilité des streamers sont décrits. En particulier, il a été montré que le streamer n'est conducteur que durant une réillumination totale de sa branche principale. En présence de surtensions, l'existence d'une tension d'accélération corrélée à l'apparition des streamers rapides est mise en évidence. Trois modes de propagation différents sont identifiés et caractérisés: 2e™ mode (2 à 4 km/s), 3eme mode (10 à 20 km/s) et 4cme mode (>100 km/s). Une corrélation entre la forme, la vitesse et la charge des streamers a été mise en évidence et la chute de tension dans le streamer a été déterminée. Les calculs de la charge et du champ sur l'électrode plane réalisés par la Méthode de Simulation de Charge (CSM) en considérant différents modèles macroscopiques en présence d'une chute de tension ont permis de conclure que les streamers sont comparables à des objets assez conducteurs de forme simple (cylindre ou sphère). Une corrélation qualitative entre le champ macroscopique à l'extrémité des streamers calculé par CSM, et la vitesse a été obtenue. E existe un champ critique =400 kV/cm, au-delà duquel les streamers sont toujours rapides (> 10 km/s). Ce travail propose deux mécanismes complémentaires permettant d'expliquer la constance de la vitesse des streamers positifs dans l'huile minérale: l'effet de la chute de tension et/ou l'effet électrostatique dû à la ramification des streamers. H a été montré que la forme globale des streamers détermine le champ à leur extrémité et par conséquent les modes de propagation. Ceci a été vérifié en étudiant l'influence de la géométrie des électrodes (effet d'écran), des solides isolants (effet de la position) et de la nature du liquide (effet des additifs)The aim of this work is to study the propagation of the "streamers" and their electrical properties in mineral oil at long distances under pulsed voltage (up to 480 kV) under various voltage conditions (from the minimum propagation voltage to the high overvoltages), inter-electrode distance (2. 5 to 35 cm), electrode geometry (plane-to-plane, semi-uniform, planar sphere) of solid insulators. This work makes a contribution on the characterization of the breakdown phenomena and the mechanisms involved in the positive streamers. For voltages below the breakdown voltage, stopping, transition to breakdown and conductivity of the streamers are described. In particular, it has been shown that the streamer is conductive only during a total re-ignition of its main branch. In the presence of overvoltages, the existence of an acceleration voltage correlated with the appearance of the fast streamers is highlighted. Three different propagation modes are identified and characterized: 2nd mode (2 to 4 km / s), 3rd mode (10 to 20 km / s) and 4th mode (> 100 km / s). A correlation between the shape, speed and load of the streamers was highlighted and the voltage drop in the streamer was determined. Calculations of the charge and field on the plane electrode carried out by the Load Simulation Method (CSM), considering different macroscopic models in the presence of a voltage drop, have led to the conclusion that the streamers are comparable to objects conductors of simple shape (cylinder or sphere). A qualitative correlation between the macroscopic field at the end of the streamers calculated by CSM, and the speed was obtained. E there exists a critical field = 400 kV / cm, beyond which the streamers are always fast (> 10 km / s). This work proposes two complementary mechanisms allowing to explain the constancy of the speed of the positive streamers in the mineral oil: the effect of the voltage drop and / or the electrostatic effect due to the branching of the streamers. It has been shown that the overall shape of the streamers determines the field at their end and hence the propagation modes. This has been verified by studying the influence of electrode geometry (shielding effect), insulating solids (positional effect) and the nature of the liquid (additive effect)
45
Clermont, Paul Daniel Stanley. "Characterization and prediction of flow electrification phenomena in fuel tanks of aeronautical structures." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2258/document.
Abstract:
Avec la nouvelle génération d'avions composites, une attention est portée sur les systèmes de carburant vis-à-vis de la prévention des décharges électrostatiques (ESD) durant les phases de remplissage des réservoirs. La plupart des travaux réalisés en aéronautique a été menée sur des réservoirs métalliques. Toutefois, l'introduction des matériaux composites a soulevé de nouvelles interrogations, puisque ces matériaux peuvent avoir un comportement différent des métaux vis-à-vis de l'électrisation par écoulement, qui justifient pleinement de nouvelles analyses. Afin de définir correctement les structures des réservoirs et leur protection contre les risques ESD, il est crucial de comprendre comment un empilement complexe de matériaux se comporte en termes de création de charge lorsque ces matières sont en contact avec un carburant d'avion. La structure de ces matériaux et leurs propriétés électriques contrôlent le potentiel électrique atteint dans le réservoir à travers un équilibre entre la production, l'accumulation et la fuite des charges électriques. Ce potentiel peut dépasser le point d'éclair du mélange air/vapeurs de carburant et provoquer une inflammation. Diverses mesures de protection peuvent être adoptées pour contrôler ce phénomène, comme utiliser des additifs antistatiques dans les carburants, des réservoirs métalliques à la masse ou encore des réservoirs faits de matériaux non métalliques mais ne favorisant pas l'accumulation de charges. C'est principalement en réponse à cette dernière solution que ce travail est orienté afin de guider vers le choix optimaux des matériaux et une meilleure définition des structures du réservoirWith the new generation of composite aircrafts an attention is carried out on fuel systems with respect to prevention of electrostatic discharges (ESD) during the filling phases of the tanks. Most of the work realized in aeronautics (during the 60's) was conducted on metallic fuel tanks. However, the introduction of composite materials has raised new questions, since those materials can have a different behavior than metallic ones with respect to flow electrification, which fully justify new analyses. In order to properly define the tank structures and their protection against ESD hazards, it is crucial to understand how a complex stack of materials (conductive or not, multilayered or homogeneous, painted or not) constituting a fuel tank behaves with respect to the mechanisms of charge creation by flow electrification when these materials are in contact with aviation fuel. The structure of these materials and their electrical properties control the electric potential reached in the tank through a balance between the production, accumulation and leakage of the electrical charge. This potential may exceed the flash point of the fuel vapors/air mixture and induce ignition. Various protective measures can be adopted to control this phenomenon such as using antistatic additives in the fuels, lowering the rates ofthe fuel injection inside the tank, using only bonded metallic tanks or tanks made of non-metallic materials which do not favor charge accumulation or local charge trapping. It is majorly in response to the latter solution that this work is oriented in order to guide optimum choices of materials and a better definition of the tank structures
46
Bouras, Meriem. "Etude comparative et optimisation de prétraitements des écorces de bois pour l'extraction des composés phénoliques." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2245.
Abstract:
Ce travail de recherche porte sur l’intensification de l’extraction des polyphénols à partir des écorces de chêne pédonculé et d’épicéa commun par des technologies innovantes : les champs électriques pulsés (CEP), les ultrasons (US) et les micro-ondes (MO). Ces prétraitements permettent l’amélioration de l’extraction par endommagement des membranes et/ou parois cellulaires. L’effet de chacune de ces techniques (CEP, US et MO) sur l’extraction des polyphénols a été mis en évidence à travers une étude d’optimisation quantitative et qualitative : suivi du rendement des polyphénols, de l’activité antioxydante et caractérisation chimiques des composés extraits.Une étude comparative des prétraitements (CEP, US et MO) couplés à une diffusion en milieu hydro-alcoolique alcalin, a permis de mieux comprendre les mécanismes mis en jeu lors d’un traitement d’un tissu fibreux. L’étude a prouvé que l’efficacité du procédé est indépendante de la famille d’arbre à laquelle appartiennent les écorces (résineux ou feuillus). De plus, pour valoriser les écorces de bois, l’application d’un prétraitement par CEP (20 kV/cm, 200 impulsions, 3,2 kJ/g bois) suivi d’une diffusion semble être une alternative aux ultrasons, micro-ondes et à l’extraction avec des écorces préalablement broyées. En effet, grâce à l’action électrique et mécanique des CEP, ce prétraitement permet d’obtenir un extrait riche en polyphénols (10,5 g EAG/100g MS pour l’épicéa soit 83 % d’efficacité et 5 g EAG/100g MS pour le chêne soit 82 % d’efficacité)This research work focuses on the intensification of polyphenols extraction from Quercus robur and Norway spruce barks using innovative technologies : pulsed electric field (PEF), ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE). These pre-treatments enhance the release of intracellular compounds by damaging the membrane and/or cell wall. The effect of each of these technologies (PEF, UAE and MAE) on polyphenols extraction has been highlighted in a quantitative and qualitative optimization analysis by evaluating the polyphenols concentration, antioxidant activity and by the chemical characterization of the extracted compounds.A comparative study of pre-treatments (PEF, UAE and MAE) coupled with an extraction step in an alkaline hydro-alcoholic medium allowed us to better understand the involved phenomena. The induced process efficiency is independent of the tree family to which the bark belongs (coniferous and hardwood). For bark valorization, the application of PEF treatment (20 kV/cm, 200 pulses, 3.2 kJ/g bark) followed by a diffusion step seems to be an alternative to ultrasound and microwave assisted extractions and to the extraction from grinded barks. In fact, the electrical and mechanical effect of PEF treatment allow to obtain an extract rich in polyphenols (10.5 g GAE/100g DM and an efficiency of 83 % for Norway spruce and 5 g GAE /100g DM and an efficiency of 82 % for Quercus robur bark)
47
Vu, Thi Anh Tho. "Etude de l'origine des décharges partielles sur des substrats céramiques enrobés." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00612433.
Abstract:
Ce travail concerne l'étude du phénomène de décharges partielles dans les matériaux isolants utilisés en électronique de puissance. En utilisant des méthodes de détection électrique et optique, le mécanisme de décharge partielle sur des substrats d'AlN dans l'huile silicone a été étudié sur un grand nombre d'échantillons. La variation de la nature du substrat (AlN, Al2O3 et composite verre/époxy) et du matériau d'encapsulation (huile silicone, huile de colza, huile minérale de transformateur, liquide d'imprégnant du condensateur Jarylec et Ugilec) met en évidence l'origine des décharges partielles de l'ensemble substrat - encapsulant. Les décharges partielles sur les substrats céramiques frittés ne dépendent pas du passivant, et se produisent dans le volume du substrat. L'évolution temporelle de la lumière émise dans les liquides en configuration pointe - plan et sur le substrat dans différents liquides montre que l'émission de lumière est un phénomène très complexe influencé par de nombreux paramètres : électroluminescence du solide, de l'encapsulant, décharges partielles, absorption des matériaux. Le phénomène d'électroluminescence du liquide est activé par une illumination extérieure. Les mesures de spectroscopie diélectrique haute tension n'apportent pas d'information supplémentaire sur le phénomène de décharges partielles, car les pertes correspondantes sont très faibles. Mots clés : Décharge partielle, électroluminescence, Nitrure d'aluminium, Alumine, huile silicone, diélectrique liquide, électronique de puissance.
48
Nejezchleb, Martin. "Analýza degradačních produktů organického barviva po rozkladu v diafragmovém výboji." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216463.
Abstract:
The diploma thesis is focused on the identification of degradation products of organic dye Saturn Red L4B resulting by degradation in diaphragm discharge, using separation techniques with mass spectrometric detection.
49
Girard, Fanny. "Analyse physico-chimique de milieux liquides d’intérêt biologique exposés à des plasmas froids produits à pression atmosphérique et température ambiante." Thesis, Pau, 2017. http://www.theses.fr/2017PAUU3025/document.
Abstract:
Les plasmas froids sont des gaz partiellement ionisés, très riches d’un point de vue physico-chimique. Cette propriété se retrouve dans des plasmas froids aujourd’hui générés à pression atmosphérique et température ambiante et a été mise à profit depuis une quinzaine d’années environ pour des applications biomédicales (hématologie, dermatologie, cancérologie, odontologie etc…). L’efficacité de ces plasmas froids dans le domaine de la médecine a été prouvée par de nombreuses études. Cependant, les phénomènes biologiques mis en jeu ne sont pas encore bien compris, et il primordial de savoir quels pourraient être les éventuels effets secondaires indésirables de ces milieux ionisés réactifs. Le premier niveau d’interaction des plasmas avec le vivant est celui avec les milieux liquides, qui sont présents en surface des tissus, des cellules in vivo ou en culture. Depuis une décennie, une attention particulière a donc été portée aux interactions des plasmas avec les liquides, pour apporter un niveau de compréhension supplémentaire. La compréhension de ces interactions a constitué l’axe de ce travail. Différents réacteurs à plasmas froids (générés à pression atmosphérique et température ambiante) ont été développés, notamment afin de contrôler les interactions du plasma avec l’air ambiant qui peuvent être problématiques pour les applications visées. La nature du gaz servant à initier le plasma a été modifiée, pour connaître son influence sur la réactivité chimique de la phase gaz. Pour cela, des mesures de spectroscopie d’émission optique (SEO) ont été nécessaires. Par ailleurs, de nouveaux capteurs électrochimiques et des approches méthodologiques ont été développés pour identifier et quantifier les espèces réactives de l’oxygène et de l’azote (RONS) produites dans des milieux liquides physiologiques, exposés à ces gaz ionisés. Les analyses électrochimiques ont été combinées à de la spectroscopie d’absorption UV-visible ainsi qu’à d’autres méthodes de chimie (pH-métrie/conductimétrie). Un des objectifs visés est d’établir une corrélation entre les espèces réactives générées dans la phase gaz et dans la phase liquide. Enfin, des expérimentations nous ont permis d’analyser la production des RONS dans des liquides in situ en temps réel. Les mesures de SEO montrent qu’il existe de nombreuses espèces chimiques excitées au sein des différents plasmas (NO°, HO°, O, N2+ (FNS) etc…). Les analyses de la phase liquide ont révélé la présence d’espèces stables de l’oxygène et de l’azote (H2O2, NO2-, NO3-), directement reliées aux espèces détectées dans les plasmas. De plus, les diverses méthodologies d’analyse chimique mises en place ont permis la détection et la quantification de RONS tels que l’anion peroxynitrite ONOO-. L’ensemble des résultats obtenus devrait permettre d’appréhender de façon plus fine les effets induits par différents plasmas froids dans des milieux liquides physiologiques afin d’établir un lien avec les études menées sur des cellules en culture et sur la peau dans le cadre d’un programme de recherche financé par l’ANR, Agence Nationale de la rechercheCold plasmas are partially ionized gases, very rich in a physico-chemical point of view. This property characterizes cold plasmas today generated at atmospheric pressure and ambient temperature and was used since about fifteen years approximately for biomedical applications (haematology, dermatology, cancer research, odontology etc.). The efficiency of these cold plasmas in the field of the medicine was proved by numerous studies. However, the involved biological phenomena are not still well included, and it is essential to know what could be the possible unwanted side effects of these reactive ionized gases. The first level of interaction of plasmas with living matter is the one with the liquid phase, which is present on the tissue surface, in vivo cells or in culture. For a decade, a particular attention was thus worn in the interactions of plasmas with liquids, to bring a level of additional understanding. The understanding of these interactions constituted the axis of this work. Various cold plasmas reactors (generated at atmospheric pressure and ambient temperature) were developed, in order to control the interactions of these plasmas with the ambient air which can be problematic for the aimed applications. The nature of the gas used to initiate the plasma was modified, to know its influence on the chemical reactivity of the gas phase. For that purpose, measurements of optical emissive spectroscopy (OES) were necessary. Besides, new electrochemical sensors and methodological approaches were developed in order to identify and quantify the reactive nitrogen and oxygen (RONS) produced in physiological liquid media, exposed to these ionized gases. The electrochemical analyses were combined UV-visible absorption spectroscopy as well as other methods of chemistry (pH-metry/conductimetry). One of the aimed objectives is to establish a correlation between the reactive species generated in the gas phase and in the liquid phase. Finally, experiments allowed us to analyze the production of RONS in liquids in situ and in real time. OES measurements showed that there are numerous chemical species generated in various plasmas (NO°, HO°, O, N2+ (FNS) etc.). The analyses of the liquid phase revealed the presence of stable oxygen and nitrogen species (H2O2, NO2-, NO3-), directly correlated with the species detected in plasmas. Furthermore, the diverse methodologies of chemical analysis allowed the detection and quantification of RONS such as the peroxynitrite anion ONOO-. The obtained results should allow to arrest in a finer way the effects led by various cold plasmas in physiological liquid media to establish links with the studies led on cultured cells and on skin within the framework of a research program financed by the ANR, National Agency of the Research
50
Wengler, Julien. "Synthèse organique en micro-réacteur plasma." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS274.
Abstract:
Cette thèse rapporte l’intégration d’un plasma non-thermique dans une puce microfluidique. Elle estime la capacité du plasma à devenir un outil de synthèse à part entière pour une chimie « verte », grâce à des conditions douces et à l’absence de catalyseur. Peu de travaux de chimie par plasma ont traité des liquides et aucun n’a réussi à obtenir à la fois une grande conversion et une sélectivité élevée. Nous avons développé et fabriqué une puce en verre et polymère (NOA) comprenant un canal en serpentin de 1 m de long, dont la section en forme de marche stabilise un écoulement biphasique gaz-liquide. Une haute tension sinusoïdale appliquée à deux électrodes d’ITO a produit une décharge de Townsend à pression atmosphérique homogène tout au long du canal. Le comportement hydrodynamique de l’écoulement a été déterminé par une caméra CCD. Les décharges ont été caractérisées par des mesures optiques au moyen d’une caméra intensifiée et par des mesures électriques. Le traitement de cyclohexane liquide a été accompli avec un plasma d’oxygène pur. L’analyse par CPG du liquide sortant a attesté l’oxydation partielle du cyclohexane en un mélange de cyclohexanol, de cyclohexanone et d’hydropéroxyde de cyclohexyle. Les conversions et sélectivités typiques qui ont été atteintes sont respectivement 10–20% et 70–80%. Une simulation numérique a été réalisée dans le but de déterminer les voies réactionnelles principales de l’oxydation ; une étude des mécanismes a été proposée. Le succès de cette fonctionnalisation contrôlée d’un alcane pourrait constituer un début de remise en cause des barrières de principe contre l’utilisation industrielle des plasma en chimie de synthèseThe present thesis relates the integration of nonthermal plasma inside a biphasic gas-liquid microfluidic chip. It evaluates the ability of plasma activation to become a synthetic tool for a greener organic chemistry operating in mild conditions and without catalyst. Few preceding works on plasma chemistry involved a liquid phase and none of them was able to handle the high reactivity of plasma to achieve both high conversion rate and selective reactions. We developed and fabricated a glass-polymer microfluidic chip comprising a one-metre-long serpentine channel, in which a parallel gas-liquid flow was stabilized thanks to a specific step-like cross-sectional shape. An AC high voltage linked to transparent ITO electrodes produced a homogeneous atmospheric pressure Townsend discharge all along the channel. We assessed the behaviour of the flow through optical observations and characterized the discharge through electrical measurements and real time intensified-CCD monitoring. Liquid cyclohexane was successful treated with pure oxygen plasma inside our chip. The GC analysis of the outflowing liquid revealed a partial oxidation of cyclohexane into a mixture of cyclohexanol, cyclohexanone (both industrially known as "KA oil"), and cyclohexyl hydroperoxide, with a routine performance of 10-20% conversion for 70-80% selectivity. A numerical simulation was performed to identify the main reactive route and a mechanistic study was conducted. Through this controlled activation and functionalization of an alkane by means of plasma discharges, we claim to have successfully overcome some of the principle barriers towards an industrially relevant plasma chemistry