Добірка наукової літератури з теми "Electro-atomization"

Abstract The urgency of the study is conditioned by the necessity of perfection of the methods of electro-aerosol disinfection and disinsection of the air and the surfaces of premises, medical and preventive treatment of animals, and plant protection. The objective of the paper is aimed at revealing the regularities of electro-physical processes when charging an aerosol in electro-aerosol generators, improvement of the methods of electro-aerosol generation. The leading approach to the research of this problem is mathematical modelling of electrotechnical, dynamic and kinetic processes in electro-aerosol generators, allowing revealing the basic regularities of electro-aerosol generation. Experimental studies are aimed at assessment of the main characteristic of the electro-aerosol generator – convection current. As a result of the studies, a mathematical model of electro-aerosol generation with the mechanical method of atomization was obtained. The regularities of charging a fluid thread, arising at the edge of the generator, when applying electric field. The configuration of the electric field of cylindrical electrodes, taking into account the influence of the bulk charge of the electro-aerosol cloud, was considered. Electrostatic pressure of the electric field of the generator on fluid streams was taken into consideration. An equation for determining the average radius of drops of the electro-aerosol during mechanical atomization by the perforated cage was obtained. The mathematical model of electro-aerosol generation is obtained in the form of the equation of convection current, being one of the basic characteristics of the process of electro-aerosol generation, allowing defining the efficiency of electrization of aerosol particles and the degree of their fragmentation. Theoretical calculations are verified experimentally. Materials of the paper can be useful for the researchers, post-graduate students, engineers, engaged in designing, manufacturing and exploiting electro-aerosol equipment.

Monodisperse aerosols show therapeutic advantages, but they are difficult to generate. A new method (electrohydrodynamic atomization) is described. A high voltage is applied to a nozzle through which a solution, containing dissolved drug, is pumped. At the nozzle tip, a liquid cone is formed and a stream of monodisperse droplets is released. The droplet diameter is governed by the density, conductivity, and the flow rate of the fluid. The droplets are charged and need to be neutralized. Therefore, a corona discharge system is used. Methylparahydroxybenzoate was used as a model drug, and additional data were generated by using beclomethasone dipropionate (BDP). At a flow rate of 1 ml/h and 0.5% methylparahydroxybenzoate, 1.58-μm particles were produced with a geometric SD of 1.18. Increasing the flow rate to 3 ml/h and the concentration to 3% resulted in 4.55-μm particles with a geometric SD of 1.29. The experiments with BDP resulted in similar particle sizes. The mass of BDP was found to range between 1.42 and 6 μg/l air. Aqueous solutions cannot be sprayed by using this setup. This method can be used to deliver antiasthma drugs to patients.

Le secteur aéronautique doit relever des défis environnementaux majeurs pour les décennies à venir. Afin de réduire son impact environnemental, des objectifs ambitieux ont été fixés par des instances comme l’ACARE, visant une neutralité carbone d'ici 2050. Parmi ces objectifs, une réduction de 90 % des émissions d’oxydes d’azote par rapport à 2000, une baisse de 55 % des émissions de CO₂ d’ici 2030 par rapport à 1990 comme une diminution des particules fines et des traînées de condensation sont donc attendus. Pour y parvenir, l’amélioration de la combustion dans les moteurs, principale source de ces émissions, est cruciale. Un des leviers d’optimisation est l’atomisation, qui contrôle la distribution du combustible dans la chambre de combustion. Une atomisation maîtrisée réduit les zones riches en carburant, limitant ainsi la formation de particules fines. Actuellement, des systèmes aéromécaniques génèrent de fines gouttelettes via des jets d’air et des orifices calibrés. Une alternative prometteuse est l’électro-atomisation, qui utilise des champs électriques intenses pour produire des gouttelettes de petites dimensions. Cette thèse explore l’électro-atomisation et son potentiel pour l’aéronautique. Les propriétés électriques de deux carburants – un kérosène et un mélange substitut composé de dodécane et d’éthanol – sont analysées à différentes températures, notamment leur conductivité et permittivité électriques. Ces caractéristiques permettent de comprendre la capacite de chargement électrique des liquides diélectriques. Un banc expérimental dédié a été développé pour étudier la production de gouttes à faibles débits sous haute tension. L’influence du débit et de la tension sur la taille et la charge électrique des gouttes est analysée, avec pour objectif d’approcher la charge de Rayleigh, seuil où une goutte explose pour former des gouttelettes plus fines, ce qui pourrait améliorer la combustion. Cette analyse étudie également l’équilibre entre forces électriques et tension superficielle dans la formation des gouttes
The aviation sector must address major environmental challenges in the coming decades. To reduce its environmental impact, ambitious targets have been set by organizations such as ACARE, aiming for carbon neutrality by 2050. These goals include a 90% reduction in nitrogen oxide emissions compared to 2000, a 55% decrease in CO₂ emissions by 2030 relative to 1990, as well as a reduction in fine particulate matter and contrail formation. Achieving these objectives requires improvements in combustion within engines, location of the main source of these emissions. One key optimization lever is atomization, which could controls the distribution of kerosene in the combustion chamber. Effective atomization minimizes fuel-rich zones, thereby reducing the formation of fine particles. Currently, aerodynamic systems generate fine droplets using air jets and calibrated orifices. A promising alternative is electro-atomization, which utilizes strong electric fields to produce droplets.This thesis explores electro-atomization and its potential for the aviation industry. The electrical properties of two fuels—a kerosene and a substitute mixture of dodecane and ethanol—are analyzed at different temperatures, focusing on their electrical conductivity and permittivity. These properties provide insights into the charging behavior of dielectric liquids.A dedicated experimental setup has been developped to study droplet production at low flow rates under high voltage. The influence of flow rate and voltage on droplet size and charge is analyzed, with the objective to approach the Rayleigh charge limit, a threshold at which a droplet explodes into finer droplets, potentially enhancing combustion. This analysis also examines the balance between electric forces and surface tension in droplet formation

碩士
國立成功大學
航空太空工程學系碩博士班
90
The electro-assisted atomization distinguishes itself from conventional atomization method by introducing the coulomb force and having extraordinary performance over conventional ones especially on droplet-size and monodispersity. Despite of these it still falls in the regime of “atomization”, for the sake that in the whole process disturbances is induced and amplified to generate liquid film or jet breakup phenomenon, just as in the conventional cases. This research focused on the establishing of EHDA data base, observing the various modes and transitions between each, and, analyzing the behavior and limits in cone-jet phenomena. By taking ethanol liquid solution as working fluid in series of EHDA experiments, qualitative observations of modes, transitions between them, and tendency of potential change on the boundary of cone-jet phenomena region have been obtained. Observations show that mode changes in the same way, from dripping to spindle, microdripping, cone-jet, multi-cone-jet, multispindle no matter what degree of alcohol volumetric concentration the solution got. And on the other hand the uniqueness of cone-jet phenomena has been found from both energy and reacting force points of view: the tendency of boundary electric potential change vs. flow rate is found being able to be split into three main sub-tendency, classified as (△KE/△SE) = 10^-2~10^-1、10^-1~10^-0、10^-0~10¹; and reacting force type on the working fluid can be described as one which surface tension force and gravity being negligible, ratio between effective coulomb force and gravity force falls in the region of 1 < r <10².

碩士
國立中山大學
材料科學研究所
90
A thin film deposition system using ultrasonic atomization is designed and constructed. The coatings have been produced by pyrolysis using a solution of indium chloride in deionized water. Solution containing precursors is transported by carrying gas to the heated substrate where deposition is accomplished. In this study sample series obtained with of varying process parameters such as the flow rate of carrying gas, the tin concentration, and substrate temperature. The electrical properties of indium oxide thin film was improved using SnCl4‧5H2O as a dopant. The effects of doping in crystalline, surface morphology, optical transmittance and electrical conductivity of the deposition thin films were examined and the best optimal percentage of doping for the transmittance and electrical properties were found. Weak diffraction peaks of crystalline indium oxide were observed in XRD pattern of the thin films deposition at 250℃. The grains size of crystalline thin films grows with increasing substrate temperature. There is no change in XRD spectra between undoped and tin-doped indium oxide obtained with the same deposition temperature. The resistivity of thin films decreased greatly when dopant atom was added. The electrical resistivity of undoped indium oxide is ~10-2Ω-cm, while that of ITO films reaches a minimum of 9.54×10-4Ω-cm when doping is in the range 2~ 6%.The UV-Visible spectra indicate that the optical transmittance of all films is between 75~88%. The transmittance was not strongly affected by doping concentration.

碩士
國立中山大學
材料科學研究所
90
The thin film deposition system using ultrasonic nebulization was adopted in this study. SnCl4.5H2O, SbCl3, and TaCl5 were used as solutes. Ethanol was used as the solvent. Solutions of different Sn4+ concentration, Sb concentration (Sb/Sn atomic ratio) in Sn, and Ta concentration (Ta/Sn atomic ratio) in Sn were mixed. The mist was generated from a solution by the agitation of an ultrasonic device operating at about 1.65MHz. The mist was carried to the heated substrate (corning 7059 glass) by the flow of nitrogen gas so that it was decomposed by heat. SnO2-x films were deposited on the substrate due to the pyrolysis reaction. The experiment included six series: Sn4+ concentration series, Sb-doping series, temperature series, Ta-doping series, aging time series and nebulization rate series. SnO2-x films were analyzed by XRD, UV-Visible, SEM, and Hall-measurement. The optimum deposition conditions were obtained through analyses of these six series. The film deposition rate of nonaged solution was faster than aged solution. When the nebulization rate of solution was 1.6 ml/min, the resistivity of undoped SnO2 film obtained with the substrate kept at 450 oC is 2.364×10-2Ω-cm and the maximum transmittance of the visible light is 78.7%. When Sb/Sn atomic ratio in the solution was 2%, the resistivity of Sb doped SnO2 film obtained with the substrate kept at 525 oC is 2.77×10-3Ω-cm and the maximum transmittance of the visible light is 71% . When Ta/Sn atomic ratio in the solution was 0.1%, the resistivity of Ta doped SnO2 film obtained with the substrate kept at 450 oC is 3.917×10-2Ω-cm and the maximum transmittance of the visible light is 85% In this study, the electro-optical properties of Sb and Ta doped SnO2 thin films derived from an ultrasonic nebulization process were reported and discussed carefully through film characterizations.

Many applications among aerospace, defense and energy generation require materials being capable to perform in high temperature environments. Nb-base alloys are becoming particularly interesting if the temperatures exceed ~1050°C as they are outperforming even the most advanced Ni- and Co-base alloys. Notably, conventional production methods for Nb-base alloys are challenging, especially if parts with complex shapes are to be manufactured. The use of powder-based processes e.g. AM or HIP, opens up new opportunities to economically produce complex-shaped parts. However, for these processes the application of suitable high-quality powders is mandatory. In this context, the production of Nb-base alloys as powder feedstock using the electrode induction-melting gas atomization (EIGA) is reported. Powders and additively manufactured parts were investigated by X-ray diffraction, scanning electron microscopy, mechanical tests, and electro-thermal mechanical testing (ETMT). The mechanical performance, i.e., strength of parts processed by laser beam powder bed fusion (PBF-LB) clearly outperforms that of conventionally manufactured parts.

Abstract The control of combustion is a key topic for diesel engine development in terms of performance and pollutant emissions. The combustion process is piloted through the proper injection strategy, which depends on the features of the injection system. Mechanical-hydraulic models of high-pressure injection systems often support the accurate tuning of the injection strategy. The higher is the accuracy in the modeling of the electro-injector behavior, the deeper is the role of the simulation. Under such a viewpoint, the validation of the models is undoubtedly fundamental. One of the most crucial information characterizing the injector relies on the measurement of the needle displacement. Needle displacement affects rate, timing and quantity of injected fuel; it also influences the flow features within the nozzle, which are then reflected by the primary atomization process. Needle is considered hardly-accessible due to the injector architecture itself, making difficult the measurement of displacement. Nevertheless, the problem has been handled in different ways and three measurement techniques have been proposed. On one side, there is the measurement based on eddy-current transducers; on the other side, there are two alternative procedures, based on the use of optical sensors. However, in all cases, the needle is traced indirectly, since the position of the control plunger of the needle is observed. The current contribution presents a novel experimental technique for the measurement of needle displacement. The method is based on the direct visualization of the needle, allowing for the detailed definition of its law of motion through digital imaging, when the injector is characterized on a test-rig under transient conditions. The paper describes the details of the diagnostic scheme, the experimental facility and the digital imaging set-up. The main features and the capabilities of the method are discussed, in comparison with the other available techniques.