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Boskovic, Lucija. « Influence of Submicron Particle Shape on Behaviour during Filtration and Separation Processes ». Thesis, Griffith University, 2008. http://hdl.handle.net/10072/366111.
Texte intégralRésumé :
Filtration is the most efficient method of aerosol monitoring and control. A number of theories (Bradley, 1932); (Hamaker, 1937); (Johnson et al., 1971); (Wang and Kasper, 1991); (Dahneke, 1995); (Wall et al., 1990) have been developed to describe the particle interaction with surface of a filter and to estimate the probability of the particle adhesion onto a surface. A range of the particle, filter and process parameters could contribute to the strength of the adhesion. Some of them are: hardness and cross-sectional shape of the fiber, smoothness of either the fiber or particle, air humidity, the effect of particle shape and many others. Obviously, the particle size (and correspondingly the surface area) also plays a crucial role in the bouncing processes. However, despite its importance in the research field the detailed mechanisms of the particle-fiber collision and possibility for the particle to bounce or to be re-entrained have not been fully explored. Therefore, there is a need for a theoretical and experimental knowledge concerning the influence of particle bouncing on filtration and separation processes. Although, some work on the effect of particle shape on filtration process has been done, there is still need for further research regarding the influence of motion of the particles of different shape along a fiber...Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
Science, Environment, Engineering and Technology
Full Text
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Hoyos, Velasquez Angela Maria. « Performance d’une colonne de lavage vis-à-vis des particules de fumées d’incinération : étude expérimentale au sein d’une usine d’incinération ». Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2025. http://www.theses.fr/2025IMTA0460.
Texte intégralRésumé :
Parmi les dispositifs de traitement des fumées les plus utilisés, figurent les laveurs à pulvérisation. Bien qu'efficaces pour absorber des gaz acides, les laveurs à pulvérisation ne sont pas conçus pour capturer les particules submicroniques. Toutefois, des études en laboratoire ont montré qu'il est possible de collecter davantage de particules fines en ajustant leurs conditions opératoires. Dans cette thèse, la performance de collecte des particules par les laveurs à pulvérisation a été évaluée dans des conditions réelles d’une usine d’incinération de déchets à deux échelles : (i) en exploitant un laveur à échelle réduite alimenté par des fumées réelles de l’incinération de déchets ménagers, et (ii) en quantifiant l'efficacité de collecte des particules d’un laveur industriel d’un site d’incinération de déchets dangereux. Des simulations numériques CFD ont été réalisées pour dimensionner le dispositif à échelle réduite et analyser l'écoulement à l'intérieur des laveurs. Une étude paramétrique a été conduite pour étudier l'influence des conditions opératoires sur les performances du laveur à échelle réduite. Les résultats indiquent que la réduction du diamètre des gouttelettes et la hausse du rapport entre les débits liquide/gaz améliorent la collecte des particules de toute taille. Aucune influence du temps de séjour du gaz n'a été constatée. Les modèles mécanistiques de collecte testés surestiment les résultats dans les conditions réelles d’exploitation. Les performances de collecte des particules du laveur industriel se sont avérées quasi nulles/négatives, en raison de phénomènes réactionnels et de transferts entre les gouttelettes, les gaz et les particulesWet scrubbers are among the most used industrial flue gas treatment devices. Although effective at absorbing acidic gases, wet scrubbers are not designed to capture submicronic particles. However, laboratory studies have shown that it is possible to improve their fine particle collection efficiency by adjusting operating conditions. In this thesis, the performance of wet scrubbers for collecting particles was evaluated under real conditions of a waste incineration plant at two scales: (i) by operating a downscaled wet scrubber fed with real flue gases from the incineration of household waste, and (ii) by quantifying the particle collection efficiency of an industrial scrubber at a hazardous waste incineration plant. CFD numerical simulations were performed to design the downscaled system and analyze the flow patterns inside the scrubbers. A parametric study was conducted to investigate the influence of operating conditions on the performance of the downscaled scrubber. The results showed that reducing the droplet diameter and increasing the liquid/gas flow ratio improved particle collection across all sizes. No influence of gas residence time was observed. The mechanistic collection models tested overestimate the results under real operating conditions. The performance of the industrial scrubber for collecting particles was found to be nearly zero/negative due to reaction and transfer phenomena between the droplets, the gases, and the particles
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Boudhan, Rachid. « Performance of pulse-jet bag filter regarding particle removal for nano-waste incineration conditions ». Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0022/document.
Texte intégralRésumé :
Les performances de filtration d’un filtre à manche vis-à-vis de particules submicroniques et nanométriques ont été évaluées à l’échelle du laboratoire durant plusieurs cycles de colmatage/décolmatage. La distribution granulométrique des particules (aérosol de combustion) était représentative de celle rencontrée en incinération de nano-déchets en sortie de chambre de combustion à l’échelle du laboratoire. Le filtre à manche opérait en conditions réalistes, représentatives de celles rencontrées dans les lignes de traitement des fumées d’incinération de déchets en termes de température, humidité, vitesse de filtration, présence de réactifs et conditions de décolmatage. Le flux d’air et le filtre à manche étaient chauffés à 150°C, la teneur en eau était de 10-12% (soit 3% d’humidité relative HR), et la vitesse de filtration était fixée à 1,9 cm.s⁻¹. Un mélange de particules de taille submicronique de charbon actif et de bicarbonate de sodium, utilisées dans les lignes de traitement des fumées d’incinération pour l’abattement des dioxines/furanes et des gaz acides, était généré simultanément avec l’aérosol de combustion. L’étude s’est centrée sur les performances de filtration au début de la durée de vie du filtre à manche, avant stabilisation de la perte de charge résiduelle du filtre résultant des précédents cycles de filtration. La perte de charge maximale du filtre était fixée à 150 Pa pour tous les cycles de filtration avant décolmatage par rétro-soufflage à air comprimé. Les performances du filtre à manche ont été évaluées en termes d’évolution de sa perte de charge et de son efficacité de collecte (totale et fractionnelle) au cours des cycles de colmatage/décolmatage. De plus, des études expérimentales et théoriques ont été menées afin d’étudier l’influence de divers paramètres sur les performances de filtration du filtre en configuration manche ou plane, tels que l’humidité de l’air (3% HR versus 0% HR à 150°C), la température (150°C versus 24°C), la vitesse de filtration (1,9 cm.s⁻¹ versus 1,4 cm.s⁻¹) et l’influence de l’injection de réactifs. Les principaux résultats de cette étude sont : (i) importante efficacité de capture des particules du filtre à manche en conditions représentatives des lignes de traitement des fumées d’incinération : efficacité minimale de collecte de 98,5% mesurée pour des particules de taille 74 ± 15 nm (diamètre de mobilité électrique), (ii) influence du gâteau résiduel de particules au début de chaque cycle de filtration sur les performances de traitement, (iii) influence significative de l’humidité de l’air sur la structure du gâteau de particules probablement due à l’augmentation des forces d’adhésion entre les particules en présence d’humidité (150°C – 3% HR soit environ 100 g d’eau par kg d’air sec) ; augmentation plus rapide de la perte de charge du filtre à manche en présence d’humidité (150°C – 3% HR) qu’en conditions d’air sec (150°C – 0% HR)Filtration performance of a pulse-jet bag filter was evaluated at the laboratory-scale regarding submicronic particles with a nanosized fraction during clogging/unclogging cycles. The particle size distribution was representative to those encountered at the outlet of a nano-waste incineration device at laboratory-scale. The bag filter was operated in conditions as similar as possible to those found in flue gas treatment of waste incineration plants, in terms of temperature, humidity, filtration velocity, injection of sorbent reagents and unclogging conditions. The air flow and the bag filter were heated to 150°C, the water content was maintained in the air flow in the range of 10-12% (3% of relative humidity RH), and filtration velocity throughout the bag filter was fixed at 1.9 cm.s⁻¹. A mixture of submicronic suspended particles of activated carbon and sodium bicarbonate, both used in flue gas treatment systems mainly for the removal of dioxins/furans and acid gases, was generated simultaneously with the aerosol representative of combustion emissions.The study focused on the filtration performance at the beginning of the bag filter’s lifetime filter for the 11 first clogging-unclogging cycles before stabilizing the residual pressure drop reached after pulse-jet unclogging. The maximum pressure drop was set at 150 Pa for all filtration cycles. Once the maximum pressure drop was reached, the filter was unclogged using the pulse-jet system. The performance of the bag filter was evaluated in terms of the evolution of pressure drop, fractional and total particle collection efficiencies, during the clogging/unclogging cycles.Moreover, an experimental and theoretical study was carried out on the influence of different parameters on the filtration performance of bag filter and flat filter, such as influence of humidity (3% RH versus 0% RH at 150°C), temperature (150°C versus 24°C), filtration velocity (1.9 cm.s⁻¹ versus 1.4 cm.s⁻¹) and the influence of the injection of sorbent reagents.The main results of this study are: (i) high collection efficiency of the bag filter in representative conditions of flue gas treatment of waste incineration: minimun particle collection efficiency of 98.5% for particle diameter of 74 ± 15 nm (electrical mobility diameter), (ii) influence of residual particle cake at the beginning of the filtration cycles on the bag filter performance, (iii) significant influence of humidity on the porosity of the particle cake due to the capillary condensation of water between the particles in presence of humidity (150°C - 3% RH i.e. almost 100 g of water per kg of dry air). Faster increase of bag filter pressure drop in presence of humidiy (150°C - 3% RH) as compared to the dry conditions (150°C - 0% RH)
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Garcia-Lopez, Alicia. « Hybrid model for characterization of submicron particles using multiwavelength spectroscopy ». Scholar Commons, 2005. http://scholarcommons.usf.edu/etd/2889.
Texte intégralRésumé :
The area of particle characterization is expansive; it contains many technologies and methods of analysis. Light spectroscopy techniques yield information on the joint property distribution of particles, comprising the chemical composition, size, shape, and orientation of the particles. The objective of this dissertation is to develop a hybrid scattering-absorption model incorporating Mie and Rayleigh-Debye-Gans theory to characterize submicron particles in suspension with multiwavelength spectroscopy.Rayleigh-Debye-Gans theory (RDG) was chosen as a model to relate the particles joint property distribution to the light scattering and absorption phenomena for submicron particles. A correction model to instrument parameters of relevance was implemented to Rayleigh-Debye-Gans theory for spheres. Behavior of nonspherical particles using RDG theory was compared with Mie theory (as a reference).
A multiwavelength assessment of Rayleigh-Debye-Gans theory for spheres was conducted where strict adherence to the limits could not be followed. Reported corrections to the refractive indices were implemented to RDG to try and achieve Mies spectral prediction for spheres.The results of studies conducted for RDG concluded the following. The angle of acceptance plays an important role in being able to assess and interpret spectral differences. Multiwavelength transmission spectra contains qualitative information on shape and orientation of non-spherical particles, and it should be possible to extract this information from carefully measured spectra. There is disagreement between Rayleigh-Debye-Gans and Mie theory for transmission simulations with spherical scatterers of different sizes and refractive indices.
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Mihaylova, Dessislava Dimitrova. « Submicron Particles and Inflammation ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bioteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18590.
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Iron nanoparticles occur naturally in the environment, but their exposure increases dramatically due to the field of nanotechnology and –medicine. It is poorly understood how the intracellular cooperative mechanisms of submicron particles and microorganisms function on mammalian immune system. In this study, superparamagnetic iron oxide (SPIO) submicron particles will be used to benefit the research within environmental diseases, addressing the biocompatibility of these particles. The size-dependent effects in the immune system of two carboxyl coated SPIO particles with stated sizes 100 nm and 1 µm will be studied in vitro. It would be interesting to determine whether these particles were able to activate the inflammasome, but still, the precise molecular mechanisms for the activation remain unknown. In order to reveal the biocompatibility of these particles, tests were performed as a function of particle concentration ranging from 0.01 to 100 µg/mL using both whole blood and peripheral blood mononuclear cells (PBMC) isolated from healthy donors. The monocytes were first primed with Lipopolysaccharide from Escherichia coli 0111:B4 strain, followed by stimulation with increasing concentrations of the submicron particles. Flow cytometry on whole blood samples identified up-regulation of CD11b monocytes and granulocytes by the particles. In addition, Terminal Complement Complex analyses proved activation of the complement system. It is possible that the particles have been coated with C3b by the complement and phagocytized by the monocytes through CD11b/CD18 receptor. Cytokine secretion from monocytes and whole blood was measured with sandwich ELISA and Bio-plex. The smaller particles seemed to induce higher inflammatory responses than the larger ones. It was, however, interesting to find that the particles themselves caused secretion of active IL-1β without being primed in advance. The mechanisms of the NLRP3 inflammasome activation might be explained by ROS production due to iron imbalance in the cytoplasm. Toxicity of the particles was seen at 10 µg/mL, suggesting their potentially low biocompatibility above this concentration. However, it is suggested better biocompatibility of the silica coated 1 µm particles than the polysaccharide coated 100 nm particles.
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Mortazavi, Ramin. « Reentrainment of Submicron Solid Particles ». VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1334.
Texte intégralRésumé :
In this work, an experimental method is developed to study the effects of particle size, flow rate, pulsation, particle/substrate material, and temperature on the short-term reentrainment of submicron particles. The particles tested are in the size range of 10-900 nm and are deposited by wetting the inside of capillary tubes with a liquid suspension. The tubes are then dried in a desiccator. The particles are reentrained under turbulent dry air flow conditions and a condensation particle counter is used to measure the number of entrained particles.There has been very limited work done with nanoscale particles in general and no previous experimental work has reported about this particular parameter set. In order to interpret the data, a bimodal lognormal probability density for the ratio of adhesion force to removal forces is suggested. The majority of particles is attached to the surface by strong forces and cannot be entrained. However, a small fraction of particles, called loose particles, is attached to the surface by much smaller forces. Based on experimental data, an analytical equation for the fraction of loose particles in terms of a dimensionless force is developed. This dimensionless force is a function of particle size and gas flow rate. The temporal variations of fraction of deposited particles are calculated by incorporating the fraction of loose particles with the model of Wen and Kasper (1989).The experimental data confirmed the theoretical expectation that entrainment strongly depends on particle size and decreases as the size of the particle decreases. Both higher flow rates and pulsation of the flow increase the entrainment. Pulsation causes the distribution of forces to broaden. It is shown that the effect of particle/substrate material on entrainment can be predicted by the compound Hamaker constant provided that the morphology and the roughness of the system remain the same. Otherwise, the effect of roughness or morphology may override the effect of Hamaker constant.
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Suwannasom, Nittiya [Verfasser]. « Biocompatibility of Biopolymer Submicron Particles / Nittiya Suwannasom ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2019. http://d-nb.info/1202044433/34.
Texte intégral
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Imani, Jajarmi Ramin. « Acoustic separation of submicron particles in gaseous flows ». Licentiate thesis, KTH, Mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167629.
Texte intégralRésumé :
The separation of submicron particles suspended in gaseous flows is a problem of great importance and is the subject of sustained research efforts. This is motivated by several challenges presented by modern science and technology requiring high separation efficiencies for submicron particles.Continuous acoustic particles separation is a novel technique based on the acoustophoresis phenomenon, in which a particle within an acoustic field is manipulated using acoustic forces on its surface. This technique has the potential to overcome some of the limitations of common techniques for the separation of submicron particles, as well as performing advanced tasks such as sorting particles according to their size or density.In this thesis, the separation of submicron solid particles suspended in air is investigated experimentally, with a focus on the effect of key design parameters (acoustic, flow, geometry) on the efficiency of the process. A simple method based on laser light scattering was also used to provide qualitative information on the particle number density as a function of position in the channel. This technique allowed to quickly investigate the effect of a wide range of parameters on the acoustic separation efficiency including the pressure amplitude, the frequency of the standing wave, the average flow velocity and the parallelism of the channel walls. The results demonstrate conclusively that acoustic manipulation is possible for submicron particles and that the acoustic force scales following the trends expected from theoretical models developed in the continuum regime. From the size of the particles used it however follows that the observed separation is the result of transition regime acoustophoresis, with a Knudsen number on the order of 0.2.QC 20150522
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Kebler, David George 1960. « Coagulation of submicron colloids by supramicron silica particles ». Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/191969.
Texte intégralRésumé :
Values of a (coagulation efficiency) for coagulation of aluminum (hydr)oxide colloids by supramicron silica particles were generally near 0.01. Although the freshly suspended particles were oppositely charged, dissolved silica from the particulate silica adsorbs to the colloids reversing their charge. Bicarbonate also adsorbs and shifts the pHiep of the aluminum (hydr)oxide colloids. The addition of dissolved Al(III) had a similar effect on both types of particles. Dissolved silica adsorbs to the hydrous aluminum oxide surface and undergoes ligand exchange. This exchange can be simulated by a constant capacitance model for adsorption of aqueous species to the oxide surface and fits laboratory titration data.
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Gibson, Fredrick W. Jr. « Stabilization of Submicron Metal Oxide Particles in Aqueous Media ». Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30645.
Texte intégralRésumé :
An investigation into the parameters that define a good anchor block for a copolymer steric stabilizer was performed. The study focused on the effects of different functional groups on the adsorption properties of polymers. In addition, the effect of chain architecture as well as the impact of a hydrophobic end-group on polymer adsorption properties was determined. To complement the adsorption studies, a streaming potential instrument was built for use in measuring the adsorbed layer thickness of nonionic polymers on SiO2. The research concluded with an examination of the effect of thermally induced insolubility on adsorption of a hydrogen-bonding polymer.
Functional group effects were studied by measuring the adsorption isotherms of poly(2-ethyl-2-oxazoline), PEOX, poly(ethylene oxide), PEO, poly(vinyl alcohol), PVOH, and poly(ethylene imine), PEI, which was modified such that a 1,3-butanediol substituent replaced its imine hydrogens, on SiO2, TiO2, and Al2O3. PEOX and PEO, relatively basic polymers compared to PVOH were observed to adsorb only on the most acidic metal oxide, SiO2. PVOH, however, was observed to adsorb on all three metal oxides, but to a lesser degree on SiO2 as compared to the more basic PEOX and PEO. These initial results were indicative of hydrogen-bonding mechanisms, a form of acid-base interaction.
The most significant observation in the adsorption studies was that the linear hydroxyl modified PEI materials and their dendritic analogs adsorb on the metal oxides both above and below the i.e.p. This indicates that both electrostatic and hydogen-bonding mechanisms are driving the adsorption. The dendritic polymers, particularly a 4th generation dendrimer based on diaminopropane with a molecular weight of 16,640 g/mol adsorbed at a higher level when compared to the 41.3K g/mol PVOH and 30K g/mol PEOX. In addition to the dual adsorption mechanism, it was determined that the dendritic architecture appears to facilitate adsorption, as does the presence of the hydrophobic endgroup. The level of adsorption for all of the hydroxyl containing linear PEI and dendritic materials on the three metal oxides was high enough for them to be considered as anchor blocks in a copolymer steric stabilizer.
The streaming potential instrument used to measure the adsorbed layer thickness on SiO2. Adsorbed layer thickness of PEOX Mw = 10K and 30K g/mol were measured at approximately 1nm and 4.4 nm, respectively. In the case of the PEOX Mw = 30K g/mol homopolymer, the measured layer thickness was higher than that for a 23K g/mol PEO homopolymer. The degree of polymerization of the PEO is approximately 525, while for the PEOX it was only 300. This result was not expected.
Finally, adsorption of PEOX was studied at the cloud point to determine whether insolubility could promote adsorption, while hydrogen-bonding, the room temperature driving force for adsorption, would decrease. Adsorption isotherm measurements were performed at 72 °C, and 75 °C, as the cloud point of the 30K PEOX was determined to be 73 °C. It was apparent that the adsorption decreased as temperature increased, indicating that without hydrogen bonding, thermally induced insolubility does not drive adsorption.Ph. D.
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Peltier, Richard Edward. « Ambient Submicron Particles In North America : Their Sources, Fate, and Impact ». Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19750.
Texte intégralRésumé :
Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008.Committee Chair: Weber, Rodney J.; Committee Member: Bergin, Michael H.; Committee Member: Huey, L Gregory; Committee Member: Ingall, Ellery D.; Committee Member: Nenes, Athanasios.
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Chowdhury, Rina 1965. « Synthesis of submicron copper coated polystyrene particles by electroless deposition ». Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277911.
Texte intégralRésumé :
A method for the synthesis of submicron copper coated polystyrene particles by electroless deposition has been developed. In this technique, the carboxylated and sulfated polystyrene latex particles of 0.1 μm and 0.24 μm diameter, are first activated by conditioning in a solution of tetraammine palladium (II) chloride monohydrate and then plated in an electroless bath containing cupric sulfate, EDTA-disodium salt, some stabilizers and basic formaldehyde at 72 ± 1°C. The interaction between carboxylic acid groups and Pd(NH₃)₄Cl₂.H₂O has been studied using uv spectroscopy. Copper coated carboxylated polystyrene particles with a mean diameter of 0.4 μm and a standard deviation of 9% of the mean diameter have been synthesized. The size, shape and purity of these particles have been determined by SEM, EDX, and ESCA analysis. The microcrystallinity of the particles has been determined by XRD technique.
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Chari, Geethanjali. « Enhanced submicron particle deposition using thermophoresis and roughness elements ». Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428552.
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Schmidt, Frank Dr Ing. « Transport und Abscheidung submikroner Partikel - Transport and deposition of submicron particles ». Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-08022001-085456/.
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In this study transport and deposition of submicron particles in turbulent and laminar flows is investigated theoretically. Beginning with the modelling of transport processes in pipe flows, transport onto surfaces and in industrial gas cleaning systems has been calculated. Deposition of particles takes place due to convective diffusion, sedimentation,thermophoresis and impaction. Although different geometries have been investigated a characteristical deposition behaviour has been found with a deposition minimum for submicron particles with diameters larger than 0.1 mm. Transport of these particles often depends on thermo- or electrophoresis.
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Imani, Jajarmi Ramin. « Acoustic separation and electrostatic sampling of submicron particles suspended in air ». Doctoral thesis, KTH, Strömningsfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196857.
Texte intégralRésumé :
We investigate experimentally the effects of acoustic forces on submicron aerosol in a channel flow. This technique can potentially overcome some of the limitations of conventional separation systems and provide advanced manipulation capabilities such as sorting according to size or density. The theoretical framework for acoustophoresis at such small length scales where molecular effects are expected to be significant is still incomplete and in need of experimental validation. The main objectives of this thesis are to identify the physical limitations and capabilities of acoustophoretic manipulation for submicron aerosol particles. Two sets of experiments were carried out: first, qualitative results revealed that acoustic manipulation is possible for submicron particles in air and that the acoustic force follows the trend expected by theoretical models developed for particles in inviscid fluids. The acoustic force on submicron particles was estimated in a second set of measurements performed with quantitative diagnostic tools. Comparison of these results with available theoretical models for the acoustic radiation forces demonstrates that for such small particles additional forces have to be considered. At submicron length scales, the magnitude of the forces observed is orders of magnitude higher than the predictions from the inviscid theory. One potential application for acoustophoresis is specifically investigated in this thesis: assist electrostatic precipitation (ESP) samplers to target very small aerosols, such as those carrying airborne viruses. To identify the shortcomings of ESP samplers that acoustophoresis should overcome, two ESP designs have been investigated to quantify capture efficiency as a function of the particle size and of the air velocity in a wind tunnel. The results reveal that both designs have limitations when it comes to sampling submicron aerosol particles. When exposed to polydispersed suspensions they behave as low-pass filters.QC 20161125
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Johnson, Ben T. « Experimental analysis of crankcase oil aerosol generation and control ». Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10968.
Texte intégralRésumé :
Crankcase ventilation contributes significantly to diesel engine particulate emissions. Future regulations will not only limit the mass of particulate matter, but also the number of particles. Controlling the source of crankcase emissions is critical to meeting the perennial legislation. Deficiency in the understanding of crankcase emissions generation and the contribution of lubricating oil has been addressed in detail by the experimental study presented in this thesis. A plethora of high speed laser optical diagnostics techniques have been employed to deduce the main mechanisms of crankcase oil aerosol generation. Novel images have captured oil atomisation and passive oil distribution around the crankcase of an optically accessed, motored, four cylinder, off highway, heavy duty, diesel engine. Rayleigh type ligament breakup of oil films present on the surface of dynamic components, most notably the crankshaft, camshaft and valve rockers generated oil drops below 10 micrometers. Data illustrated not only crankcase oil aerosol generation at source, but it has provided valuable information on methods to control oil aerosol generation and improve oil circuit efficiency. The feasibility of utilising computational fluid dynamics to predict crankcase oil aerosol generation has been successfully assessed using the experimental data. Particle sampling has characterised the crankcase emissions from both a fired and motored diesel engine crankcase. The evolution of submicron crankcase particles down to 5 nm has been recorded from both engines, including the isolated contribution of engine oil, at a wide range of engine test points. Results have provided constructive insight into the generation and control of this complex emission. The main mechanism of crankcase oil aerosol generation was found to be crankshaft oil atomisation. This atomisation process has been analysed in detail, involving high speed imaging of primary and satellite drop generation and high speed digital particle image velocity of the crankshaft air flow. A promising mechanism of regulating and controlling crankcase oil aerosol emissions at source has been studied experimentally.
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Kloypan, Chiraphat [Verfasser]. « One-pot Formulation of Protein Submicron Particles and Their Haemocompatibility / Chiraphat Kloypan ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2019. http://d-nb.info/1202044700/34.
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Garbarienė, Inga. « Origin, chemical composition and formation of submicron aerosol particles in the atmosphere ». Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140520_134625-72680.
Texte intégralRésumé :
The objective of the work was to investigate physical and chemical properties and sources of the atmospheric aerosol particles in the submicron fraction by combining different analytical techniques. The dependence of concentrations of organic and elemental carbon in different air masses was determined and the contribution of regional and local sources to the net aerosol particle pollution was estimated. Analysis of the size distribution of carbonaceous aerosol particles in background and urban areas was performed. Biogenic organic aerosol made up 15 % of the organic aerosol mass at the Preila atmospheric pollution research station, but in the North Atlantic air masses this factor was up to 50 %. Aerosol and stable isotope ratio mass spectrometry has revealed that traffic is the primary source of aerosol particles in the city, while biomass burning is the primary source at the Rūgšteliškis background station. It was determined that secondary anthropogenic organic compounds were dominating (76 %) in Vilnius, while in Rūgšteliškis secondary biogenic organic compounds made up 50 % of the total organic aerosol mass. The influence of the long-range air mass transport on the local origin aerosol particle formation and transformation has been evaluated and it has been shown that volcanic aerosol particles can significantly change the concentration, chemical composition and size distribution of local aerosol particles in the submicron range.Disertacija skirta smulkiosios aerozolio dalelių frakcijos šaltinių, fizikinių ir cheminių savybių įvertinimui kompleksiškai apjungiant įvairius tyrimo metodus. Darbe susieti elementinės ir organinės anglies koncentracijų pokyčiai su tolimąja oro masių pernaša, įvertinta regiono bei vietinių šaltinių įtaka bendrai aerozolio dalelių taršai. Aprašyti anglies turinčių aerozolio dalelių pasiskirstymai pagal dydį foninėse vietovėse ir miesto aplinkoje. Naudojant aerozolio masių spektrometrą Preilos atmosferos užterštumo tyrimų stotyje buvo identifikuotas biogeninis organinių medžiagų šaltinis, kuris vidutiniškai sudaro 15 % nuo organinių medžiagų masės, tačiau Šiaurės Atlanto oro masėje biogeninių medžiagų indėlis siekia net 50 %. Atlikus kompleksinę aerozolio ir stabiliųjų anglies izotopų masių spektrometrinę analizę buvo nustatyta, kad pirminis anglies turinčio aerozolio dalelių šaltinis mieste yra autotransportas, o Rūgšteliškio foninėje vietovėje – biomasės deginimas. Taip pat buvo nustatyta, kad Vilniuje dominavo antropogeninės antrinės organinės medžiagos (76 %), o Rūgšteliškyje vyravo biogeninės antrinės organinės medžiagos (apie 50%). Vertinant tolimosios oro masių pernašos įtaką vietinės kilmės aerozolio dalelių formavimuisi ir kaitai, buvo nustatyta, kad vulkaninės kilmės aerozolio dalelės turi įtakos submikroninės aerozolio dalelių frakcijos koncentracijai, cheminei sudėčiai ir pasiskirstymui pagal dydį.
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Fateen, Seif-Eddeen K. (Seif-Eddeen Khaled) 1971. « Magnetophoretic focusing on submicron particles dispersed in a polymer-stabilized magnetic fluid ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8497.
Texte intégralRésumé :
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2002.Includes bibliographical references.
Magnetophoresis is the migration of particles upon the application of an inhomogeneous magnetic field. The overall goal of this work was to investigate the magnetophoretic focusing of non-magnetic particles suspended in magnetic fluids, which are colloidal suspensions of nano-sized magnetic particles. With the magnetic fluid as the solvent, dispersed non-magnetic particles behave as if they were diamagnetic due to the difference in magnetic susceptibility between them and the surrounding magnetic continuum. When an inhomogeneous magnetic force is applied, a magnetic force acts on the colloidal particles, the magnitude of which is linearly proportional to the volume of the particles, the difference in the magnetic susceptibilities of the particles and the surrounding magnetic fluid, and the gradient of the square of the magnetic field. One potential application for this phenomenon is in the separation of submicron biological particles such as viruses, cell fragments, DNA and inclusion bodies. Magnetic fluids have several characteristics that make them attractive for use in separation. For example, they can be tailored to the separation needs at hand, manipulated using external magnetic fields, and completely removed through magnetic filtration. Since the scope of the work was to use physical forces for attaining the desired separations, the magnetic particles were designed and synthesized without any chemical affinity to the solute to be separated. They were prepared by coprecipitation of iron (II) and (III) ions to form magnetite, which is coated by a comb copolymer that serves two purposes: to limit growth of magnetite to about 10 nm and to stabilize the particles against aggregation.
(cont.) The polymer was prepared by a reaction between amine-terminated polyethylene oxide and polyacrylic acid. Characterization of the particles was done experimentally and theoretically. Dynamic light scattering was used to measure the diffusion coefficient and the hydrodynamic diameter of the particles, while transmission electron microscopy was used to measure the diameter of the magnetic core. Since the structure of the magnetic fluid is an important parameter in its application in any magnetophoretic separation, we characterized the aggregation behavior of the magnetic fluids using different theoretical techniques. Monte Carlo simulation was used to understand the clustering in sterically-stabilized magnetic fluids. Simulation results agree favorably with the scattering experiments with regards to the cluster sizes and fractal dimensions. The characterization of a closely related system, a charge stabilized magnetic fluid, was also performed to explain the finite cluster size observed experimentally. Next, we investigated magnetophoretic focusing in the synthesized magnetic fluid, as a means to separate submicron colloidal particles based on size. The magnetophoresis concepts were validated experimentally by monitoring the dynamic evolution of the concentration profile of fluorescently-tagged polymer beads of various sizes in a magnetic fluid upon the application of an inhomogeneous magnetic field. Polymer beads larger than 0.2 /um focused at the point of zero force, and the effect of the magnetic field on the particles was correlated with their size...
by Seif-Eddeen K. Fateen.
Ph.D.
20
Annavarapu, V. N. Ravikanth (Venkata Nagandra Ravikanth). « Size based separation of submicron nonmagnetic particles through magnetophoresis in structured obstacle arrays ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59872.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
The focus of this work was on developing a novel scalable size based separation technology for nonmagnetic particles in the submicron size range utilizing magnetophoretic forces. When a nonmagnetic particle is immersed in a magnetic fluid and subjected to magnetic field gradients, it behaves like a magnetic hole and experiences magnetic buoyancy forces proportional to its volume. This size dependence of magnetic buoyancy forces can be exploited to selectively focus larger nonmagnetic particles from a mixture and thus we can fractionate nonmagnetic particles on the basis of size. We designed a separation system composed of a regular array of iron obstacle posts which utilized magnetic buoyancy forces to perform size based separations. A Lagrangian particle tracking model was developed which could describe the behavior of a nonmagnetic particle in regions of inhomogeneous magnetic field gradients. Particle trajectories were simulated for a number of obstacle array geometries and over a range of operating conditions in order to understand the nature of the magnetic buoyancy force and aid in separation system design. Based on the results of the trajectory simulations, an experimental set up was conceptualized and built to demonstrate capture and separation of nonmagnetic particles using magnetic buoyancy forces. Capture visualization experiments were performed utilizing fluorescence microscopy which showed visual evidence of focusing and preferential capture of larger nonmagnetic particles. Experiments also yielded results qualitatively consistent with the Lagrangian trajectory model. Pulse chromatography experiments were also performed in order to quantitatively understand the capture and separation behavior. The results obtained showed quantitative evidence of preferential capture of larger particles. Particle capture efficiencies were compared with predictions from simulations and were found to be qualitatively consistent. Finally, the potential of this separation technology was demonstrated by performing proof-of-concept separation experiments with a mixture of 840 nm and 240 nm particles.
by V. N. Ravikanth Annavarapu.
Ph.D.
21
Linardos, S. « Preparation of submicron PZT particles with the sol-gel technique and direct measurement of inter-particles forces with atomic force microscope ». Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427149.
Texte intégral
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Wright, Matthew Darren. « Submicron particle size distribution and charge state in urban areas using mobility particle sizers : measurements and instrumentation considerations ». Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544324.
Texte intégral
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Chakravorty, Utshab. « STUDY OF CHARACTERIZATION OF SUBMICRON COAL PARTICLES DISPERSED IN AIR AND CAPTURE OF COAL PARTICLES BY WATER DROPS IN A SCRUBBING COLUMN ». UKnowledge, 2012. http://uknowledge.uky.edu/cme_etds/16.
Texte intégralRésumé :
Present day water spray based dust removal technologies do not effectively remove respirable submicron coal and silica dust particles in the underground coal mines causing Coal worker’s pneumoconiosis (CWP). The objective of this research was to study the electrostatic charges present in the airborne coal dust in order to develop efficient water spraying based dust removal technology where water drops charged using ionic compounds and surfactants would be used to capture the oppositely charged coal particles. In an experimental scrubbing column, coal particles dispersed in an air stream by a Fluidized Bed Aerosol Generator were captured by water drops sprayed by an atomizer. Characterization studies performed using an Aerodynamic Particle Sizer and Aerosol Electrometer showed that airborne coal particles have a significant amount of positive charge with an average of 140 elementary units of charge. The capture efficiencies of the water drops evaluated were found to be higher than those predicted by previously determined mathematical models. It was predicted that apart from the effects of Brownian diffusion, interception and impaction, the effect of Coulombic attraction was present and the charge of the water drops was predicted to be between - 2 x 10-6 C and -2 x 10-4 C.
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Pluhar, Bettina [Verfasser]. « Design and synthesis of submicron polymer particles for the selective capture of proteases / Bettina Pluhar ». Ulm : Universität Ulm, 2017. http://d-nb.info/1127139894/34.
Texte intégral
25
Chaiwaree, Saranya [Verfasser]. « Investigation of interactions between biopolymer submicron particles and tumour cells carrying albumin receptors / Saranya Chaiwaree ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2021. http://d-nb.info/1234982285/34.
Texte intégral
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Vlasenko, Alexander Lvovich. « Aerosol flow of the heterogeneous interaction between submicron mineral dust particles and gaseous nitric acid / ». Bern : [s.n.], 2006. http://www.zb.unibe.ch/download/eldiss/06vlasenko_a.pdf.
Texte intégral
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Stratigou, Evdokia. « Identification and characterisation of physicochemical processes controlling indoor concentrations of submicron aerosols and volatile organic compounds ». Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0007/document.
Texte intégralRésumé :
Cette thèse développe les connaissances scientifiques sur l’origine et le comportement des polluants intérieurs en phases gazeuse et particulaire. Une description complète des processus physiques contrôlant les concentrations de polluants en air intérieur dans une pièce inoccupée et non meublée a été réalisée. En utilisant des paramètres bien quantifiés (taux de renouvellement d’air, facteur de pénétration et vitesse de dépôt), nous avons pu appliquer un modèle de bilan massique aux particules. Les résultats ont montré que, en l’absence significative de sources intérieures, une caractérisation fine des paramètres ci-dessus permettait de décrire de manière satisfaisante les concentrations intérieures en PM2.5 et PM10 à partir des données extérieures, tandis que les PM1 montrent une variabilité significativement plus marquée due aux transformations physicochimiques. Par la suite, les composés organiques volatils (COV) et la composition chimique des particules submicroniques ont été mesurés en temps réel lors d’une campagne intensive. Un enrichissement important des concentrations en COV a été observé lorsque l’air ambiant pénètre à l’intérieur du bâtiment, en particulier pour les COV oxygénés qui présentent une dépendance significative avec l’humidité relative, tandis que pour les particules les changements observés dépendent de leur composition chimique et de leur diamètre, montrant une diminution de 20% pour les PM1 à 86% pour les plus grosses particules (>5 μm). L’excès d’ammonium observé dans les deux environnements a permis de déconvoluer les nitrates organiques des inorganiques, ceux-ci présentant une dépendance plus forte avec la température, révélant une décomposition thermique plus importante en air intérieur. En résumé, l’environnement intérieur agit principalement comme une source d’émissions continues de COV, alors qu’une tendance inverse est observé pour les particules, du fait de transformations possibles pouvant se produire même dans les conditions les plus simples, sans occupant ni mobilierThis thesis improves the scientific knowledge on the origin, behavior and fate of gas and particle-phase pollutants indoors under unoccupied unfurnished conditions. A first campaign provided a complete description of the physical processes controlling the indoor concentrations. Using well quantified parameters (air exchange rate, penetration factor and deposition rate), a mass balance model provided insights for the particle budget closure. The results showed that when indoor sources are not significant, a careful characterization of the abovementioned parameters allows to estimate PM2.5 and PM10 in a satisfying manner from outdoor data. However the PM1 fraction shows a significantly higher variability due to physicochemical transformations. Subsequently, a second intensive campaign was performed to investigate volatile organic compounds (VOC) and PM1 chemical composition in real time. A strong increase in VOC concentrations was observed when outdoor air penetrates indoors, especially oxygenated VOC which exhibited a significant dependence on relative humidity, while the changes observed for particles once indoors depend on their chemical composition and diameter, showing a decrease from 20% for submicron particles up to, 86% for large ones (>5. µm). The investigation of ammonium neutralization revealed an excess of ammonium indoors and outdoors, which is attributed to organic- in addition to inorganic-bonded ammonium nitrate. The latter showed a stronger dependency on temperature gradient from outdoors to indoors, revealing stronger thermal decomposition once indoors. In summary, the indoor environment acts mainly as a continuous emission source of VOCs, while the opposite trend is observed the particles due to possible transformations that can occur even under the simplest conditions, with no occupants and no furnishing
28
Stratigou, Evdokia. « Identification and characterisation of physicochemical processes controlling indoor concentrations of submicron aerosols and volatile organic compounds ». Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0007.
Texte intégralRésumé :
Cette thèse développe les connaissances scientifiques sur l’origine et le comportement des polluants intérieurs en phases gazeuse et particulaire. Une description complète des processus physiques contrôlant les concentrations de polluants en air intérieur dans une pièce inoccupée et non meublée a été réalisée. En utilisant des paramètres bien quantifiés (taux de renouvellement d’air, facteur de pénétration et vitesse de dépôt), nous avons pu appliquer un modèle de bilan massique aux particules. Les résultats ont montré que, en l’absence significative de sources intérieures, une caractérisation fine des paramètres ci-dessus permettait de décrire de manière satisfaisante les concentrations intérieures en PM2.5 et PM10 à partir des données extérieures, tandis que les PM1 montrent une variabilité significativement plus marquée due aux transformations physicochimiques. Par la suite, les composés organiques volatils (COV) et la composition chimique des particules submicroniques ont été mesurés en temps réel lors d’une campagne intensive. Un enrichissement important des concentrations en COV a été observé lorsque l’air ambiant pénètre à l’intérieur du bâtiment, en particulier pour les COV oxygénés qui présentent une dépendance significative avec l’humidité relative, tandis que pour les particules les changements observés dépendent de leur composition chimique et de leur diamètre, montrant une diminution de 20% pour les PM1 à 86% pour les plus grosses particules (>5 μm). L’excès d’ammonium observé dans les deux environnements a permis de déconvoluer les nitrates organiques des inorganiques, ceux-ci présentant une dépendance plus forte avec la température, révélant une décomposition thermique plus importante en air intérieur. En résumé, l’environnement intérieur agit principalement comme une source d’émissions continues de COV, alors qu’une tendance inverse est observé pour les particules, du fait de transformations possibles pouvant se produire même dans les conditions les plus simples, sans occupant ni mobilierThis thesis improves the scientific knowledge on the origin, behavior and fate of gas and particle-phase pollutants indoors under unoccupied unfurnished conditions. A first campaign provided a complete description of the physical processes controlling the indoor concentrations. Using well quantified parameters (air exchange rate, penetration factor and deposition rate), a mass balance model provided insights for the particle budget closure. The results showed that when indoor sources are not significant, a careful characterization of the abovementioned parameters allows to estimate PM2.5 and PM10 in a satisfying manner from outdoor data. However the PM1 fraction shows a significantly higher variability due to physicochemical transformations. Subsequently, a second intensive campaign was performed to investigate volatile organic compounds (VOC) and PM1 chemical composition in real time. A strong increase in VOC concentrations was observed when outdoor air penetrates indoors, especially oxygenated VOC which exhibited a significant dependence on relative humidity, while the changes observed for particles once indoors depend on their chemical composition and diameter, showing a decrease from 20% for submicron particles up to, 86% for large ones (>5. µm). The investigation of ammonium neutralization revealed an excess of ammonium indoors and outdoors, which is attributed to organic- in addition to inorganic-bonded ammonium nitrate. The latter showed a stronger dependency on temperature gradient from outdoors to indoors, revealing stronger thermal decomposition once indoors. In summary, the indoor environment acts mainly as a continuous emission source of VOCs, while the opposite trend is observed the particles due to possible transformations that can occur even under the simplest conditions, with no occupants and no furnishing
29
Lancereau, Quentin. « Modélisation d'un collecteur électrostatique compact en régime laminaire pour la capture de bio-particules submicroniques aéroportées ». Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENI111/document.
Texte intégralRésumé :
La détection d'agents biologiques dans l'air ambiant est devenue un enjeu majeur notamment en environnement hospitalier et dans la protection contre le bioterrorisme. Dans ce contexte, la miniaturisation des dispositifs d'analyse permet d'envisager leur utilisation directement sur la zone d'étude. Afin d'obtenir un échantillon concentré et représentatif, la filtration de l'air reste cependant un point délicat. Parmi les différents principes exploitables pour la collecte de particules aéroportées, l'emploi des forces électriques semble être prometteur pour améliorer les performances des dispositifs qui se trouvent généralement fondés sur des forces inertielles. Dans cette étude, une modélisation fine des collecteurs électrostatiques a été conduite pour une géométrie fil / cylindre. Elle décrit tout d'abord les champs hydrodynamiques d'un écoulement charriant des inclusions dans lequel est imposée une décharge couronne. Une injection éventuelle de vapeur dans la chambre de collecte a nécessité ensuite la détermination des champs de température et concentration de la vapeur. Une analyse dimensionnelle inspectionnelle a montré que ces champs possèdent deux termes de couplage fort dont on a justifié l'omission dans cette étude ; les phénomènes physiques mis en jeu ont alors pu être classés selon une cascade d'influences non réciproques et la résolution numérique du modèle s'en est trouvée facilitée. Quatre configurations d'écoulement différentes, caractérisées par des recirculations d'origine électro hydrodynamiques, ont été identifiées et leurs impacts sur les rendements de collecte quantifiés. De plus, une procédure de dimensionnement des filtres électrostatiques fondée sur un nombre de Deutsch représentatif des rendements a été mise en place. Son exploitation a montré l'intérêt de la mise en parallèle de petits collecteurs pour filtrer des débits d'air importants. Cette étude s'est achevée par l'analyse des effets engendrés par l'injection de vapeur dans la chambre de collecte. Elle a jeté les bases d'une explication pour l'augmentation des rendements de collecte résultant de cette injectionDetection of airborne biological agents has become a major challenge especially in hospitals and the protection against bioterrorism. In this context, the miniaturization of analytical devices allows to consider their direct use in the field. To obtain a representative and concentrated sample, air filtration remains a delicate point. Among the various principles used to collect airborne particles, the use of electrical forces seems to be promising to improve performance beyond these of devices that are based on inertial forces.In this study, a detailed model of electrostatic collectors was developed in the wire/cylinder geometry. It first describes the hydrodynamic flow fields carring inclusions in which a corona discharge is imposed. Afterwards, the possible injection of steam into the collection chamber required the determination of the temperature and vapor concentration fields. An inspectionnal dimensional analysis justified the omission of two strong coupling terms. Therefore, in this study, the involved physical phenomena could be classified according to a non-reciprocal influences cascade and the numerical model is become simpler. Four different flow patterns, characterized by their electrohydrodynamic secondary flows, were identified and their impact on the collection efficiencies was quantified. In addition a design procedure of electrostatic filters, based on a representative efficiency Deutsch number, has been developed. This procedure shows the interest of parallelizing small collectors to filter important airflows. This study was completed by the analysis of the effects of steam into the collection chamber. It provides the basis for an explanation of the collection efficiencies increase related to this injection
30
Klein, Thomas [Verfasser]. « Wet chemical synthesis of nano and submicron Al particles for the preparation of Ni and Ru aluminides / Thomas Klein ». Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1231792027/34.
Texte intégral
31
Weimer, Silke. « Particle emission of traffic and wood combustion and its impact on spatial distributions of submicron particulate matter / ». Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17995.
Texte intégral
32
Penicot-Bauge, Pascale. « Étude de la performance de filtres à fibres lors de la filtration d'aérosols liquides ou solides submicroniques ». Vandoeuvre-les-Nancy, INPL, 1998. http://docnum.univ-lorraine.fr/public/INPL_T_1998_PENICOT_BAUGE_P.pdf.
Texte intégralRésumé :
Cette étude concerne la filtration par un filtre à fibres d'un gaz contaminé soit par des particules solides submicroniques soit par un aérosol liquide submicronique. Après une synthèse de l'ensemble des travaux réalisés antérieurement, nous nous intéressons dans un premier temps à caractériser les différents filtres (très haute efficacité et moyenne efficacité) mis à notre disposition. Les résultats expérimentaux relatifs à la filtration de particules solides nous ont permis de détailler le processus de colmatage et de décrire en particulier l'évolution de la perte de charge, de l'efficacité, du profil de pénétration de l'aérosol au sein du medium. Des observations au microscope montrent que dans une première étape du colmatage, des dendrites sont formées sur les fibres dans la profondeur du filtre et que dans une seconde étape un gâteau se construit sur la surface du filtre. L’originalité de la partie expérimentale réside dans la caractérisation du gâteau et la détermination du point de transition entre les deux phases de la filtration. Un nouveau modèle théorique a été développé et permet de rendre compte de l'ensemble des résultats expérimentaux. La filtration d'un aérosol liquide a été décrite et a mis en évidence l'existence d'une masse seuil pour laquelle on observe une brutale augmentation de la perte de charge du filtre, correspondant à la présence d'un film liquide forme sur la surface du filtre. L’influence de certains paramètres opératoires a été étudiée ainsi que la nature de l'aérosol, en particulier la tension superficielle du liquide. Enfin, diverses approches ont permis de décrire théoriquement les phénomènes observés et d'ouvrir différentes perspectives de modélisation plus fines.
33
Ye, Quan-Lin, Hirofumi Yoshikawa, Shunji Bandow et Kunio Awaga. « Green magnetite (Fe3O4) : Unusual optical Mie scattering and magnetic isotropy of submicron-size hollow spheres ». American Institite of Physics, 2009. http://hdl.handle.net/2237/12624.
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Tammaro, Marco. « Heterogeneous condensation for submicronic particles abatement ». Tesi di dottorato, 2010. http://www.fedoa.unina.it/8008/1/Tammaro_Marco_23.pdf.
Texte intégralRésumé :
It is now well established that the emission of sub-micrometric particulate matter entrained in flue gases of industry and vehicles exhausts, is one of the most critical treats for human health because of the toxicological effects of ultrafine particles on the respiratory system and their ability to cross alveoli’s membranes reaching the circulatory system too.
Albeit this scenario, the traditional particle abatement devices are mainly designed and optimised to treat particles larger than 1 μm, but they are far less effective towards the sub-micrometric particles. In particular, the existing technologies are far less efficient in collecting sub-micrometric particles, especially in the range 0.1 - 1 μm, called Greenfield gap.
The aim of this work is the study of the heterogeneous condensation, a promising method that can be used to achieve very high particles removal efficiency with reduced costs: particles undergoing heterogeneous condensation increase their diameter by deposition of a liquid film on the particles surface, generating a liquid-solid aerosol with desired diameter. Therefore, this process can be used as a preconditioning technique to enlarge the particles diameter at micrometric size, allowing the use of conventional separators for gas cleaning. Although largely studied for its effect on atmospheric phenomena and for the application to particle measurement techniques (the CPC units), heterogeneous condensation has never been used at industrial scale as a method for gas cleaning.
In this study, theoretical and experimental analyses on the heterogeneous condensation have been carried out. For this purpose instrumented lab scale equipment has been designed, constructed and tested. Experimental protocols and measurement techniques have been optimized. The core of the equipment is the growth tube, that consists in a glass tube where the particle laden gas flows comes into contact with a supersaturated water vapour environment, generated by a liquid film flowing on the tube internal walls.
Preliminary experimental tests have been carried out to define adequate experimental protocols and to find out the most reliable techniques to measure the size and concentration of the liquid-solid aerosol in the water saturated gas that exists the growth tube. Afterwards, an experimental campaign has been carried out to study the heterogeneous condensation of soot particles produced by a ethylene-air premixed flame at different working conditions. Eventually, the experiments have been interpreted through a simplified theoretical model that allows a good description of observed results. Experimental and modelling results eventually provide preliminary guidelines for the design of a pilot scale unit to be tested for future experimentation.
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Cozzolino, Gennaro. « Water condensation for submicronic particles abatement ». Tesi di dottorato, 2013. http://www.fedoa.unina.it/9503/1/Cozzolino_Gennaro_25.pdf.
Texte intégralRésumé :
Control of particulate matter (PM) emissions from industrial processes is important for protection of human health and the environment. A promising technique for submicron PM abatement is by condensing water vapor onto the particles, which enhances particle growth and improves the performance of traditional particle collection devices. This thesis analyzes the flue gases cleaning process by means of activation heterogeneous water nucleation mechanism on particles surface as a function of working condition, inlet temperature and vapor concentration, with particular emphasis on the effect of their dimension, number concentration, morphology and chemical nature on nucleation activation process. The temporal evolution of particles growths process has been studied with a proper experimental apparatus. Submicronic particles with a different wettability (C, Fe and Ni) have been produced by means of an aerosol spark generator. Vapor condensation on submicronic particles has been followed along the axis of the laminar flow chamber in dependence of operative conditions and particles characteristics by measuring the intensity of vertical and horizontal component of elastically scattered light and then evaluating the polarization ratio. Furthermore a series of off-line measurements have been performed to characterize solid particles. The results obtained represent a first database for kinetic data of condensation process. They show that particle growth mechanism involves different physical processes. By means a specific numerical modeling the polarization ratio of composite sphere made by a water shell hosting a solid particles was been calculated. In such a way the final size of droplet and so the particle growth factor have been evaluated. The main result obtained is that particle covering process related to its morphology and chemical properties is active at under-saturation conditions even if their size variation is relatively low. While for supersaturation conditions the particles coverage is enhanced by mass transport of vapor toward particles surface. In such a case the final size of the composite droplet is of the order of micron. It is worthwhile to note that both mechanisms are particularly effective for particles capture showing an unitary activation efficiency in the operative conditions considered. It is worth noting that extreme working conditions may be useful for the particle coverage. In addition, this work demonstrated that the theoretical prediction related to classical nucleation theory could be used to determine the process effectiveness at higher vapor concentration and lower inlet temperature, even though it fails to predict the induction time. At low values of vapor concentration, this approach was not valid in predicting the occurrence of the vapor condensation on particles. For this purpose the theory of capillary condensation seems to be an useful tool to predict the vapor deposition on particles and the induction time of growth process in so severe condition. In this PhD thesis, it was assessed that the characteristic induction and growth times are compatible with practical applications. The identification and estimation of this information can be useful in the design and dimensioning of a real abatement unit.
36
Liao, Bo-Xi, et 廖伯熙. « The Transfer Function of Nanoparticles and Submicron Particles in the Aerosol Particle Mass Analyzer ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/10749705273892429261.
Texte intégralRésumé :
碩士國立交通大學
環境工程系所
101
The Aerosol Particle Mass Analyzer (APM, Kanomax, Japan) is one of the popular instruments to measure the mass of nanoparticles and submicron particles. In previous studies, particle diffusion loss in the APM was speculated to be the reason why simulated response functions for the APM overestimated the experimental data. But no models were available to quantify the differences (Lall et al., 2009, Tajima et al., 2011). This thesis studies the transfer function of the APM by using a 2-D numerical model for nanoparticles and submicron particles. At first, the flow field in the annular classifying region of the APM is assumed to be parabolic. It is found that the transfer functions simulated by the present model are in good agreement with previous studies which also considered the parabolic flow profile. But transfer functions are still overestimated just like previous studies. After solving detailed flow and particle concentration fields in the APM by considering the forced vortex due to the rotating classifying region as well as inlet and outlet regions in the calculation domain, recirculation flow regions are found to exist in the APM. These recirculation flow regions lead to enhanced convection-diffusion loss of nanoparticles in the APM. As a result, the present model improves the accuracy of the transfer functions and response spectra of the APM significantly. Based on the numerical results, a modified Ehara model is developed to ease the calculation of the transfer function. Using these models, it is expected that accurate real time mass distribution measurement of both nanoparticles and submicron particles can be realized in the future.
37
Yu, Mei-chou, et 余美周. « Crossflow filtration of Submicron Particles ». Thesis, 1996. http://ndltd.ncl.edu.tw/handle/99545533942418649849.
Texte intégralRésumé :
碩士淡江大學
化學工程學系
84
The mechanism of cake formation in crossflow filtration of submicron particlesis studied. The Brownian dynamic method is used to trace the loci of slurryparticles and to simulate the packing structure of submicron particles infiltrations. The values of critical angle of friction are determined byanalyzing the forces exerted on the depositing particles and are used toestimate the probability of particle deposition under various operatingconditions. The major factors affecting the particle deposition ,such asuch as crossflow velocity, filtration rate, filtration pressure, particlediameter, temperature and concentration of suspension are discussed. Themigrations of particles in the filter cake are simulated to understand therelationships between local porosity and local specific filtration resistanceof cake and solid compressive pressure. A numerical program is also designedto simulate the attenuation of filtration rate during a course of filtration.The predicted results have a deviation of less than 10﹪
38
Lin, Chun-Yu, et 林春育. « Preparation of submicron-sized porous polyimide particles ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/s69ffu.
Texte intégralRésumé :
碩士中原大學
化學工程研究所
93
The objective of this work is to prepare porous or hollow polyimide particle. Submicron monodisperse poly(amic acid) particles prepared by using precipitation polycondensation were have been used as seeds. Diluents (water, acetic anhydride, aetonitrile) was added to swell seeds. Subsequently, porous or hollow polyimide was formed by chemical imidization with adding acetic anhydride as dehydration agent or by thermal imidization. The main objectives of this study are: (1) to investigate the effect of the kind and amount of diluents on the surface and interior morphology on the polymer particles, and expect to understand the mechanism of porous or hollow particle formation. (2) to investigate the effects of kind of the imidization on morphology formation of the polyimide particles. From the experimental results, porous poly(amic acid) particle can be prepared by using water as diluent. When acetic anhydride or acetonitrile as the diluent, respectively, the multihollow particles turn into hollow particle with increasing the amount of diluent. In order to clarify the multihollow or hollow structure in detail, the evaporation behavior of toluene of solid particles and multihollow or hollow particles is investigate. Thermal imidization can destroy the structure of porous or hollow particles. Chemical imidization can retain the structure of porous or hollow polyimide particles, but the degree of imidization and thermal property of polyimide is poor than those of thermal imidization.
39
Yu, Yi-Hsuan, et 尤逸玄. « Cross-flow Filtration of Deformable Submicron Particles ». Thesis, 1999. http://ndltd.ncl.edu.tw/handle/55239419298179983318.
Texte intégralRésumé :
碩士淡江大學
化學工程學系
87
The mechanism of cross-flow filtration of deformable submicron particles is studied. This research includes force analysis on depositing particles, dynamic analysis on local cake properties, and cross-flow filtration experiments. Cross-flow microfiltration were carried out by using pseudomas susprnsions. The effect of operating conditions, such as cross-flow velocity, filtration pressure, and suspension concentration, on the filtration performance are deeply discussed. The results show that the filtration rates increase with the increase of cross-flow velocity, decrease of filtration pressure, and decrease of suspension concentration. The photographs of scanning electronic microscope show that a skin layer with most compact structure may form nearby the membrane surface for the filtration of deformable particles. A numerical program based on material balance and theory is established for simulating the local porosity, filtration resistance, and solid copressive pressure in a filter cake. The variation of specific surface area due to area contact between particles during a filtration is taken into account. It can be found that a skin layer which control the filtration rate will form near the filter membrane in a membrane filtration of deformable submicron particles. Although the thickness of a skin layer is only 10% for whole cake, it plays a role of 90% filtration resistance.
40
賴志政. « Mechanism of cake formation for submicron particles ». Thesis, 1992. http://ndltd.ncl.edu.tw/handle/45982803714654468683.
Texte intégral
41
Lee, Meng-Chun, et 李孟駿. « Flow-Regulated Dielectrophoretic Manipulation of Submicron particles ». Thesis, 2006. http://ndltd.ncl.edu.tw/handle/89345354968426934339.
Texte intégralRésumé :
碩士國立成功大學
化學工程學系碩博士班
94
The motion of submicron particles under the condition of simultaneous flow and ac dielectrophoresis (DEP) is investigated experimentally using a microfluidic approach. Experiments are conducted within a PDMS microchannel integrated with arrays of castellated microelectrodes. Submicron latex particles are suspended in an electrolyte aqueous solution. The response of dielectrophoretic particle motion to the change in dielectric properties is carried out using different electrolyte concentrations. Results show that particle aggregation patterns are different from those of conventional DEP. Various new patterns of particle aggregation are identified, depending on the flow rate, the frequency of an applied electric field and the electrolyte conductivity. A scaling analysis is devised to explain the effects at work in accordance with experimental observations. The study provides new strategies for manipulating submicron particles in a continuous manner.
42
La, Motta Franesco. « Innovative processes for submicron particle removal ». Tesi di dottorato, 2017. http://www.fedoa.unina.it/11840/1/PhD%20thesis_LaMotta.pdf.
Texte intégralRésumé :
The removal of fine (FP dp < 2000 nm) and ultrafine particles (UFP dp <100 nm) from anthropogenic flue gases is becoming a priority of environmental chemical engineering because of their toxicity for humans and their contribution in climate change. In fact, once inhaled, particles finer than 300-500 nm penetrate the deepest regions of the lungs and even cross the cellular membranes, reaching the circulatory system and causing a wide range of health problems. In addition, fine and ultrafine particles affect atmosphere and climate characteristics in complex and sometimes still undetermined ways, according to their physical nature. In general, the presence of high particles contamination in the atmosphere is associated to reduction of visibility in cities and scenic areas, cloud formation, secondary reactions of atmospheric pollutants and radiative forcing phenomena.
Fine and ultrafine particles are primarily emitted by combustion processes some of which are located close to high population density area (vehicular traffic, harbours, industrial areas, residential heating) increasing significantly the exposure risk: while the overall particle exposure appears as a limited concern, regional effects are often significant and affect a wide fraction of the world population.
Following the pertinent regulation on air quality and pollution control, the design of conventional fine particle abatement devices was optimised to achieve a very high reduction (even higher than 99.5%) of the emitted particles in mass. Therefore, they are very effective in removing the largest particles (whose weight highly influences the mass removal efficiency) but are far less efficient toward the particles ranging from 100 to 2000 nm, range called Greenfield Gap.
To this end, new technologies able to effectively handle both coarse, fine and ultrafine particles are under development. Among them, it is worth mentioning wet electrostatic precipitators, agglomerates, wet electrostatic scrubbers, pool scrubbing and condensational growth assisted treatment units.
The rationales for using condensational growth as a pre-treatment are that the liquid-solid aerosols can be more easily captured because, their size is larger than the critical regions and the presence of a water shell may favour their sticking with the water-gas interface. Condensational growth can be adopted to increase the removal efficiency of different wet particle removal technologies.
The purpose of this work was to study an innovative system to remove fine and ultrafine particles. The concept design was to couple the gas treatment devices with the condensational growth aimed to enhance the particles collection. Among the removal techniques, the work focused on the bubble columns and the wet electrostatic scrubbers. The concept design consisted to pre-treat particles laden gas in a growth unit in order to generate a solid-liquid aerosol with larger size that, fed to the removal units, was more easily captured. The growth unit consisted in a growth tube (GT), made up by a glass cylinder high 40 cm and with an internal diameter of 1.5 cm. The concept of the growth unit was to make in contact the aerosol with a warmer liquid film. The supersaturation levels depended on the temperature gradient and the gas velocity. The bubble column (BC) consisted in a glass bottle filled with distilled water (ID= 10 cm, H= 20 cm) having a porous ceramic distributor (D=8 mm) placed 1 cm above the bottom from which the gas enters the bottle and a gas outflow at the bottle cap. The wet electrostatic scrubber (WES) consisted in a cylinder in plexiglass 40 cm high and with an internal diameter of 4.5 cm. It is equipped with an electrospray unit that houses on the top of the chamber. The lateral surface of the reactor presents two 10 mm holes for gas inlet and outlet.
Two different set of experiments were carried out. A first set of experiments was carried out to measure the aerosol growth obtained in the GT and to verify the conditions at which the heterogeneous condensation took place. The second one was meant to measure the particles abatement in the GT, BC, WES and the entire GT-BC and GT-WES systems.
The experiments were performed at a gas flow rate of 48 L/h with the GT operated at liquid temperature between 30 and 70°C. Five different materials were tested: sodium chloride, titanium dioxide, carbon black and calibrated nanoparticles of polystyrene with a mean volume diameter of 100 and 200 nm. The aerosol was generated by an aerosol generator (TOPAS ATM 221) and monitored by two different diagnostic system: the TSI 3340, based on a light scattering measure, and a TSI 3910, based on the electrical mobility measure.
The experimental results on the particle growth showed that at the exit of the GT the initial wide distribution changed towards more narrow shape and moved towards larger particles. This behaviour was observed for all the materials and the mode of their distributions at the highest temperature was roughly 350 nm. Moreover, the supersaturation levels established in the GT for each film temperature were evaluated and it was observed that the particles started to grow at supersaturation level much lower than that one predicted by the classical theory. A deep investigation of the physic of the condensational growth was accomplished in order to explain these experimental evidences.
The experimental results on the particle abatement showed that the GT contributed to the particle removal and had a “cut-off” for particles larger than 500 nm. The tests run with the whole systems showed that indeed the efficiencies of both the BC and the WES improved significantly when the particle growth was observed. The BC had the maximum increment of roughly 100% at 70°C for all the tested aerosols, while the WES had the maximum improvement at 50°C for most of the tested particles, suggesting the presence of an optimum between the particles growth process and its capture mechanisms.
43
Chen, Chun-hung, et 陳俊宏. « Interactions between Amphoteric Submicron Polymer Particles and Proteins ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43486876481867744624.
Texte intégralRésumé :
碩士國立臺灣科技大學
化學工程系
93
Amphoteric latex particles were prepared by the surfactant-free emulsion polymerization, with methyl methacrylate (MMA) as the hydrophobic monomer, methacrylic acid (MAA) as the hydrophilic monomer, and V-50 as the cationic initiator. First, the seed latex particles were prepared by the batch surfactant-free emulsion polymerization. Second, the latex products were synthesized by the semibatch seeded surfactant-free emulsion polymerization. These submicron particle surfaces have amino groups and carboxyl groups at the same time. Therefore, they display pH-sensitiy. The particle surfaces have net positive charge, owing to the ionized amino groups at low pH. The particle surfaces have net negatively charge, owing to the ionized carboxyl groups at high pH. Isothermal adsorption of BSA, pepsin or lysozyme on amphoteric latex particles were carried out. Adsorption of proteins onto the particles leads to change in the turbidity, particle size and zeta potential. When amphoteric latex particles and proteins have the opposite net charge, the self-promoting adsorption process may occur due to charge neutralization and this could lead to flocculation. In contrast, electrostatic repulsion forces between amphoteric latex particles and proteins with similar charges play an important role in the colloidal stability. This will then retard the adsorption of protein molecules onto the particle surfaces. Therefore, latex particles exhibit excellent colloidal stability.
44
Liao, Chun-Shien, et 廖俊賢. « Eohanced Collection Efficiency of Submicron Particles by Electrocyclone ». Thesis, 1997. http://ndltd.ncl.edu.tw/handle/88306225921092482050.
Texte intégralRésumé :
碩士國立中興大學
環境工程學系
85
The submicron particles were the most difficult to be collected by the conve ntional dust removal devices. The purpose of this study was to investigate the applicability of using an electrocyclone to collect the submicron particles. The electrocyclone were Stairmand high-efficiency and tangential inlet-type wi th electrode inserted into the center of cyclone outlet. Two cyclones were tes ted in this study and their diameters were 13.3 cm and 25.0 cm. Totally four e lectrodes of various diameters and lengthes were used and the experiments were conducted under various inlet flow velocities, applied voltages, and mass loa dings. The inlet velocities and the applied voltages were varied between 5.7 t o 26.0 m/s and 0 to 50 kV, respectively.The submicron particles were ammonium chloride aerosols generated by mixingthe vapors of HCl and NH4 OH. The results showed that The electric field significantly improve theperformance of submic ron particles. Such enhancement effect was reduced withhigher flow rate. The b est collection efficiencies of the ammonium chlorideaerosols by the electrocyc lones could achieve to 86 %. Thinner electrode was more effective than the thi ck one. However the shorter electrode was found more economical. In general th e larger electrocyclone was less effective than the smaller one under the same operational condition, but both had the same efficiency when both consumed th e same corona power ratio. It indicated that the corona power ratio was the un ique parameter to determine the collection efficiency of the submicrone partic les by using electrocyclone.
45
Weng, Yu-ting, et 翁郁婷. « Interactions between Submicron Polymer Particles and Binary Proteins ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/m8pqp9.
Texte intégralRésumé :
碩士國立臺灣科技大學
化學工程系
95
Submicron polymer particles were prepared by emulsion polymerization with methyl methacrylate (MMA) as the hydrophobic monomer, sodium persulfate as the initiator, and HS-10 as the surfactant. These particle surfaces have sulfate groups (-SO4-) and sulfonate groups (-SO3-) at the same time. Therefore, they are relatively insensitive to changes in pH. The adsorption of binary proteins (BSA and lysozyme) on the particles was studied. Isothermal adsorption of binary proteins onto the particles leads to changes in the zeta potential, particle size and turbidity. At the low ionic strength, the total maximum protein adsorption occurs in the pH range of 7－8. This may well be due to lysozyme adsorption onto the particles first and this will result in increased net negative charge particles and therefore promote the adsorption of BSA. Another reason is that BSA and lysozyme have opposite net charges, they’ll aggregate with each other first by electrostatic attraction forces. Then electrostatic attraction forces between lysozyme of the binary proteins mixture and submicron latex particles bring about the enhanced total adsorbed amount.
46
Jung, Chang Chia, et 張家榮. « Synthesis and characterization of amphoteric submicron polymer particles ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/93877120219592856143.
Texte intégralRésumé :
碩士國立臺灣科技大學
化學工程系
90
The seed latex particles were prepared by batch soap-free emulsion polymerization. The latex products were then synthetized by semibatch seeded soap-free emulsion polymerization. As a result of different AAP and MAA concentrations in the recipes used, latex particles carrying different charges and displaying pH-sensitivity were obtained. At high pH, the Zeta potential of latex particles (ζ) increases with increasing [MAA]. At low pH , ζ increases with increasing [AAP]. Isothermal adsorption of latex particles with Lysozyme, Pepsin, or Hemoglobin were carried out. When the aqueous solution environment was varied, the properties of the adsorbed latex particles were quite different. At pH = 3, Pepsin adsorbed on the particle surfaces, but Lysozyme could not adsorb on the particle surfaces. At pH = 7, Lysozyme adsorbed on latex particle surfaces (C2-1) by electrostatic interaction, whereas Pepsin adsorbed on latex particle surfaces by hydrophobic interaction. At pH = 9.5, Lysozyme adsorbed on particle surfaces, whereas Pepsin was incapable of adsorbing.
47
Esposito, Martina. « ELECTROSTATIC SCRUBBING OF SUBMICRON PARTICLES : EXPERIMENTAL AND MODELING ». Tesi di dottorato, 2018. http://www.fedoa.unina.it/12629/1/Martina_Esposito_PhD_Thesis.pdf.
Texte intégralRésumé :
This work contributes to the development of the technology of Wet Electrostatic Scrubbing (WES) at industrial scale by improving the current knowledge on corona charger unit design and designing, by building and setting up a pilot scale WES for specific industrial applications. This work was developed jointly by the Department of Chemical, Material and Industrial Production Engineering of the University of Naples Federico II” and the Ecology Division of the Boldrocchi s.r.l. .
The Wet Electrostatic Scrubber is an upgrade of a conventional wet scrubber: it was proved that the electric forces are the main responsible for particle capture, more than the other physical phenomena that might be present in the scrubber.
Therefore, the first topic covered by the study was the assessment of design criteria to scale up corona charger for particle charging. To understand the actual particle charge distribution of an ensemble of particles entering a corona device, several parameters have to be defined: particles residence time, local electric field and ion concentration, particle shape and composition. These parameters are generally considered on their mean value, but this approach is not adequate for predicting particle charges for a more complex system. For this reason, using the simulation program Ansys Fluent to gain some information concerning particle behavior in the reactor, two different particle charging models will be compared to experimental data.
To provide a reliable assessment of particle charge, we developed a particle capture model in a WES unit coupling the particle capture model with the results of a dedicated computational Fluid dynamic analysis performed using Ansys Fluent. The model was used to describe the experimental data obtained by our research group in a smaller WES pilot tested in several conditions during the EFP7 DEECON project. In particular, this model includes a dedicated assessment of droplets size and charge distribution, which can be achieved properly only by experimental data and the relevant fluid dynamic parameters as gas residence time distribution, droplets spatial distribution and gas-droplets relative velocities, which are evaluated through the computational program Ansys Fluent (explained in Chapter 3 in detail).
Averaged values of particle charges were determined using theoretical models and mean values of electric field, ion concentration and residence time in the pilot scale corona charger. This predictive model was applied to the case study and compared with the experimental data. In order to overcome the limited knowledge on particle charging, a reversed approach to data analysis was proposed. In this case, the data on particle capture in the WES were used to calculate the charge deposited on the particles and the achieved data were considered in terms of total aerosol current, applied voltage and particle size.
These information were used to define design and operating conditions for the pilot WES system (operating at gas flow rates ranging from 5500 to 10.000 Nm3/h) build and operated at the Boldrocchi factory in Biassono (MB, Italy). The pilot scale system was operated in several conditions using reference Arizona test dust particles. The experimental data demonstrated that the WES units are able to achieve particle removal efficiencies higher than 90% in number, for particles from 150 to 800 nm, with results consistent with the design specifications.
48
Engstrom, Joshua David 1978. « Stable submicron protein particles : formation, properties, and pulmonary applications ». 2007. http://hdl.handle.net/2152/15975.
Texte intégralRésumé :
The spray freezing into liquid (SFL) and thin film freezing (TFF) processes were utilized to produce 300 nm protein particles with surface areas on the order of 31 - 73 m²/g and 100% protein activities. Despite a cooling rate of ~10²-10³ K/s in SFL and TFF, the particle sizes and surface areas were similar to those observed in the widely reported process, spray freeze-drying (SFD), where cooling rates reach 10⁶ K/s. In SFL and TFF, the thin liquid channels between the ice domains were sufficiently thin and freezing rates of the thin channels sufficiently fast to achieve the similar particle morphologies. Therefore, the extremely rapid cooling rate in the SFD process was not necessary to form the desired submicron protein particles. In SFL and TFF the surface area/volume ratio of the gas-liquid formed on the liquid protein formulations (46-600 cm⁻¹) was 1-2 orders of magnitude lower than in SFD (6000 cm⁻¹), leading to far less protein adsorption and aggregation. This larger exposure to the gas-liquid interface resulted in lower protein activities in SFD. Although protein stabilities are high in conventional lyophilization, cooling rates are on the order of 1 K/min resulting in large 30 to 100 [mu]m sized particles. Thus, the intermediate cooling rate regime for SFL and TFF, relative to SFD and lyophilization, offers a promising route to form stable submicron protein particles of interest in pulmonary and parenteral delivery applications. The rod-shaped protein particles produced by SFL and TFF are beneficial for forming suspensions stable against settling in hydrofluoroalkanes (HFA) for pressurized metered dose inhaler (pMDI) delivery. The flocculated rods are templated by atomized HFA droplets that evaporate and shrink to form particles with optimal aerodynamic diameters for deep lung delivery. Fine particle fractions of 38-48% were achieved. This novel concept for forming stable suspensions of flocs of rod shaped particles, and templating and shrinking the flocs to produce particles for efficient pMDI deep lung delivery is applicable to a wide variety of drugs.text
49
Wang, Min-Neng, et 王敏能. « Preparation and Characterization of submicron-sized Hollow Polyimide Particles ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/sb5r4x.
Texte intégralRésumé :
碩士中原大學
化學工程研究所
93
The objective of this work is to prepare polyimide particles with hollow void. Hollow polyimide particles were prepared by using monodisperse polystyrene as seeds, prepared by emulssionless polymerization. Diamine solution was swollen into seeds and then added dianhydride solution to proceed condensation polymerization, after dehydrating to imidization and extracting the seeds. We can get the hollow polyimide particles, subsequently. The effects by changing the recipes and reaction conditions, the morphology of the hollow polyimide particles, and physical properties, such as: thermal stability, crystallinity…etc., were investigated. From the experimental results, we can get the morphology with no aggregation by increasing the swelling time and stirring rate. Using PVP as a stabilizer can get better morphology of the hollow polyimide particles than that of SDS. The thickness and the size of the hollow polyimide particles were increased with the increasing of the amount of the added monomer and in the range between 180nm and 240nm . The 3% weight loss of particles was around 530 and 580℃.
50
Chou, Meng-Chun, et 周孟君. « Cytotoxicity of Submicron Particles with High Organic Carbon Contents ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/86946808945469630367.
Texte intégralRésumé :
碩士國立陽明大學
環境衛生研究所
93
Objective: To evaluate the effects of ambient particulate’s size and PAH components on the production of interleukin-8 (IL-8) in normal human bronchial epithelial cells (BEAS-2B). Methods: We collected ambient particulate and incense and cigarette samples by using Micro-Orifice Uniform Deposit Impactors (MOUDI), and used a gas chromatography/mass spectrometry (GC-MS) to determine the contentsof PAHs. BEAS-2B cells were exposed to 80 �慊/ml particle suspensions for 8 hours in order to induce interleukin-8 (IL-8) release, which were determined by enzyme-linked immunosorbent assay (ELISA). We measured cellular lipid peroxidation by the LPO-586 method and the ability of particles to generate reactive oxygen species (ROS) in a cell-free system with the dithiothreitol (DTT) assay. Results: The PAHs of ambient particles reside mostly in particles less than 0.18 �慆 in diameter. . Also various particle sizes sector PAHs toxic strong and the weak ratios are higher than other particles by particle size sector. The particle contents of B[b]F, B[k]F, B[a]p, B[e]p, I[cd]P, B[ghi]P, and Cor are significantly correlated. The ratio of high toxicity to low toxicity PAHs is highest in the PM0.32-0.56 range. For particles size , the IL-8 release was significantly higher than the control group,but there was no significant difference among the various particle size ranges. , cigarette particles induced significantly more IL-8 release than incense particles. PM0.18-0.32,PM0.1-0.18, and PM< 0.056 from incense samples induced significsantly more IL-8 release than PM0.56-1. Particles from cigarette samples induced significantly more IL-8 release than control groups, but there was no significant difference among sizes. . The cigarette particles generated ROS more than incense particles; ROS were negatively associated with IL-8(R= -0.67, p<0.05). The cigaretter particles caused higher lipid peroxidation than incense particles. IL-8 were significantly associated with LPO production (R=0.6, p<0.05). Conclusion: This study can not demonstrated the effects of ambient particulate matter’s(PM) size and PAHs components on the production of interleukin-8 (IL-8) in normal human bronchial epithelial cells (BEAS-2B). Further analysis with particle components may shed light on the mechanisms.