Tesis: "Gas-particles"

1

Omota, Florin. "Adhesion of catalyst particles to gas bubbles." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2005. http://dare.uva.nl/document/77898.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Zhao, Fan. "Modelling of gas-solid flows with non-spherical particles." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/34398.

Texto completo

Resumen

Dispersed multiphase flows are common in nature and industry and are governed by complex physical phenomena. The complex features of the turbulence continuity carrier phase and the dispersed phase make the problem of a dispersed multiphase flow much more complex than a single phase flow. This research work focuses on modelling and analysing one type of dispersed multiphase flows: solid particles suspended in a turbulent channel flow. The aim of this thesis is to numerically investigate the effects of Stokes number, particle shape and particle volume fraction on the behaviour of gas-solid turbulent channel flows with non-spherical particles. This study not only considers spherical particles but also studies non-spherical fibre-like ellipsoids suspended in the channel flow. To fully describe the complex dynamics of non- spherical particles, the rotational motion and orientation is efficiently and accurately re- solved by applying unit Quaternions. To address inevitable numerical errors caused by the Quaternion integration algorithms in previous studies, a novel Quaternion integration method is derived, validated and applied for more accurately updating the unit Quaternions. This work also derives a new Quaternion equation to relate second order tensor variables between different frameworks. This research work applies four-way coupling to accurately model the complex gas-solid turbulent channel flows, and the fluid-particle, particle-particle and particle-wall interactions are all taken into account. Important conclusions from this work are summarized as follows. In four-way coupled simulations, the average viscosity of the fluid flow is not affected by the particles, whereas the turbulence intensity is reduced by adding small heavy particles. The average direct dissipation by the particles is negligible, and the primary mechanism by which the particles affect the flow is by altering the turbulence structure near and around the turbulence kinetic energy peak. For non-spherical particles, the distributions of the orientation angles clearly demonstrate that ellipsoids tend to align within the plane that lies perpendicular to the span-wise direction in the very near wall region, follow the stream-wise direction in the buffer layer, and almost randomly distribute in the central region of the channel.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Rees, Andrew Christopher. "The behaviour of buoyant particles in gas-fluidised beds." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613955.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Cowan, John D. "A billiard model for a gas of particles with rotation /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2004.

Buscar texto completo

Resumen

Thesis (Ph.D.)--Tufts University, 2004. Adviser: Boris Hasselblatt. Submitted to the Dept. of Mathematics. Includes bibliographical references (leaves 61-62). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Hardy, Matthew Philips. "Numerical investigation of gas-powered delivery of micro particles to tissue." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289337.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Soliman, Salah M. "Micro-Particles and Gas Dynamics in an Axi-Symmetric Supersonic Nozzle." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1313772443.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Kim, Donghee. "Nucleation and coagulation of particulate matter inside a turbulent exhaust plume of a diesel vehicle." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2305.

Texto completo

Resumen

Thesis (Ph. D.)--West Virginia University, 2002. Title from document title page. Document formatted into pages; contains xv, 198 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 165-177).

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Zhang, Ning. "Motion and distribution of micro-sized solid particles in turbulent gas flow /." Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Kassaee, Mohamad Hadi. "Internal surface modification of zeolite MFI particles and membranes for gas separation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44906.

Texto completo

Resumen

Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. Modification of zeolite structures with organic groups offers a potential new way to change their properties of zeolites, beyond the manipulation of the zeolite framework structure and composition. The main goals of this thesis research are to study the organic-modification of the MFI pore structure, and to assess the effects of such modification on the adsorption and transport properties of zeolite MFI sorbents and membranes. In this work, the internal pore structure of MFI zeolite particles and membranes has been modified by direct covalent condensation or chemical complexation of different organic molecules with the silanol defect sites existing in the MFI structure. The organic molecules used for pore modification are 1-butanol, 1-hexanol, 3-amino-1-propanol, 1-propaneamine, 1,3-diaminopropane, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. TGA/DSC and 13C/29Si NMR characterizations indicated that the functional groups were chemically bound to the zeolite framework, and that the loading was commensurate with the concentration of internal silanol defects. Gas adsorption isotherms of CO2, CH4, and N2 on the modified zeolite materials show a range of properties different from that of the bare MFI zeolite. The MFI/3-amino-1-propanol, MFI/2-[(2-aminoethyl)amino]ethanol, and MFI/benzenemethanol materials showed the largest differences from bare MFI. These properties were qualitatively explained by the known affinity of amino- and hydroxyl groups for CO2, and of the phenyl group for CH4. The combined influence of adsorption and diffusion changes due to modification can be studied by measuring permeation of different gases on modified MFI membranes. To study these effects, I synthesized MFI membranes with [h0h] out-of-plane orientation on α-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores. A detailed fundamental study of the CO2 adsorption mechanism in modified zeolites is necessary to gain a better understating of the adsorption and permeation behavior of such materials. Towards this end, an in situ FTIR study was performe.For the organic molecules with only one functional group (1-butanol, benzenemethanol, and 1-propaneamine), physical adsorption was found - as intuitively expected - to be the only observed mode of attachment of CO2 to the modified zeolite material. Even in the case of MFI modified with 1,3-diaminopropane, only physical adsorption is seen. This is explained by the isolated nature of the amine groups in the material, due to which only a single amine group can interact with a CO2 molecule. On the other hand, chemisorbed CO2 species are clearly observed on bare MFI, and on MFI modified with 3-amino-1-propanol or 2-[(2-aminoethyl)amino]ethanol. Specifically, these are carbonate-like species that arise from the chemisorption of CO2 to the silanol group in bare MFI and the alcohol groups of the modifying molecule. The possibility of significant contributions from external surface silanol groups in adsorbing CO2 chemisorbed species was ruled out by a comparative examination of the FTIR spectra of 10 μm and 900 nm MFI particles modified with 2-[(2-aminoethyl)amino]ethanol.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Gallen, Lucien. "Prediction of soot particles in Gas Turbine Combustors using Large Eddy Simulation." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0058.

Texto completo

Resumen

Les futures réglementations en termes d'émission de polluants, notamment sur les particules fines (PM), qui s'appliquent aux chambres de combustion de nouvelle génération nécessitent de nouvelles approches de conception. Afin de réduire la formation des particules de suies, la compréhension des processus de formation et de transports des particules est nécessaire. La chimie et la dynamique de ces particules de suies dépendent fortement de la taille et de la morphologie de celle-ci, leur prédiction requière donc calculer la distribution en taille des particules. Pour cela, des méthodes Eulériennes sont utilisées (Moments, Sectionnels), ou des méthodes stochastiques Lagrangiennes sont proposées. Dans ce travail, une méthode semidéterministique basée sur l'approche Lagrangienne est proposée. Parallèlement, une description précise de la chimie, notamment pour les précurseurs de suies nécessaire aux modèles détaillés de formation de suies est développée. La méthodologie incluant la description des précurseurs de suies et le transport de celles-ci est calculée dans deux configurations de type aéronautiques. La première est la configuration FIRST, une flamme étudiée au DLR opérant à haute pression dans un milieu confiné et stabilisée à l'aide d'un swirleur. L'impact du choix du précurseur de suies ainsi que la prise en compte des transferts radiatifs est évaluée. La température et la fraction volumique des suies sont en accord avec les mesures expérimentales. La seconde configuration est le bruleur UTIAS Jet A-1 où le Jet A-1 est un carburant aéronautique, il est caractérisé par une flamme swirlée diphasique et étudié à l'université de Toronto au Canada. La simulation aux grandes échelles de cette configuration procure de nouvelles connaissances sur la formation des particules des suies dans les flammes turbulentes diphasiques. Un très bon accord avec les données expérimentales est observé pour cette configuration concernant les particules de suies Expected stringent legislation on particulate matter (PM) emission by gas turbine combustors is currently motivating considerable efforts to be better understand, model and predict soot formation. This complex phenomenon is very difficult to study in detail with experiment, and numerical simulation is an essential complementary tool. Considering that the chemistry of soot particles strongly depends on their size, the numerical prediction of soot formation requires the description of their size distribution. To do so, either Eulerian methods (sectional or moments) or stochastic Lagrangian approaches are reported in the literature. In the present work, a far more simple semi-deterministic Lagrangian approach is proposed. An accurate description of the gaseous phase including first Polycyclic Aromatic Hydrocarbons is also developed as a necessary input to detail soot model. The combination of reduced chemistries with Lagrangian soot tracking is applied to canonical laminar sooting flames, later to two complex configurations representative of an aeronautical combustors. The first one is the FIRST configuration, a gaseous confined pressurized swirled flame studied experimentally at DLR. Impact of precursors species and radiative transfers through the resolution of Radiative Transfer Equation (RTE). Good predictions are obtained compared to experiments for predicted temperature and soot volume fraction. The second target configuration is the UTIAS Jet A-1 burner and corresponds to a confined turbulent spray flame burning aviation jet fuel A-1 studied experimentally at UTIAS Toronto. LES of this configuration provides a qualitative and quantitative understanding of soot evolution in turbulent spray flames. Numerical predicted soot volume fraction using Lagrangian soot tracking and an ARC mechanism including pyrolysis method is compared to experimental measurements. Results show the ability of the proposed methodology relying on ARC chemistry for Jet A-1 including pyrolysis method and Lagrangian soot tracking, to predict accurately soot compared to available measurements

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Bavarian, Farshad. "Hydrodynamics of gas-liquid fluidization in annular fluidized bed and fluidization of cylindrical particles under high gas holdup conditions /." Connect to resource, 1987. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157058483.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Tortorelli, Joseph Patrick. "The effect of external gas/slurry contact on the flotation of fine particles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28874.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Gilbert, Marcus. "Investigation into the use of a tapered element oscillating microbalance for real-time particulate measurement." Morgantown, W. Va. : [West Virginia University Libraries], 2002. http://etd.wvu.edu/templates/showETD.cfm?recnum=2549.

Texto completo

Resumen

Thesis (M.S.)--West Virginia University, 2002. Title from document title page. Document formatted into pages; contains xii, 74 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 61-62).

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Croft, Shiona Andrea. "The analysis of unfired propellant particles by gas chromatography - mass spectrometry : a forensic approach." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/17251/1/Shiona_Croft_Thesis.pdf.

Texto completo

Resumen

In Australia, the 0.22 calibre ammunition is the most encountered ammunition type found at a crime scene [1]. Previous analysis of gun shot residue (GSR) and unfired propellant has involved studying the inorganic constituents by Scanning Electron Microscopy or similar technique. However, due to the heavy metal build up that comes with some ammunition types, manufacturing companies are now making propellant that is safer to use. Therefore, it has become appropriate to study and analyse unfired propellant by other means. One such technique is unfired propellant analysis by gas chromatography – mass spectrometry (GC-MS). This technique focuses on the organic constituent make up of the propellant paying particular attention to diphenylamine, ethyl centralite and dibutyl phthalate. It was proposed that different batches of ammunition could be discriminated or matched to each other by using this technique. However, since the main constituents of unfired propellant are highly reactive, it was not possible to accomplish batch determination of ammunition. However, by improving extraction techniques and by removing oxygen (a catalyst for the degradation of diphenylamine) a superior method was established to help in the analysis of unfired propellant. Furthermore, it was shown that whilst differentiating batches of the same ammunition was not possible, the improved methods have helped identify different types of the same brand of ammunition. With the aid of future studies to fully explore this avenue, the analysis of unfired propellant could one day become an integral part of forensic science.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Croft, Shiona Andrea. "The analysis of unfired propellant particles by gas chromatography - mass spectrometry : a forensic approach." Queensland University of Technology, 2008. http://eprints.qut.edu.au/17251/.

Texto completo

Resumen

In Australia, the 0.22 calibre ammunition is the most encountered ammunition type found at a crime scene [1]. Previous analysis of gun shot residue (GSR) and unfired propellant has involved studying the inorganic constituents by Scanning Electron Microscopy or similar technique. However, due to the heavy metal build up that comes with some ammunition types, manufacturing companies are now making propellant that is safer to use. Therefore, it has become appropriate to study and analyse unfired propellant by other means. One such technique is unfired propellant analysis by gas chromatography – mass spectrometry (GC-MS). This technique focuses on the organic constituent make up of the propellant paying particular attention to diphenylamine, ethyl centralite and dibutyl phthalate. It was proposed that different batches of ammunition could be discriminated or matched to each other by using this technique. However, since the main constituents of unfired propellant are highly reactive, it was not possible to accomplish batch determination of ammunition. However, by improving extraction techniques and by removing oxygen (a catalyst for the degradation of diphenylamine) a superior method was established to help in the analysis of unfired propellant. Furthermore, it was shown that whilst differentiating batches of the same ammunition was not possible, the improved methods have helped identify different types of the same brand of ammunition. With the aid of future studies to fully explore this avenue, the analysis of unfired propellant could one day become an integral part of forensic science.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Qin, Tong. "Numerical Simulations of Interactions of Solid Particles and Deformable Gas Bubbles in Viscous Liquids." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19225.

Texto completo

Resumen

Studying the interactions of solid particles and deformable gas bubbles in viscous liquids is very important in many applications, especially in mining and chemical industries. These interactions involve liquid-solid-air multiphase flows and an arbitrary-Lagrangian-Eulerican (ALE) approach is used for the direct numerical simulations. In the system of rigid particles and deformable gas bubbles suspended in viscous liquids, the Navier-Stokes equations coupled with the equations of motion of the particles and deformable bubbles are solved in a finite-element framework. A moving, unstructured, triangular mesh tracks the deformation of the bubble and free surface with adaptive refinement. In this dissertation, we study four problems. In the first three problems the flow is assumed to be axisymmetric and two dimensional (2D) in the fourth problem. Firstly, we study the interaction between a rising deformable bubble and a solid wall in highly viscous liquids. The mechanism of the bubble deformation as it interacts with the wall is described in terms of two nondimensional groups, namely the Morton number (Mo) and Bond number (Bo). The film drainage process is also considered. It is found that three modes of bubble-rigid wall interaction exist as Bo changes at a moderate Mo. The first mode prevails at small Bo where the bubble deformation is small. For this mode, the bubble is hard to break up and will bounce back and eventually attach to the rigid wall. In the second mode, the bubble may break up after it collides with the rigid wall, which is determined by the film drainage. In the third mode, which prevails at high Bo, the bubble breaks up due to the bottom surface catches up the top surface during the interaction. Secondly, we simulate the interaction between a rigid particle and a free surface. In order to isolate the effects of viscous drag and particle inertia, the gravitational force is neglected and the particle gains its impact velocity by an external accelerating force. The process of a rigid particle impacting a free surface and then rebounding is simulated. Simplified theoretical models are provided to illustrate the relationship between the particle velocity and the time variation of film thickness between the particle and free surface. Two film thicknesses are defined. The first is the thickness achieved when the particle reaches its highest position. The second is the thickness when the particle falls to its lowest position. The smaller of these two thicknesses is termed the minimum film thickness and its variation with the impact velocity has been determined. We find that the interactions between the free surface and rigid particle can be divided into three regimes according to the trend of the first film thickness. The three regimes are viscous regime, inertial regime and jetting regime. In viscous regime, the first film thickness decreases as the impact velocity increases. Then it rises slightly in the inertial regime because the effect of liquid inertia becomes larger as the impact velocity increases. Finally, the film thickness decreases again due to Plateau-Rayleigh instability in the jetting regime. We also find that the minimum film thickness corresponds to an impact velocity on the demarcation point between the viscous and inertial regimes. This fact is caused by the balance of viscous drag, surface deformation and liquid inertia. Thirdly, we consider the interaction between a rigid particle and a deformable bubble. Two typical cases are simulated: (1) Collision of a rigid particle with a gas bubble in water in the absence of gravity, and (2) Collision of a buoyancy-driven rising bubble with a falling particle in highly viscous liquids. We also compare our simulation results with available experimental data. Good agreement is obtained for the force on the particle and the shape of the bubble. Finally, we investigated the collisions of groups of bubbles and particles in two dimensions. A preliminary example of the oblique collision between a single particle and a single bubble is conducted by giving the particle a constant acceleration. Then, to investigate the possibility of particles attaching to bubbles, the interactions between a group of 22 particles and rising bubbles are studied. Due to the fluid motion, the particles involved in central collisions with bubbles have higher possibilities to attach to the bubble. Ph. D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Jarrett, Ronald P. "Evaluation of opacity, particulate matter, and carbon monoxide from heavy-duty diesel transient chassis tests." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1599.

Texto completo

Resumen

Thesis (M.S.)--West Virginia University, 2000. Title from document title page. Document formatted into pages; contains xvi, 129 p. : ill. Includes abstract. Includes bibliographical references (p. 78-82).

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Dewsbury, Kevin H. "Hydrodynamic study of free rise of solid particles and gas bubbles in non-Newtonian fluids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0017/MQ58025.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Mort, P. E. "The deposition of sub-micrometer particles from hot turbulent gas to a cold rough surface." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385217.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Ahmed, Shafkat. "Interactions of Gas Particles with Graphene during Compressible Flow Exfoliation: A Molecular Dynamics Simulations Study." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588278674983556.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Rodriguez, Alexander. "The removal of an airborne low-volatility heavy metal from exhaust gases through condensation onto sorbent particles." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035970.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Albertsson, Galina. "Effect of the presence of a dispersed phase (solid particles, gas bubbles) on the viscosity of slag." Thesis, KTH, Mikro-modellering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133495.

Texto completo

Resumen

The viscosities of a set of silicone oils containing different size ranges of charcoal or paraffin particles as well as the viscosities of silicone oil foams were measured at room temperature in order to determine the effect of dispersed phase on the viscosity of a liquid and its effect on foaming ability. The effective viscosity of the samples increased with volume fraction of the second phase. The foaming ability was improved by the presence of the particles. The improved foaming effect was for the most part not a result of the increased viscosity. No connection between the particle size and the effective viscosity could be determined. On the other hand particle morphology and the particle size distribution had effect on the effective viscosity. The viscosity data were compared with a number of existing equations for the estimation of effective viscosity. Einstein-Roscoe equation is suitable for two-phase mixtures containing globular particles with narrow particle size distribution and low interfacial tension. New mathematical models are required for effective viscosity prediction, where the suspending phase viscosity, effect of the interfacial tension, as well as the particle morphology should be taken in consideration.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Anderson, Emmet Raymond. "A spectrographic study of the absorption and scattering of light by small particles in the gas phase." Diss., The University of Arizona, 1994. http://hdl.handle.net/10150/187030.

Texto completo

Resumen

A new technique for studying small particles optically in the laboratory is described. A modern spectrograph using an image intensifier tube coupled to a CCD as a detector provides sensitivity comparable to that of a spectrometer using a photomultiplier tube, while preserving the advantages of a spectrograph. Using the instrument, small particles of sodium were studied in light scattering in the gas phase, and gas phase extinction measurements were made of magnesium, carbon, and C₆₀ (Buckminsterfullerene). In the scattering spectra of sodium, the ability of a spectrograph to image along the slit was used to simultaneously observe along a cross section of a small particle cloud, so it was possible to record the transition from the atomic vapor to diatomic sodium to small particles to larger particles. The gas phase surface plasmon feature of magnesium appeared quite different from previous measurements of particles collected on a substrate. On the other hand the spectra of carbon appeared to be quite similar to measurements on a substrate. The measurements of C₆₀ appear to be of the molecular vapor rather than of small particles.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Isenor, Merrill. "Characterization of aerosol particles at low temperatures in a bath gas cooling cell and Bessel beam optical trap." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52299.

Texto completo

Resumen

This thesis focuses on low temperature studies of ensembles of aerosol particles formed in a bath gas cooling cell (78 K) and of single aerosol particles trapped in a counter-propagating Bessel beam optical trap (228-260 K). Ensemble particle measurements provide average data for all particles within the ensemble. These measurements are directly applicable to the study of clouds and aerosols in the atmospheres of a variety of planets and moons. Conversely, single particle measurements offer insight into behaviours which may be dependent on a particular particle property, such as particle size. Single particle data complement that obtained from ensemble measurements. The ensemble particle studies are performed with rapid-scan Fourier-transform infrared (FTIR) spectroscopy to determine intrinsic particle properties (size, shape, composition, and architecture) and the temporal evolution of these properties. The assignments based on infrared spectra are supported by calculations using the vibrational exciton model. In this work, several mixed water aerosol ensembles are considered: carbon dioxide-water, ammonia-water, and acetylene-water aerosols. Each of these aerosol systems have relevance to the atmospheres of planets and moons (e.g. Mars, Saturn, Jupiter, Enceladus ). All three mixtures are studied under similar pressure and temperature conditions. While ammonia-water and acetylene-water are found to form molecularly mixed particles, there is no evidence of molecular mixing in carbon dioxide-water aerosol particles. Measurements are performed at low temperatures to study the freezing and evaporation of single aerosol particles. Our new experimental setup consists of a counter-propagating Bessel beam optical trap for trapping of micron and submicron sized particles down to temperatures of 223 K. The measurements in this thesis present the first freezing studies of single particles into the submicron size range. A series of freezing studies for supercooled liquid hexadecane, dodecane, and water particles are presented here, along with preliminary evaporation experiments for supercooled hexadecane droplets. These measurements show that the low temperature trap is an attractive device to study freezing and evaporation of single particles. Science, Faculty of Chemistry, Department of Graduate

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Xu, Mingyuan Xu. "Study of Gas-Solid Slugging Fluidized Bed with Geldart D Particles Using High-Temperature Electrical Capacitance Volume Tomography." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500623814771833.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Hitchins, Jane. "Dispersion of particles from vehicle emissions." Thesis, Queensland University of Technology, 2001.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Johnson, Lynne Alison. "Modelling particle emissions from traffic flows." Thesis, Queensland University of Technology, 2000.

Buscar texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Tang, Wen-Tzung. "Hydrodynamics, mixing, gas-liquid mass transfer, and biological applications of a three phase fluidized bed of low density particles /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487597424139205.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Subhono, Boya. "Deploying nanotechnology for oil and gas flow assurance : understanding the transport and penetration of nano-particles in porous media." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/9284/.

Texto completo

Resumen

Scaling problem is one of the common engineering challenges in ‘flow assurance’ in the oil and gas industry. Since mechanical or chemical treatment frequently requires sacrifice in fluid production, it is often preferable to avoid this problem, for example by conducting a scale squeeze treatment. This treatment includes an injection of scale inhibitor to hinder scale formation in the rock. Its effectiveness corresponds to its attachment lifetime in the rock formation. This is where nanotechnology has an important role for its capability to enhance the attachment of the scale inhibitor on the rock surface. The question that arises is how and where the injected nanoparticles are distributed and attached on the walls of the rock pores. It is difficult and costly to perform evaluations in pores of a rock formation in an actual oil field. Therefore developing a computer simulation is necessary. This research has successfully demonstrated a development of simulator to explore the science and engineering of nanoparticle transport in microchannels. The phenomenon in the system are explored using a combination of model experimental systems and novel Finite Element Analysis (FEA) computational simulations of fluid flow in microchannels of porous structures. The effect of the advection, diffusion, microchannel’s surface roughness and curvature variety to the nanoparticle transport in the system are investigated. It is discovered that the adsorption is encouraged by diffusion when the advection is insignificant. When advection is significant, a plenty of injected nanoparticle is needed to achieve similar adsorption in a system with diffusion domination. Nanoparticles are transported less effectively in microchannel with high curvature configuration. The density of the adsorption distribution in this type of microchannel is less uniform than in microchannel with simpler curvature. Rough surface increases the adsorption, where the distribution of nanoparticles into dead-end region in the microchannel system is governed by diffusion. The modelling framework in this thesis is versatile to use for modelling any transport that is coupled with surface phenomenon in microchannel system by changing the utilised governing equations and assumptions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Li, Wanguang. "Experimental study of the thermophoretic force and evaporation rates for single microparticles in the Knudsen regime /." Thesis, Connect to this title online; UW restricted, 1995. http://hdl.handle.net/1773/9929.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

De, Vos Wouter Phillip. "The effect of particle shape on solid entrainment in gas-solid fluidisation." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-08282008-144243/.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

SABIA, CARMINE. "Numerical Investigation of Particles Breakage and Growth in Gas-Solid Processes: Spiral Jet Milling and Polyolefin Polymerization in Fluidized Bed Reactors." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971518.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Betioli, Mario Luis Penteado. "Estudo experimental da distribuição de pressão estatica no escoamento gas-solido em um leito recirculante." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267005.

Texto completo

Resumen

Orientadores: Marco Aurelio Cremasco, Alexandre de Paula Peres Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica Made available in DSpace on 2018-08-08T18:40:27Z (GMT). No. of bitstreams: 1 Betioli_MarioLuisPenteado_M.pdf: 23779149 bytes, checksum: 6c1ff800d2c4c61f6e72eab4a95e69f2 (MD5) Previous issue date: 2007 Resumo: Este trabalho tem por objetivo apresentar a distribuição axial de pressão estática ao longo de um leito fíuidízado circulante (CFB) para diversos valores de velocidade de gás e fluxo mássico de sólidos; para tanto, avaliou-se a influência da concentração de sólidos presente em um escoamento gás-sólido ao longo de todo o CFB, o que possibilitou estudar, em um mesmo sistema, a fluidodinâmica dos reatores downer e riser, de uma seção que os une - uma curva em "U" - assim corno de um sistema de recirculação de sólidos. Os CFBs são utilizados em diversas indústrias, particularmente naquelas que envolvem processos de craqueamento catalítico em leito fluidizado (FCC). O FCC é um processo de refino de petróleo utilizado para aumentar a produção de gasolina e GLP (gás liquefeito de petróleo) de uma refinaria, por meio da conversão de frações pesadas, provenientes da destilação do petróleo (gasóleo e resíduos), em trações mais leves. Os experimentos foram conduzidos em uma planta piloto instalada no Laboratório de Processos em Meios Porosos (LPMP) da DTF/FEQ/UMCAMP, denominada Unidade Multipropósito de Craqueamento Catalítico. Realizaram-se ensaios utilizando vazões de ar iguais a 7,5m3/h, 10m3/h, 15 m3/h, 20 m3/h, 25 m3/h, 30 m3/h alimentadas: i) na entrada do downer; ii) na entrada da curva em "U"; iii) numa combinação da entrada do downer e da entrada da curva era "U". Os fluxos mássicos de sólidos utilizados para cada vazão de ar foram iguais a 0,000kg/m2s, 0,032kg/m2s, 0,076kg/m2s, 0,120kg/m2s, 0,164kg/m2s e 0,208kg/m2s alimentados na entrada do downer. Decorrente deste estudo experimental, além do perfil axial de pressão, foi avaliado um modelo simplificado para a descrição da fluidodinâmica em questão, cujos resultados obtidos para diferença de pressão foram comparados com aqueles obtidos de forma experimental, estes por meio de deflexão Abstract: The aim of this work is to present the axial distribution of static pressure throughout a circulating fluidized bed (CFB) for diverse values of gas velocity and solids circulation rate; for this, it was evaluated the influence of the present solids concentration in a gas-solid flow throughout the entirety CFB, which made it possible to study, in the same system, the fluid-dynamics of the downer and riser reactors, of a section joining them --- a "IT bend - as well as of a solid recirculation system. The CFBs have been used in several industries, particularly m those involving processes of fluid catalytic cracking (FCC). The FCC is a refining process of petroleum used to increase the gasoline production and LPG {liquefied petroleum gas) of a refinery, by the conversion of weighed fractions, proceeding from petroleum distillation (gasoil and residues), in lighter fractions. The experiments have been led in a pilot plant installed in the Laboratory of Processes in Porous Media (LPMP) of the DTF/FEQ/UNICAMP, called Multipurpose Unit of Catalytic Cracking. Assays have been performed using air flow rates equal to 7,5m³/h, 10m³/h, 15 m³/h, 20 m³/h, 25 m³/h, 30 m³/h fed: i) in the entrance of the downer; ii) in the entrance of the "U" bend; iii) in a combination of the entrance of the downer and the entrance of the "U" bend. The solids circulation rates used for each air flow rate were equal to 0,000kg/m²s, 0,032 kg/m²s, 0.076 kg/m²s, 0,120 kg/m²s, 0,I64 kg/m²s and 0.2O8 kg/m²s fed in the entrance of the downer. Due to this experimental study, besides the pressure axial profile, a simplified pattern for the fluid-dynamics description in question was evaluated, whose results obtained for pressure difference were compared with those obtained through experiments, the latter being by the means of pressure gauge deflection Mestrado Engenharia de Processos Mestre em Engenharia Química

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Lim, McKenzie C. H. "Chemical and physical characterization of aerosols from the exhaust emissions of motor vehicles." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16428/1/McKenzie_Lim_Thesis.pdf.

Texto completo

Resumen

The number concentration and size distribution of particles in Brisbane have been studied extensively by the researchers at The International Laboratory for Air Quality and Health, Queensland University of Technology (Morawska et al., 1998, 1999a, 1999b). However, the comprehensive studies of chemical compositions of atmospheric particles, especially with regard to the two main classes of pollutants (polycyclic aromatic hydrocarbons and trace elements), that are usually of environmental and health interest, have not been fully undertaken. Therefore, this thesis presents detailed information on polycyclic aromatic hydrocarbons (PAHs) and elemental compositions of vehicle exhausts and of urban air in Brisbane. The levels of polycyclic aromatic hydrocarbons (PAHs) and elements in three of Brisbane's urban sites (Queensland University of Technology, Woolloongabba and ANZ stadium sites) were measured. The most common PAHs found in all sites were naphthalene, phenanthrene, anthracene, fluoranthene, pyrene and chrysene while Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Si, Sn, Sr and Zn were the most common elements detected in the total suspended particles and fine particle (PM2.5). With the aid of multivariate analysis techniques, several outcomes were obtained. For example: -- Major human activities such as vehicular and industrial sources were the most contributing pollution sources in Brisbane. However, these two sources have different influential strength on the compositions of the polycyclic aromatic hydrocarbons and trace inorganic elements found in the urban air. -- Woolloongabba bus platform was the most polluted site on the basis of the elemental and PAH compositions in its air samples while QUT site was the worst polluted site in terms of PM2.5 elemental contents. These results demonstrated that the impact of traffic related pollutants on Brisbane's urban air is significant. This led to the investigations of the direct emissions of pollutants from exhaust vehicular source in the second part of this research work. The exhaust studies included the investigations of PAHs, trace inorganic elements and particles. At the time of the study, the majority of vehicles in Brisbane used low sulfur diesel (LSD) fuel or unleaded petrol (ULP). However, the importance of vehicles using ultra low sulfur diesel (ULSD) and liquefied petroleum gas (LPG) is constantly growing. Therefore, the exhaust emission studies on chassis dynamometer from heavy duty non-catalyst-equipped buses powered by LSD and ULSD with 500 ppm and 50 ppm sulfur contents respectively as well as passenger cars powered by ULP and LPG were explored. The outcomes of such studies are summarized as follows: -- Naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, fluoranthene and pyrene were frequently emitted by the buses powered by LSD and ULSD. However, buses powered by ULSD emitted 91% less PAHs than those powered by LSD. On the other hand, Mg, Ca, Cr, Fe, Cu, Zn, Ti, Ni, Pb, Be, P, Se, Ti and Ge were found in measurable quantities in the exhaust of the buses. The emissions of the elements were found to be strongly influenced by the engine driving conditions of the buses and fuel parameters such as sulfur content, fuel density and cetane index. -- Naphthalene, fluorene, phenanthrene, anthracene, pyrene, chrysene, benzo(a)anthracene and benzo(b)fluoranthene were predominantly emitted by ULP and LPG cars. On the average, the total emission factors of PAHs from LPG cars were generally lower than those of ULP cars, but given the large variations in the emission factors of cars powered by the same type of fuel, differences in the emission factors from both car types were statistically insignificant. In general, platinum group elements and many other elements were found in the exhausts of cars powered by both fuels. Emissions of inorganic elements from the cars were dependent on the type and the mileage of the cars. For example, ULP cars generally emitted higher levels of Cu, Mg, Al and Zn while LPG cars emitted higher level of V. In addition, cars with higher mileages were associated with higher emissions of the major elements (Zn, Al, Fe, V and Cu). -- Buses powered by ULSD usually emitted fewer particles, which were generally 31% to 59% lower than those emitted by LSD powered buses. Similarly, cars powered by LPG emitted less particles from those powered by ULP fuel. However, more nanoparticles (those with aerodynamic diameters of less than 50 nm) were emitted by LPG powered cars than their ULP counterparts. Health effect assessment of the exhaust PAHs was evaluated in terms of benzo(a)pyrene toxicity equivalent (BAPeq). The potential toxicities of PAHs emitted by ULSD powered buses were generally lower than those emitted by their LSD counterparts. A similar trend with lower emissions of PAHs from LPG cars than from ULP cars was observed when otherwise identical passenger cars were powered by LPG and ULP fuels. In summary, this thesis has shown that the majority of airborne particles found around Brisbane have anthropogenic origins, particularly vehicle emissions, and that fuel or lubricant formulations and engine operating conditions play important roles in the physical and chemical characteristics of pollutants emitted by vehicles. The implications of these results on worldwide strategies to reduce the environmental and health effects of particles emitted by motor vehicles were discussed. In this regard, direct emission measurements from vehicles powered by LSD, ULSD, ULP and LPG unveiled the relative environmental benefits associated with the use of ULSD in place of LSD to power diesel engines, and of LPG in place of ULP to power passenger cars.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Lim, McKenzie C. H. "Chemical and physical characterization of aerosols from the exhaust emissions of motor vehicles." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16428/.

Texto completo

Resumen

The number concentration and size distribution of particles in Brisbane have been studied extensively by the researchers at The International Laboratory for Air Quality and Health, Queensland University of Technology (Morawska et al., 1998, 1999a, 1999b). However, the comprehensive studies of chemical compositions of atmospheric particles, especially with regard to the two main classes of pollutants (polycyclic aromatic hydrocarbons and trace elements), that are usually of environmental and health interest, have not been fully undertaken. Therefore, this thesis presents detailed information on polycyclic aromatic hydrocarbons (PAHs) and elemental compositions of vehicle exhausts and of urban air in Brisbane. The levels of polycyclic aromatic hydrocarbons (PAHs) and elements in three of Brisbane's urban sites (Queensland University of Technology, Woolloongabba and ANZ stadium sites) were measured. The most common PAHs found in all sites were naphthalene, phenanthrene, anthracene, fluoranthene, pyrene and chrysene while Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Si, Sn, Sr and Zn were the most common elements detected in the total suspended particles and fine particle (PM2.5). With the aid of multivariate analysis techniques, several outcomes were obtained. For example: -- Major human activities such as vehicular and industrial sources were the most contributing pollution sources in Brisbane. However, these two sources have different influential strength on the compositions of the polycyclic aromatic hydrocarbons and trace inorganic elements found in the urban air. -- Woolloongabba bus platform was the most polluted site on the basis of the elemental and PAH compositions in its air samples while QUT site was the worst polluted site in terms of PM2.5 elemental contents. These results demonstrated that the impact of traffic related pollutants on Brisbane's urban air is significant. This led to the investigations of the direct emissions of pollutants from exhaust vehicular source in the second part of this research work. The exhaust studies included the investigations of PAHs, trace inorganic elements and particles. At the time of the study, the majority of vehicles in Brisbane used low sulfur diesel (LSD) fuel or unleaded petrol (ULP). However, the importance of vehicles using ultra low sulfur diesel (ULSD) and liquefied petroleum gas (LPG) is constantly growing. Therefore, the exhaust emission studies on chassis dynamometer from heavy duty non-catalyst-equipped buses powered by LSD and ULSD with 500 ppm and 50 ppm sulfur contents respectively as well as passenger cars powered by ULP and LPG were explored. The outcomes of such studies are summarized as follows: -- Naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, fluoranthene and pyrene were frequently emitted by the buses powered by LSD and ULSD. However, buses powered by ULSD emitted 91% less PAHs than those powered by LSD. On the other hand, Mg, Ca, Cr, Fe, Cu, Zn, Ti, Ni, Pb, Be, P, Se, Ti and Ge were found in measurable quantities in the exhaust of the buses. The emissions of the elements were found to be strongly influenced by the engine driving conditions of the buses and fuel parameters such as sulfur content, fuel density and cetane index. -- Naphthalene, fluorene, phenanthrene, anthracene, pyrene, chrysene, benzo(a)anthracene and benzo(b)fluoranthene were predominantly emitted by ULP and LPG cars. On the average, the total emission factors of PAHs from LPG cars were generally lower than those of ULP cars, but given the large variations in the emission factors of cars powered by the same type of fuel, differences in the emission factors from both car types were statistically insignificant. In general, platinum group elements and many other elements were found in the exhausts of cars powered by both fuels. Emissions of inorganic elements from the cars were dependent on the type and the mileage of the cars. For example, ULP cars generally emitted higher levels of Cu, Mg, Al and Zn while LPG cars emitted higher level of V. In addition, cars with higher mileages were associated with higher emissions of the major elements (Zn, Al, Fe, V and Cu). -- Buses powered by ULSD usually emitted fewer particles, which were generally 31% to 59% lower than those emitted by LSD powered buses. Similarly, cars powered by LPG emitted less particles from those powered by ULP fuel. However, more nanoparticles (those with aerodynamic diameters of less than 50 nm) were emitted by LPG powered cars than their ULP counterparts. Health effect assessment of the exhaust PAHs was evaluated in terms of benzo(a)pyrene toxicity equivalent (BAPeq). The potential toxicities of PAHs emitted by ULSD powered buses were generally lower than those emitted by their LSD counterparts. A similar trend with lower emissions of PAHs from LPG cars than from ULP cars was observed when otherwise identical passenger cars were powered by LPG and ULP fuels. In summary, this thesis has shown that the majority of airborne particles found around Brisbane have anthropogenic origins, particularly vehicle emissions, and that fuel or lubricant formulations and engine operating conditions play important roles in the physical and chemical characteristics of pollutants emitted by vehicles. The implications of these results on worldwide strategies to reduce the environmental and health effects of particles emitted by motor vehicles were discussed. In this regard, direct emission measurements from vehicles powered by LSD, ULSD, ULP and LPG unveiled the relative environmental benefits associated with the use of ULSD in place of LSD to power diesel engines, and of LPG in place of ULP to power passenger cars.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Jiang, Chengliang. "Germania-based Sol-gel Coatings and Core-shell Particles in Chromatographic Separations." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7683.

Texto completo

Resumen

Chapter one reviewed the development of sol-gel stationary phase for gas chromatograph (GC). Inorganic sol-gel precursor creates the substrate support for stationary phase bind to silica surface through the condensation of silanol groups, the rough surface with enhanced surface area enlarger the capacity of the sol-gel stationary phase, the porosity of sol-gel structure decreases the mass transferring coefficient, the term C in Van Deemter equation, which makes sol-gel stationary phase thicker coating up to 1 um but keeps the high resolution for gas chromatography. Chemical bound stationary phase significantly improve GC column with better thermal stability and solvent stability. Partial derivatizations of known polymers have not increased the column performance but remained at the same level of 3200 plates per meter. The sol-gel chemistry with essential structure rebuilding will make sol-gel stationary phase to a new level. The chapter two reported the non-silica-based metal alkoxide oxide as the new building block, cooperated with known polymer poly(dimethyldiphenylsilanoxan), developed the original nonpolar feature of the stationary phase to broad the polarity from the nonpolar to extreme polar, overcome the thermal stability for other types of polar column. The theoretical plate number reached the 3200 plates per meter, and the optimized plate number arrived at the top level at 3800 plates per meter. The basic recipe and preparation of sol-gel process were verified by tungsten alkoxide incorporated with poly(dimethyldiphenylsilanoxan) as the stationary phase which arrived the same plate number level at 3800 per meter. Chapter three demonstrated the preparation of core-shell particle for HPLC. Conventional silica core particles were prepared with stÖbe methods. The extended layer of germanium oxide coating was made with acid and alkaline as a catalyst. EDS characterize the extended layers of germanium oxide has been coated at ratio 12/1(Ge/Si). Then the carbon loading with C 18 for surface derivatization were also confirmed with EDS testing. 2 um core-shell particles were successfully prepared from the external composition (1.7 um core, 0.3 um shell). The function of the core-shell particles was slurry packed with 5cm regular steel column and the capillary column with sol-gel frit. The preliminary HPLC testing showed the core-shell particles had more retention ability compare with 4 um commercial core particles. The backpressure of the short steel column and capillary both were beyond the pressure limit of conventional HPLC pump. Chapter three demonstrates the new ideal of the surface sol-gel process for GC stationary phase. Without the catalyst, the sol solution has constant viscosity and gelation time is much longer, the sol-gel reaction was taking on the silica surface only, to accomplish the thinner coating for sol-gel stationary phase. From the retention time of the grob mixture, the surface sol-gel coated 2 meters of column acquired the half retention time, grob mixture analytes were eluted within 7 minutes, compared with conventional sol-gel coated column eluted within 14 minutes. Without the TFA as the catalyst, the sol-gel matrix may not form effective surface area and porosity to support the functional polymer for separation, the column performances were two third of the protocol column, at 1500-2500 plate number per meter. The coating results proved the sol-gel stationary phase could be fulfilled with diluted sol solution by static coating. Basic parameters for dynamic coating and static coating with conventional coating and surface sol-gel were acquired for further development. The germania and niobium precursor is highly active, the water amount in the solvents used as received without drying process can meet the surface sol-gel coating without precipitates and gelation formed before finishing coat. For germania -PDMDPS column, thermal stability is very important because of the temperature for remaining the low residual OH- group in silica and germania film at 350 °C.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Alois, Stefano [Verfasser], Jörn [Akademischer Betreuer] Sesterhenn, Jörn [Gutachter] Sesterhenn, and Manfred [Gutachter] Lane. "Contact electrification in aerosolized micron-sized solid particles: dependence upon size, chemical composition and gas properties / Stefano Alois ; Gutachter: Jörn Sesterhenn, Manfred Lane ; Betreuer: Jörn Sesterhenn." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1176623559/34.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Brunton, Rosalind Elizabeth. "Strong correlation effects in heavy fermion and double exchange systems." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300345.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Rapisarda, Andrea. "Hydrodynamic characterization of two/three phase flow regimes in stirred tank." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

Buscar texto completo

Resumen

Questo progetto di ricerca riguarda i processi di miscelazione in sistemi multifase meccanicamente agitati(regime turbolento). I sistemi studiati sono: gas-liquido, solido-liquido e gas-solido-liquido. Lo scopo è quello di analizzare il movimento delle particelle solide all'interno di un recipiente agitato, calcolandone la velocità(n) alle quali si è ottenuto lo stato di estrazione delle particelle(nJD), della completa dispersione(nCD) e del loading(nloading), attraverso l'uso di due diversi valori di diametro delle particelle. Le misure sono state effettuate utilizzando due giranti su un albero e condotte con 6 diverse portate di gas e (da 3 a 6) concentrazioni X di particelle solide. La presente ricerca dimostra che i valori di nloading non dipendono dalla concentrazione X di particelle nel sistema con acqua come fase liquida per entrambi i diametri di particelle dp, nel sistema con 0.4 Kmol/m3 di NaCl per dp1 e nel sistema con 0.8 Kmol/m3 di NaCl per dp2. Nei sistemi con acqua e 0.4 Kmol/m3 di NaCl come fase liquida, i valori di nCD aumentano con l'aumento della concenrtrazione di particelle. I valori di nJD aumentano significamente con l'aumento della concentrazione solida, per entrambi i diametri di particelle nel sistema a coalescenza(con acqua) e non coalescenza con concentrazione di elettrolita 0.8 Kmol/m3 di NaCl. La stessa dipendenza di nJD=f(X) è osservata per 0.4 Kmol/m3 di NaCl per dp2. Per l'intera gamma di concentrazioni solide X, per lo stesso valore ddel diametro delle particelle, si ottengono valori inferiori di velocità di nloading, nCD, nJD per la configurazione delle giranti CD6-PBT.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Lančarič, Vít. "Odlučování drobných prachových částic při spalování uhlí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231278.

Texto completo

Resumen

Thesis are focus for detailed description of fine solid particulates which are product from flue gas. Introduction type of Technologies for capture fine solid particulates. Calculation of electrostatic separator for specific coal and wood boiler.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Chobot, Ivan. "Drobné prachové částice v plynných produktech spalování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230414.

Texto completo

Resumen

Goal of this dissertation is introduce the problem of small dust particles present in the gaseous products of combustion. Further I´m looking technologies cyclone and an electrostatic filter to capture small particles and comparing the effectiveness of separability. Dissertation is concluded by designed cyclone and an electrostatic filter.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Boglaienko, Daria. "Capture and Densification of Floating Hydrophobic Liquids by Natural Granular Materials." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3261.

Texto completo

Resumen

Densification and submergence of floating crude oil is proposed as a novel oil spills treatment method. Surface application of dry granular materials (e.g., quartz sand, limestone) on top of a floating oil layer increases the density of the floating oil phase/granule mixture and leads to formation of relatively large and stable aggregates with significant amounts of captured oil. The aggregates separate from the floating hydrophobic phase and settle by gravity. Implementation of this method will reduce the impact radius of a spill and its mobility, preventing direct contamination of beaches, coastal flora and fauna. The major objective of this research was to examine interactions of particles with hydrophobic liquid-water interface from different perspectives. The important characteristics of the process, such as oil removal efficiencies, optimal particle-to-oil ratios and particle size ranges, were experimentally defined. A series of experiments was conducted to investigate aggregation and dissolution rate constants of the submerged hydrophobic liquids in salt water and deionized water, and to study the impact of the surface porosity of the granular particles on oil capture efficiencies. In addition to crude oil (South Louisiana crude, MC 252), aggregation volumes of quartz sand with other hydrophobic liquids (alkanes and aromatics) were analyzed in relation to wetting characteristics and physical properties of the liquids. A classification of the main types of oil-particle aggregates was developed based on the formation characteristics of the aggregates. Moreover, under specific conditions, depending on the application rates of the granular materials, unique interactions of the particles with the hydrophobic liquid-water interface were observed and defined (bowl formation and roping). These concepts can be utilized to control surface mobility of floating oils, especially during the initial stages of an oil spill, while the oil layer is intact, and when other treatment methods may not be suitable near coastal areas, where transport of floating oils can significantly impact coastal ecosystems.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Abdelsayed, Victor Maher. "Experimental Studies on Nucleation, Nanoparticle's Formation and Polymerization from the Vapor Phase." VCU Scholars Compass, 2004. http://scholarscompass.vcu.edu/etd/1109.

Texto completo

Resumen

This research is divided into three major parts. In part I, the critical supersaturations required for the homogeneous nucleation of 2,2,2-trifluorothanol (TFE) vapor have been measured over a temperature range (266-296 K) using an upward thermal diffusion cloud chamber (DCC). The measured supersaturations are in agreement with the predictions of both the classical and the scaled theory of nucleation. Moreover, the condensation of supersaturated TFE vapor on laser-vaporized magnesium nanoparticles has been studied under different experimental conditions, such as the supersaturation, the pressure and the electric field. In part II, the laser vaporization controlled condensation (LVCC) technique was used to prepare Au-Ag alloy nanoparticles in the vapor phase using designed targets of compressed Au and Ag micron-sized powder mixtures of selected composition. The results showed that the optical properties of these nanoparticles could be tuned depending on the alloy composition and the laser wavelength. Different intermetallic nanoparticles (FeAl and NiAl) from the vapor phase has also been prepared, using the same approach.In this work, the fraction of the charged particles generated during the laser vaporization process was used to prepare a new class of nanoparticle assemblies in the LVCC chamber under the influence of an electric field. The results showed that the electric field required to induce the formation of these nanoassemblies is material and field dependent. By coupling the LVCC chamber with the differential mobility analyzer, size-selected nanoparticles have been prepared in the vapor phase. The prepared nanoparticles were characterized by different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible spectroscopy. In part III, new methods were developed to prepare nanoparticle-polymer composites from the vapor phase. In the first method, the LVCC method was used to prepare a carbonaceous cross-linked resin, with different nanoparticles (Ni, Pt and FeAl) embedded inside. In the second method, free radical-thermally initiated polymerization was used to polymerize a monomer vapor of styrene on the surfaces of activated Ni nanoparticles.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Melchiori, Tommaso. "Study of non catalytic gas-solid reactions: development of a single particle model." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423565.

Texto completo

Resumen

This thesis investigates single particle models to describe non catalytic gas-solid reactions. A comparative study was made between the traditional shrinking core model and more detailed continuous models, involving the solution of microscopic balances for the solid and gas phases inside a single porous particle. Such a study proved that in some cases the use of the shrinking core model can lead to severe errors in the prediction of conversion, and that kinetic parameters in SCM are affected by the particle size. Different diffusion models were tested for the continuous model, and the inaccuracy of the Fick law compared to multicomponent Stefan-Maxwell was evaluated, depending on the concentration of the reaction gas in the mixture. The thesis also proved that natural convection inside the particle can be neglected by changing the balance from mass to molar basis or vice versa, depending on the type of reaction considered. An equation for the local particle porosity was also included, to account for the local changes of gas diffusivity as effect of the reaction. The effect of the pore size distribution was studied, by writing the particle model as a population balance, including different diffusive resistances for different pore sizes, for the cases when Knudsen or solid state diffusion can be important. Sintering phenomena were included, by extending the grain model with an empiric equation. Simulations with simultaneous gas solid reactions were performed, also considering non uniform initial distributions of the solid phases inside the particle: sensitivity studies proved that the position of the solid reagents in the particle may have a great influence on the model results, even when intra particle diffusion is fast compared to the chemical reactions. Gas-solid models were also used to simulate real processes. In particular, thanks to collaboration with an industrial research project, a kinetic study with a CFD model was developed, applying a shrinking core model to simulate real reactors for the direct reduction of iron ores with syn gas at high temperature and pressure. Finally, thanks to the collaboration with the Technical University of Eindhoven, a continuous model was used to simulate reactions of reduction of iron-titanium oxides in chemical looping combustion processes, comparing the results with experimental data. Questa tesi investiga modelli di singola particella per descrivere reazioni gas-solido non catalitiche. E’ stato fatto uno studio comparativo fra il tradizionale shrinking core model e modelli continui più dettagliati che comprendono la risoluzione dei bilanci microscopici per le fasi gas e solida dentro una singola particella porosa. Tale studio ha provato che in alcuni casi lo shrinking core model può condurre ad errori importanti nella predizione della conversione, e che i parametri cinetici nel SCM dipendono dalla dimensione della particella. Sono stati testati diversi modelli di diffusione all’interno del modello continuo, e la non accuratezza della legge di Fick rispetto alla Stefan-Maxwell multicomponente è stata valutata, a seconda della concentrazione del gas reagente nella miscela. La tesi prova anche che la convezione naturale all’interno della particella può essere trascurata cambiando i bilanci da massivi a molari o vice versa, a seconda del tipo di reazione considerata. Un’equazione che descrive la porosità locale della particella è stata inclusa al modello, per tener conto dei cambiamenti della diffusività effettiva del gas per effetto della reazione. L’effetto della distribuzione della dimensione dei pori è stato investigato, riscrivendo il modello di particella come bilancio di popolazione, includendo diverse resistenze diffusive per diverse dimensioni dei pori, per i casi in cui La diffusione di Knudsen o la diffusione in stato solido possono essere importanti. Fenomeni di sinterizzazione sono stati inclusi, estendendo il tradizionale grain model con un’equazione empirica. Sono state fatte simulazioni di reazioni gas solido con più reazioni, considerando anche distribuzioni disomogenee delle fasi solide all’interno della particella: studi di sensitività hanno dimostrato che la posizione dei reagenti solidi nella particella possono avere un effetto importante sui risultati del modello, anche nel caso in cui la diffusione all’interno della particella è veloce rispetto alle reazioni chimiche. Modelli di reazione gas-solido sono stati usati anche per simulare processi reali. In particolare, grazie alla collaborazione con un progetto di ricerca industriale, uno studio cinetico con modelli CFD è stato sviluppato, applicando lo shrinking core model per simulare reattori reali per la riduzione diretta di ossidi di ferro con gas di sintesi ad alte temperature e pressioni. Infine, grazie alla collaborazione con l’Università Tecnica di Eindhoven, un modello continuo è stato usato per simulare reazioni di riduzione di ossidi di ferro-titanio in processi di chemical looping combustion, confrontando i risultati con i dati sperimentali.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Fisher, Dave S. "Two-Photon Polarization Spectroscopy of Atomic Cesium Using Circularly Polarized Light." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1292444234.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Girault, Ivan. "Développements formels et numériques vers la simulation numérique directe avec particules résolues de la combustion d'hydrogène en lit fluidisé." Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEP083.

Texto completo

Resumen

Ce travail de thèse a été réalisé dans le cadre du projet ANR MIMOSAH qui vise à caractériser la combustion d'hydrogène en lit fluidisé, en présence de particules partiellement inertes, avec prise en compte de réactions de surface. L'objectif est de modéliser la combustion en milieu particulaire de la micro à la macro-échelle, avec une double approche numérique et expérimentale. Cette thèse concerne l’approche numérique à l’échelle microscopique, et plus particulièrement le développement d'une stratégie numérique pour la simulation numérique directe de la combustion d’hydrogène en présence de particules complètement résolues. Le point de départ de ce travail est le code RESPECT, basé sur la résolution d'une formulation monofluide sur maillage Cartésien, doublée d'une méthode de pénalisation visqueuse pour traiter l'interaction fluide solide. Initialement, le code avait été validé uniquement dans un contexte incompressible et anisotherme, sans inclure de modèles pour les phénomènes de combustion gazeuse et de chimie de surface. Ce travail présente donc une série de développements formels puis numériques, en vue d'intégrer la description de ces phénomènes dans le code RESPECT This thesis work was carried out as part of the ANR MIMOSAH project, which aims to characterize the combustion of hydrogen in a fluidized bed, in the presence of partially inert particles, taking into account surface reactions. The objective is to model combustion in a particulate environment from micro to macro scale, using a dual numerical and experimental approach. This thesis focuses on the numerical approach at the microscopic scale, particularly the development of a numerical strategy for the direct numerical simulation of hydrogen combustion in the presence of fully resolved particles. The starting point of this work is the RESPECT code, based on the resolution of a single-fluid formulation on Cartesian grids, coupled with a viscous penalization method to handle fluid-solid interaction. Initially, the code had only been validated in an incompressible and anisothermal context, without including models for gaseous combustion phenomena and surface chemistry. This work presents a series of formal and numerical developments aimed at integrating the description of these phenomena into the RESPECT code

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Pérez, Grau Laura. "The urban health effects and impact of anthropogenic and natural air pollution." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7195.

Texto completo

Resumen

The differential role that airborne particulate matter (PM) size fractions, sources, and components play in producing adverse health effects is not fully understood. Specific gaps include the role of PM generated by traffic and the effects of PMs generated by natural sources. Source specific air pollution epidemiological research still lacks integration in the risk assessment process, a fundamental tool to inform policy makers and the public about the current situation or the impact of future or past air pollution policies. This thesis addresses both these gaps. To explore the effects of PM from different sources, we investigated the association between different PM size fractions and mortality in Barcelona, Spain and used PM chemical composition data to help determine the different sources and components linked to toxicity. To illustrate that local air pollution risk assessments are useful tools in evidence-based public health, we estimated the health and economic benefits that would result from different scenario of improved air quality in the Barcelona metropolitan area and in two communities of Southern California. These case studies include new methods to integrate into the risk assessment process the recent epidemiological evidence related to the effects of traffic exposure.This thesis contributes to a better understanding of the link between particulate matter size fraction, sources, and components and health effects, and to improve air pollution health impact assessment methods. Both contributions have important implications for public health and air pollution public policy. El papel diferencial en que las diferentes fracciones de partículas en suspensión en el aire (PMs), sus fuentes y componentes producen efectos adversos para la salud no está completamente entendido. Las lagunas actuales incluyen el papel de las PMs generadas por el tráfico y los efectos de las PMs generadas por fuentes naturales. La investigación epidemiológica relacionada con fuentes todavía falta ser integrada en el proceso de evaluación de impacto, una herramienta fundamental para informar a los tomadores de decisiones y el público sobre la situación actual o el impacto de futuras o pasadas políticas de contaminación atmosférica. Esta tesis trata estas áreas. Para explorar el papel de las PMs generadas por diferentes fuentes, se ha investigado la asociación entre diferentes fracciones de PMs y mortalidad en Barcelona (España) y se ha usado datos de composición química de PMs para identificar las fuentes y los componentes relacionados con la toxicidad. Para ilustrar que las evaluaciones de impacto a nivel local son herramientas útiles en salud pública, se ha estimado el beneficio en salud y económico que resultaría de diferentes escenarios de mejora de la calidad del aire en el área metropolitana de Barcelona y en dos comunidades de California del Sur. Estos estudios de casos incluyen nuevos métodos para integrar en las evaluaciones de impacto las nuevas evidencias epidemiológicas que relacionan la exposición al tráfico con los efectos en salud. Esta tesis contribuye a un mayor entendimiento del vínculo entre las fracciones de PM, sus fuentes y componentes y los efectos en salud así como a la mejora de los métodos de las evaluaciones de impacto. Estas contribuciones tienen importantes implicaciones para la salud pública y las políticas públicas de contaminación atmosférica.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Bass, Stephen Frank. "Optical properties of laboratory-generated polar stratospheric cloud particles." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275366.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Demarthon, Romain. "Modélisation et simulation d’un étage haute température pour la purification d’un gaz chargé en goudrons et en particules carbonées par assistance plasma." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3001/document.

Texto completo

Resumen

Afin de répondre aux besoins croissants en énergie primaire, le groupe Europlasma a développé le procédé CHO-Power permettant de valoriser énergétiquement un mélange de refus de tri d’ordures ménagères et de résidus de biomasse. L’une des particularités de ce procédé est l’utilisation d’un réacteur de dégradation thermique des goudrons et des particules solides fines par assistance plasma. L’objectif de cette étude de mieux appréhender les mécanismes réactionnels mis en jeu lors de l’épuration thermique du gaz. Dans cette optique, un réacteur pilote a été dimensionné puis construit sur la plate-forme de Recherche et Développement d’Europlasma. Il a été ensuite nécessaire de modifier le schéma réactionnel permettant la modélisation numérique de la dégradation des goudrons. Ce schéma réactionnel, couplé à l’utilisation d’un logiciel de mécanique des fluides numérique, permet de représenter les processus couplés (chimie, aéraulique, transferts thermiques) se déroulant au sein du réacteur. Deux modifications importantes ont été alors apportées au modèle cinétique simplifié jusque-là utilisé : la modélisation d’une phase discrète réactive permettant de prendre en compte la gazéification des particules de résidus carbonés et l’ajout de nouvelles voies réactionnelles afin de mieux modéliser la formation des particules de suie et de ses précurseurs. À terme, la comparaison des valeurs expérimentales à celle issues de la modélisation numérique permettra de valider ou non le schéma réactionnel dans sa globalité In order to contest to the high world demand for primary energy, the Europlasma group developed a new process, called CHO-Power, to enhance the thermochemical potential of a mixture of urban waste and biomass residues. One of the characteristics of this process is the use of a high temperature reactor assisted by a plasma torch for tar and soots thermal cracking. The aim of this study to improve the knowledge of the global reaction mechanism involved during the thermal treatment of gas. In this context, a pilot plant reactor was designed and built on the Europlasma Research and Development Center. During this work, the reaction pathway used to represent tars cracking at high temperature has been enhanced. Coupled to a computational fluid Dynamics Software, allow simulating the complex processes occurring within the reactor (aeraulics, reaction, and heat transfer). Two major changes were made to the simplified kinetic model previously used: the modeling of a discrete and reactive phase to take into account the possible particle gasification of carbonaceous residues and the addition of new reaction pathways to enhance the modeling of the formation of soot and its precursors. The comparison between the experimental and numerical values will validate or not the global reaction scheme and will give important information about the next evolution of the tar degradation scheme

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Wu, Xuemei. "Monte-Carlo modeling of turbulent dispersion of small particles in channels." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17389.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Gas-particles"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros