Dissertations / Theses on the topic 'Partial heating'
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Partain, Seth Collins. "Fused deposition modeling with localized pre-deposition heating using forced air." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/partain/PartainS0507.pdf.
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Trtílek, Petr. "Predikovaná a skutečná spotřeba energie v budovách." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409962.
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This diploma thesis deals with comparison of predicted and actual energy consumption in buildings. The predicted consumption is determined by calculating the energy performance certificate of the selected building and the actual consumption is monitored in the building on the Open Garden premises of the Partnership Foundation in Brno. The theoretical part deals both with the energy consumption in buildings and with the methodology of energy performance calculation.
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Taipe, Stiw Harrison Herrera. "Modelagem computacional do escoamento bifásico em um meio poroso aquecido por ondas eletromagnéticas." Universidade Federal de Juiz de Fora (UFJF), 2018. https://repositorio.ufjf.br/jspui/handle/ufjf/6519.
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Neste trabalho estamos interessados em estudar, mediante simulações computacionais, se o aquecimento eletromagnético é capaz de melhorar o deslocamento do óleo pela água. Nesta direção, nos baseamos nos resultados obtidos pela equipe da TU Delft da Holanda, que desenvolveu experimentos de laboratório que demonstravam a distribuição da temperatura em um meio poroso, onde o óleo está sendo deslocado pela injeção de água, gerada por aquecimento eletromagnético. Para tanto, definimos o modelo matemático que governa o problema em questão regido por equações diferenciais parciais das leis de conservação de massa e energia. Assim, partindo da caracterização do contínuo e estendendo a lei de Darcy para o caso multifásico, através da introdução do conceito de permeabilidades relativas dos fluidos, derivamos um sistema acoplado de equações diferenciais parciais com coeficientes variáveis e termos não lineares formulados em função da velocidade de Darcy para o escoamento bifásico (água, óleo) aquecido por ondas eletromagnéticas. O modelo matemático é discretizado utilizando o método de diferenças finitas no tempo e no espaço e a técnica Splitting. Dessa forma dividimos o sistema de equações diferencias parciais em dois subsistemas. O primeiro subsistema consiste em resolver a parte difusiva e reativa e o segundo subsistema tem por objetivo a resolução do termo convectivo. O método numérico desenvolvido é validado por simulações computacionais que visam a comparação com os resultados obtidos experimentalmente e com soluções semi-analíticas, para este problema, que foram derivadas pelo método do princípio de Duhamel. Além disso, o método proposto quando aplicado para o caso geral da simulação do escoamento bifásico com aquecimento eletromagnético demonstrou um ganho de 1.67%, se comparado ao método sem aquecimento.
In this work we are interested in studying, through computational simulations, if the electromagnetic heating is able to improve the displacement of the oil by water. In this direction, we rely on the results obtained by the TU Delft team from the Netherlands, which developed laboratory experiments that demonstrated the temperature distribution in a porous medium where the oil is being displaced by the injection of water generated by electromagnetic heating. For this, we define the mathematical model that governs the problem in question governed by partial differential equations of the laws of conservation of mass and energy. Thus, starting from the characterization of the continuum and extending Darcy’s law to the multiphase case, by introducing the concept of relative permeabilities of fluids, we derive a coupled system of partial differential equations with variable coefficients and non-linear terms formulated as a function of the velocity of Darcy for two-phase flow (water, oil) heated by electromagnetic waves. The mathematical model is discretized using the finite difference method in time and space and the Splitting technique. In this way we divide the system of partial differential equations into two subsystems. The first subsystem consists of solving the diffusive and reactive part and the second subsystem aims to solve the convective term. The numerical method developed is validated by computational simulations aimed at the comparison with the results obtained experimentally and with semi-analytical solutions, for this problem, which were derived by the Duhamel principle method. In addition, the proposed method when applied to the general case of simulation of the biphasic flow with electromagnetic heating demonstrated a gain of 1.67%, when compared to the non-heating method.
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Black, Jennifer May. "Particle motion and heat transfer in rotary drums." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/11987.
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Abdul, Ghani S. A. A. "An investigation into water ingress through ground vehicle heating ventilation and air conditioning unit." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268509.
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Slapak, Rikard. "O⁺ heating in the high altitude cusp and mantle due to wave-particle interaction." Licentiate thesis, Luleå tekniska universitet, Rymdteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26562.
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This thesis is composed of three articles, which have the common denominator that they are studies of heating of oxygen ions in the high altitude cusp and mantle in the terrestrial magnetosphere. All data analysis are based on observational data from the Cluster satellites. Oxygen ions originate in the ionosphere, from where they flow up along open cusp field lines. This upflowing ionospheric plasma is generally gravitationally bound and will return as ionospheric downflow. However, if the plasma is sufficiently energized it may overcome gravity and reach the magnetosphere. Further energization is able to put the plasma on trajectories leading downstream along the magnetotail, which may cause the plasma to escape into the magnetosheath. This thesis considers energization of oxygen ions through wave-particle interactions. We show that the average electric spectral densities in the altitude range of 8-15 Earth radii are able to explain the average perpendicular temperatures, using a simple gyroresonance model and 50% of the observed spectral density at the O+ gyrofrequency. We also show that the phase velocities derived from the observed low frequency electric and magnetic fields are consistent with Alfvén waves. Strong heating is sporadic and spatially limited. For three case studies of strong heating, we show that the regions of enhanced wave activity are at least one order of magnitude larger than the gyroradius of the ions, which is a condition for the gyroresonance model to be valid. An analysis indicates that enhanced perpendicular temperatures can be observed over several Earth radii after heating has ceased, suggesting that high perpendicular-to-parallel temperature ratio is not necessarily a sign of local heating. This also explains why we sometimes observe enhanced temperatures and low spectral densities. Three events of very high temperatures and simultaneously observed high spectral densities were studied, and we showed that the temperatures could be explained with the simple gyrofrequency model. We have also provided average diffusion coefficients at different altitudes, which can be used for ion heating and outflow modeling.Godkänd; 2011; 20111007 (riksla); LICENTIATSEMINARIUM Ämnesområde: Rymdteknik/Space Engineering Examinator: Docent Hans Nilsson, IRF Kiruna Diskutant: Doktor Stephan Buchert, IRF Uppsala Tid: Fredag den 11 november 2011 kl 10.00 Plats: IRF, Kiruna
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Kowsary, Farshad. "Radiative characteristics of spherical cavities having partially or completely specular walls." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54222.
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The radiant exchange problem for an isothermal spherical cavity having diffuse-specular walls is solved and the distribution of the local heat transfer for various opening angles and surface emissivities is obtained. Subsequently, the overall emission from the cavity (i. e., the apparent emissivity of the cavity) is calculated for various opening angles and surface conditions. In addition, the overall absorption characteristics of spherical cavities having purely specular walls is investigated analytically for the case of collimated radiation entering the cavity. Various opening angles and surface conditions are considered. The Monte Carlo method is utilized to support the results obtained from the analytical calculations. Results show that in spherical cavities the apparent emissivity is not very sensitive to the degree of specularity of the cavity wall. Also, there are situations in which the diffuse cavity is a more efficient emitter than a specular cavity. Absorption characteristic results show that for cavities having purely specular walls the absorption of collimated radiation is highly dependent on the angle of incidence of radiation on the opening for small opening angles.Ph. D.
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Lohe, Martin R., Kristina Gedrich, Thomas Freudenberg, Emanuel Kockrick, Til Dellmann, and Stefan Kaskel. "Heating and separation using nanomagnet-functionalized metal–organic frameworks." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138610.
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A magnetic functionalization of microcrystalline MOF particles was realized using magnetic iron oxide particles. Such magnetic MOFs can be separated using a static magnetic field after use in catalytic processes and heated by an external alternating magnetic field to trigger desorption of encaged drug moleculesDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Deliyanakis, Nicholas. "A study of tokamak energy and particle transport, based on modulated electron cyclotron resonance heating." Thesis, University of Oxford, 1989. http://ora.ox.ac.uk/objects/uuid:b5426c92-b6ee-43fb-ad46-6fcb9ae9b4fe.
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A dynamical technique for the study of tokamak energy and particle transport has been developed. The plasma in the medium-sized DITE tokamak was perturbed by the application of modulated electron cyclotron resonance heating, with wave-launching from the high-field side. These experiments were carried out with absorption at various distances from the plasma centre, over a range of densities. Energy transport through the electron channel was dominant, and the variations in electron temperature and density were measured using the soft X-ray, electron cyclotron emission and microwave interferometer diagnostics. Analysis in the frequency domain enabled the propagation of the thermal wave to be followed. The observed behaviour was generally indicative of diffusive propagation of the thermal perturbation. Further observations indicated a modulation of the horizontal plasma shifts, diffusive propagation to the edge and a low modulation level of line-averaged density. In some atypical cases, the observed behaviour was qualitatively different; this type of behaviour was accompanied by a pronounced sawtooth oscillation locked with the modulation. Two models have been employed for the interpretation of these results. The first model, based on the diffusive thermal transport of the perturbation, has led to results in good agreement with the experimental data. Values of the electron thermal diffusivity were deduced, in good agreement with those obtained from the alternative techniques of power balance analysis and sawtooth heat pulse propagation analysis; such agreement has not been universally obtained in similar experiments. The width of the absorption region has emerged as an important consideration in this analysis. A more complex model, including non-linear, coupled equations of particle and energy balance, has produced results in partial agreement with the experimental data, supporting, to some extent, the presence of coupled transport. It has been demonstrated how perturbation techniques can afford a useful means of testing transport models.
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Paz, Pavel Zenon Sejas. "Estudo analítico da injeção de água com aquecimento eletromagnético em um meio poroso contendo óleo." Universidade Federal de Juiz de Fora, 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/405.
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Neste trabalho apresentamos um estudo analítico sobre a recuperação de óleo pesado utilizando injeção de água, que é aquecida por meio de ondas eletromagnéticas de alta freqüência. Recentemente, foi feito um experimento (descrito em [12]), onde a água foi injetada num meio poroso, aquecida por meio de ondas eletromagnéticas. Os resultados do experimento mostram que o aquecimento mediante ondas EM melhora o deslocamento do óleo pela água. Desta maneira, apresenta-se a injeção de água com aquecimento por ondas EM como um método viável na recuperação de óleo. Consideraremos um modelo matemático simples descrevendo o experimento mencionado acima, que consiste de duas leis de balanço, uma para a energia e outra para a massa da água. O objetivo do trabalho é usar o Princípio de Duhamel e a Teoria das Leis de Conservação para encontrar soluções semi-analíticas deste modelo simplificado. Segundo [8], utilizamos o Princípio para achar a solução da equação de balanço de energia do tipo Convecção-Reação-Difusão para o problema de transporte de calor num meio poroso na presença de uma fonte de ondas eletromagnéticas. A equação de balanço para a massa da água é uma equação diferencial parcial não linear de primeira ordem do tipo Buckley-Leverett (Veja [4] e [7]). Ela será resolvida usando a Teoria das Leis de Conservação. Segundo [15], a solução deste problema contém ondas de rarefação e choque.
In this work, we present the results obtained by analytical study of heavy oil recovery by water flooding and electromagnetic (EM) heating of high frequency. Recently, an experiment was made, where water was injected into a porous medium, warmed by means of electromagnetic waves. The experiment results show that EM heating improves the displacement of oil by water. Thus, the water flooding combined with EM heating is a viable method for oil recovery. We consider a simple mathematical model describing this experiment consisting of two balance laws for energy and water mass. The goal is to use Duhamel’s Principle and the Theory of Conservation Laws to find semi-analytical solutions of this simplified model. We use the principle solve the energy balance equation of convection-reaction-diffusion type for heat transport problem in a porous medium in the presence of a source of electromagnetic waves. The balance equation for the mass of water is a nonlinear partial differential equation of first order of Buckley-Leverett type. It is solved using the Theory of Conservation Laws.
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Dieckmann, Mark Eric. "A survey of elementary plasma instabilities and ECH wave noise properties relevant to plasma sounding by means of particle in cell simulations." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327557.
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Lohe, Martin R., Kristina Gedrich, Thomas Freudenberg, Emanuel Kockrick, Til Dellmann, and Stefan Kaskel. "Heating and separation using nanomagnet-functionalized metal–organic frameworks." Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27764.
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A magnetic functionalization of microcrystalline MOF particles was realized using magnetic iron oxide particles. Such magnetic MOFs can be separated using a static magnetic field after use in catalytic processes and heated by an external alternating magnetic field to trigger desorption of encaged drug molecules.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Knott, Ryan Christopher. "High temperature durability of metals for use in a particle heating receiver for concentrated solar power." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53117.
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An experimental investigation is presented on a novel High Temperature Falling Particle Receiver for Concentrated Solar Power (CSP) to quantify the extent of erosion of the receiver structural materials by the flowing particulate matter. The current receiver design uses a series of metal wire mesh screens to slow down the particulate flow through the receiver in order to increase their residence time thereby achieving the desired temperature rise within the receiver without the need for particulate recirculation. The solid particulates are gravity fed through the receiver where they absorb the incident thermal energy before flowing to a high temperature storage bin upstream of a heat exchanger where the heat stored in the particulate material is transferred to the working fluid for the power cycle. To assess the effective life of the receiver, this experimental investigation is undertaken. This thesis includes the development of an apparatus to test wire meshes under high temperature and particle abrasion conditions, and the presentation and analysis of these results.
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Yamaguchi, Hiroyuki. "Simulation study of energetic particle physics in perturbed helical plasmas." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215531.
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Hannah, Iain G. "Particle heating and acceleration in solar flares : energisation at a reconnecting X-point and RHESSI microflare observations." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425320.
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Yahya, Mahzoun. "Heating Value and Energy Recovery Potential of Sewage Sludge and Suspended Solids in Municipal Wastewater Treatment Plant." Kyoto University, 2018. http://hdl.handle.net/2433/232029.
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Prudek, Michal. "Relaxační centrum ve Velkém Meziříčí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240299.
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This thesis describes design of new relaxation centre building in town of Velké Meziříčí and creation of blueprints for building construction. Blueprints are furthermore supplemented by extensions for heating and concrete structures. The relaxation centre houses a wellness centre, a café, a hair and make-up salon with possibility of massage and an outdoor shop. The building is located in southern part of Velké Meziříčí – an urban area of both residential and industrial buildings. The centre is a three storey building with partial basement, flat single-layered roof and stairway, which serves as an access point for ventilation engine room located on top of the roof structure. This last element is distinguished from the rest of the building by different coloured façade panelling and serves as a dominant. Wellness centre covers the whole of ground floor and is interfaced with the first floor by additional wellness centre spaces and staff spaces. The first floor also includes the outdoor shop. Café and hair salon are situated on the second floor. Architectonic design is created in similarity to surrounding buildings and in relation to cardinal direction. Land lot is utilized for wellness centre purposes.
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Green, Adam. "Structure and Dynamics of Two Flow Fields Used for Particle Deposition onto and Removal from a Substrate." ScholarWorks @ UVM, 2016. http://scholarworks.uvm.edu/graddis/554.
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A series of experimental studies was performed to investigate two separate fluid impingement flow systems intended for removal of particles from a surface or deposition of particles onto a surface. One of these flow systems is generated using a nozzle that incorporates both tilted jets and suction to create what we call a "bounded vortex flow", consisting of an annular swirling jet and a wall-normal vortex with axial upflow into a suction outlet. The other flow system is generated by a combination of acoustic streaming and substrate heating from an ultrasonic source. The primary methods used in the study for flow field measurements included laser-induced fluorescence (LIF) and particle-image velocimetry (PIV). Thermocouples are utilized for gathering temperature information from the ultrasonic induced flow. For the bounded vortex flow, different jet/suction flow rates and different nozzle-substrate separation distances were examined. In the acoustic-generated flow system, different acoustic intensities and transducer-substrate separation distances and different choices of substrate material were examined. Both flow systems achieve high levels of shear stress on the impingement surface via a combination of flow oriented toward and/or away from the surface and via formation of vortex structures near the impingement surface. In the bounded flow configuration, the vortex flow is oriented with axis normal to the impingement surface, whereas in the acoustic-generated flow a series of vortex rings form with axes parallel to the impingement surface. For both flow fields, conditions are observed with high impingement surface shear stress that are well suited to particle removal from the impingement surface. However, as the variables controlling the flows are varied, other conditions are observed in which the flow fields become unstable, leading to oscillatory flows that generally have much smaller shear stress values on the impingement surface. The rate of fluid mixing, as characterized by upward and downward flows normal to the impingement surface, is also generally decreased after these flow transitions have occurred, implying that the unstable flows will be less suited for both particle deposition on and particle removal from the impingement surface.
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Bigongiari, Alessandra. "High Intensity Laser-Plasma Grating Interaction : surface wave excitation and particle acceleration." Palaiseau, Ecole polytechnique, 2012. http://pastel.archives-ouvertes.fr/docs/00/75/83/55/PDF/alebigo_TESI_rapporteurs.pdf.
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Les ondes de surface ont été observées pour la première fois par Wood en 1902 qui note des anomalies dans le spectre de diffraction d'une lumière continue sur un réseau métallique. Pour certaines longueurs d'onde, le spectre diffracté présente des lignes noires que Fano interprète quelques années plus tard (1941) comme dues à l'excitation d'ondes de surface. De façon analogue, on peut exciter par laser de façon résonante une onde plasma de surface à la surface d'un plasma sur-dense créé par interaction laser-solide, si les conditions d'excitation de l'onde sont satisfaites. L'onde de surface se propage le long de l'interface plasma-vide et se caractérise par un champ électrique résonant haute-fréquence localisé. Dans ce travail, la dynamique du plasma et les champs associés à l'excitation par laser de l'onde de surface sont décrits numériquement avec des simulations bidimensionnelles Particule-In-Cell dans lesquelles la surface du plasma est initialement pré-structurée de sorte à satisfaire les conditions d'excitation de l'onde de surface. L'intensité laser a été variée entre Iλ2 =10^15 et 10^20 μm^2/Wcm^2 afin d'étudier la transition entre un régime d'excitation non-relativiste et relativiste. Les simulations dans lesquelles l'onde de surface est excitée sont comparées à celles où elle ne l'est pas et le couplage du laser avec la cible est analysé. Pour différents paramètres du laser et de la cible, nous avons considéré les quatre aspects suivants de l'interaction laser plasma : i) l'absorption laser et le champ électrique à la surface du plasma, ii) le champ magnétique quasi-statique généré, iii) le chauffage électronique et iiii) l'accélération des ions. Nous avons démontré la possibilité d'exciter une onde plasma de surface pour une large gamme d'intensité laser. Lorsque l'onde de surface est excitée, la composante perpendiculaire à la surface du plasma du champ électrique est amplifiée par rapport au champ laser sur la surface plasma-vide d'un facteur allant de 3. 2 à 7. 2 selon les cas. L'absorption augmente également fortement de 27% lorsque l'onde de surface n'est pas excitée à 73% lorsqu'elle l'est pour Iλ2=10^19 μm^2/Wcm^2 par exemple. Cette étude nous a permis de définir les conditions optimales pour lesquelles le couplage entre le laser et l'onde de surface est le plus efficace. Elles correspondent au régime d'intensité laser relativiste dans lequel le mécanisme d'absorption principale est le " vacuum heating " : les particules gagnent de l'énergie en oscillant dans le champ électrique perpendiculaire à la cible. En présence de l'onde de surface, cette oscillation est fortement augmentée par la présence du champ localisé de l'onde de surface plus intense que le celui du laser. La possibilité de créer des champs magnétiques quasi-statiques auto-générés en présence d'une onde de surface a de plus été étudiée analytiquement et les résultats ont été comparés à ceux des simulations. Les structures de champ obtenues suggèrent que l'intensité du champ magnétique généré induit un confinement partiel des particules sur la surface de la cible lorsque l'onde de surface est excitée. Enfin, nous avons observé un effet induit par l'excitation de l'onde de surface encore plus fort dans des cibles minces dans lesquelles les électrons peuvent circuler d'un bord à l'autre de la cible et interagir plusieurs fois avec le champ de l'onde. Le champ de charge d'espace ainsi créé au cours de l'interaction induit une augmentation importante de l'énergie des ions émis sur les deux faces de la cible mince. L'ensemble de ce travail nous a permis de montrer que l'excitation d'une onde de surface par interaction laser-plasma structuré est un mécanisme physique prometteur pour augmenter l'énergie des particules émises. C'est un point particulièrement intéressant pour les applications liées à la production de protons énergétiques telles que la thérapie hadronique ou à celle d'électrons de hautes énergies indispensables dans le processus de fusion inertiel dans lequel le schéma de l'allumeur rapide est utiliséeSurface waves in solids were first observed by Wood in 1902 as an anomaly in the diffraction of a continuous light source from a metal grating: the diffracted spectrum presented dark lines corresponding to certain wavelengths, which were later explained (Fano, 1941) in terms of the excitation of a surface wave sustained by the grating. Similarly to the metal grating case, a surface plasma wave (SPW) can be resonantly excited by a laser pulse at the surface of a laser-produced over-dense plasma, if the correct matching conditions are provided. SPWs propagate along the plasma-vacuum interface and are characterized by a localized, high frequency, resonant electric field. In the present work we describe numerically the dynamics of the plasma and the field distribution associated to SPW excitation, using two-dimensional particle-in-cell (PIC) simulations, where the plasma surface is initially pre-formed so that the SPW excitation conditions are fulfilled. We examine the surface wave excitation for a large range of laser intensities (Iλ2 =10^15-10^20 μm^2/Wcm^2) in order to study the transition from the non-relativistic to the relativistic regime. The simulations in which the wave is resonantly excited are compared to cases in which the resonant conditions are not provided and the coupling of the laser with the target is analyzed. We have considered the following aspects of the laser-plasma interaction, for different laser and target parameters: i) the laser absorption and the electric field at the surface ii) the generation of a quasi-static magnetic field iii) the electron heating and iiii) the ion acceleration. The possibility to excite a surface plasma wave on a structured target for a large range of laser energies has been demonstrated. In the cases where the surface wave is excited the electric field component normal to the target is amplified at the surface by a factor ranging from 3. 2 to 7. 2 with respect to the laser field. The absorption is also increased,for example it raises from 27% when the SPW is not excited up to 73% for Iλ^2=10^9 μm^2/Wcm^2. We have defined the optimal conditions for efficient coupling which increase laser absorption, that correspond to the relativistic laser intensities (Iλ^2>10^19 μm^2/Wcm^2). In this regime the main absorption mechanism is vacuum heating, associated to particles oscillating in the field perpendicular to the target, which is enhanced by the stronger, localized field of the SPW. The generation of a quasi-static magnetic field has been studied analytically and compared to the result of PIC simulations. The different field structure in presence of a SPW and for a flat target suggests that the enhanced field strength has caused partial confinement of particles at the target surface when SPW is present. The effects of the surface wave are more pronounced in thin laminar targets where electrons recirculate into the target interacting several times with the wave. Efficient electron heating increases the energy of the ions which are accelerated at both the irradiated and not irradiated target surface by the hot electrons space charge field. For the thinnest target (3. 5 μm) the ion cut-off energy is about 14 Mev, approximately twice the value obtained when the SPW is not excited
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Palaniappan, Sevugan. "Ohmic heating of foods : studies on microbicidal effect of electricity, electrical conductivity of foods, and heat transfer in liquid- particle mixtures /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487757723995203.
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Meige, Albert, and albert@meige net. "Numerical modeling of low-pressure plasmas: applications to electric double layers." The Australian National University. Research School of Physical Sciences and Engineering, 2006. http://thesis.anu.edu.au./public/adt-ANU20070111.002333.
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Inductive plasmas are simulated by using a one-dimensional particle-in-cell simulation including Monte Carlo collision techniques (pic/mcc). To model inductive heating, a non-uniform radio-frequency (rf) electric field, perpendicular to the electron motion is included into the classical particle-in-cell scheme. The inductive plasma pic simulation is used to confirm recent experimental results that electric double layers can form in current-free plasmas. These results differ from previous experimental or simulation systems where the double layers are driven by a current or by imposed potential differences. The formation of a super-sonic ion beam, resulting from the ions accelerated through the potential drop of the double layer and predicted by the pic simulation is confirmed with nonperturbative laser-induced fluorescence measurements of ion flow. It is shown that at low pressure, where the electron mean free path is of the order of, or greater than the system length, the electron energy distribution function (eedf) is close to Maxwellian, except for its tail which is depleted at energies higher than the plasma potential. Evidence supporting that this depletion is mostly due to the high-energy electrons escaping to the walls is given.
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A new hybrid simulation scheme (particle ions and Boltzmann/particle electrons), accounting for non-Maxwellian eedf and self-consistently simulating low-pressure high-density plasmas at low computational cost is proposed. Results obtained with the improved hybrid model are in much better agreement with the full pic simulation than the classical non self-consistent hybrid model. This model is used to simulate electronegative plasmas and to provide evidence supporting the fact that propagating double layers may spontaneously form in electronegative plasmas. It is shown that critical parameters of the simulation were very much aligned with critical parameters of the experiment.
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Alozie, Nehemiah Sabinus Iheadindueme. "Issues of particulate matter emission from diesel engine and its control." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/12822.
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Particulate matter (PM) emitted from diesel engines encompasses soluble (volatile) and insoluble (non-volatile) matter. The concept of volatility or solubility depends on the method of separation. The volatile matter includes sulphates and nitrates which are bound to water vapour; and myriads of hydrocarbon species. The solid matter is comprised of black carbon and ash. Its mitigation combines the use of internal engine design and operating factors like fuel injection and spray, air and fuel mixing, chamber designs and fuel improvements. Control technologies that act on the exhaust gases are called ‘after-treatments' which include the use of oxidation catalysts, filter trap and reductant of nitrogen oxides along the exhaust system. The central issues of this thesis are measurement schemes that involve stripping the PM of volatile matter in order to determine the actual values of nano-size solid carbon particles that pose significant health risk and their mitigations. In the experimental measurements, exhaust gases were generated at low engine load which are rich in unburnt hydrocarbons that nucleate into particles at low temperatures. Similarly, exhaust gases generated at medium load contain volatile and soot components; these were used to study dilution effects on PM emission. The interplay of mixing and cooling was used to explain the behaviour of saturation characteristics of the volatile fractions in the dilution process which influenced nucleation of volatile species. The parameters of particle number concentration reduction factor (PCRF) and volatile removal efficiency (VRE) were used to give extended interpretation to dilution of PM during conditioning, than mere dilution ratios. On this basis, comparison was made on the effect of carrier gases on dilution process and it was found that air is superior when there is need for volatile reduction while nitrogen is better when it is necessary to freeze further reaction, especially at low dilution ratios. In addition, a two-stage hot dilution technique was used to mimic the Particle Measurement Programme (PMP) prescription, and it gave better PCRF and VRE values. The study of PM mitigation by filter traps focused on burning-off the accumulated matter to allow free flow of exhaust gases, and the energy it takes to initiate and maintain PM combustion. Therefore a fundamental study of soot oxidation relevant to regeneration of diesel particulate filter (DPF) was made. This was extended to investigate if blending of petrodiesel with biodiesel affects PM oxidation. It is deducible that oxidation of PM generated from fuel with biodiesel blends is slightly faster compared to that from pure petrodiesel. A feasible use of microwave power to regenerate catalysed and non-catalysed silicon carbide (SiC) diesel particulate filters (DPFs) using an available multimode microwave cavity was also carried out. Results show that with catalysed DPFs, catalyst light-off temperature reduced by 100oC under the influence of microwave irradiation, while for non-catalysed DPF, regeneration was achieved within 550-600oC at a time estimated to be lower compared to electrical resistance heating approach.
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Rassou, Sébastien. "Accélération d'électrons par onde de sillage laser : Développement d’un modèle analytique étendu au cas d’un plasma magnétisé dans le régime du Blowout." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS066/document.
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Une impulsion laser intense se propageant dans un plasma sous-dense (ne< 10¹⁸ W.cm⁻²) et de durée très courte (τ₀< 100 fs), , on atteint le régime de la bulle. Les champs électriques dans ces bulles, de l’ordre de 100 GV/m, peuvent accélérer un faisceau d’électrons jusqu’au GeV sur des distances de l’ordre du centimètre. Dans ce régime, les électrons expulsés par la force pondéromotrice du laser forment une fine et dense couche à la surface d'une cavité d'ions restés immobiles. Les propriétés de ce régime sont examinées par l’intermédiaire d’un modèle analytique, que nous avons développé en nous inspirant du travail de W. Lu et S. Yi. En nous plaçant dans ce régime prometteur, nous avons étudié les mécanismes d’injection et de piégeage dans l'onde de sillage. Dans l’injection optique, les polarisations parallèles ou circulaires positives conduisent respectivement à une injection mettant en jeu du chauffage stochastique, ou à l’injection froide. Un paramètre de similarité est introduit, celui-ci permet de déterminer la méthode d’injection la plus appropriée pour maximiser la charge injectée. Enfin, le modèle analytique présenté en première partie est étendu afin d’étudier l’onde de sillage dans le régime de la bulle lorsqu’un champ magnétique longitudinal initial est appliqué au plasma. Lorsque le plasma est magnétisé deux phénomènes remarquables se manifestent, d'une part une ouverture apparaît à l'arrière de la bulle et d'autre part un mécanisme d'amplification du champ magnétique longitudinale est induit par la variation du flux magnétique. Les prédictions de notre modèle analytique sont confrontées aux résultats de simulations PIC 3D issues du code CALDER-Circ. La conséquence immédiate de la déformation de l'onde de sillage est la réduction, voire la suppression de l'auto-injection. L’application d’un champ magnétique longitudinal, combinée à un choix judicieux des paramètres laser-plasma, permet de réduire la dispersion en énergie des faisceaux d’électrons produits après injection optiqueAn intense laser pulse propagating in an under dense plasma (ne< 10¹⁸ W.cm⁻²) and short(τ₀< 100 fs), the bubble regime is reached. Within the bubble the electric field can exceed 100 GV/m and a trapped electron beam is accelerated to GeV energy with few centimetres of plasma.In this regime, the electrons expelled by the laser ponderomotive force are brought back and form a dense sheath layer. First, an analytic model was derived using W. Lu and S. Yi formalisms in order to investigate the properties of the wakefield in the blowout regime. In a second part, the trapping and injection mechanisms into the wakefield were studied. When the optical injection scheme is used, electrons may undergo stochastic heating or cold injection depending on the lasers’ polarisations. A similarity parameter was introduced to find out the most appropriate method to maximise the trapped charge. In a third part, our analytic model is extended to investigate the influence of an initially applied longitudinal magnetic field on the laser wakefield in the bubble regime. When the plasma is magnetized two remarkable phenomena occur. Firstly the bubble is opened at its rear, and secondly the longitudinal magnetic field is amplified - at the rear of the bubble - due to the azimuthal current induced by the variation of the magnetic flux. The predictions of our analytic model were shown to be in agreement with 3D PIC simulation results obtained with Calder-Circ. In most situations the wake shape is altered and self-injection can be reduced or even cancelled by the applied magnetic field. However, the application of a longitudinal magnetic field, combined with a careful choice of laser-plasma parameters, reduces the energy spread of the electron beam produced after optical injection
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Nakashima, Gabriela Tami. "Use of sugarcane trash for solid biofuel production: physicochemical characterization and influence of storage time." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8955.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
In the sugarcane plantation it was common to use fire to facilitate the cutting and harvesting of sugarcane. However, Law 11,241 / 02 in São Paulo State provides the gradual elimination of this straw burning of sugarcane. The largest producer of sugarcane in Brazil is the São Paulo State, which has about 4.7 million hectares of planted area. It is estimated that one hectare produces about 14 tons of trash. Therefore, the mills have been trying to incorporate this trash in burning with the bagasse for power generation. However, high concentrations of mineral impurities are impossible its use for energy purposes. The aim of the study was to investigate the influence of storage time and particle size in the physicochemical characterization of the sugarcane trash. It was used the sugarcane trash inside and outside of the bale collected at different storage time (0, 1 and 2 years). The collected material was separated into four different particle sizes (> 0.420mm, 0.250-0.420mm, < 0.250mm and mix). The analyzes involved particle size distribution, proximate analysis, the high heating value (HHV), the chemical analysis of the components of the ashes, the images in the Scanning Electron Microscope (SEM), the Klason lignin content, the holocellulose content and extractives. There were variations in the results of the ash content with different particle sizes. It was observed a higher concentration of mineral impurities in smaller particles (< 0.250mm). The HHV varied from 15.9 to 18.3 MJ.kg-1 and showed no statistical difference for the treatments. The results indicate that the sugarcane trash presents problems related to mineral impurities which constrain its use as a solid fuel in the industry. The particle size interferes in their physicochemical characteristics. The trash can be stored in field and the time storage did not affect the quality for use as solid biofuel.
No manejo da cana-de-açúcar era comum a utilização do fogo para facilitar o corte e colheita da cana. No entanto, a Lei 11.241/02 do estado de São Paulo prevê a eliminação gradual da queima da palha da cana-de-açúcar. O maior produtor de cana-de-açúcar do Brasil é o estado de São Paulo, que possui aproximadamente 4,7 milhões de hectares de área plantada. É estimado que 1 hectare produza cerca de 14 toneladas de palha. Logo, as usinas vêm tentando incorporar esta palha na queima para geração de energia, juntamente com o bagaço. Porém, as altas concentrações de impurezas minerais estão impossibilitando seu uso para fins energéticos. O trabalho teve como objetivo o estudo da influência do tempo de estocagem e da granulometria na caracterização físico-química do palhiço da cana-de-açúcar. Foi utilizado o palhiço de canade-açúcar da superfície e do interior do fardo coletados em diferentes períodos de estocagem, 0, 1 e 2 anos. O material coletado foi separado em 4 granulometrias diferentes (> 0,420mm, 0,250-0,420mm, < 0,250mm e mix). As análises realizadas foram a distribuição granulométrica, a análise imediata, o poder calorífico superior (PCS), a análise química dos componentes das cinzas, as imagens no Microscópio Eletrônico de Varredura (MEV), o teor de lignina Klason, a holocelulose e os extrativos. Houve variações nos resultados do teor de cinzas com as diferentes granulometrias. Observou-se maior concentração de impurezas minerais nas partículas mais finas (< 0,250mm). O PCS variou entre 15,9 a 18,3 MJ.kg-1 e não apresentou diferença estatística para os tratamentos. Os resultados indicam que a palha de cana-de-açúcar apresenta problemas relacionados às impurezas minerais, que dificultam e restringem seu uso como combustível sólido na indústria. A granulometria da palha interferiu nas suas características físico-químicas. O palhiço pode ser estocado no campo e o tempo de estocagem não interferiu na qualidade para o uso como combustível sólido.
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Boivie, Klas. "On the Manufacturing of SFF Based Tooling and Development of SLS Steel Material." Doctoral thesis, KTH, Production Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3814.
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Adler, Jeanette. "Film Formation and Surface Tension Studies of Powder Coatings." Thesis, KTH, Fibre and Polymer Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3935.
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In industrial use of paint systems a swift processing is crucial. Another very important issue is to improve the quality of the final coating. This report investigates the film formation process of powder coatings, specially the spreading of individual powder particles. The obtained results can be used to understand and control the film formation process. In this way the desired levelling can be achieved and thus the desired gloss or other surface characteristics that may be required. This means that the method could be used when evaluating different polymer and additive combinations that could be used to change film formation behaviour or curing time for powder coating systems to suit various substrates. It makes it possible to avoid and minimize different surface defects as orange peel or cratering in the powder coated film.
We used a reflection optical microscope to better understand the film formation process and especially the spreading of a powder melt on surfaces with various surface energies. The obtained data were: the particle diameter, the area, area ratio and the contact angle of the powder particle as a function of time and temperature. This information can be used to derive the surface tension of any powder melt.
In this report we evaluate the dependencies of temperature, heat rate and surface energy for powder coatings on different substrates. The method provides information that can be used to optimize the film formation of a specific powder coating/substrate combination. This method can be used to evaluate the powder spreading and levelling on different substrates from a surface tension point of view.
We found, as expected, that the powder flows out on a hydrophilic surface and is inhibited by a hydrophobic. The increase of the area ratio on a hydrophilic surface was about five times as the initial area coverage and on a hydrophobic surface only two times the initial area coverage. The contact angle between the melted powder particle on the different surface types could be calculated. The melt surface tension could be calculated since three substrates surfaces with various surface energies were used. The melt surface tension was found to be about 18.5 mN/m.
Sammanfattning
Vid industriell användning av ett färgsystem är det viktigt med en snabb och smidig målningsprocess. En viktig del är att förbättra kvaliteten på den färdiga ytan. Denna rapport undersöker filmbildningsprocessen för pulverfärg, närmare bestämt spridningen av individuella pulverpartiklar. Resultaten från utvärderingen av denna metod kan användas för att bättre förstå och få kontroll över filmbildningsprocessen. Med denna undersökningsmetod kan den önskade utslätningen uppnås och därmed den önskade glansen eller annan yteffekt som kan vara önskvärd.
Metoden kan användas för att utvärdera olika polymer- och additivkombinationer som kan användas för att ändra filmbildningens uppförande eller bestämma härdningstiden för en pulverfärg att passa ett visst substrat. Metoden gör det möjligt att förhindra och minska olika ytdefekter såsom apelsinskals- eller kratereffekter i pulverfärgens yta.
Ett optiskt reflectionsmikroskop användes för att bättre kunna förstå filmbildningsprocessen och särskilt spridningen av smält pulver på substrat med olika ytenergier. De mätdata vi fick var partikeldiameter, area, areaförändring och kontaktvinkeln för pulverpartiklar som funktion av tid och temperatur. Ur denna information kunde pulversmältans ytenergier härledas.
I denna rapport utvärderas pulvrets beroende av temperatur, uppvärmning och ytenergi på olika substrat. Denna metod ger information som kan användas för att optimera filmbildningen av en specifik kombination av pulverfärg och substrat. Denna metod kan också användas för att utvärdera pulverspridning och utjämning av färgfilmen på olika substrat med avseende på ytenergierna.
Som förväntat flyter pulvret ut på hydrofila ytor och utflytningen ändras på en hydrofob yta. På en hydrofil yta sprider sig partikeln till fem gånger den ursprungliga arean över substratet och motsvarande två gånger för en hydrofob yta. Kontaktvinkeln mellan en smält pulverpartikel på olika sorters substrat från utförda mätningar beräknas utifrån utförda mätningar. Kontaktvinklar mellan pulver och olika substrat kan användas för att beräkna smältans ytspänning. Smältans ytspänning kan beräknas då experiment gjorts på tre sorters ytor med olika kända ytenergier. Smältans ytspänning var 18,5 mN/m.
Slutsatsen är att det går att observera och utvärdera resultaten av utsmältningsförloppet för pulverfärg med denna metod.
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Carrié, Michaël. "Accélération de protons par laser à ultra-haute intensité : étude et application au chauffage isochore." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00608050.
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L'interaction d'impulsions lasers brèves et intenses avec un plasma est une source intéressante d'ions énergétiques. Les travaux effectués au cours de cette thèse s'articulent autour de deux grandes thématiques : la production de protons par laser, et leur utilisation pour le chauffage isochore, avec, pour principal outil d'étude, la simulation à l'aide de codes numériques (cinétique particulaire et hydrodynamique). Dans un premier temps, nous avons étudié le comportement de l'énergie cinétique maximale des protons qu'il est possible d'accélérer avec le mécanisme du Target Normal Sheath Acceleration (TNSA), en régime sub-ps, en fonction de différents paramètres, notamment de la durée d'impulsion laser. Nous avons montré que l'allongement de la durée d'impulsion, à énergie laser constante, est responsable du préchauffage et de la détente du plasma avant l'arrivé du pic d'intensité. Les gradients de densité ainsi produits (face avant et face arrière) peuvent favoriser, ou au contraire pénaliser, le gain en énergie cinétique des protons. Les résultats obtenus ont servi à l'interprétation d'une étude expérimentale réalisée au Laboratoire d'Optique Appliquée. Nos efforts se sont ensuite concentrés sur l'élaboration d'un modèle semi-analytique rendant compte de l'énergie cinétique maximale des protons accélérés par le biais du TNSA. Ce modèle permet de retrouver l'ordre de grandeur des intensités nécessaires, de l'ordre de 6x1021 W/cm², pour atteindre des énergies de proton supérieures à 150 MeV avec des impulsions laser de quelques joules et plusieurs dizaines de fs. Dans la dernière partie de cette thèse, nous nous sommes intéressés à l'utilisation de ces faisceaux de protons pour le chauffage isochore. Nous avons caractérisé, dans un premier temps, les fonctions de distribution produites par des cibles composées d'un substrat lourd (A >> 1) sur la face arrière duquel est déposé un plot d'hydrogène (schéma d'Esirkepov). Ensuite, à partir de simulations hydrodynamiques, nous avons étudié le temps caractéristique de détente de la cible chauffée en modifiant des paramètres tels que la distance à la source de protons, l'intensité et la tache focale du laser, et la densité surfacique du plot. Nous avons enfin étendu cette étude aux cibles cylindriques et nous avons montré qu'il est possible de réduire les effets liés à la divergence naturelle du faisceau de protons et ainsi d'obtenir des températures plus élevées.
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Li, Rui. "Solar pyrolysis of agricultural, forest and metal-contaminated biomass." Thesis, Perpignan, 2020. http://www.theses.fr/2020PERP0026.
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La biomasse est une source d'énergie renouvelable qui peut contribuer à résoudre la crise énergétique et les problèmes environnementaux. La pyrolyse est un procédé thermochimique de conversion la biomasse en biocarburants. L'énergie solaire permet d’améliorer le bilan matière et énergie de la pyrolyse de la biomasse pour produire des carburants, des produits chimiques et des biomatériaux transportables. Dans cette étude, nous avons étudié expérimentalement la pyrolyse solaire de sous-produits agricoles, forestiers et de bois contaminé par des métaux lourds. Dans le cas de la biomasse de sous-produits agricoles et forestiers, la sciure de pin, les noyaux de pêche, les tiges et marcs de raisin, a été utilisée comme matières premières dans un réacteur de laboratoire. Nous avons étudié l'influence des conditions opératoires (c.-à-d. la température de 800 à 2000°C, la vitesse de chauffage de 10 à 150°C/s et la composition de lignocellulose) sur les rendements de production des produits de la réaction (c.-à-d. gaz, tar (liquide) et char (solide)) et la composition du gaz de synthèse. Généralement le rendement en gaz augmente avec la température et la vitesse de chauffe pour les divers types de résidus de biomasse, tandis que le rendement en liquide progresse de façon opposée. Les teneurs en lignine, hémicellulose et cellulose, ainsi que la taille des pastilles d’échantillon, des sous-produits étudiés ont un impact sur la distribution des produits de pyrolyse solaire rapide. La teneur en lignine est associée à des rendements plus élevés en char et en liquide, mais moins en gaz. La pyrolyse de l'hémicellulose produit plus de composés volatils, mais moins de char et de tar que la pyrolyse de la cellulose.La pyrolyse solaire des déchets de litière de poulet et des pailles de riz de différentes tailles de particules (280 et 500 µm) a été effectuée dans différentes conditions solaires afin d'étudier les paramètres de fonctionnement optimaux, tels que la température, la taille des particules et la vitesse de chauffe, pour produire des gaz de pyrolyse à haute valeur calorifique. La température a l'effet le plus important sur le rendement en gaz pendant la pyrolyse. Les produits gazeux à partir de la pyrolyse de la biomasse assistée par l'énergie solaire contiennent une forte concentration de produits combustibles.La biomasse peut être contaminée par des métaux lourds. Des expériences ont été conçues pour étudier les effets des métaux lourds (cuivre et nickel) sur les produits de pyrolyse solaire du saule imprégné. Les résultats de cette étude indiquent que la pyrolyse solaire de la biomasse contaminée par des métaux lourds permet de produire du gaz de synthèse riche en hydrogène et monoxyde de carbone. De plus, les effets de ces métaux lourds sur la composition chimique, la structure et la morphologie du charbon de pyrolyse du saule imprégné ont été étudiés. Les résultats prouvent que la température de pyrolyse affecte les propriétés du charbon.Un modèle de conduction a été développé pour décrire le phénomène de pyrolyse à partir de l’évolution du profil de température à l'intérieur des pastilles. Un schéma cinétique de la littérature impliquant les réactions primaires et secondaires est adopté pour effectuer les simulations des transferts couplés. Une méthode aux différences finies est utilisée pour résoudre l'équation de transfert de chaleur avec un schéma explicite. Le modèle est résolu pour deux dimensions (c'est-à-dire le temps et la position axiale) afin de le rendre plus simple et de gagner du temps de calculBiomass, as a renewable energy source, can contribute to relieving the energy crisis and environmental pollutions. Pyrolysis is an attractive thermochemical process to convert biomass into biofuels. Solar energy processes improve the heat and mass balance of the biomass pyrolysis to produce transportable fuels, chemicals, and biomaterials. In the present study, solar pyrolysis of agricultural and forestry by-product biomass and metal-polluted wood has been examined. Pine sawdust, peach pit, grape stalk, and grape marc, were used as the raw materials as the agricultural and forestry by-products in a series of solar pyrolysis experiments in a lab-scale reactor. We studied the impacts of operating conditions (i.e., temperature from 800 to 2000°C, heating rate from 10 to 150°C/s, and lignocellulose composition) on the product yields (i.e., gas, tar, and char) and syngas composition. The gas yield of different biomass residues generally increases with the temperature and heating rate, while the liquid yield shows an opposite trend. Lignin, hemicellulose, and cellulose contents, as well as pellet size, of the by-products studied have an impact on the product profile under fast solar pyrolysis. Lignin content is associated with greater char and tar yields, but less gas yields. Hemicellulose pyrolysis produces more volatiles, but less char and tar yields than cellulose pyrolysis.Solar pyrolysis of chicken-litter waste and rice husk of different particle sizes (280 and 500 µm) was performed at different solar conditions aiming at investigating optimal operating parameters, such as temperature, particle size, and heating rate, to produce pyrolysis gasses with high calorific value. Temperature was found to have the highest effect on the gas yield during pyrolysis. Gases produced from solar assisted biomass pyrolysis have high concentration of combustible products which can be directly used as fuels.Biomass can be contaminated by heavy metals. Experiments were carried out to study the effects of heavy metals (copper and nickel), in combination with heating temperature and heating rate, on solar pyrolysis products of impregnated willow. Results of the investigation indicate that solar pyrolysis of heavy metal contaminated biomass is promising to produce valuable syngas such as hydrogen and carbon monoxide. Additionally, the effects of these heavy metals on the chemical composition, structure, and morphology of pyrolysis char from the impregnated willow were studied. Results prove that heavy metal and solar pyrolysis temperature affect the char properties. A conduction model was developed to describe the behavior of temperature inside the pellets. A kinetic scheme from literature involving the primary and the secondary reactions is adopted to carry out the simulations of temperature. A finite difference method was used for solving the heat transfer equation with an explicit scheme. The model is solved for two dimensions (i.e., time and axial position) in order to make it simpler and save computational time
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Jheng, Jia-Siang, and 鄭佳祥. "Application of Induction Heating to Partial Hardening of Workpiece." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/14992422127164220299.
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碩士國立臺灣大學
機械工程學研究所
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Abstract The characteristics of high frequency induction heating were that it could heat the surface of metal workpiece at a specific part quickly. The time of heating was so short that the oxidation and decarburization were negligible. This article used these features of high frequency induction heating to strengthen the metal workpiece. This experiment includes two parts: 1. To harden the tip of the sewing needle, which was manufactured from SK4 carbon tool steel. In order to make the sewing needle possessing toughness and partial high hardness, double quenching was performed in this experiment and the parameters affecting the hardness distribution and microstructure of the needles were discussed. The parameters were that whether using partial quenching or not and the different time holding in quenching temperature. 2. Workpiece could be heated quickly and reach to high temperature by high frequency induction heating. To make use of these characteristics, low-carbon steel was carburized in a short time at high temperature. Carburizing time and temperature are variables of this experiment. The parameters affecting the hardness distribution, microstructure, and carburization depth were discussed. The major results are shown as follows: 1. It would indeed get the result of tough needle and hard pinpoint when the sewing needle was hardened locally by high frequency induction heating in advance, because more Fe3C of the pinpoint would be dissolved into the matrix. 2. When low-carbon steel was heated by high frequency induction heating and carburized at high temperature for seconds, the speed of carburization was very fast. In addition, the effect of surface hardening was very good after quenching. Compared with the traditional method, this new method saves more time than the old one. 3. When high frequency induction heating was used in gas carburization, the Ledeburite would be developed in the surface if the carburizing temperature is above the eutectic point of cast iron. It may be useful in the surface modification of steel because of high hardness, good wear resistance and corrosion resistance.
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Li, Bo-Yi, and 李柏毅. "Particle Swarm Optimization of Fuzzy Temperature Control for Smart Electric Heating Clothing." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/44r6k3.
Full textAbstract:
碩士國立臺灣海洋大學
系統工程暨造船學系
102
Following the medical and science technology are developed rapidly and human society is become an aging population society gradually, life cares for elderly are respected by people. The most important life care is to against cold and to keep warm efficiently in winter. In consideration of above reasons, this paper presents to develop a smart electric heating clothing (SEHC) with a constant temperature control function by adopted a programmable system on chip (PSoC). However, conventional electric heating clothing in commercial markets has drawbacks of longer rising time, larger energy consumption, and shorter operational time. Therefore, there are three different temperature controllers, i.e. bang-bang temperature controller (BBTC), fuzzy temperature controller (FTC), and particle swarm optimization (PSO) based FTC, were adopted in this study to enhance the system performance and decrease energy consumption in the designed SEHC. The proposed PSO-based FTC was adjusted weighting factors of the conventional FTC by a PSO to optimize and decrease the electric power of the integrated system. In the experimental results, the rising time of 123.2 s, 127.7 s, and 135.0 s are by adoption of the BBTC, the FTC, and the PSO-based FTC, respectively; the energy consumption by utilizing the FTC and the PSO-based FTC could be reduced 2.4% and 18.6% related to the BBTC effectively. Hence, it could extend the operational time by using PSO-based FTC in the designed SEHC.
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Chen, Xiang-Shu, and 陳湘書. "Optimal Control Strategy of Heat Pump Water Heating System Using Particle Swarm Optimization." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/th5vx8.
Full textAbstract:
碩士國立臺北科技大學
能源與冷凍空調工程系碩士班
98
The heat pump system coordination boiler provides the hot water is one which of heating patterns present uses for the hospital and the hotel, however in the actual operation, as a result of the hot water demand''s change, in the running operation, often has some problem, such as the peak price period, when the water load demand for the client at a time when storage tank up into the cold water so the water temperature is low, causing the boiler to increase energy use; At this point, if the load demand to be high-end supplemented using the heat pump heat into cold water, will help to reduce energy use. Before the end of the load in the water up into the cold water to stop the use of off-peak electricity price periods supplemented into the cold water and heating using heat pumps, so that the energy consumption during peak electricity transferred to off-peak price period, the economy will help to reduce spending. Therefore, how different time points in the heat pump and pump control, forming optimal operation problem, which is the focus of this study is to investigate. In this actual case, using the particle swarm optimization, set the life-cycle cost as the objective function, heat pump、water pump start and stop status of the state variables, with known client load of water, storage tank, heating system components, the peak and off-peak electricity price periods, through the numerical simulation program for the system to find heat pump、water pump start and stop each time the state of the lowest life-cycle cost control operating mode, and with only heat pump start and stop optimization of control operation mode and the current operating mode of the two control (water temperature control, water level control) for life-cycle costs, energy costs and energy consumption comparison of the system to seek out the best control strategy to improve the economic efficiency of heat pump water heating system and achieve the government to promote energy conservation and carbon reduction targets, as domestic manufacturers to develop and conduct heat pump systems engineering reference to follow. Indoor swimming-pool is usually conducted through a suitable introduction of fresh air to maintain indoor design condition. Since water is evaporated from the pool surface, the exhausted air contains more water and specific enthalpy. In response to this indoor air, heat pump is generally used in heat recovery for indoor swimming pools. This paper utilizes particle swarm algorithm to optimize heat pump system
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Chang, Chun-Hao, and 張峻豪. "Optimal Control Strategy of Solar Heat Pump Water Heating System Using Particle Swarm Optimization." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/y6c338.
Full textAbstract:
碩士國立臺北科技大學
冷凍空調工程系所
100
Auxiliary heating source for solar water heating systems is commonly using in boilers. Heat pump''s energy efficiency is much higher than electrical heating. Heat pump’s instant heating ability is weaker than boiler. Therefore, when we want to replace the boiler into solar heat pump water heating system, we need to design the equipment capacity and find operating model to optimize the system efficiency? How to set the initial temperature on the tank? The smaller initial temperature on the tank is will result in the higher efficiency in the solar collectors and heat pump, but when the initial temperature is too low will cause the temperature cannot reach the demand temperature. The simulation results show that in all day load. The solar heat pump water heating system can save about 4.5% of the life cycle cost than using the solar boiler water heating system. The solar heat pump water heating system can save about 6.7% of the life cycle cost than using the heat pump water heating system. When only consider the system load at night. The solar heat pump water heating system can save about 15.1% of the life cycle cost than using the solar boiler water heating system. The solar heat pump water heating system can save about 17.4% of the life cycle cost than using the heat pump water heating system. The solar heat pump water heating system operation at night can save about 17.4% of the life cycle cost than at all day use. Applying the Particle Swarm Optimization in the solar heat pump water heating system can find the optimized operating mode and the best equipment capacity. Heat pump and water pump optimum control mode can transfer the electricity from peak electric price to off-peak electric price. The optimum heat pump capacity and the solar collector pieces can avoid excessive construction costs, not only to achieve the goal of the energy saving, but also economic benefits are very significant.
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Chen, Li-Kai, and 陳立凱. "A model for heating of liquid -particle mixtures in a continuous flow ohmic heater." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/17111941772119054068.
Full textAbstract:
碩士國立臺灣大學
生物產業機電工程學研究所
90
ABSTACT In ohmic heating, the temperature of liquid -particle mixtures affects the quality of food. Understanding the temperature history of mixtures in process would be helpful to apply ohmic heating. In this search, we use exact solution incorporated with numerical analysis to build a model for heating of liquid-particle mixtures in a continuous flow ohmic heater and to compute the temperature history with solid and liquid phases. Simulations show that the temperature of mixtures with higher electrical conductivity particulates rises faster than that with lower electrical conductivity particulates. With the increase of solid contents in the mixtures, a particle’s electrical resistance within a circuit will be a significant component of the overall resistance. The solid will likely heat faster than the liquid. High solid content mixtures in Ohmic heating will promote more uniform temperature distribution inside the particle and might be promising. Keywords: ohmic heating, mathematic model, liquid-particle mixtures.
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Kung, Chung-Kuan, and 龔仲寬. "Optimization of Heat Pump Heating System in Indoor Swimming Pool Using Particle Swarm Algorithm." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/5y96bg.
Full textAbstract:
碩士國立臺北科技大學
能源與冷凍空調工程系碩士班
95
Indoor swimming-pool is usually conducted through a suitable introduction of fresh air to maintain indoor design condition. Since water is evaporated from the pool surface, the exhausted air contains more water and specific enthalpy. In response to this indoor air, heat pump is generally used in heat recovery for indoor swimming pools. This paper utilizes particle swarm algorithm to optimize heat pump system. The optimized parameters include continue parameters: outdoor air mass flow, and heat conductance of heat exchanger; and discrete parameters: compressor type and boiler type. In a case study, life cycle energy cost is considered as an objective function, and optimal introduced mass flow of outdoor air and optimal design for heating system are found by using Particle Swarm algorithm. From the convergence of solution progress and the consistency for finding the best solution, we conclude that the Particle Swarm algorism is effective method for optimizing the heating system of indoor swimming pool.
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Thanapal, Siva Sankar. "Gasification of Low Ash Partially Composted Dairy Biomass with Enriched Air Mixture." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8927.
Full textAbstract:
Biomass is one of the renewable and non-conventional energy sources and it includes municipal solid wastes and animal wastes in addition to agricultural residue. Concentrated animal feeding operations produce large quantities of cattle biomass which might result in land and water pollution if left untreated. Different methods are employed to extract the available energy from the cattle biomass (CB) which includes co-firing and gasification. There are two types of CB: Feedlot biomass (FB), animal waste from feedlots and dairy biomass (DB), animal waste from dairy farms. Experiments were performed in the part on gasification of both FB and DB. Earlier studies on gasification of DB with different steam-fuel ratios resulted in increased production of hydrogen. In the present study, dairy biomass was gasified in a medium with enriched oxygen percentage varying from 24% to 28%. The effect of enriched air mixture, equivalence ratio and steam-fuel ratio on the performance of gasifier was studied. Limited studies were done using a mixture of carbon dioxide and oxygen as the gasification medium and also a methodology was developed to determine the gasification efficiency based on mass and heat contents of gas. The results show that the peak temperature within the bed increases with increase in oxygen concentration in the gasification medium. Also carbon dioxide concentration in the mixture increases with corresponding decrease in carbon monoxide with increase in oxygen concentration of the incoming gasification medium. The peak temperature increased from 988°C to 1192°C as the oxygen concentration increased from 21% to 28% at ER=2.1. The upper limit on oxygen concentration is limited to 28% due to high peak temperature and resulting ash agglomeration. Higher heating value (HHV) of the gases decreases with increase in equivalence ratio. The gases produced using carbon dioxide and oxygen mixture had a higher HHV when compared to that of air and enriched air gasification. Typically the HHV of the gases increased from 2219 kJ/m³ to 3479 kJ/m³ when carbon dioxide and oxygen mixture is used for gasification instead of air at ER=4.2 in the absence of steam.
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Pattani, Varun Paresh. "Nanoparticle-mediated photothermal therapy of tumors : a comparative study of heating efficiencies for different particle types." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1482.
Full textAbstract:
Cancer is one of the most notorious diseases affecting the human population today with very few effective treatments. Due to the disparate nature of cancers, it is difficult to obtain a treatment that can cure cancer. Thus, there is a large influx of research towards cancer therapies, leading to one of the discovery that cancer cells (tumors) have a low thermotolerance in comparison to normal cells. If the temperature of the cancer cells is increased into the hyperthermia range (~45°C) thermal damage occurs, causing cell death by protein denaturation and membrane disruption. A recent development in this field has been in the photothermal treatment of tumors, which is starting to utilize plasmonic particles to enhance the specificity of the treatment. The plasmonic nanoparticles, specifically gold, can reach the tumor site using passive targeting and when irradiated with a tuned laser will emit heat localized to a small region around the nanoparticle killing the surrounding cancer cells. This process has been shown to reduce tumor size in vivo with gold nanoshells and gold nanorods.
However, it has not been shown which particle is better at delivering the heat to the tumor site. Therefore in this study, it will be shown which particle generates the most heat. Solutions of tissue simulating phantom and different concentrations of nanoparticles were irradiated with a laser to measure the increase in temperature. Additionally, simulations were performed using Mie Theory for nanoshells and the Discrete Dipole Approximation for nanorods. Based on the physical parameters of the nanoshells and nanorods used in this experiment, the adjusted absorption cross-section was determined. It was found that nanoshells generated the most amount of heat on a per particle basis, and that it was necessary to have a nanorod concentration of 5.5 times the concentration of nanoshells to generate the same amount of heat as nanoshells. These results were confirmed using Monte Carlo and Finite Difference Modeling of the nanoparticle heating experiments. However, the choice of nanoparticle still depends on the application and the targeting efficiency in vivo.text
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(9643427), Troy A. Seberson. "Heating and Cooling Mechanisms for the Thermal Motion of an Optically Levitated Nanoparticle." Thesis, 2020.
Find full textAbstract:
Bridging the gap between the classical and quantum regimes has consequences not only for fundamental tests of quantum theory, but for the relation between quantum mechanics and gravity. The field of levito-dynamics provides a promising platform for testing the hypotheses of the works investigating these ideas. By manipulating a macroscopic particle's motion to the scale of its ground state wavefunction, levito-dynamics offers insight into the macroscopic-quantum regime.
Ardent and promising research has brought the field of levito-dynamics to a state in which these tests are available. Recent work has brought a mesoscopic particle's motion to near the ground state. Several factors of decoherence are limiting efficient testing of these fundamental theories which implies the need for alternative strategies for achieving the same goal. This thesis is concerned with investigating alternative methods that may enable a mesoscopic particle to reach the quantum regime.
In this thesis, three theoretical proposals are studied as a means for a mesoscopic particle to reach the quantum regime as well as a detailed study into one of the most important factors of heating and decoherence for optical trapping. The first study of cooling a particle's motion highlights that the rotational degrees of freedom of a levitated symmetric-top particle leads to large harmonic frequencies compared to the translational motion, offering a more accessible ground state temperature after feedback cooling is applied. An analysis of a recent experiment under similar conditions is compared with the theoretical findings and found to be consistent.The second method of cooling takes advantage of the decades long knowledge of atom trapping and cooling. By coupling a spin-polarized, continuously Doppler cooled atomic gas to a magnetic nanoparticle through the dipole-dipole interaction, motional energy is able to be removed from the nanoparticle. Through this method, the particle is able to reach near its quantum ground state provided the atoms are at a temperature below the nanoparticle ground state temperature and the atom number is sufficiently large.The final investigation presents the dynamics of an optically levitated dielectric disk in a Gaussian standing wave. Though few studies have been performed on disks both theoretically and experimentally, our findings show that the stable couplings between the translational and rotational degrees of freedom offer a possibility for cooling several degrees of freedom simultaneously by actively cooling a single degree freedom.
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McCurrin, Casey. "Flow and Temperature Fields Generated by a Thermally Activated Interventional Vascular Device." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11620.
Full textAbstract:
Concern for the nonphysiologic energy required to actuate medical devices utilizing “smart material” properties of shape memory polymer (SMP) compels a rigorous investigation into the flow and temperature fields surrounding a thermally activated catheter device. Multiple analyses include the theoretical approaches of exact analytical solutions and finite difference modeling combined with the experimental techniques of particle image velocimetry (PIV) and laser-induced fluorescence (LIF). The attained velocities and temperatures related to the convective heat transfer impact the potential for blood or tissue damage caused by intravascular heating.
The clinical scenario involving a catheter device receiving heat within an artery is modeled in its simplest form as a cylindrical metal cap on the tip of a hollow glass rod placed inside of a long straight tube of constant cross-sectional area. Using a working fluid with properties comparable to blood, flow rates and energy input is then varied to determine their effects on velocity fields and temperature gradients.
Analytical solutions for both the straight tube and concentric annulus demonstrate the two velocity distributions involved, as flow moves past the gap between
the catheter and artery wall and then converges downstream to the Poiseuille solution for steady pipe flow of an incompressible fluid. To solve for the transition between the velocity profiles, computational fluid dynamics software simulates a finite volume model identical to the experimental setup used for intravascular heating experiments.
PIV and LIF, both experimental techniques making use of similar hardware, determine velocity fields and temperature distributions, respectively, by imaging fluid seeding agents and their particular interaction with the light sheet. The velocity and temperature fields obtained experimentally are matched with the analytical and finite volume analysis through fluid properties, flow rates, and heating rates.
Velocities determined during device heating show a small increase in local velocity, due to temperature dependent viscosity effects. When the device is centered in the model, flow patterns constrain the heat flow near the center axis and away from the channel walls. Increasing flow rate consequently decreases temperature rise, as the heat is carried more quickly downstream and away from the heat source.
Using multiple analyses, fluid velocity and temperature distributions are first theorized with analytical and finite element methods and then validated through experimental imaging in a physical model.
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Lewis, Elliott William. "Development and Application of a Method for Gas-phase Temperature Measurements in Particle-laden Flows." Thesis, 2022. https://hdl.handle.net/2440/136045.
Full textAbstract:
Suspensions of particles in a carrier flow of gas are utilised in, or being
developed for, several high-temperature industrial processes. These include
for material transformations in calciners and kilns, as fuel in particulate
burners and as the medium for radiation absorption in concentrated solar
thermal receivers. The efficiency, stability, and emissions from such systems
is strongly dependent on the temperature distribution of both the particle
and fluid phases, each of which can be highly variable both spatially and
temporally. While these systems are widely utilised, there is still a lack of
fundamental understanding of the heat transfer processes due to the complexity
of turbulent particle-laden flows with a high particle volume fraction.
Therefore, this work aims to provide insight into these processes for future
optimisation of non-isothermal particle-based systems. This is performed by
adapting and applying the technique of laser induced fluorescence (LIF) to
measure the gas-phase temperature in a particle-laden flow that is heated
using high-flux radiation.
This thesis presents the first demonstration of LIF in the densely loaded
conditions present in particle-laden flows relevant to industrial application,
with the potential for strong optical interference from elastic scattering of
radiation from the excitation laser by particles. The two-colour method for
thermometry, with toluene as the fluorescent tracer, was used to provide
spatially resolved measurements from a < 1 mm thick planar cross-section
of the flow. The particle distribution was measured simultaneously with
the temperature by imaging the laser light scattered by particles (particle
nephelometry). The accuracy and precision of the two-colour LIF method
was assessed for a series of particle materials and diameters, including
materials that luminesce following absorption of the excitation laser light. The
results show that optical filters effectively suppress the detection of elastically
scattered light, with other sources of measurement uncertainty including
particle luminescence, laser attenuation, and signal trapping identified and
assessed. The systematic error in the measurement from these combined sources was shown to increase with local particle loading, but be independent
of particle diameter.
The two-colour LIF and particle nephelometry methods were applied to
simultaneously measure the gas-phase temperature and particle distributions
in a particle-laden flow heated using high-flux radiation, evaluated for systematically
varied series of particle diameter, particle volumetric loading, and
heating power. The measurements were recorded in a particle-laden jet flow
issuing from a long, straight pipe with well-defined inlet and co-flow conditions,
with the particles heated using an axisymmetric, well-characterised
infra-red radiative source generating a beam with a peak flux of up to 42.8
MW/m2 on the axis. The resulting gas-phase temperature profile increased
monotonically with distance down-stream from the start of the heating region,
at up to 2,200 ◦C/m on the jet centreline. Additionally, attenuation of
the heating beam was shown to lead to an asymmetric temperature profile in
the jet flow.
The rate of increase of the gas temperature was shown to be directly
proportional to both the heating flux and the time-averaged particle volumetric
loading, within the range of conditions investigated. The temperature
decreased significantly with an increase in particle diameter, due to the
dependence of radiative and convective heat transfer processes to different
exponents of the diameter. The experimental results for the temperature rise
on the jet centreline were shown to match the trends from a simplified analytical
model. Importantly, the model also predicts that the particle temperature
is significantly greater than the gas, from the heating region to the edge of the
measurement region investigated. The asymmetry of the flow temperature
due to attenuation of the heating beam is also shown to increase with an
increase in the particle loading and a decrease in the particle diameter (i.e.,
an increase in the total cross-sectional area of particles in the flow).
The instantaneous distributions of both the gas-phase temperature and
particle locations were demonstrated to be highly non-uniform in the radiatively
heated particle-laden flow. The particle distributions were analysed
using Voronoi diagrams to determine the locations of particle clusters. Void
regions (i.e., with no nearby particles) were also identified. The gas-phase
temperature around particles was shown to be dependent on the local particle
loading, with the measured temperature inside of clusters also greater than
that outside of clusters. Localised regions of relatively high or low temperature
compared to their surroundings were also identified from the instantaneous
images, with these regions shown to remain coherent to the downstream
edge of the measurement region. The high temperature regions are
shown to be typically associated with regions of high local particle-loading, while regions with low temperature are shown to be in the void regions or
with a low particle loading. These results suggest that the structures in the
flow are long-lived with a sufficient particle-gas temperature difference, both
within the heating region and in the near-field downstream, for convection
between the particles and gas to influence the gas-phase temperature field
more significantly than entrainment, mixing, and convection within the gas
flows.Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2022
40
Meige, Albert. "Numerical modeling of low-pressure plasmas: applications to electric double layers." Phd thesis, 2006. http://hdl.handle.net/1885/45749.
Full textAbstract:
Inductive plasmas are simulated by using a one-dimensional particle-in-cell simulation including Monte Carlo collision techniques (pic/mcc). To model inductive heating, a non-uniform radio-frequency (rf) electric field, perpendicular to the electron motion is included into the classical particle-in-cell scheme. The inductive plasma pic simulation is used to confirm recent experimental results that electric double layers can form in current-free plasmas. These results differ from previous experimental or simulation systems where the double layers are driven by a current or by imposed potential differences. The formation of a super-sonic ion beam, resulting from the ions accelerated through the potential drop of the double layer and predicted by the pic simulation is confirmed with nonperturbative laser-induced fluorescence measurements of ion flow. It is shown that at low pressure, where the electron mean free path is of the order of, or greater than the system length, the electron energy distribution function (eedf) is close to Maxwellian, except for its tail which is depleted at energies higher than the plasma potential. Evidence supporting that this depletion is mostly due to the high-energy electrons escaping to the walls is given. ¶ A new hybrid simulation scheme (particle ions and Boltzmann/particle electrons), accounting for non-Maxwellian eedf and self-consistently simulating low-pressure high-density plasmas at low computational cost is proposed. Results obtained with the “improved” hybrid model are in much better agreement with the full pic simulation than the classical non self-consistent hybrid model. This model is used to simulate electronegative plasmas and to provide evidence supporting the fact that propagating double layers may spontaneously form in electronegative plasmas. It is shown that critical parameters of the simulation were very much aligned with critical parameters of the experiment.
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Cox, Sebastian Penleigh. "The impact of fishbones on neutron rate in beam-heated plasmas in MAST." Master's thesis, 2015. http://hdl.handle.net/1885/112493.
Full textAbstract:
A plasma instability has been associated with loss of fusion rate
in tokamaks since the introduction of beam-heating in the
1980’s: the Fishbone. Losses of fusion rate on tokamaks during
the heating phase present a significant obstacle in reaching the
ignition condition required to harness nuclear fusion as a power
source. If the conditions exacerbating fusion rate losses during
these events can be understood, they can be mitigated.
We examine a wide selection of fishbone events from MAST to
determine the characteristics associated with greater losses in
fusion rate. Quantities for expressing the behaviour of fusion
rate are discussed, and statistically significant changes in
fusion rate as a function of fishbone phase are examined. Using
correlation analysis and sub-classifying the dataset based on
observed loss characteristics indicates that fishbone behaviour
is significantly more complex than previously believed.
Correlation analysis using the full dataset found no reliable
quantity that relates plasma conditions during the fishbone to
changes in the fusion rate.
To study a fishbone undergoing loss, a reduced model of
wave-particle resonant interaction between fishbone harmonics and
fast ions was built. This models the physical process of fast
ions losing energy to the plasma by redistributing the fast ion
distribution function in velocity-space. When resonant
interactions with higher fishbone harmonics are included, the
reduced-model accesses regions of the fast ion distribution
function at higher velocities. This results in a larger effect on
the modelled fusion rate. Small changes in the fast ion
distribution in these regions produces changes in fusion rate
that match experimentally observed losses. These results suggest
the possibility of developing inference diagnostics for the fast
ion distribution function using MHD spectroscopy.