Дисертації з теми "Transfer phenomena"
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White, R. P. "Spectroscopic probes for electron transfer phenomena." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382862.
Повний текст джерелаWeber, Thomas Anthony. "Expatriate knowledge transfer phenomena in defense corporations." Thesis, Indiana Institute of Technology, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10239973.
Повний текст джерелаExpatriate knowledge transfer is often disrupted, which creates a loss of learning for the sending organization. Lack of knowledge transfer also causes a loss of competitive advantage for corporations. This study investigates barriers to knowledge transfer for expatriates in a US-based defense company. This research examines knowledge transfer through the lived experiences of expatriates, focusing on the characteristics of “ability to transfer” and “motivation to transfer” and their representation as “noise” in the communication system. This research uses qualitative methods to explore whether barriers to knowledge transfer exist within a corporation. This phenomenological case study provides a way to understand the social interaction between expatriates and their organization from the expatriates’ perspective. This research contributes to the understanding of the phenomenon around knowledge transfer. The data collected from the expatriates showed many different themes, but the most prevalent was their reliance on their social networks. The most common barrier for knowledge transfer dealt with supervisory interactions and the lack of formal knowledge documentation processes. There were also many other barriers noted by the expatriates, but these barriers were overcome through an expatriate’s focus on personal responsibility.
Henkel, Jochen [Verfasser]. "Oxygen Transfer Phenomena in Activated Sludge / Jochen Henkel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2010. http://d-nb.info/1106115945/34.
Повний текст джерелаTura, R. "Heat transfer and airflow phenomena in multilouvred ducts." Thesis, Coventry University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374680.
Повний текст джерелаXiang, Yuanyuan. "Mass Transfer Phenomena in Rotating Corrugated Photocatalytic Reactors." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/30342.
Повний текст джерелаVlachopoulos, Georgios. "Phenomena affecting ink transfer in offset lithographic printing." Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa42395.
Повний текст джерелаCocchini, Ugo. "Mass transfer phenomena through porous and non-porous membranes." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/8024.
Повний текст джерелаEccles, Errol R. A. (Errol Ray Antonio). "Flow and heat transfer phenomena in aerated vibrated beds." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74281.
Повний текст джерелаLong, Siyuan. "Cast fibrous MMCs : transfer phenomena and micro-structure formation." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362437.
Повний текст джерелаTruong, Bao H. (Bao Hoai). "Effects of surface parameters on boiling heat transfer phenomena." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/76925.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 148-156).
Nanofluids, engineered colloidal dispersions of nanoparticles in fluid, have been shown to enhance pool and flow boiling CHF. The CHF enhancement was due to nanoparticle deposited on the heater surface, which was verified in pool boiling. However, no such work has been done for flow boiling. Using a cylindrical tube pre-coated with Alumina nanoparticles coated via boiling induced deposition, CHF of water was found to enhance up to 40% compared to that of the bare tube. This confirms that nanoparticles on the surface is responsible for CHF enhancement for flow boiling. However, existing theories failed to predict the CHF enhancement and the exact surface parameters attributed to the enhancement cannot be determined. Surface modifications to enhance critical heat flux (CHF) and Leidenfrost point (LFP) have been shown successful in previous studies. However, the enhancement mechanisms are not well understood, partly due to many surface parameters being altered at the same time, as in the case for nanofluids. Therefore, the remaining objective of this work is to evaluate separate surface effect on different boiling heat transfer phenomena. In the second part of this study, surface roughness, wettability and nanoporosity were altered one by one and respective effect on quenching LFP with water droplet was determined. Increase in surface roughness and wettability enhanced LFP; however, nanoporosity was most effective in raising LFP, almost up to 100°C. The combination of the micro posts and nanoporous coating layer proved optimal. The nanoporous layer destabilizes the vapor film via heterogeneous bubble nucleation, and the micro posts provides intermittent liquid-surface contacts; both mechanisms increase LFP. In the last part, separate effect of nanoporosity and surface roughness on pool boiling CHF of a well-wetting fluid, FC-72, was investigated. Nanoporosity or surface roughness alone had no effect on pool boiling CHF of FC-72. Data obtained in the literature mostly for microporous coatings showed CHF enhancement for well wetting fluids, and existing CHF models are unable to predict the enhancement.
by Bao Hoai Truong.
Ph.D.
Schmidt, Martin Jurgen. "Bubble phenomena in narrow gap electrolysis cells." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322262.
Повний текст джерелаHou, Xiaofei. "Numerical modeling of complex heat transfer phenomena in cooling applications." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/309294.
Повний текст джерелаDebido a la transferencia de calor y de cambio de fase, fenomenología multifase y multicomponente se encuentra en las aplicaciones de refrigeración. Dependiendo de la estructura de interfaz multifase pueden clasificarse como flujo separado (flujo estratificado), de transición o mezclado flujo y flujo disperso. Dependiendo de los diferentes estados de flujo de dos fases, se deben aplicar diferentes modelos. La presente tesis se centra principalmente en flujo separado. Modelos de mezcla homogénea de dos fluidos se emplean para simular fenómenos de enfriamiento en multifase. Este trabajo se divide en dos partes principales. En la primera parte, un algoritmo de modelo de dos fluidos de la superficie libre se presenta. El modelo de dos fluidos se utiliza generalmente como una herramienta para simular flujo disperso. En la segunda parte, el modelo de mezcla homogénea para flujo multicomponente se emplea para resolver el problemas de evaporación. Finalmente se simulan flujos turbulentos con influencia de la fuerza de flotabilidad. El objetivo a largo plazo es acoplar los dos modelos, que podrían resolver todos los regímenes de flujo y tendrian aplicación en problemas industriales. La presente tesis se compone de seis capítulos. El primer capítulo está dedicado a una introducción a los modelos de mezcla homogénea de dos fluidos empleados en el flujo multifásico / multicomponente. La clasificación de múltiples fases se explica y se revisa la bibliografia existente. El segundo capítulo se centra principalmente en la aplicación del Fractional Step Method en bifasico. Con el algoritmo propuesto, el modelo de dos fluidos adecuado para el flujo disperso se extiende al flujo separado. El modelo para mezcla homogénea se introduce en el tercer capítulo con las mismas ecuaciones de masa, cantidad de movimiento, energía y concentración. Se aplica en casos de evaporación y condensación. El flujo laminar completamente desarrollado en un conducto horizontal se estudia en primer lugar considerando propiedades físicas constantes para verificar el modelo en un flujo laminar. La simulacion de convección natural en una cavidad con propiedades físicas variables y película de líquido se realiza numéricamente para validar el modelo de película descendente. Finalmente, el flujo de convección mixta se investiga en un film descendente. Los efectos de los diferentes parámetros en la evaporación y el flujo son investigados mediante experimentos numéricos. En el cuarto capítulo, la laminarización de flujo turbulento forzado en un tubo vertical con flujo de calor constante se estudia para validar la capacidad de predicción de los modelos LES en el flujo de convección mixta de transición turbulenta-laminar con fuerte fuerza de flotación. Se llevan a cabo estudios numericos y los resultados se comparan con los datos experimentales existentes. A lo largo de toda el conducto, el estado de flujo sigue un proceso complicado, que incluye turbulencia.
Prinos, Panagiotis. "A study of momentum transfer phenomena in compound channel flows." Thesis, University of Ottawa (Canada), 1985. http://hdl.handle.net/10393/4968.
Повний текст джерелаWorm, Steven Lee. "Experimental measurement of heat transfer phenomena in a solid adsorbent." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16487.
Повний текст джерелаMielke, Eric. "Study on the Transport Phenomena in Complex Micro-Reactors." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36040.
Повний текст джерелаHoogenboezem, Teunis Adrianus. "Heat transfer phenomena in flow through packed beds / Teunis Adrianus Hoogenboezem." Thesis, North-West University, 2006. http://hdl.handle.net/10394/4300.
Повний текст джерелаThesis (M.Ing. (Mechanical Engineering)--North-West University, Potchefstroom Campus, 2007.
Bahmanyar, Hossein. "Drop breakage and mass transfer phenomena in a rotating disc contactor." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253321.
Повний текст джерелаMATSUBARA, Shigeki, and Yasuyoshi INAGAKI. "Incremental Transfer in English-Japanese Machine Translation." The Institute of Electronics, Information and Communication Engineers, 1997. http://hdl.handle.net/2237/11131.
Повний текст джерелаAli, Rashid. "Phase Change Phenomena During Fluid Flow in Microchannels." Doctoral thesis, KTH, Tillämpad termodynamik och kylteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26796.
Повний текст джерелаQC 20101206
Yamauchi, Akira. "Heat transfer phenomena and mold flux lubrication in continuous casting of steel /." Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3121.
Повний текст джерелаKoren, Chai. "Modeling conjugate heat transfer phenomena for multi-physics simulations of combustion applications." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC001/document.
Повний текст джерелаOxycombustion is seen as one mean to attain the wished goals in terms of efficiency optimisation and Greenhouse Effect Gases emissions reduction for industrial furnaces. The extreme operating conditions, high pressure and temperature, lead to a strong interaction between the different phenomena which take place inside the combustion chambe r: Combustion, turbulence and heat transfer. To better design these futur oxyfuel processes, a mean to study the related physics with a reasonable computational cost and return time. Such studies require the use of high-fidelity numerical resolution tools, and in order to model the multi-physics interaction in a cost efficient way, code coupling. The operating conditions being extreme : High pressure and temperature, a strong interaction exists between the different phenomena occuring inside the chamber. To better understand the physics inside oxycombustion chambers,a multiphysics high-fidelity simulation methodology is developped
Xiao, Rong Ph D. Massachusetts Institute of Technology. "Wetting and phase-change phenomena on micro/nanostructures for enhanced heat transfer." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/79285.
Повний текст джерелаPage 76 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 71-75).
Micro/nanostructures have been extensively studied to amplify the intrinsic wettability of materials to create superhydrophilic or superhydrophobic surfaces. Such extreme wetting properties can influence the heat transfer performance during phase-change which is of great importance in a wide range of applications including thermal management, building environment, water harvesting and power production. In particular, superhydrophilic surfaces have been of interest to achieve thin film evaporation with high heat fluxes. Meanwhile, superhydrophobic surfaces with dropwise condensation promises higher heat transfer coefficients than typical filmwise condensation. My thesis work aims at improving fundamental understanding as well as demonstrating practical enhancements in these two areas. A key challenge to realizing thin film evaporation is the ability to achieve efficient fluid transport using superhydrophilic surfaces. Accordingly, we developed a semi-analytical model based on the balance between capillary pressure and viscous resistance to predict the propagation rates in micropillar arrays with high aspect ratios. Our experimental results showed good agreement with the model, and design guidelines for optimal propagation rates were proposed. For micropillar arrays with low aspect ratio and large spacing between pillars, however, we identified that the microscopic sweeping of the liquid front becomes important. We studied this phenomenon, explained the effect of such microscale dynamics on the overall propagation behavior, and proposed a strategy to account for these dynamics. While these propagation studies provide a means to deliver liquid to high heat flux regions, we investigated a different configuration using nanoporous membrane that decouples capillarity from the viscous resistance to demonstrate the potential heat dissipation capability. With nanoporous membranes with average pore diameters of 150 nm and thicknesses of 50 [mu]m, we achieved interfacial heat fluxes as high as 96 W/cm2 via evaporation with isopropyl alcohol. The effect of membrane thickness was studied to offer designs that promise dissipation of 1000 W/cm 2 . Meanwhile, we developed new metrology to measure transient heat transfer coefficients with a temporal resolution of 0.2 seconds during the evaporation process. Such a technique offers insight into the relationship between liquid morphology and heat transfer behavior. Finally, for enhanced condensation, we demonstrated immersion condensation using a composite surface fabricated by infusing hydrophobic oil into micro/nanostructures with a heterogeneous coating. With this approach, three key attributes to maximize heat transfer coefficient, low departure radii, low contact angle, and high nucleation density, were achieved simultaneously. We specifically elucidated the mechanism for the increase in nucleation density and attribute it to the combined effect of reduced water-oil interfacial energy and local high surface energy sites. As a result, we demonstrated approximately 100% enhancement in heat transfer coefficient over state-of-the-art superhydrophobic surfaces with the presence of non-condensable gases. This thesis presents improved fundamental understanding of wetting, evaporation, and condensation processes on micro/nanostructures as well as practical implementation of these structures for enhanced heat transfer. The insights gained demonstrate the potential of new nanostructure engineering approaches to improve the performance of various thermal management and energy production applications.
by Rong Xiao.
Ph.D.
Simonetti, Marco. "Study of convective heat transfer phenomena for turbulent pulsating flows in pipes." Thesis, Orléans, 2017. http://www.theses.fr/2017ORLE2057/document.
Повний текст джерелаWaste Energy Recovery represents a promising way to go further in fuel saving and greenhouse emissions control for Internal Combustion Engine applications. Although several technologies have been investigated in the past few years, the convective heat transfers, playing an important role in the energy exchanges at the engine exhaust, has not receive enough attention. Heat transfers, in such applications, occur in pulsating conditions because of the engine operating conditions, making thus the actual knowledge of the heat transfer phenomena limited and not exploitable. Nowadays there is not any model capable to predict convective heat transfers for pulsating flows. In this context, the present thesis addresses the purpose to study the convective heat transfer phenomena, by an experimental approach, occurring for turbulent pulsating flows in pipes. In the first part of this work, an experimental apparatus has been designed to reproduce an exhaust type pulsating flow in fully managed conditions, as well as, several measurement techniques have been developed to know the instantaneous profiles of air temperature and velocity. Many experiments have been performed in order to characterize the impact of the flow pulsation on the convective heat transfers. In the second part of this work, the experimental results have been analyzed with two different approaches: firstly, with a 1D assumption the time-average convective heat transfers has been computed, and the major mechanism responsible of the heat transfer enhancement has been pointed out. Furthermore, it has been possible to highlight the mathematical term representative of such mechanism, which should be accounted in future to define a more adapted numerical model for the heat transfer prediction. In a second phase with a 2D assumption, and, with an energy and a fluid-mechanic computational phase, the radial transport of thermal energy has been characterized for a pulsating flow
Kawai, Shunsuke. "Numerical Analysis on Free Convection and Mass Transfer Phenomena in Electrochemical System." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/88043.
Повний текст джерела0048
新制・課程博士
博士(工学)
甲第15006号
工博第3180号
新制||工||1478(附属図書館)
27456
UT51-2009-R730
京都大学大学院工学研究科機械理工学専攻
(主査)教授 木田 重雄, 教授 稲室 隆二, 教授 中部 主敬
学位規則第4条第1項該当
Mitchell, William James. "Transport phenomena in viscous flow and particle motion in fluidized beds /." Title page, table of contents and abstract only, 1988. http://web4.library.adelaide.edu.au/theses/09ENS/09ensm682.pdf.
Повний текст джерелаLi, Yichen. "Phase-field Modeling of Phase Change Phenomena." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99148.
Повний текст джерелаMaster of Science
Phase change phenomena, such as freezing and melting, are ubiquitous in our everyday life. Mathematically, this is a moving boundary problem where the phase front evolves based on the local temperature. The phase change is usually accompanied with the release or absorption of latent heat, which in turn affects the temperature. In this work, we develop a phase-field model, where the phase front is treated as a diffuse interface, to simulate the liquid-solid transition. This model is consistent with the second law of thermodynamics. Our finite-element simulations successfully capture the solidification and melting processes including the interesting phenomenon of recalescence.
Kapadia, Jaimin Maheshbhai. "DNA transfer in the soil bacterium Rhodococcus." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/honors/565.
Повний текст джерелаKanel, Jeffrey Scott. "Effects of some interfacial phenomena on mass transfer in agitated liquid-liquid dispersions." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/11257.
Повний текст джерелаFrayce, Denis. "Hydrodynamics, heat and mass transfer phenomena in reverberatory furnaces : mathematical modelling and experimentation." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74665.
Повний текст джерелаMumby, Richard. "The physical and chemical aspects of transfer phenomena in off-set lithographic printing." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396908.
Повний текст джерелаOrtiz, de Gortari A. B. "Exploring 'Game Transfer Phenomena' : a multimodal research approach for investigating video games' effects." Thesis, Nottingham Trent University, 2015. http://irep.ntu.ac.uk/id/eprint/27888/.
Повний текст джерелаDiette, Christophe. "Measurement and analysis of forced convection phenomena in blade cooling channels." Valenciennes, 2003. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/c76547a4-820c-48f8-9717-ced740f0cb38.
Повний текст джерелаEn matière de moteurs d'avion à turbine à gaz, une Température d'Entrée de Turbine (TET) aussi élevée que possible est souhaitée. Augmenter sa valeur permet en effet d'obtenir un rendement thermodynamique plus élevé tout en réduisant le rapport poids-poussée et la consommation spécifique (SFC). Parce que la TET maximum permise est liée aux limites de température supportées par les composants de la turbine, le choix des matériaux et la conception des circuits de refroidissement d'aubes sont cruciaux. Cette recherche rend compte d'une étude expérimentale et numérique sur les cavités internes de refroidissement d'aubes. Des sections de passage différentes sont examinées, en fonction de la région de l'aube à refroidir. Plusieurs paramètres en ce qui concerne les promoteurs de turbulence et les conditions de l'écoulement, sont variés pour définir une solution optimale en termes de transfert de chaleur et pertes de charges. Des simulations numériques sont réalisées pour appuyer l'analyse de l'écoulement. La comparaison de ces résultats avec les mesures aérodynamiques se révèle très satisfaisante. Enfin, des diagrammes sont proposés, pour décrire l'écoulement dans chaque cavité étudiée. De cette étude, il ressort une meilleure compréhension des phénomènes mis en jeu dans les cavités de refroidissement, ainsi qu'une base de données détaillée. Cette dernière est utile pour la validation de codes de calcul et l'optimisation des systèmes de refroidissement
Raymond, Alexander William. "Investigation of microparticle to system level phenomena in thermally activated adsorption heat pumps." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34682.
Повний текст джерелаHu, Weiwei. "Characterization of hydrodynamic forces and interfacial phenomena in cell culture processes." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1167409370.
Повний текст джерелаVasic, Aleksander Z. "High temperature properties and heat transfer phenomena for steam at temperatures up to 5000K." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/9641.
Повний текст джерелаRossi, Giacomo <1990>. "Highlighting Charge Transfer Phenomena in Photo-catalytic Compounds Using Optical and X-ray Techniques." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amsdottorato.unibo.it/8398/1/Tesi_Dottorato_Giacomo_Rossi_versione_depositata.pdf.
Повний текст джерелаSchonewille, Ronald Hiram. "Oxidation of copper-sulphur matte by submerged gas injection, mass transfer rates and physical phenomena." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ28054.pdf.
Повний текст джерелаZhou, Chunguang. "Gasification and Pyrolysis Characterization and Heat Transfer Phenomena During Thermal Conversion of Municipal Solid Waste." Doctoral thesis, KTH, Energi- och ugnsteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154587.
Повний текст джерелаQC20141028
Donato, Adam Armido. "Multiscale Modeling and Uncertainty Quantification of Multiphase Flow and Mass Transfer Processes." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/51246.
Повний текст джерелаPh. D.
Svenkeson, Adam. "How Cooperative Systems Respond to External Forces." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500014/.
Повний текст джерелаMichaïe, Sandra. "Experimental study of the fundamental phenomena involved in pool boiling at low pressure." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI040/document.
Повний текст джерелаBoiling is an efficient heat transfer mode used in numerous thermal or energy systems. In some systems boiling takes place at low pressure. The static head of the liquid column over the wall where bubbles nucleate is then not negligible against the saturation pressure at the free surface level. The pressure and the induced subcooling degree therefore cannot be considered as homogeneous around growing bubbles, resulting in non-homogeneous thermophysical properties in the fluid. The relative influence of the forces acting on a growing bubble differs from higher pressure conditions, yielding specific bubble dynamics features. Heat transfer is consequently also affected. The effect of the pressure on pool boiling was experimentally investigated during the isolated bubbles regime taking place from a single activated nucleation site. Experiments were first conducted with water for a wide range of subatmospheric pressures. Four distinct bubble dynamics behaviors were identified through high-speed camera visualizations. An adapted image processing of the recordings enabled the measurement of several bubble dynamics characteristics. In order to generalize the concept of pool boiling at "low pressure" and to get a better understanding of the related fundamental phenomena, new experiments were performed with a second fluid, cyclohexane, chosen from original thermodynamic similarity with water boiling at pressures lower than atmospheric. The comparison of fluids’ behaviors made possible the identification of parameters governing the specific phenomena occurring during boiling at low pressure. Besides, the experimental facility was improved to provide new functionalities. The high-speed measurement of the heat flux transferred under the growing bubble, its synchronization with the high-speed videos images and the study of boiling on enhanced surfaces are in particular made possible. Results are encouraging for a better understanding of the specific behaviors of low pressure boiling and for its future implementation in practical applications
Schulz, Sebastian [Verfasser]. "Flow and heat transfer phenomena in a complex impingement system for integrally cooled turbine blades / Sebastian Schulz." München : Verlag Dr. Hut, 2018. http://d-nb.info/1155056094/34.
Повний текст джерелаKaralis, Aristeidis 1978. "Novel photonic phenomena in nanostructured material systems with applications and mid-range efficient insensitive wireless energy-transfer." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44444.
Повний текст джерелаIncludes bibliographical references (p. 195-204).
A set of novel mechanisms for the manipulation of light in the nanoscale is provided. In the class of all-dielectric material systems, techniques for the suppression of radiative loss from incomplete-photonic-bandgap structures are developed: the cancellation of radiation channeled into discrete modes of the substrate, for resonant small-modal-volume cavities with patterned substrates, and the broadband mode-matching across the coupling interface, for large-bandwidth butt-coupled devices. Moreover, a hybrid plasmonic-dielectric material platform is introduced, able to localize light counter intuitively in low-index regions, by employing the unique subwavelength and cutoff properties of polaritonic waves, and to support dispersionless (to unusually-high orders) broadband-slow or stopped subwavelength light, by utilizing a simple planar multilayered dielectric structure. This platform can achieve a significant reduction in all (temporal, spatial and energy) light-scales and could enable compact and efficient optical buffers and active devices. A method for mid-range efficient and insensitive wireless energy-transfer is proposed. A condition of 'strong coupling' of resonances is identified as necessary and sufficient for efficient energy-exchange, and is shown to be satisfied at mid-range distances by carefully-designed high-Q subwavelength resonances of realistic systems both theoretically and experimentally, in the latter case by powering a 60W light-bulb wirelessly across a 2m-distance using two 60cm-diameter resonant objects and with 45% efficiency. A technique for further efficiency enhancement and radiation suppression is suggested, based on employing destructive interference between the coupled-objects' radiated far-fields. The scheme is also found fairly insensitive to the near-presence of extraneous objects, especially when utilizing the special class of magneto-quasi-static resonances.
(cont.) Applications of the proposed wireless-powering method can be found in both the macro- and micro-worlds, and range among industrial, technological, medical, consumer and more.
by Aristeidis Karalis.
Sc.D.
URBANI, DANIELE. "Overcoming light and mass transfer phenomena in gas-liquid biphasic reactions: introduction of the aerosol methodological paradigm." Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2496482.
Повний текст джерелаI fenomeni di trasferimento di massa sono un fattore limitante soprattutto nelle reazioni di chimica organica gas-liquido. Questo problema può essere superato sfruttando l'enorme aumento del rapporto superficie-volume quando si nebulizza una soluzione. Ogni goccia generata in questo modo reagirà come un singolo reattore. In questa tesi sono ampiamente studiate sia la foto-ossidazione selettiva di solfuri organici a solfossidi, sia l'utilizzo di CO2 per la sintesi di carbonati ciclici partendo dai corrispondenti epossidi. Una reazione modello è stata scelta per lo studio dell'ossidazione fotochimica di un solfuro solubile in acqua al corrispondente solfossido mediata dall’ ossigeno di singoletto: Per questa reazione sono stati costruiti diversi setup strumentali con l'obiettivo di migliorare la conversione finale e il recupero di massa del processo. Un reattore aerosol fotochimico è stato quindi progettato e costruito in collaborazione con l'Università di KULeuven, permettendo di raggiungere il 95% di conversione finale e la completa selettività verso il solfossido. Il fattore di accelerazione della cinetica di reazione è 144 rispetto alle condizioni di reazione classica. L'espansione metodologica della reazione modello verso solfuri organici non solubili in acqua è stata poi portata avanti in condizioni bulk ponendo le basi per ulteriori esperimenti in aerosol. In questo caso una miscela acqua:etanolo è stata scelta come solvente verde per questioni di sicurezza e sostenibilità ambientale. I cambiamenti climatici rappresentano una minaccia per la vita umana, e i loro effetti sull'ambiente e sullo sviluppo economico e sociale sono ampiamente studiati. Evidenze scientifiche inequivocabili collegano il cambiamento climatico alle emissioni di gas a effetto serra ed identificano la CO2 come uno di questi gas. Per questo motivo si è pensato di utilizzare la CO2 come gas reattivo nella sintesi dello stirene carbonato partendo dallo stirene ossido: Questa sintesi è stata identificata come la reazione modello per studi futuri. Senza alcuna esperienza precedente in questo campo è stato necessario effettuare un ampio studio della letteratura scientifica con l'obiettivo di identificare il miglior catalizzatore adatto ad un reattore aerosol. Il complesso KI/tetraetilen glicole è stato scelto come catalizzatore per il confronto tra la reazione bulk e quella aerosol per le sue caratteristiche, ideali per questa tipologia di sintesi. Lo studio cinetico a diverse temperature della reazione modello in condizioni di bulk e aerosol ha permesso di ottenere fattori di accelerazione fino a 1,85. Sfortunatamente non è stato possibile, durante il periodo di dottorato, lavorare con un reattore a flusso di aerosol per la reazione con la CO2 a causa della configurazione inadeguata dei reattori a disposizione e alla bassa reattività del gas. Per ovviare a questa mancanza è stato progettato e costruito un reattore aerosol modulare potenzialmente in grado, nel prossimo futuro, di sfruttare pienamente i vantaggi dell'aerosol: Nonostante la difficile raccolta dati, dettata del nuovo approccio scelto sulle tecnologie CCU, i risultati raggiunti sono stati sufficienti per ottenere un partenariato in un progetto NATO chiamato TANGO. Il gruppo di ricerca si concentrerà quindi sulla sintesi di nuovi catalizzatori supportati su nanoparticelle magnetiche che, si spera, possano convertire lo stirene ossido in stirene carbonato con un alta resa e tempi di reazione più rapidi. Tutti gli esperimenti necessari andranno a sfruttare il reattore modulare recentemente progettato e costruito a partire dall'esperienza maturata sulla reazione modello. La reazione modello riportata in questa tesi sarà anche il benchmark per le reazioni future.
CARDELLINI, ANNALISA. "Modelling of Multi-Scale Phenomena in Nanoparticle Suspensions." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2687171.
Повний текст джерелаPaquet, Emil Friedrich. "Establishing a facility to measure the efficiency of structured packing under total reflux." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6834.
Повний текст джерелаENGLISH ABSTRACT: Structured packing is often the preferred choice for column internals because of its low pressure drop and high efficiencies compared to that of trays and random packing. However, the mass transfer phenomena in these gas-liquid contacting devices is still not well understood, even though it is widely used in industry. A contributing factor to this is the lack of understanding and availability of experimental data in the open literature. These shortcomings complicate the design of a distillation column and make practical experience essential. There is thus a need for more experimental data, especially for packings where only limited information is available. The focus of this study was to establish a testing facility that can be used to measure the efficiency of structured packing under total reflux, and not to measure vast quantities of experimental data; the latter will be done in future. The facilities available at Stellenbosch University limited the internal diameter of the column to 0.2 m, which is sufficient to test higher surface area structured packings (≥350 m2/m3). The column is used with a thermosyphon reboiler that uses steam as the heating source and is equipped with a total condenser. Two sections are used for the packed bed that allow for a total packed height of 3.78 m (2x1.89 m). The column is set up to operate under total reflux and was designed to operate at pressures ranging from 0.3 to 1 bar abs, vapour flow rates of 0.73 – 3.65 (m/s) (kg/m3)0.5 and liquid flow rates of 5 – 25 m3/(m2.h). It was found that the 2-butanol/iso-butanol and the p-xylene/o-xylene systems are suitable test mixtures for this pilot plant setup. The VLE data from Kutsarov et al. (1993) and Zong et al. (1983) for p-xylene/o-xylene and 2-butanol/iso-butanol are thermodynamic consistent and was validated by VLE experiments done in this study. It was found that the experimentally obtained efficiency (HETP) and pressure drop data for Mellapak 350Y compared well with published results of Spiegel and Meier (1987). With regard to the predictive models, it was found that i) the SRP model predicted the HETP of Mellapak 350Y structured packing accurately in the pre-loading region and slightly over predicted the HETP in the loading region, whereas ii) the Delft model over predicted HETP and iii) the Billet and Schultes model under-predicted HETP under the entire tested range (i.e. over-predict efficiency). With regard to the pressure drop data i) the Billet model iv accurately predicted the pressure drop over the entire tested range, whereas ii) the SRP model accurately predicted the pressure drop in the pre-loading region and slightly over predicted the pressure drop in the loading region and iii) the Delft model over predicted the pressure drop over the entire range and followed an almost parallel trend to the results from the SRP model. It was also found that information in the field of mass transfer in a packed column is far from saturated, and there is a need for more experimental data and better understanding of the mass transfer phenomena in packed columns.
AFRIKAANSE OPSOMMING: Gestruktureerde pakking het ʼn laer drukval en ʼn hoër effektiwiteit in vergelyking met willekeurige pakkings en plate, en is daarom dikwels die voorkeur keuse vir pakkings materiaal in ʼn distilleer kolom. Die massa-oordrags verskynsels in hierdie gas-vloeistof kontaktors word egter nog nie goed verstaan nie, ten spyte van die grootskaalse aanwending in die nywerheid. ʼn Bydraende faktor is die tekort aan eksperimentele data in die ope literatuur. Die tekortkomings bemoeilik die ontwerp van distilleerkolomme en maak praktiese ervaring ʼn noodsaaklike vereiste. Daar is dus ʼn behoefte aan meer eksperimentele data veral vir pakkings waar daar min of geen data beskikbaar is nie. Die fokus van die studie was om ʼn toetsfasiliteit op te rig wat gebruik kan word om die effektiwiteit van gestruktureerde pakking onder totale terugvloei kondisies te bepaal, en dus nie om ‘n groot hoeveelheid data te genereer nie; laasgenoemde sal wel deel uitmaak van toekomstige studies. Die fasiliteite beskikbaar by die Universiteit van Stellenbosch het die binne diameter van die kolom beperk tot 0.2 m. Die diameter is voldoende om gestruktureerde pakkings met ʼn hoë oppervlakarea te toets byvoorbeeld pakkings met areas 350 m2/m3 en hoër. Die kolom gebruik ‘n verdamper (met stoom as energie bron) om die vloeistof te verdamp en ‘n totale kondensator (verkoel met verkoelingswater) om die damp te laat kondenseer. Twee seksies van 1.89 m elk word gebruik vir die gepakte bed en die kolom het dus ‘n totale pakkingshoogte van 3.78 m. Die kolom is opgestel vir totale terugvloei en is ontwerp om bedryf te word by drukke tussen 0.3 en 1 bar abs, damp snelhede van 0.73 tot 3.65 (m/s) (kg/m3)0.5 en vloeistof vloeitempo’s tussen 5 en 25 m3/(m2.h). 2-butanol/iso-butanol en p-xylene/o-xylene is gevind om geskik te wees as mengsels vir die toetsopstelling. Die damp-vloeistof fase-ewewig data van Kutsarov et al. (1993) en Zong et al. (1983) vir p-xylene/o-xylene and 2-butanol/iso-butanol is termodinamies konsistent en is gevalideer deur damp-vloeistof fase ewewig toetse in die studie. Daar is gevind dat die eksperimenteel bepaalde effektiwiteit en drukval data vir Mellapak 350Y pakking goed vergelyk met gepubliseerde data van Spiegel and Meier (1987). Die eksperimenteel bepaalde effektiwiteit data is met waardes van beskikbare modelle model vergelyk en daar is gevind dat: i) die SRP voorspel die effektiwiteit van Mellapak 350Y pakking akkuraat in die ‘pre-loading’ gebied maar toon afwykings van die eksperimentele data in die ‘loading’ gebied, ii) die Delft model voorspel ‘n hoër hoogte ekwivalent aan ‘n teoreties plaat (HETP) oor die hele gebied terwyl iii) die Billet en Schultes model weer ‘n laer HETP voorspel oor die hele gebied. Met betrekking toe die drukval data i) voorspel die Billet model die drukval akkuraat oor die hele gebied, ii) die SRP model voorspel die drukval korrek in die ‘pre-loading’ gebied maar begin afwyk van die eksperimentele data in die ‘loading’ gebied en iii) die Delft model voorspel groter waardes vir drukval oor die hele gebied en volg amper ʼn parallelle tendens met die SRP model. In die studie is daar gevind dat daarin die gebied van massa-oordrag nog ʼn tekort is aan eksperimentele data en daar baie navorsings geleenthede is.
Wang, Xiaohua. "Characterization of Mesoscopic Fluid-like Films with the Novel Shear-force/Acoustic Microscopy." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/736.
Повний текст джерелаShi, Lei. "Application of Laser-Based Instrumentation to Study Fluid Flow and Heat Transfer Phenomena in Standing-Wave Thermoacoustic Devices." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521787.
Повний текст джерелаGuardo, Zabaleta Alfredo. "Computational Fluid Dynamics Studies in Heat and Mass Transfer Phenomena in Packed Bed Extraction and Reaction Equipment: Special Attention to Supercritical Fluids Technology." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6455.
Повний текст джерелаLa Dinámica de Fluidos Computacional (CFD) como herramienta de modelado numérico permite obtener una visión mas aproximada y realista de los fenómenos de flujo de fluidos y los mecanismos de transferencia de calor y masa en lechos empacados, a través de la resolución de las ecuaciones de Navier - Stokes acopladas con los balances de materia y energía y con un modelo de turbulencia si es necesario. De esta forma, esta herramienta permite obtener los valores medios y/o fluctuantes de variables como la velocidad del fluido, la temperatura o la concentración de una especie en cualquier punto de la geometría del lecho empacado.
El objetivo de este proyecto es el de utilizar programas comerciales de simulación CFD para resolver el flujo de fluidos y la transferencia de calor y de masa en modelos bi/tri dimensionales de lechos empacados, desarrollando una estrategia de modelado aplicable al diseño de equipos para procesos de extracción o de reacción catalítica. Como referencia se tomaran procesos de tecnología supercrítica debido a la complejidad de los fenómenos de transporte involucrados en estas condiciones, así como a la disponibilidad de datos experimentales obtenidos previamente en nuestro grupo de investigación. Estos datos experimentales se utilizan como herramienta de validación de los modelos numéricos generados, y de las estrategias de simulación adoptadas y realizadas durante el desarrollo de este proyecto.
An understanding of the heat and mass transfer phenomena in a porous media implies the study of the fluid transport model within the void space; this fact is of fundamental importance to many chemical engineering systems such as packed bed extraction or catalytic reaction equipment. Experimental and theoretical studies of flow through such systems often treat the porous medium as an effectively homogeneous system and concentrate on the bulk properties of the flow. Such an approach neglects completely the complexities of the flow within the void space of the porous medium, reducing the description of the problem to macroscopic average or effective quantities. The details of this local flow process may, however, be the most important factor influencing the behavior of a given physical process occurring within the system, and are crucial to understanding the detailed mechanisms of, for example, heat and mass dispersion and interface transport.
Computational Fluid Dynamics as a simulation tool allows obtaining a more approached view of the fluid flow and heat and mass transfer mechanisms in fixed bed equipment, through the resolution of 3D Reynolds averaged transport equations, together with a turbulence model when needed. In this way, this tool permit to obtain mean and fluctuating flow and temperature values in any point of the bed.
The goal of this project is to use commercial available CFD codes for solving fluid flow and heat and mass transfer phenomena in two and three dimensional models of packed beds, developing a modeling strategy applicable to the design of packed bed chemical reaction and extraction equipment. Supercritical extraction and supercritical catalytic reaction processes will be taken as reference processes due to the complexity of the transport phenomena involved within this processes, and to the availability of experimental data in this field, obtained in the supercritical fluids research group of this university. The experimental data priory obtained by our research group will be used as validation data for the numerical models and strategies dopted and followed during the developing of the project.
Rolon, Soto Juan Enrique. "Coherent Exciton Phenomena in Quantum Dot Molecules." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1314742055.
Повний текст джерела