Teses / dissertações sobre o tema "Vapour expansion"
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Poullain, Thomas. "Etude numérique et expérimentale de l’évaporation sous vide d’alliages métalliques : application à la refusion VAR de Zircaloy-4". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0189.
Texto completo da fonteComposition and chemical segregation control is primordial when producing high value-added materials, such as zirconium alloys for nuclear industry. Vacuum processing allows production very high purity ingot, however it also presents an additional problematic concerning control and prediction of alloy elements evaporation. This PhD dissertation aims at improving prediction of volatile metallic species evaporation during vacuum elaboration, especially during Zircaloy 4 VAR (Vacuum Arc Remelting).First, the evaporation kinetics and the expansion of the metal vapour produced during vacuum melting is investigated. The study is done with a combination of volatilisation experiments using an experimental electron beam furnace and particle based numerical simulation (FPM) of vapour behaviour. Our volatilisation studies on pure metals, Ti and Zr, show the importance of collisions above the liquid on the vapour expansion and its recondensation. Determination of Fe and Sn vapour expansion during Zy4 vacuum melting combined with particle simulation, allowed us to determine thermodynamic activity coefficients values for these elements in liquid Zy4.Then, metallic vapour expansion under VAR conditions is studied, with particular interest shown to condensation flows on the different surfaces. Application of our numerical model to Zy4 shows that the vapour deposited on the mould has a very different composition compared to the alloy. Finally, the particle model is coupled to an ingot growth model and we study the influence of evaporation, condensation and crown reincorporation with regard to volatile solute segregation and depletion. This coupling also provides a first prediction of crown thickness and composition and we compare them to industrial crown samples
Semeraro, Emanuele. "Experimental investigation on hydrodynamic phenomena associated with a sudden gas expansion in a narrow channel". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066516/document.
Texto completo da fonteThe sharp vaporization of superheated liquid sodium is investigated. It is suspected to be at the origin of the automatic shutdown for negative reactivity, occurred in the Phénix reactor at the end of the eighties.An experimental apparatus has been designed and operated to reproduce the expansion of overpressurized air, superposed to water in a narrow vertical rectangular section channel.When expansion begins, the initial flat interface separating the two fluids becomes corrugated under the development of two-dimensional Rayleigh-Taylor instabilities. The interface area increases significantly and becomes even 50 times larger than the initial value. Since the channel is very narrow, instabilities along the channel depth do not develop.The gas expansion in a narrow channel can be divided into two main phases: Rayleigh-Taylor (linear and non-linear) and multi-structures (transition and chaotic) phases. The former is characterized by the dynamic of corrugated profile and the interface area results proportional to the amplitude of corrugation The latter is influenced by the behavior of the liquid structures dispersed in gas matrix and the interface area is mainly proportional to the number of liquid structures.The distribution of volume fraction suggests a model of channel flow consisting of three regions: the regular profile of peaks, the spike region and the structures tails. The analysis of sensibility to surface tension confirms that, with a lower surface tension, the fluids configuration is more unstable. The interface corrugations are more pronounced and more structures are produced, leading to a higher increment of the interface area
Hwang, Moonkyu. "Numerical modeling of the expansion phase of vapor explosions". Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/16761.
Texto completo da fonteSouza, Rafaela Faciola Coelho de. "Estudo da influência da sucção na pressão de expansão de materiais argilosos com a técnica da transferência de vapor". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-19102015-105616/.
Texto completo da fonteThis thesis presents the quantification and characterization of expansion, especially the influence of suction on samples of sedimentary materials from Corumbatai Formation that occurs in Sao Paulo. Undisturbed and compacted samples with different moisture contents were tested with swelling pressure tests at constant volume method by flooding, and also with suction control by vapour transfer technique. Compacted mixtures of this material with bentonite in differents proportions, and mixtures of bentonite with sandy non-expansive material from the Botucatu Formation were also tested. The suction control was performed by the use of NaCl salt solutions at concentrations prepared to perform 40,000, 25,000, 10,000 and 5,000 kPa suctions. For the tests, it was developed a system for load application and automatic retrieval of pressure. To accelerate the wetting process by vapour, we used an external reservoir connected to an air pump adapted to promote air circulation inside the edometric cell, specially made for this study. The expansion results in flooding tests showed increasing swelling pressure with decreasing moisture content. Consequently there was an increase in the initial suction of the tested samples, which kept increasing as the rate of bentonite was raised in the mixtures, with a peak of ca. 700 kPa for the test with dry pure bentonite compacted. In the microstructure analysis of the samples by mercury intrusion porosimetry, the samples showed variation only in macropores after swell; and the ones compacted at optimum moisture, and subsequently air dried, showed no significant change after the swell. In scanning electron microscopy (SEM) it was possible to verify the change in the voids of the samples, as well as to visualize the variation in the structure and texture. In addition, the SEM confirmed clay minerals deterninated in mineralogical characterization. The results of controlled suction with swell tests showed absence of swell pressure for Corumbatai samples tested in undisturbed conditions, and compacted condition at optimum moisture content, and then air dried. However, when compacted in the form of dry powder, as well as when compacted dry, mixed with different proportions of bentonite, this material showed swelling pressures with vapor transfer technique, as well as mixtures of bentonite with non-expansive material of Botucatu Formation. The absence of swell was explained by the slow damping provided by the vapor transfer that although promoting increasing dampen, did not sufficiently mobilized volume variation capable of transmitting blowing pressure. Therefore, the swell tests with the vapor transfer technique were effective to evaluate the swelling just in cases where clay minerals with swell potential were present in significant proportions.
Akraiam, Atea I. Bubaker. "Metal cluster production by condensation of metal vapour in supersonic expansions and by aggregation in droplets". Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/31834.
Texto completo da fonteSuardin, Jaffee Arizon. "The application of expansion foam on liquefied natural gas (LNG) to suppress LNG vapor and LNG pool fire thermal radiation". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2906.
Texto completo da fonteSILVEIRA, HELVECIO C. K. da. "Analise de integridade estrutural de tubos de geradores de vapor deteriorados por corrosao sob tensao pelo primario na regiao de transicao de expansao junto ao espelho". reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11035.
Texto completo da fonteMade available in DSpace on 2014-10-09T14:08:43Z (GMT). No. of bitstreams: 1 07971.pdf: 6425112 bytes, checksum: 2adaba2434371c9ca93a67fa4d783fb9 (MD5)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
Patiño, Pérez Jorge. "Experimentación de nuevas configuraciones destinadas a la mejora del COP en ciclos de compresión de vapor que utilizan CO2 como refrigerante". Doctoral thesis, Universitat Jaume I, 2013. http://hdl.handle.net/10803/125529.
Texto completo da fonteCon el fin de contribuir y fomentar el uso del fluido natural CO2 como refrigerante, se ha elaborado la presente tesis doctoral que está centrada en estudios teóricos y posterior análisis experimental del funcionamiento de una planta frigorífica de compresión de vapor que emplea CO2 como refrigerante en condiciones supercríticas. Esta nueva iniciativa permite minimizar al máximo el impacto medioambiental generado por las emisiones de refrigerantes artificiales, aunque requiere de una tecnología completamente nueva debido a las propiedades físicas del propio refrigerante. El objeto de este análisis se centra en continuar buscando aquellas configuraciones que logren mejorar el rendimiento energético de las instalaciones que empleen R744 como refrigerante.
En la presente tesis doctoral se ha efectuado un estudio experimental de una configuración con un sistema de expansión en una única etapa, donde se ha analizado la influencia del aceite en la masa de refrigerante a cargar en la instalación y en el comportamiento de la misma. Este funcionamiento se compara con el comportamiento que adopta un ciclo que cuenta con un sistema de doble etapa de expansión y depósito intermedio entre ambas etapas, que le proporciona la masa que necesita en todo momento. Además, se estudia el comportamiento de la instalación al insertar en ambas configuraciones un IHX. Por otro lado, en este trabajo también se ha llevado a cabo un análisis experimental de la instalación operando en régimen supercrítico frente al modo de operación en régimen subcrítico cuando las condiciones externas lo permiten. De esta forma, se evalúa la posibilidad de operar con ambos sistemas a partir de una instalación dimensionada para operar en régimen supercrítico. El último análisis experimental realizado se basa en la búsqueda de nuevas configuraciones para mejorar el rendimiento energético del equipo, donde se estudia la extracción de vapor en el depósito de acumulación y la posterior inyección ó recompresión en diferentes puntos de la instalación.
Estos análisis experimentales se han complementado con estudios de carácter teórico. El primer estudio teórico se ha basado en el modelado de la instalación frigorífica para analizar la energía calorífica generada en el foco caliente y destinada a activar otras aplicaciones. El segundo estudio ha consistido en el modelado matemático de dos tipos diferentes de intercambiadores de calor, uno de tubo concéntrico y flujo paralelo y otro de flujo cruzado con tubos aleteados externamente.
Gana, Inès. "Caractérisation physique et chimique des substances à activité thérapeutique : application aux études de profil de stabilité et de préformulation". Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB164/document.
Texto completo da fonteThe development of a drug for a given therapeutic target requires several steps, which can be summarized by drug screening, a preclinical phase and a number of clinical phases. These steps allow the selection of an active substance and a verification of its therapeutic efficacy and toxicological safety. The latter two criteria define the quality of the drug, which once demonstrated, must be guaranteed throughout its shelf life. Quality is assessed through stability studies that are carried out with the raw material of the active substance (preformulation phase) and with the final product. The intrinsic stability of the active substance depends on its chemical and physical properties and their characterization is the core of the stability studies, which in addition consists of sensitivity studies of the active pharmaceutical ingredient (API) for environmental factors that can modify the intrinsic properties of the substance. The approach presented in this work is based on the one hand on the assessment of the chemical stability, i.e. the reactivity of APIs through chemical purity studies and forced degradation in solution, and on the other hand on the assessment of the physical stability. For the latter, crystalline polymorphism is of great importance, as is the ability of the API to form hydrates or solvates. The study of crystalline polymorphism is based on the construction of pressure-temperature phase diagrams in accordance with thermodynamic requirements leading to the stability condition domains of the different crystalline forms. The stability behavior of five APIs used or meant for oral applications has been studied as part of this work. The chemical analysis of tienoxolol, an antihypertensive drug, has demonstrated its sensitivity for hydrolysis and oxidation. Seven degradation products were identified and patterns of fragmentation have been established. Pressure-temperature phase diagrams have been constructed for bicalutamide and finasteride, drugs against prostate cancer, using a topological approach based on data available in the literature. The study demonstrates that the thermodynamic relationship (enantiotropy or monotropy) between crystalline forms under ordinary conditions can change depending on the pressure. This is important for drug development as it demonstrates how stability information can be obtained by standard laboratory measurements accessible to industrial research laboratories without the necessity to carry out experiments under pressure. The topological approach for the construction of phase diagrams has subsequently been validated by measuring transition temperatures as a function of pressure. Experiments have been carried out with benzocaine, a local anesthetic, and with cysteamine hydrochloride, a drug used against cystinosis. Two crystalline forms were observed in the case of benzocaine. They exhibit an enantiotropic relationship that becomes monotropic at high pressure. For cysteamine hydrochloride, a new crystalline form (form III) was discovered. The thermodynamic relationship between the new form III and the known form I is enantiotropic for the entire temperature and pressure range. Cysteamine hydrochloride’s sensitivity to water has been studied, as it is hygroscopic. It has been demonstrated that it becomes deliquescent in the presence of water and no trace of a hydrate has been found. Finally, a study combining thermal and chromatographic methods showed that, under the effect of temperature, cysteamine hydrochloride turns into cystamine in the solid as well as in the liquid state, The latter is known to be an important impurity of cysteamine hydrochloride. In conclusion, the approach developed in this work allowed to characterize the stability properties of a number of APIs and to determine the factors that may change these properties and influence the intrinsic stability (...)
Glos, Jan. "Modelování a řízení toků elektrické a tepelné energie v plně elektrických automobilech". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-433039.
Texto completo da fonteHANG, THONG. "AN IMPROVED HARD SPHERE EXPANSION CONFORMAL SOLUTION THEORY TO PREDICT VAPOR LIQUID EQUILIBRIA". Thesis, 1986. http://hdl.handle.net/1911/15977.
Texto completo da fonteYun, Geun Woong. "Control of Vapor Dispersion and Pool Fire of Liquefied Natural Gas (LNG) with Expansion Foam". Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8279.
Texto completo da fonteKWON, YONG JUNG. "CONFORMAL SOLUTION METHOD WITH THE HARD CONVEX BODY EXPANSION THEORY FOR PREDICTING VAPOR-LIQUID EQUILIBRIA". Thesis, 1986. http://hdl.handle.net/1911/16079.
Texto completo da fonteGALOPPI, GIOVANNI. "DEVELOPMENT OF A RADIAL PISTON EXPANDER FOR VAPOR COMPRESSION CYCLES". Doctoral thesis, 2017. http://hdl.handle.net/2158/1082547.
Texto completo da fonteCHEN, YING-CHUAN, e 陳穎釧. "Prediction of vapor-liquid equilibria of non-polar fluids by applying a modified hard convex body expansion method". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/40853516121158990673.
Texto completo da fonteO'Donnell, Kane. "Field ionization detection for atom microscopy". Thesis, 2010. http://hdl.handle.net/1959.13/802939.
Texto completo da fonteHelium has the highest ionization energy of any species and is as a consequence difficult to detect by conventional means. On the other hand, it is the ideal surface probe, having no net charge or spin, a low mass and a short de Broglie wavelength. Therefore, there exists a strong incentive to develop a microscopy technique based on helium atom scattering. The purpose of this thesis is to investigate in detail how an efficient helium detector might be developed using the phenomenon of field ionization, an ionization method that relies on quantum mechanical tunneling rather than the more conventional electron impact ionization techniques. In particular, the work focusses on the potential use of a novel nanomaterial, carbon nanotubes, as the source of the high electric fields required for field ionization detection. In Chapter 1 we review the history of field ionization research and the properties and synthesis methods for carbon nanotubes. Chapter 2 describes the experimental apparatus and procedures used for the present research, and Chapter 3 introduces the theoretical framework and background for field ionization. In Chapter 4, the prototypical field ionization system is considered from a detector viewpoint. The work demonstrates that existing theory is not sufficiently quantitative for describing a field ionization detector and therefore a semi-empirical theory is advanced for that purpose. Chapter 5 considers the problem of nanotube field enhancement in detail using computational methods, leading to a complete description of the maximum field enhancement of a nanotube array based on the four fundamental array parameters. Efforts to synthesize carbon nanotubes in the Newcastle plasma-enhanced chemical vapor deposition system are described in Chapter 6. Several procedures are developed for reproducible growth of nanotube films and the chemical vapor deposition system is characterized with single parameter studies. Chapter 7 presents the results of electron field emission and helium field ionization experiments carried out using the grown nanotube films. We demonstrate for the first time the field ionization of helium using a planar film of carbon nanotubes. Finally, we conclude the investigation of field ionization detection in Chapter 8 with a discussion on how such a detection method integrates into a helium microscope and in particular we detail the design and initial calculations for the planned Newcastle helium microscope.
O'Donnell, Kane. "Field ionization detection for neutral atom microscopy". 2010. http://hdl.handle.net/1959.13/802939.
Texto completo da fonteHelium has the highest ionization energy of any species and is as a consequence difficult to detect by conventional means. On the other hand, it is the ideal surface probe, having no net charge or spin, a low mass and a short de Broglie wavelength. Therefore, there exists a strong incentive to develop a microscopy technique based on helium atom scattering. The purpose of this thesis is to investigate in detail how an efficient helium detector might be developed using the phenomenon of field ionization, an ionization method that relies on quantum mechanical tunneling rather than the more conventional electron impact ionization techniques. In particular, the work focusses on the potential use of a novel nanomaterial, carbon nanotubes, as the source of the high electric fields required for field ionization detection. In Chapter 1 we review the history of field ionization research and the properties and synthesis methods for carbon nanotubes. Chapter 2 describes the experimental apparatus and procedures used for the present research, and Chapter 3 introduces the theoretical framework and background for field ionization. In Chapter 4, the prototypical field ionization system is considered from a detector viewpoint. The work demonstrates that existing theory is not sufficiently quantitative for describing a field ionization detector and therefore a semi-empirical theory is advanced for that purpose. Chapter 5 considers the problem of nanotube field enhancement in detail using computational methods, leading to a complete description of the maximum field enhancement of a nanotube array based on the four fundamental array parameters. Efforts to synthesize carbon nanotubes in the Newcastle plasma-enhanced chemical vapor deposition system are described in Chapter 6. Several procedures are developed for reproducible growth of nanotube films and the chemical vapor deposition system is characterized with single parameter studies. Chapter 7 presents the results of electron field emission and helium field ionization experiments carried out using the grown nanotube films. We demonstrate for the first time the field ionization of helium using a planar film of carbon nanotubes. Finally, we conclude the investigation of field ionization detection in Chapter 8 with a discussion on how such a detection method integrates into a helium microscope and in particular we detail the design and initial calculations for the planned Newcastle helium microscope.