An experimental investigation was made to determine the role of gravitational and surface tension forces in the migration of liquid water through fiberglass insulation materials. Straightforward experimental procedures were devised to effectively isolate and quantify flow parameters considered important in describing the flow mechanisms involved. The study was conducted to supplement an earlier investigation into the thermal performance of wetted insulation materials. Darcy's Law was found to apply for the regime of flow encountered in which liquid water flows under the force of its own weight in horizontal rooftop insulation. Experimental determination of the constant of proportionality in Darcy's Law, the hydraulic conductivity, is all that is needed to describe the migration of liquid water in saturated fiberglass insulation. Capillary forces, originally thought to play a significant role in the movement of liquid water through fiberglass insulation, were found to be negligible. Capillary rise up a column of insulation measured no higher than 13 mm. / M.S.

Thesis (M.S.)--University of Alabama at Birmingham, 2009. / Title from PDF t.p. (viewed July 21, 2010). Includes bibliographical references (p. 70-72).

Made available in DSpace on 2014-06-11T19:29:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-12-18Bitstream added on 2014-06-13T18:39:08Z : No. of bitstreams: 1 moretti_jp_me_bauru.pdf: 623430 bytes, checksum: 8a8b037467da86497bd4f13030b6c3d1 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os defletores de calor automotivos são constituídos de uma carcaça de aço aluminizado que envolve um isolante térmico, fisicamente bastante semelhante ao papel, entrentanto com uma composição elevada de partes inorgânicas, chegando a cerca de 80% do material seco. Esses materiais são utilizados para a proteção de vários componentes fundamentais nos veículos presentes em locais de temperaturas extremamentes elevadas, tais como o bloco do motor e o sistema de exaustão de gases. Essa proteção garantes a integridade de peças vitais sensíveis ao calor, como por exemplo, os circuitos eletro-eletrônicos. Neste trabalho, recortes do elemento defletor de calor foram reciclados em sistema manual e em escala industrial e propriedades como espessura, densidade, compreensibilidade, retorno, teor de cinzas, efetividade da deflexão de calor, além da análise por termogravimetria e microscopia eletrônica de varredura com acoplamento de sistema de energia dispersiva (EDS) foram realizados. Os produtos reciclados demonstraram resultados positivos quanto aos ensaios de deflexão de calor, teor de cinzas, ensaio termogravimétrica e visualmente dos espectros de energia dispersiva, indicando a manutenção da composição geral do material após os processos de reciclagem realizados. Os resultados dos ensaios físicos, como espessura, densidade, resistência à tração após quatro horas a sem graus Celsius, resistência à tração após 22 horas a 200 graus Celsius, compreessibilidade e retorno, compressibilidade e retorno após 22 horas a 200 graus Celsius, apontaram variações de acordo com a prensagem exercida no material, indicando a necessidade de melhorias nos processos de reciclagem utilizados / The automotive heat shields are made of an aluminized steel housing that surrounds a thermal insulator, physically quite similar to paper, though with a composition of inorganic parts high, reaching about 80% of dry material. These materials are used to protect several key components in vehicles sites present in extremely high temperatures, such as the engine block and the exhaust gas system. This protetion ensures the integrity of vital parts sensitive to heat, such as electric and electronic circuits. In this paper, clippings element baffe heat were recycled in manual in industrial scale and properties such as thickness, density, compressibility, recovery, ignition loss, effectiveness of heat deflection, and thermogravimetric analysis and scanning electron microscopy with coupling energy dispersive system (EDS) were performed. The recycled product showed positive results regarding heat deflection tests, ash content, thermogravimetric test and visually energy dispersive spectra, indicating maintaining the overall composition of the material after recycling processes performed. The results of the physical tests such as thickness, density, tensile strengh after four hours at one hundred degrees Celsius tensile strength after twenty-two hours to two hundred degrees Celsius, and recovery, compressibility, compressibility and recovery after twenty-two hours to two hundred degrees Celsius, showed variations according to the press exerted on the material, pointing to the need for improvements in recycling processes used

Orientador: Sandro Donnini Mancini / Banca: Jane Maria Faulstich de Paiva / Banca: Maria Lucia Pereira Antunes / Resumo: Os defletores de calor automotivos são constituídos de uma carcaça de aço aluminizado que envolve um isolante térmico, fisicamente bastante semelhante ao papel, entrentanto com uma composição elevada de partes inorgânicas, chegando a cerca de 80% do material seco. Esses materiais são utilizados para a proteção de vários componentes fundamentais nos veículos presentes em locais de temperaturas extremamentes elevadas, tais como o bloco do motor e o sistema de exaustão de gases. Essa proteção garantes a integridade de peças vitais sensíveis ao calor, como por exemplo, os circuitos eletro-eletrônicos. Neste trabalho, recortes do elemento defletor de calor foram reciclados em sistema manual e em escala industrial e propriedades como espessura, densidade, compreensibilidade, retorno, teor de cinzas, efetividade da deflexão de calor, além da análise por termogravimetria e microscopia eletrônica de varredura com acoplamento de sistema de energia dispersiva (EDS) foram realizados. Os produtos reciclados demonstraram resultados positivos quanto aos ensaios de deflexão de calor, teor de cinzas, ensaio termogravimétrica e visualmente dos espectros de energia dispersiva, indicando a manutenção da composição geral do material após os processos de reciclagem realizados. Os resultados dos ensaios físicos, como espessura, densidade, resistência à tração após quatro horas a sem graus Celsius, resistência à tração após 22 horas a 200 graus Celsius, compreessibilidade e retorno, compressibilidade e retorno após 22 horas a 200 graus Celsius, apontaram variações de acordo com a prensagem exercida no material, indicando a necessidade de melhorias nos processos de reciclagem utilizados / Abstract: The automotive heat shields are made of an aluminized steel housing that surrounds a thermal insulator, physically quite similar to paper, though with a composition of inorganic parts high, reaching about 80% of dry material. These materials are used to protect several key components in vehicles sites present in extremely high temperatures, such as the engine block and the exhaust gas system. This protetion ensures the integrity of vital parts sensitive to heat, such as electric and electronic circuits. In this paper, clippings element baffe heat were recycled in manual in industrial scale and properties such as thickness, density, compressibility, recovery, ignition loss, effectiveness of heat deflection, and thermogravimetric analysis and scanning electron microscopy with coupling energy dispersive system (EDS) were performed. The recycled product showed positive results regarding heat deflection tests, ash content, thermogravimetric test and visually energy dispersive spectra, indicating maintaining the overall composition of the material after recycling processes performed. The results of the physical tests such as thickness, density, tensile strengh after four hours at one hundred degrees Celsius tensile strength after twenty-two hours to two hundred degrees Celsius, and recovery, compressibility, compressibility and recovery after twenty-two hours to two hundred degrees Celsius, showed variations according to the press exerted on the material, pointing to the need for improvements in recycling processes used / Mestre

CAPES / Com o avanço da miniaturização de componentes e dispositivos eletrônicos ocorrida nos últimos anos, a utilização de materiais dielétricos e a necessidade de informações precisas sobre o comportamento dielétrico apresentado por estes materiais aumentou consideravelmente. Neste trabalho é apresentado inicialmente as motivações para o estudo do comportamento dielétrico e da modelagem da função resposta dielétrica. A partir da teoria proposta por Debye e identificando suas peculiaridades, são exploradas algumas extensões deste modelo e analisada a interpretação da função resposta proposta por estes. Muitos modelos assumiam a existência de múltiplas interações envolvendo os dipolos com o meio dielétrico, as quais contribuíam para a dinâmica do comportamento dielétrico, somente mais tarde é que estas múltiplas interações ganharam uma conexão entre a resposta dielétrica observada com as propriedades intrínsecas do material. Por meio do modelo proposto por Dissado e Hill e assumindo dados experimentais disponíveis na literatura para alguns materiais, foi testada a validade da função resposta resultante do modelo, na qual veri cou-se a capacidade da mesma em ajustar as curvas para as componentes real e imaginária da permissividade para uma grande variedade de materiais dielétricos. A partir das simulações e análises realizadas, ficou evidente a dependência do comportamento dielétrico com a temperatura, fato este que deverá ser abordado em trabalhos futuros. / With the improvement of miniaturization of electronic components and devices occurred in recent years, the use of dielectric materials and the need for accurate information about the dielectric behavior displayed by these materials has increased considerably. In this work is initially presented the motivations for the study of dielectric behavior and the modeling of the dielectric response function. From the theory proposed by Debye and identifying its peculiarities, are exploited some extensions of this model and analyzed the interpretation of response function proposed by these. Many models used to assume the existence of multiple interactions involving the dipoles with the dielectric medium, which contributed to the dynamics of the dielectric behavior, only later the multiple interactions won a connection between the dielectric response observed with the intrinsic properties of the materials. Through the model proposed by Dissado and Hill and assuming experimental data available in bibliography for some materials, was tested the validity of the response function resulting from the model, in which was veri ed the ability of the same to adjust the curves for the real and imaginary components of permittivity to a wide variety of dielectric materials. From the simulations and analyzes performed, was evident the dependence of dielectric behavior with temperature, a fact that should be discussed in future works.

Orientador: Kamal Abdel Radi Ismail / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-21T13:16:24Z (GMT). No. of bitstreams: 1 HenriquezGuerrero_JorgeRecarte_M.pdf: 22581929 bytes, checksum: 43baa03f4d321404f2af400b3968e721 (MD5) Previous issue date: 1996 / Resumo: Este trabalho apresenta uma abordagem diferente em relação ao conceito de janelas termicamente efetivas, isto é, janelas que reduzem a energia transmitida para dentro ou fora de uma sala. A idéia é usar um painel de vidro duplo preenchido com material de mudança de fase (pcm), cuja temperatura de fusão é determinada por critérios de conforto térmico. A investigação inclui modelamento dos mecanismo de transferência de calor e radiação através do painel, caracterização ótica de janelas convencionais e compostas, e simulação numérica. As amostras incluem vidros comerciais simples de diferentes espessuras e painéis de vidro duplo de diferentes espessuras e espaçamento entre vidros, preenchidos com ar, pcm e finalmente pcm colorido. O modelo é unidimensional transiente e a simulação numérica foi implementada através do método de diferenças finitas na sua forma explícita. Dos resultados da simulação numérica e dos testes de caracterização óticos foram levantadas curvas de ganho térmico, distribuição de temperatura através do painel e evolução da temperaturas da superfícies interna e externas do painel ao longo de um período de 24 horas de forma a verificar o efeito do pcm no desempenho térmico da janela composta / Abstract: This work present a new concept for thermally effective windows, that is windows which reduce the energy transfer to and fIom the internal ambient. This idea behind this concept is to use a pcm fill in the gap between the two glass panels. The fusion temperature of the pcm is selected according to the thermal cornfort criterion. The investigation includes modeling of the mechanisms of heat transfer relevant to the window problem, the thermal radiation through the glass panels, the optical characterization of conventional and composite window configurations and finally the numerical simulation of these configurations. Because of the lack of information on the thermal and optical properties of national gla~s and specially on the composite configuration optical tests were realized to determine the transmittance and reflectivity of simple glass panels of different thicknesses and spacings, air and pcm filled glass panels and finally coloured pcm filled glass panels. The model is a transient one dimensional and the numerical solution is based upon explicit finite difference scheme. the numerical simulations and the optical tests realized allow the determination of the heat gain, the temperature distribution across the glass panels, the outlet and the inlet instantaneous surface temperatures and finally the overall thermal performance of any glass panels including the proposed system / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica

Les phénomènes de charge des isolants ont été étudiés à l'aide d'un MEB (Microscope Electronique à Balayage). L'effet de la température sur ces phénomènes a été également discuté. Cette étude concernera, plus particulièrement, la mesure des courants induits sous irradiation électronique (courants de conduction et de déplacement) et la détermination du rendement d'émission électronique secondaire. Notre travail est porté en premier lieu sur des échantillons de verre à base de silice. Nous avons prouvé que l'augmentation de la température fait diminuer la capacité de charge du verre. Les résultats sont expliqués par l'augmentation de la conductivité activée par la température qui tend à réduire la formation de la charge d'espace négative grâce à l'augmentation de la mobilité de porteurs de charge. Cette explication est confirmée par une augmentation dans le courant de fuite mesuré sur le verre en fonction de la température.La seconde partie de ce travail a été consacrée à l'étude de l'effet de la température sur le comportement du polyéthylène téréphtalate (PET) irradié avec les électrons. Nous avons montré que la température joue un rôle important dans la grande rétention de la charge accumulée à cause du un phénomène de repiégeage rapide qui se produit dans le volume de l'échantillon dans le cas de la relaxation de la charge. Nos résultats indiquent que le phénomène de «flashover» a lieu aussi bien en volume qu'au niveau de la surface de l'échantillon. L'émission électronique secondaire de ce polymère devient de moins en moins faible avec l'augmentation de la température. / The charging phenomena of insulators have been studied using a SEM (Scanning Electron Microscope). The temperature effect on these phenomena was also discussed. The study will cover, in particular, the measurement of the induced currents under electron irradiation (conduction current and displacement current) and determining the secondary electron emission yield. Our work is focused primarily on silica glass samples. We have shown that increasing of the temperature decreases the capacity of the glass. The results are explained by the increase in conductivity activated by temperature, which tends to reduce the formation of the negative space charge due to the increased mobility of charge carriers. This explanation is confirmed by an increase in the conduction current measured on the glass as a function of temperature.The second part of this work was devoted to the study of the temperature effect on the behavior of polyethylene terephthalate (PET) irradiated with electrons. We have shown that temperature plays an important role in the high retention of accumulated charge due to a rapid trapping phenomenon that occurs in the bulk sample in the case of the charges relaxation. Our results indicate that the "flashover" phenomenon occurs both in bulk and to the surface of sample. The secondary electron emission of the polymer becomes less weak with increasing temperature.

The concept of More Electric Aircraft, where is to utilize the electrical power to drive more or all aircraft subsystem instead of conventional combination of pneumatic, hydraulic, mechanical and electrical power, can be recalled to World War II. It has been proven to have more advantages for decades in terms of energy efficiency, environmental issues, logistics and operational maintenance. It can also enhance aircraft weight, volume and battle damage reconfigurability.Thanks to the new electronics technologies and the emergence of new materials, It becomes feasible for high power density electrical power components to drive the majority of aircraft subsystem. However, sustaining the transmission of hundreds of kilowatts of electrical power at low voltages is not feasible owing to the penalties incurred due to high cable weights and voltage drop may become critical. It is very easy to come up with the solution of the increase of voltage. However, higher voltage will introduce other problems such as the reliability of insulation coordination on the aircraft due to the increased probability of electrical discharge. For aircraft designers, it is very important to understand the rules of insulation coordination on the aircraft including determining clearance and creepage distances, and also have a clear investigation of the phenomena and mechanism of electrical discharges. Past research has identified a number of the concerns of operating electrical systems at higher voltages in an aerospace environment, especially for dimensioning of clearances. However, there is little study on dimensioning of creepage distances and relevantly flashover and electrical tracking on solid insulating material surfaces. This thesis firstly discusses the rules for determining clearances and creepage distances. The experimental validation work was done for breakdown in air gap and on the solid insulating material surfaces under dry condition so that some standard recommended values can be evaluated not only with theoretical values such Paschen's law. Suggestions of application of those standards were provided. Secondly, the complex electrical discharge under wet condition on solid insulating material surfaces was discussed. A mathematical model to predict this type of electrical failure -electrical tracking (the electrical discharges on solid insulation materials which will lead to physical damage in the materials) with the consideration of different environmental conditions including air pressure, ambient temperature, and pollution degrees was developed. A series of electrical tracking tests were carried out on organic materials to find out the mechanism of electrical tracking and validate the finding by the mathematic model. Finite element analysis simulations were also conducted to find out the background thermal transfer mechanism to support our explanation of those phenomena of electrical tracking. Different test techniques have ben developed for specific impact factors. Finally, the suggestions for utilization of the standards and feasible test techniques for electrical tracking under wet conditions were provided.

This master’s thesis deals with preparation of foam glass and explores the possibilies of utilization of this material as an inorganic thermal insulating filler of fired hollow bricks. Foam glass was prepared via powder sintering method from waste packaging glass, using limestone and graphite as foaming agents. After inital analysis of raw materials, the effect of mixture composition and different processing parameters on bulk density, pore size and morphology of foam glass was investigated. Last but not least, different ways of manufacturing thermal insulating bricks, by preparation of foam glass directly in the cavities of fired hollow bricks, were tested.

Les projets de mise en place dans les prochaines décennies de « super réseaux intelligents », qui prévoient la construction de centrales de production à des milliers de kms des centres de consommation, nécessite le développement à large échelle du transport de très fortes puissances par câbles à courant continu. Les principaux verrous à ce développement se situent au niveau du câble et des appareillages adéquats, qui doivent être conçus sur des critères spécifiques et comporter des matériaux isolants ayant des propriétés particulières. Outre la variation de la résistivité qui dépend fortement du champ électrique et de la température, il est établi que des charges sont injectées dans la matière isolante, donnant lieu à une charge d'espace modifiant la répartition du champ électrique. Dans le cas d'un renforcement du champ électrique, la présence de charges d'espace peut conduire à une accélération du vieillissement électrique et, par suite, à un phénomène auto-accélérant pour la rupture diélectrique. Le comportement de ces matériaux sous fortes contraintes continues et en particulier leur vieillissement reste aujourd'hui mal connu.Ce travail de thèse concerne ainsi l'étude du comportement diélectrique de résines époxydes chargées d'alumine utilisées comme supports isolants dans les disjoncteurs à isolation gazeuse en vue d'évaluer leur aptitude à être utilisées dans des appareillages de coupure haute tension continue. Les différentes propriétés diélectriques de ce matériau à l'état initial (facteur de pertes, résistivité volumique, seuils et coefficients de non linéarité, résistivité surfacique, rigidité diélectrique, évolution des charges d'espace) sont déterminées et étudiées sous contrainte électrique continue et à différentes températures.Afin de mieux évaluer l'effet à long terme de la charge d'espace sur le matériau et d'en tirer des informations approfondies pour la conception des futurs composants pour la haute tension à courant continu, une étude de vieillissement accéléré sous contraintes électriques (champs continus) et thermiques (différentes températures) est réalisée. En plus de la charge d'espace, les autres paramètres analysés (permittivité, pertes diélectriques) constituent également des marqueurs potentiels du vieillissement du matériau. L'analyse de l'évolution de ces marqueurs constitue une phase nécessaire dans la compréhension du comportement du matériau pour une utilisation en haute tension à courant continu. / The development of high voltage dc equipment requires design according to specific criteria and including materials with appropriate properties. Indeed, while in ac the dielectric behaviour is mainly determined by permittivity, which varies little for the used materials with field and temperature at power frequency, the dc behavior is determined by highly non-linear volume and surface conductivity-related phenomena. Thus, it is well known that, in dc conditions, electric charge is injected and trapped in the bulk and on the surface, affecting the distribution of the electric field. Space charge accumulation is able to increase significantly the values of the field, thus accelerating ageing and increasing the risk of breakdown. The electrode nature, the field and temperature dependence of the electrical conductivity of the insulating material are key factors involved in the high dc field phenomena.Epoxy resins form an important category of polymeric insulating materials used in a wide range of electric power installations and equipment. In particular, they have been used especially as insulating supports for ac Gas Insulated Switchgear (GIS), because of their electrical and mechanical properties. However, the behaviour of these materials under high dc stress is less known and needs thorough investigation in view of dc applications.The purpose of this thesis is to investigate dielectric behavior of epoxy resins in order to assess their suitability for use in high DC voltage switchgear and define actions and criteria support for the design of such devices.We start by presenting the most important chemical thermal and dielectric properties of polymers as well as the various properties of the epoxy resin.Dielectric properties of the material at initial state with continuous temperature and electrical stress (loss factor, volume resistivity, thresholds and nonlinearity coefficients, surface resistivity, breakdown, evolution of space charge) are determined and investigated under dc fields at different temperatures.