Estruturas como torres e chaminés industriais são bastante vulneráveis ao fenômeno de desprendimento de vórtices, devido à sua esbeltez e forma rombuda. Além disso, devido ao baixo amortecimento estrutural que possuem, essas estruturas também têm maiores chances de atingir grandes amplitudes de deslocamento, o que é causado pelo efeito de captura. Apesar de esse tipo de estrutura ser considerado simples dos pontos de vista estrutural e aerodinâmico, o estudo das vibrações transversais nessas estruturas é bastante complicado, pois envolve a interação entre tópicos complexos da mecânica dos fluidos e estrutural, tornando a determinação confiável da resposta estrutural um dos problemas mais difíceis da Engenharia do Vento. Ao longo das últimas cinco décadas, diversos pesquisadores vêm estudando esse fenômeno, buscando uma abordagem que consiga considerar todos os tópicos que envolvem o mecanismo de vibração por desprendimento de vórtices. Entretanto, apesar dos esforços, os modelos existentes para a verificação da resposta da estrutura são de caráter empírico, sendo os dois mais aceitos pela comunidade científica o modelo de comprimento de correlação de Ruscheweyh e o modelo matemático espectral de Vickery e Clark, o qual foi posteriormente aprimorado por Vickery e Basu. Primeiramente, são estudados em detalhe esses dois modelos e seus métodos derivados, os quais são apresentados em normas e códigos. Após isso, é feita uma proposta de cálculo de dimensionamento do deslocamento do topo de tais estruturas baseada no modelo de Vickery e Basu e adaptada às necessidades da NBR- 6123. E finalmente, são apresentados dados de 42 estruturas, as quais atingiram grandes amplitudes de vibração em seu topo. Essas estruturas foram dimensionadas segundo as diretrizes de cada um dos métodos estudados neste trabalho, o que demonstrou o bom desempenho do Método II do Eurocódigo, do Método do CICIND e da Proposta III-B para a NBR-6123. / Structures like towers and industrial chimneys are quite vulnerable to the vortex shedding phenomenon, due to their slenderness and non-aerodynamic form. Furthermore, due to their low structural damping, these structures are also more likely to reach large displacement amplitudes, which is caused by the lock-in effect. Although these structures are considered as simple from structural and aerodynamic points of view, the study of cross-wind vibrations in these structures is quite complicated, as it involves the interaction of complex topics of fluid and structural mechanics, turning a reliable determination of the structural response into one of the most complicated problems in Wind Engineering. Over the past five decades, several researchers have been studying this phenomenon, seeking an approach that could consider all topics involving the vibrating mechanism by vortex shedding. However, despite the efforts, the existing models for predicting the response of the structure are empirical, with the two most accepted by the scientific community being the Ruscheweyh’s correlation length model and the Vickery & Clark’s spectral mathematical model, which was further enhanced by Vickery & Basu. Firstly, these two models and their derivative methods, which are reported in standards and codes, are studied in detail. After, a calculation proposal for predicting the top displacement of such structures is presented, which is based on the Vickery & Basu model and adapted to the needs of NBR-6123. Finally, data for 42 real structures which have reached large vibration amplitudes at their tops is presented. These structures were designed according to the guidelines for each of the methods studied in this work, which demonstrated the good performance of the Eurocode II Method, of the CICIND Method and of the NBR-6123 III-B Proposal.

No description available.

Aujourd’hui à de nombreuses études sur la thermique du bâtiment pour réduire la consommation d’énergie tout en préservant le confort des usagers sont proposées. Le travail présenté ici met en avant les performances d’une technique d’isolation active par un dispositif de bardage extérieur de ce fait soumis au rayonnement solaire incident. L’étude expérimentale mise en oeuvre a permis de caractériser les échanges thermiques à l’intérieur de la lame d’air verticale (circulante ou non circulante), qui sont la clef de ce type de dispositif, en fonction des différents paramètres retenus comme pertinents. Le terme moteur est bien évidemment l’éclairement solaire. La distance parement extérieur mur support, i.e. l’épaisseur de la lame d’air, conditionne un rapport d’aspect et influe donc sur la vitesse de l’air circulant ou sur le volume tampon en situation non circulante et donc sur les échanges thermiques. Enfin les caractéristiques thermiques du parement extérieur, ici une lame de pin maritime ou un bois aggloméré, impactent assez fortement sur l’évolution temporelle des différentes. Une modélisation globale du comportement de la cheminée solaire que constitue le bardageet quelques simulations numériques ont permis de conforter ces différents résultats expérimentaux. On retiendra qu’en été, la solution optimale est un dispositif de bardage avec peu d’inertie thermique et un écoulement d’air rapide alors qu’en hiver, un dispositif avec inertie et sans écoulement contribue à assurer un bon volant thermique. / Today many studies on thermal building to reduce energy consumption while maintaining user comfort are proposed. The work presented here highlights the performance of an active isolation technique by means of exterior cladding thus subjected to solar radiation.The experimental study has been used to characterize the heat transfers inside the vertical cavity (air circulating or not), which are the key to this type of device, depending on various parameter staken as relevant. The driving factor is of course the solar irradiance. The thickness of the air gap induces an aspect ratio and thus affects the speed of the air flowing or the buffer volume and therefore the heat exchanges. Finally, the thermal characteristics of the cladding here maritime pine or chipboard, impact quite strongly on the temporal evolution of the different temperatures.The cladding and the vertical cavity act as a solar chimney, a global modeling of its behavior and some numerical simulations have strengthened the experimental results. We note that in summer, the optimal solution is a device of cladding with little thermal mass an drapid air flow while in winter, a device with large thermal mass and without flow helps to ensure a good thermal flywheel.

Diploma thesis contains introduction of a company P-D Refractories CZ a. s., where the manufacture of ceramic chimney liners is. Followed by a description and analysis of the product in the entire production cycle, material and product spectrum. Based on the results of current production is created proposal to streamline the machining technology with a view to increase productivity and reduce defective products, which means determine the material of a tool and the method of machining. The work is finished by technical-economic assessment, where the summary and recommendation of the proposed solution are.

Fire Works is a cultural center that will seem durable, welcoming and useful. The Culture center will serve as an extension of the central fireplace in the building. Something that gives light and life to the city with the activity created by the presence of the citizens. The building remains within the framework of the environment that surrounds it, a million program area with material dominance of concrete, glass and steel. / Fire Works är ett kulturcenter som ska verka tåligt, välkomnande och användbart. Kulturhuset ska fungera som en förlängning av den centrala eldstaden i byggnaden. Något som ger ljus och liv åt staden med den aktivitet som skapas av människans närvaro. Byggnaden håller sig inom ramarna för den miljö som omger den, ett miljonprogramsområde med materiell dominans av betong, glas och stål.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24679号 / 農博第2562号 / 新制||農||1100(附属図書館) / 学位論文||R5||N5460(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 澤山 茂樹, 教授 吉田 天士, 准教授 中川 聡 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

As the climate changes, hot regions like La Guajira's semi-desert will become even hotter. It is projected that the average temperature in this region will increase by 2.4 ℃ over the course of this century, with a 20 % reduction in precipitation. To ensure that these areas remain habitable in the future, implementing technical solutions will be necessary to mitigate the impacts on the people living there. A field study assessed the thermal comfort at a school in Manaure, which experiences excessively high temperatures that exceed international standards for good thermal comfort. Through subjective and objective data collection, the field study concluded that the school's thermal climate would negatively impact at least 83 % of the students. The study also found that the surface temperature of desks not exposed to sunlight reached a temperature of 43 ℃. To improve thermal comfort, three potential solutions were explored. Isolating the roof reduces incoming radiation and prevents excess heat from warming the structure. Increasing the ventilation rate helps dissipate hot air, and planting trees creates a cooler supply air temperature. Two of the three measures were implemented, and the tree-planting project is ongoing. Temperatures were measured on the roof, walls, desk and floor during a hot day. Together with a survey to students and teachers to evaluate the absolute temperature and the experienced thermal comfort. The results demonstrated that isolating the roof and installing a solar chimney on the classroom's roof can significantly lower the operative temperature to 36 ℃ and 35 ℃, respectively. These improvements can improve learning by 25 % due to better thermal comfort compared to a classroom that has not been modified. As a bonus, the acoustics were also improved in classrooms, resulting in a lower echo level. Overall, the study demonstrated that it is possible to significantly improve the thermal comfort of classrooms in semi-desert regions, even those without access to electricity. An added benefit is that these solutions have a low installation cost and no operational costs. However, further research is needed to determine the impact of heat on children and whether these measures will improve their learning outcomes. / A medida que cambie el clima, las regiones cálidas como el subdesierto de La Guajira se volverán aún más calientes. Se proyecta que la temperatura promedio en esta región aumente 2,4 ℃ en el transcurso de este siglo, con una reducción del 20 % en las precipitaciones. Para garantizar que estas áreas sigan siendo habitables en el futuro, será necesario implementar soluciones técnicas para mitigar los impactos en las personas que viven allí. Un estudio de campo evaluó el confort térmico en una escuela de Manaure, que experimenta temperaturas excesivamente altas que superan los estándares internacionales de buen confort térmico. A través de la recolección de datos subjetivos y objetivos, el estudio de campo concluyó que el clima térmico de la escuela impactaría negativamente al menos al 83 % de los estudiantes. El estudio también encontró que la temperatura de la superficie de los escritorios no expuestos a la luz solar alcanzó una temperatura de 43 ℃. Para mejorar el confort térmico, se exploraron tres posibles soluciones. Aislar el techo reduce la radiación entrante y evita que el exceso de calor caliente la estructura. El aumento de la tasa de ventilación ayuda a disipar el aire caliente y la plantación de árboles crea una temperatura del aire de suministro más fría. Se implementaron dos de las tres medidas y el proyecto de plantación de árboles está en curso. Se midieron las temperaturas en el techo, las paredes, el escritorio y el piso durante un día caluroso. Junto con una encuesta a estudiantes y docentes para evaluar la temperatura absoluta y el confort térmico experimentado. Los resultados demostraron que aislar el techo e instalar una chimenea solar en el techo del aula puede reducir significativamente la temperatura operativa a 36 ℃ y 35 ℃, respectivamente. Estas mejoras pueden mejorar el aprendizaje en un 25 % debido a un mejor confort térmico en comparación con un aula que no ha sido modificada. Como beneficio adicional, también se mejoró la acústica en las aulas, lo que resultó en un nivel de eco más bajo. En general, el estudio demostró que es posible mejorar significativamente el confort térmico de las aulas en las regiones semidesérticas, incluso aquellas sin acceso a la electricidad. Un beneficio adicional es que estas soluciones tienen un bajo costo de instalación y no tienen costos operativos. Sin embargo, se necesita más investigación para determinar el impacto del calor en los niños y si estas medidas mejorarán sus resultados de aprendizaje. / När klimatet förändras kommer redan varma regioner som halvöken i La Guajira, Colombia att bli ännu varmare. Den genomsnittliga temperaturen i regionen förväntas att öka med 2,4 ℃ under det här århundradet, samtidigt som nederbörden minskar med     20 %. För att dessa områden ska vara beboeliga i framtiden kommer det vara nödvändigt att implementera tekniska lösningar för att mildra konsekvenserna för de människor som bor där. En fältstudie genomfördes för att undersöka termisk komfort på en skola i Manaure, som upplever extremt höga temperaturer vilket överskrider internationella standarder inom termisk komfort. Genom subjektiv och objektiv datainsamling konstaterade fältstudien att skolans termiska klimat kommer påverka minst 83% av eleverna negativt. Studien visade också att temperaturen på skrivborden som inte utsatts för solljus nådde 43 ℃. Temperaturer mättes på tak, väggar, skrivbord och golv under en varm dag. Tillsammans med en undersökning till elever och lärare för att utvärdera den absoluta temperaturen och den upplevda termiska komforten. För att förbättra den termiska komforten undersöktes tre olika möjligheter. Att isolera taket minskar den inkommande strålningen och förhindrar att överflödig värme värmer upp konstruktionen. Ökningen av ventilationen hjälper till att avlägsna het luft och sist även plantera träd för att skapa en svalare utomhustemperatur. Av de tre åtgärderna genomfördes två, och projektet med att plantera träd pågår. Resultaten visade att den operativa temperaturen kan sänkas till 36 ℃ om taket isoleras och ytterligare till 35 ℃ om en solskorsten installeras på taket i klassrummen. Sammantaget kan inlärningen förbättras med åtminstone 25 % jämfört med ett klassrum som inte förbättrades. En positiv bieffekt var att akustiken i klassrummen förbättrades genom mindre eko. Sammanfattningsvis visade studien att det är möjligt att betydligt förbättra den termiska komforten i klassrum i halvökenklimat, även i klassrum utan tillgång till el. En annan fördel är att dessa lösningar har en låg installationskostnad och inga driftskostnader. Dock krävs ytterligare undersökningar för att fastställa vilken påverkan värme har på barn och om dessa åtgärder kommer att förbättra deras lärande.

<p>Solar thermosiphons integrated into the thermal envelop of buildings has been studied for their potential to take advantage of solar energy in heating buildings. The annual performance of solar thermosiphons cannot currently be predicted with the correlations from previous research. Also, no work has been done on the supply mode of a solar thermosiphon even though it has the potential to provide heating and fresh ventilation air. An investigation was done with the goal of developing a numerical model that could predict the performance of the supply mode of a solar thermosiphon. The numerical model included infrared thermal radiation and conduction through the glass, phenomenon which had not been used in previous numerical models. To validate the numerical model a novel steady state experiment was developed. This experiment included radiation as the heat source and the ability to vary geometric lengths. The performance parameters of mass flow rate and thermal efficiency were comparable between the numerical predictions and experimental results. However, due to uncertainties in the current experimental setup, full validation of the numerical model was not possible. These uncertainties would have to be addressed before the numerical model that was developed can be fully validated and used for generating correlations. After consideration of practical implementation constrains, it was shown that it was easier to implement the indoor air curtain mode of a solar thermosiphon than the supply mode. The indoor air curtain mode provides the same amount of energy from solar radiation to heat a building as the supply mode of a solar thermosiphon.</p> / Master of Applied Science (MASc)

Computational fluid dynamics was used to simulate solar chimney power plants and investigate modeling techniques and expected energy output from the system. The solar chimney consists of three primary parts: a collector made of a transparent material such as glass, a tower made of concrete located at the center of the collector, and a turbine that is typically placed at the bottom of the tower. The collector absorbs solar radiation and heats the air below, whereby air flows inward towards the tower. As air exits at the top of the tower, more air is drawn below the collector repeating the process. The turbine converts pressure within the flow into power. The study investigated three validation cases to numerically model the system properly. Modeling the turbine as a pressure drop allows for the turbine power output to be calculated while not physically modeling the turbine. The numerical model was used to investigate air properties, such as velocity, temperature, and pressure. The results supported the claim that increasing the energy into the system increased both the velocities and temperatures. Also, increasing the turbine pressure drop decreases the velocities and increases the temperatures within the system. In addition to the numerical model, analytical models representing the vertical velocity without the turbine and the maximum power output from a specific chimney were used to investigate the effects on the flow when varying the geometry. Increasing the height of the tower increased the vertical velocity and power output, and increasing the diameter increased the power output. Dimensionless variables were used in a regression analysis to develop a predictive equation for power output. The predictive equation was tested with new simulations and was shown to be in very good agreement. / Master of Science

Cette thèse présente une étude numérique d’un séchoir solaire indirect à convection naturelle destiné à sécher les produits agricoles (les figues). La première partie analyse un séchoir solaire contenant une chambre de séchage couplée à un absorbeur inversé et une cheminée solaire. Les simulations ont été faites afin de déterminer les champs dynamique et thermique sous l’influence de la variation de la configuration de la cheminée solaire et la taille de l’ouverture d’admission. Les équations de conservations basées sur le modèle de turbulence k-ε standard sont résolues par la méthode des volumes finis à l’aide du code commercial ANSYS-Fluent. La deuxième partie analyse l’effet d’ajouter un stockage thermique sous forme d’un lit en gravier dans la chambre de séchage. Le lit est modélisé comme un milieu poreux. En plus, cette étude propose l’utilisation d’une deuxième entrée d'air dans la chambre de séchage afin d’assurer une distribution thermique plus homogène au niveau des claies et de garantir un séchage plus uniforme. / This thesis presents a numerical study of an indirect natural convection solar dryer for drying agricultural products (Figs). The first part analyzes a solar dryer containing a drying chamber coupled to a reversed absorber and a solar chimney. Simulations were made to determine the dynamic and thermal fields under the influence of the variation of the solar chimney configuration and the size of the inlet opening. The governing equations based on the standard k-ε turbulence model are solved by the finite volume method using the ANSYS-Fluent commercial code. The second part analyzes the effect of adding a thermal storage in the form of a gravel bed in the drying chamber. The bed is modeled as a porous medium. Furthermore, this study proposes the use of a second air inlet in the drying chamber in order to ensure a more homogeneous thermal distribution at the level of the racks and to guarantee a more uniform drying.