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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Ventiliuojamo oro pasiskirstymas bulvių sampile / Distribution of ventilation air in the layer of potato

Želvys, Dainius 02 June 2011 (has links)
Laikant bulves storame 5 – 6 m storio sluoksnyje, aruode sunku likviduoti susidariusius gedimo židinius. Židinio pašalinimui būtina suintensyvinti ventiliavimą, kad mumifikuoti gedimo židinyje esančius sugedusius gumbus. Tyrimų tikslas - ištirti ventiliuojamo oro paskirstymo dėsningumus bulvių sandėlio sampile ir eksperimentiniame oro paskirstymo stende. Nustatyti oro paskirstymą ventiliuojamame sampile, keičiant skirstomųjų ortakių skaičių, bei ištirti ventiliavimo suintensyvinimo galimybes susidarančias gedimo zonoje. Nustatyta, kad sumažinus atidarytų skirstomųjų ortakių skaičių, galima padvigubinti ventiliavimo intensyvumą likusiuose atidarytuose ortakiuose. Esant atidarytam vienam skirstomajam ortakiui, tiekiamas 8,34 /s oro srautas. Atidarius visus aštuonis ortakius, į kiekvieną ortakį tiekiama tik 3,9 /s oro. Šalia židinio esantys produkcijos sluoksniai bus ventiliuojami žymiai mažesniu ventiliavimo intensyvumu, kas sumažina produkcijos perventiliavimo galimybes likviduojant gedimo židinį sandėlio aruode. / Holding potatoes in a thick 5-6 m layer in the bin it is difficult to eliminate originated hot spots. To remove the source it is necessary to intensify ventilation in order to mummify defective tubers in corruption source. The aim of the research is to investigate the patterns of ventilated air distribution in potato store and distribution of air in an experimental bench. To determine air distribution in ventilated store by changing the number of distribution ducts, and to explore opportunities to intensify ventilation arising in corruption area. It was found that reducing the number of opened distribution ducts the intensity of the ventilation in the remaining opened ducts can be doubled. At the invitation of one ducts supplied 8.34 m3/s air flow. After opening all eight ducts, each duct to be supplied only 3.9 m3/s in air. The layers next to the source will be ventilated with much smaller intensity, which decreases possibility to over ventilate production while eliminating corruption source in the store bin.
2

Chaleur – Humidité – Air dans les maisons à ossature bois : Expérimentation et modélisation / Heat, Air and Moisture coupled transfers in wooden frame houses : Experimental investigations and numerical modelling

Labat, Matthieu 21 November 2012 (has links)
L’évolution actuelle des exigences en termes de performance énergétique des bâtiments a fait apparaître de nouveaux enjeux et problématiques scientifiques, dont ceux liés à l’humidité. Cette étude s’appuie sur une cellule expérimentale construite sur la technologie des maisons à ossature bois et soumise aux conditions climatiques réelles de Grenoble. L’instrumentation de ce bâtiment et le suivi de l’évolution en température et en humidité dans les différentes couches de l’enveloppe permettent de définir des séquences nécessaires à la validation de modèles numériques. Dans cet objectif, un modèle existant nommé HAM-Tools a été utilisé pour simuler les transferts couplés de chaleur, d’air et d’humidité à l’échelle du bâtiment. La démarche de validation a été décomposée en plusieurs étapes, de manière à cibler des transferts spécifiques et d’en améliorer la modélisation. Ces études localisées concernent les transferts couplés de chaleur et de masse à travers les parois solides, la modélisation des transferts de chaleur à travers une lame d’air ventilée et enfin la modélisation du renouvellement de l’air intérieur en conditions naturelles. Pour estimer la précision globale du modèle, c'est-à-dire à l’échelle du bâtiment, une séquence expérimentale a été simulée en prenant en compte l’ensemble des transferts couplés simultanément. Les performances du modèle sont discutées à partir des mesures locales, c'est-à-dire dans les parois, puis globales. La bonne concordance entre mesures et résultats de simulation permet de conclure sur la validité et la généricité de la démarche mise en œuvre et les hypothèses de simulation. Plus particulièrement, il est apparu que l’outil de modélisation permet de prédire correctement le comportement moyen des parois en humidité et en température. Il est donc envisageable de l’utiliser pour simuler et estimer l’impact des constituants des parois en termes de durabilité, de performances énergétiques et de confort de l’occupant. / As energy saving is so important in buildings nowadays, envelopes performances have to be more efficient and have to deal with more obligations, such as moisture accumulation and mould growth. This study relies on an experimental wooden frame house exposed to the natural conditions of Grenoble, France. It has been widely instrumented so the wall’s temperature and humidity is monitored at different depths. As a consequence, complete dataset are available and can be used to validate numerical model. In this work, an existing numerical model named HAM-Tolls has been used to simulate the heat, air and moisture coupled transfers at the building scale. The method developed here consists in validating the numerical model step by step, with studying specific transfers separately. The first step deals with heat and mass transfers across the walls. Then, the heat transfers across a ventilated air gap and the air change rate under natural conditions have been studied much in detail. The final step of this works consists in simulating simultaneously every transfer at the building scale. This latest simulation’s results were compared both on a local and on a global point of view with the measurements. As they were found to be in good agreement, this allows concluding on the methodology efficiency, the validity of the modelling assumption and gives good hope with extending this methodology to other studies. Specifically, the simulation tool is able to predict correctly the average temperature and humidity content within the walls. Therefore, it should be suitable with estimating the wall components influence on the wall durability, its energy efficiency and its impact on the occupant’s thermal comfort.
3

Optimalizace lehkého šikmého střešního pláště k redukci letních tepelných zisků / Optimization of a lightweight pitched roof in order to reduce summer heat gains

Svobodová, Sylvia January 2020 (has links)
The thesis deals with the topic of overheating of attic rooms during the summer period. In vast majority of family houses and apartment houses with inhabited attic spaces is the roof solved as lightweight. This kind of roof assembly is not able to sufficiently resist the summer boundary conditions and leads to increased heat gains in the interior. In this work, the attention is drawn entirely to the heat penetration through the roof. Different aspects of passive cooling were applied to the roof and the impact of each change was assessed. This concerns the color of the tiles, thermal accumulation, reflective surfaces and the ventilated air layer. The temperature and velocity profiles in the ventilated cavity were monitored and an analysis of the ventilated cavity efficiency was conducted. For individual analyses was used software – based on the principles of the Finite Element Method or the dynamic simulation software. Also other methods were employed: long-term measurement of temperatures on roof models; short-term measurement of surface temperature of various kinds of roof tiles; and laboratory measurement of reflexivity. Also the effect of insect grilles on the air flow is discussed; which was tested on a ventilator track. In this publication are explained the principles of natural convection; boundary layers and the theory of the coefficient of heat transfer. This work includes a standard of the precise calculation methodology for ventilated roofs which was developed for the purpose of creating a user-friendly guide. The results of individual analyses show, a definitely positive effect of the ventilated cavity on the heat gain reduction of attic rooms. The current technical solution of a roof ridge provides the exhaust of the water vapor from a roof assembly; but for providing ventilation for reducing heat gains is insufficient. This lead to a concept of an innovative roof ridge design which enhances the air exchange between the cavity and outdoor environment.
4

Horský hotel / Mountain hotel

Sibilla, Luboš January 2013 (has links)
Diploma thesis is focused on design of a new hotel in mountain surrounding with one underground floor and five stories. The hotel has 53rooms for guests from the second to the fifth floor and two rooms for employees of hotel on the fifth floor, what means 106 beds for guests. The hotel is equipped indoor swimming pool 25x10meters, its own kitchen, dining hall, sauna, massages and Conference hall. The object consists of four dilatation units – accommodation sides and common central part and swimming pool. Roof construction is created by huge wooden truss from the second floor to the fifth floor, which sequentially subsides and formed by 70 dormers. Angle of the roof is 46° and 23°, and surface coating is smooth titanium zinc sheet. Load bearing system of whole object is designed as irregular reinforced concrete monolithic skeleton from concrete C30/37 with prestressed elements and based on prestressed reinforced concrete slab. The cladding is designed from ceramic bricks with inner additional insulation and additional insulation on outer surface, which is covered by facade with ventilated air gap, designed from cement-fibers boards, which are by color and structure imitating natural stone. Each accommodation floor is divided into two accommodation sides, central part with central stairs and two personal elevators. Each accommodation side has two protected escape routes and one fire evacuation lift. On the Ground floor, there is the reception, the dining hall, the pool hall and offices. On the underground floor, there is wellness center for guests of the hotel, technologies for the pool, HVAC engine room and kitchen. In all object, there are designed different types of hanging ceilings, because of attendance of stabile sprinkler system. In the pool hall, there will be acoustic hanging ceiling. Heating will be procured by combination of biomass boiler and heat pumps, which will be used mainly for deck heating in rooms in accommodation floors.

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