• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 30
  • 27
  • 19
  • 4
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 98
  • 98
  • 48
  • 29
  • 28
  • 25
  • 25
  • 22
  • 20
  • 17
  • 16
  • 15
  • 13
  • 13
  • 12
  • 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.
71

Mikroprocesorové řízení ohřevu bazénu se slunečními kolektory / Microprocessor control of heating of swimming pool with solar collector

Kahánek, Tomáš January 2012 (has links)
This thesis is pointed on draft of controller unit, used for control of swimming pool with solar collectors. Controller detect water temperature in a pool and collerctor. With these values controller control pump activation and 3-way valve position. Operator can set all settings in user interface which are needed for a right working. Controller unit attempt minimize energy used for a pump while working.
72

Optimalizace kombinovaného systému ohřevu TUV / Optimalization of the water heating system

Lebeda, Ladislav January 2016 (has links)
This thesis is aimed to enable energy optimization of combined water heating system. The first part deals with the assessment of the general view of thermal solar systems with autonomic power from photovoltaics and description of a particular solar system for energy optimization. Then there is chosen the control system conception based on single-board computer Raspberry Pi, which is complemented by auxiliary measuring and controlling circuit. In the following chapters is described design and implementation of software for control system including web interface. The remote monitoring and controlling of solar heating system is the main purpose of web interface.
73

Využití termických panelů pro zvýšení účinnosti chladiciho okruhu TČ / Utilization of thermal panels to increase the efficiency of the heat pump cooling circuit

Lainka, Pavel January 2016 (has links)
This thesis evaluates the connection of solar collectors with heat pump. The work demonstrates meaningful use of solar collector to increase cooling efficiency of the heat pump. Introduction The work introduces the reader to the issue and describes basic principles of the two main sources of energy used in the system - the heat pump and solar system. Next session is dedicated to analysis and evaluation of the data that was measured during system operation. A comparison of measured COP of the heat pump at two different modes of operation was used for the evaluation - with the help of the solar system and without using the solar system.
74

Entwicklung von Fertigungsverfahren zur Herstellung eines neuartigen Solarkollektors

Lüpfert, Marc 26 June 2017 (has links)
Im Rahmen der vorliegenden Arbeit wurden Fertigungstechnologien zur kostengünstigen Herstellung eines neuartigen solarthermischen Kollektors entwickelt. Dieser Kollektor soll aus einem profilierten Grundkörper aus Schaumglas bestehen, welcher mit Flachglas abgedeckt ist. Die Herstellung des Schaumkörpers wurde betrachtet von der Auswahl der Rohstoffe, über die Entwicklung geeigneter Verfahrensparameter, bis zur Formgebung. Ein Schaumkörper mit profilierter Oberfläche konnte im Maßstab von 600 x 600 x 130 mm³ hergestellt werden. Zur Kosteneinsparung wurde hierfür ein Reststoff aus der Glas verarbeitenden Industrie verwendet. Um den Kollektor in ein hydraulisches System eingliedern zu können, wurde eine Technologie zur Einbindung von Rohrleitungsanschlüssen entwickelt. Emaillierte Rohrbögen aus Gusseisen konnten im Schäumungsprozess fest in den Schaumkörper integriert werden. Weiterhin wurden zwei Möglichkeiten zur Anbindung der Deckgläser untersucht. Dabei wurden mittels Klebung durch EVA-Folie eine höhere Verbundfestigkeit erreicht als mittels Löten durch Aluminium-Blech.:Inhaltsverzeichnis Vorwort 1 1 Einleitung 3 2 Solarkollektoren – Stand der Technik 5 2.1 Überblick 5 2.2 Flachkollektor 7 2.3 Zukünftige Entwicklung 16 3 Neuer Lösungsansatz 19 3.1 Konzept 19 3.2 Wirkungsgrad 21 3.3 Herstellkosten 23 4 Angewandte Messverfahren 24 5 Grundkörper des Kollektors 29 5.1 Grundlagen Schaumglas 29 5.1.1 Was ist Schaumglas 29 5.1.2 Schaumglasherstellung 30 5.1.3 Rohstoffe 33 5.1.4 Parameter der Schaumglasherstellung 37 5.2 Vorbetrachtung 42 5.3 Schäumen von Reststoffen 43 5.3.1 Charakterisierung der Rohstoffe 43 5.3.2 Schäumungsversuche 54 5.3.3 Einfluss der Rußart 61 5.3.4 Einfluss der Atmosphäre 63 5.3.5 Schäumungsverstärkung durch Oxidationsmittel 68 5.4 Eigenschaften 73 5.4.1 Schaumfestigkeit 73 5.4.2 Solare Absorption 94 5.4.3 Korrosionsbeständigkeit 104 5.5 Schäumungsform 113 5.5.1 Werkstoffauswahl 113 5.5.2 Charakterisierung von Calciumsilikatwerkstoffen 114 5.5.3 Entformbarkeit 118 5.5.4 Modellschäumung 122 5.6 Zusammenfassung und Ausblick 134 6 Anbindung weiterer Bauteile 137 6.1 Grundlagen der Materialverbindung 137 6.1.1 Anorganische Materialverbindung 137 6.1.2 Organische Materialverbindung 141 6.2 Vorbetrachtung 148 6.2.1 Rohrleitungsanschlüsse 148 6.2.2 Verbindung Grundkörper/ Deckglas 150 6.3 Einbindung der Rohrleitungsanschlüsse 155 6.3.1 Stand der Vorarbeiten 155 6.3.2 Emailliertes Gusseisen 157 6.3.3 Dauerbeständigkeit 166 6.4 Verbindung des Grundkörpers mit dem Deckglas 168 6.4.1 Stand der Vorarbeiten 168 6.4.2 Löten 169 6.4.3 Kleben 182 6.5 Zusammenfassung und Ausblick 185 7 Zusammenfassung 187 8 Ausblick 189 Literaturverzeichnis 191 Abkürzungs- und Symbolverzeichnis 200 Abbildungsverzeichnis 202 Tabellenverzeichnis 207 Anhang 209
75

Moderní energie a snížení energetické náročnosti budov / Modern energy and decreasing the energy intensiveness of buildings

Kučera, Miroslav January 2009 (has links)
This diploma thesis deals with possible energy-savings in the municipal buildings of Spytihněv. Moreover, it discusses the possible improvements of heating features and making use of renewable resources. This is meant to be achieved by a wrapper which is less demanding on energy consumption than those which have been used until now. Attention is also paid to a more efficient system of energy distribution. Both energetic and financial points of view are taken into consideration. The thesis consists of a few parts. Introduction, the first part, deals with renewable resources issues on a theoretical level. The second part is divided according to each individual analysed premise/building. At this point energy-saving proposal, choice of a heating system, a heating pump, a solar collector as well as energy-saving and financial calculation are included.
76

Secagem solar e convencional de grãos residuais de urucum. / Solar and conventional drying of residual urucum grains.

SANTOS, Dyego da Costa. 14 June 2018 (has links)
Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-06-14T13:14:15Z No. of bitstreams: 1 DYEGO DA COSTA SANTOS - DISSERTAÇÃO PPGEA 2012..pdf: 41520705 bytes, checksum: 086b1fdd0714560722d1e4b02d15c2b0 (MD5) / Made available in DSpace on 2018-06-14T13:14:15Z (GMT). No. of bitstreams: 1 DYEGO DA COSTA SANTOS - DISSERTAÇÃO PPGEA 2012..pdf: 41520705 bytes, checksum: 086b1fdd0714560722d1e4b02d15c2b0 (MD5) Previous issue date: 2012-02 / Os grãos residuais de urucum constituem o subproduto da extração dos pigmentos bixina e norbixina na indústria de alimentos. Atualmente, a maioria desses grãos vem sendo descartada, o que gera a necessidade de aproveitamento desses resíduos, inclusive com estudos no sentido de incorporá-los à alimentação humana. Ante o exposto, objetivouse secar grãos residuais de urucum e farinhas de grãos residuais de urucum por meio convencional (secagem em estufa) e utilizando energia solar. Os grãos e as farinhas foram secados em estufa com circulação forçada de ar, nas temperaturas de 40, 50, 60 e 70 °C. Nas secagens por meio de energia solar foram utilizados dois secadores, um para secagem diurna, denominado secador solar, e o outro para secagem noturna, denominado Secador Acumulador de Calor para Secagem Noturna (ACSN). O secador ACSN é composto por dois circuitos de circulação de água independentes. No período diurno funcionava o circuito coletor solar/reservatório, o qual era interrompido durante a noite e aberto o circuito reservatório/câmara de secagem. Na secagem por exposição direta ao sol as amostras eram colocadas em bandejas em base de concreto recoberta com lona plástica (polietileno) preta. Para a representação da cinética de secagem dos grãos e das farinhas de urucum desidratados em estufa, secadores solar e noturno e por exposição direta ao sol foram empregados os modelos matemáticos de Aproximação da Difusão, Dois Termos, Midilli, Page e Thompson. Nas secagens convencionais, o aumento da temperatura de desidratação promoveu reduções nos tempos de secagem. A utilização do secador ACSN no período notumo evitou a absorção de água pelas amostras e promoveu sua secagem, o que possibilitou a obtenção de produto com menor teor de água. Para as amostras cuja secagem se iniciou no período notumo, a utilização do secador ACSN no período notumo possibilitou maiores taxas de secagem, em comparação com a testemunha, com obtenção de produto com menor teor de água. As secagens solares apresentaram tempos de desidratação menores que as observadas nas secagens convencionais. Os modelos de Aproximação da Difusão, Dois Termos, Midilli, Page e Thompson propiciaram bons ajustes aos dados experimentais da cinética de secagem das amostras de grãos e farinhas de grãos residuais de urucum com e sem óleo pelos métodos convencional e solar. / Residual annatto seeds are a subproduct derived from the extraction of bixin and norbixin pigments in the food industry. The fact that most of these seeds are typically discarded demonstrates the need for making better use of these residues, through studies aimed at incorporating them into the human diet. The objective of this study was to dry residual annatto seeds and annatto seed powder using conventional means (oven-drying) and solar energy. The seeds and powder were oven dried with forced air circulation at temperatures of 40, 50, 60 and 70 °C. Two dryers were used in the solar energy method, one for daytime drying, called a solar dryer, and the other for nighttime drying, denominated a heat accumulator for nighttime drying (ACSN). The ACSN dryer is composed of two independent water circulation circuits. The solar collector circuit/reservoir was in operation in the daytime. This was interrupted during the night, whereupon the reservoir circuit/drying chamber was opened. In solar drying, samples were collected in concrete trays covered with a black plastic tarp (polyethylene). Diffusion approximation, two term, Midilli, Page and Thompson mathematical models were used to represent the drying kinetics of annatto seeds and powder dried in an oven and solar and nighttime dryers, as well as by direct exposure to the sun. In conventional drying, an increase in temperature promoted reductions in drying time. Using the ACSN dryer at night avoided water absorption by the samples, promoting their drying and resulting in a product with lower water content. For samples dried at night, employing the ACSN dryer led to greater drying rates compared to the control sample, generating a product with lower water content. Solar dryers exhibited shorter drying times than those observed in conventional dryers. Diffusion Approximation, Two Term, Midilli, Page and Thompson models showed a good fit to experimental data derived from the drying kinetics of annatto seed samples and residual powder, with and without oil, using conventional and solar methods.
77

An?lise do desempenho t?rmico de um sistema de aquecimento solar utilizando coletor com superf?cie absorvedora em chapas de PVC

Reis, Edmilson Pedreira dos 07 August 2009 (has links)
Made available in DSpace on 2014-12-17T14:57:54Z (GMT). No. of bitstreams: 1 EdmilsonPR.pdf: 2663953 bytes, checksum: 5e759d4c2f58059b6b7f5c08d0cc24d0 (MD5) Previous issue date: 2009-08-07 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / It s presented a solar collector to be used in a system for heating bath water, whose main characteristic is its low cost. The collector consists of five plates of PVC with 10 mm thick, 200 mm in width and 1400mm in length, with an area equal to 1.4 square meters. The plates were connected in parallel to the ends of PVC tubes of  40 mm and 32 mm. The plates were coated on one side with aluminum sheets of soft drinks and beers cans open. The system worked on a thermosiphon and was tested in two configurations: the plates uncoated and coated with aluminum material, to determine the influence of material on the efficiency of the collector. For both configurations was used EPS plates below the surface to minimize heat losses from the botton. The thermal reservoir of the heating system is, also, alternative and low cost, since it was constructed from a polyethylene tank for storing water, with volume of 150 end 200 liters. It will be presented the thermal efficiency, heat loss, water temperature of the thermal reservoir at the end of the process and simulation of baths for a house with four residents. The will be demonstrated thermal, economic and material viability of the proposed collector, whose main innovation is the use of recyclables materials, cans of beer and soft drinks, to increase the temperature of the absorber plate. / Apresenta-se um coletor solar alternativo a ser utilizado em um sistema para aquecimento de ?gua destinada ao banho, cuja principal caracter?stica ? seu baixo custo. O coletor consiste de cinco placas de forro de PVC de 10 mm de espessura, 200 mm de largura e 1400 mm de comprimento com ?rea correspondente a 1,40 m?. As placas foram ligadas pelas extremidades em paralelo a tubos de PVC de 40 mm e de 32 mm. As placas, de um lado, foram revestidas com chapas de alum?nio provenientes de latinha de refrigerantes e cervejas abertas. O sistema funcionou em regime de termo-sif?o e foi testado para duas configura??es: as placas sem revestimento e revestidas com o material alum?nio, para a determina??o da influ?ncia desse material na efici?ncia do coletor. Para as configura??es estudadas utilizaram-se placas de isopor de 20 mm na superf?cie inferior para minimizar as perdas t?rmicas pela parte de baixo. O reservat?rio t?rmico do sistema de aquecimento ?, tamb?m, alternativo e de baixo custo, pois foi constru?do a partir de um reservat?rio de polietileno para armazenamento de ?gua, com volume de 150 e 200 litros. Ser?o apresentados dados de efici?ncia t?rmica, perda t?rmica, temperatura da ?gua do reservat?rio t?rmico no final do processo e de simula??o de banhos para uma resid?ncia com quatro moradores. Ser?o demonstradas as viabilidades t?rmica, econ?mica e de materiais do coletor proposto, cuja principal inova??o consiste na utiliza??o de materiais recicl?veis, latas de cervejas e refrigerantes para o aumento da temperatura da placa absorvedora
78

Intégration des systèmes à absorption solaire de petites puissances aux bâtiments - approche multifonction solaire : chauffage, ECS et rafraîchissement / Integration of low capacity solar absorption systems into buildings - a solar multifunction approach : heating, domestic hot water and cooling

Jabbour, Noel 30 September 2011 (has links)
L’introduction des nouvelles machines frigorifiques à absorption des petites puissances ouvre des nouvelles perspectives pour les systèmes solaires multifonction multi-source (SYSMFS) qui exploitent le potentiel de l’énergie solaire pour le chauffage, le refroidissement et la préparation de l’eau chaude sanitaire (ECS). Les systèmes solaires combinés (SSC), qui ont précédés les SYSMFS, manquaient néanmoins une procédure adaptée pour le dimensionnement de leurs composants principaux : le panneau solaire et le ballon solaire de stockage thermique. De point de vue de l’énergie et du coût d’investissement et d’exploitation, une méthode de dimensionnement basée sur le pic de charge ne conviendrait pas si la source d’énergie n’est pas garantie d’être stable dans le temps. Une optimisation des composants principaux par la simulation peut être alors une solution clef pour le dimensionnement optimal de SYSMFS. À partir des informations sur les SSC trouvées dans la littérature et celles de fabricant de la machine frigorifique, un schéma hydraulique initial a été élaboré pour un SYSMFS. La modélisation de ce schéma est complexe car des simulations et des modifications répétitives ont été nécessaires pour éliminer les problèmes potentiels de convergence de la solution. A partir de cette expérience, une méthodologie de conception assistée par simulation a été élaborée afin d’en profiter pour des modélisations similaires. En tant que telle, le modèle devrait être prêt pour la phase l’optimisation. Une étude paramétrique a été menée sur le modèle SYSMFS ; elle offre les donnés requises pour la comparaison des algorithmes d’optimisation qui sont testés par la suite. Le résultat de cette étude est une surface de réponse qui représente le coût du SYSMFS en fonction de la superficie du panneau solaire et du volume de stockage thermique du ballon solaire. Pour réduire le nombre des simulations requis par une étude paramétrique complète, l’utilisation d’un algorithme d’optimisation est nécessaire. Un algorithme basé sur le plan d’expérience (OptDOE) a été développé et sa performance est comparée avec celles d’un algorithme d’optimisation hybride sur une fonction de référence de Rosenbrock et sur le modèle SYSMFS. Comparé à l’algorithme hybride, OptDOE a montré une bonne performance. Le nombre de simulations est réduit et les valeurs optimales trouvées, par cette méthode, sont porches de celles de l’étude paramétrique L’OptDOE permet également de décrire le comportement du modèle SYSMFS au voisinage de l’optimum avec une fonction coût approximée. Cette information est importante surtout au cas où la fonction coût a la forme d’une vallée. Dans ce cas, des valeurs différentes de l’optimum donnent presque le même coût global. / The introduction of new low capacity absorption chillers opens new prospects for the multifunction multisource solar systems (MFSSYS) which exploit the full potential of the solar energy for heating, cooling and production of domestic hot water (DHW) purposes. The solar combisystems (SCS), which preceded the MFSSYS, lacked an adapted procedure for the sizing of their main components: the solar collector and the solar thermal storage tank. From the point of view of the energy and investment cost, a sizing method based on the peak load may fail if the energy source is not guaranteed to be stable. An optimization of the main components by simulation may be then a key solution for an optimal sizing of the MFSSYS. An initial hydraulic schematic is elaborated for the MFSSYS based on information found in the literature about the SCS and the data made available by the chiller manufacture. The modeling of this schematic is complex as redundant simulation and modification were necessary in order to eliminate the potential problems of solution convergence. From this experience, a method of simulation aided design is elaborated. Parametric runs were carried out on the MFSSYS model. They offer needed information for the comparison of the optimization algorithms which are tested later on. The outcome of these parametric runs is a response surface which represents the cost of the MFSSYS as a function of the solar collector surface area and the volume of the solar thermal storage tank. In order to reduce the number of simulations required by a complete parametric runs method, the use of optimization algorithm become a necessity. An optimization algorithm based on the design of experiments (OptDOE) is developed; its performance is compared with the one of a hybrid optimization algorithm in two cases: a reference function of Rosenbrock and the model of the MFSSYS. Compared to the hybrid optimization algorithm, OptDOE has showed good performance. The number of simulations is reduced and the optimized values, found by this method, are close to those of the parametric runs. The main advantage of OptDOE is to describe the behavior of the cost function in the neighborhood of the optimum. This information is valuable especially when the cost function has a valley-like form, which is the case for the systems we studied. In this case, the cost has approximately the same value for a large variation range of the optimized parameters.
79

Urban regeneration: Urban renewal through eco-systemic design

Cottle, Louis E 03 December 2003 (has links)
The systemic relationship between the human entity and its environment, under the constraint of its function, were used as the perfect example to design and create the systemic relationship of an urban regenerative building with its economical, environmental and social context in the Inner City of Pretoria. / Dissertation (MArch (Prof))--University of Pretoria, 2005. / Architecture / unrestricted
80

Studium tepelných poměrů a vhodných materiálů pro konstrukci energetického zásobníku pro dlouhodobé ukládání energie v podmínkách klimatu ČR / Study of thermal conditions and the appropriate materials for construction of the energy reservoir for long term storage in the conditions of climate CR

Bukvová, Veronika January 2018 (has links)
Presented work deals with appropriate ways of storing thermal energy and selection of materials for a high capacity storage unit. The thesis describes technologies currently used for long-term storage of thermal energy, the structural arrangement of the thermal unit, physical properties of the materials usable for construction of high-temperature storage units and the utilization of these materials. The thesis also describes the measuring procedure of the material characteristics and the method of evaluation. Size of the solar collector and the required volume of the storage for heat supplying of the selected building in the climatic conditions of the Czech Republic were designed.

Page generated in 0.0587 seconds