• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 22
  • 15
  • 7
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 60
  • 60
  • 32
  • 22
  • 16
  • 15
  • 11
  • 10
  • 8
  • 8
  • 8
  • 7
  • 7
  • 7
  • 6
  • 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.
31

Addressing Water Scarcity in La Guajira: A Comparative Analysis of Four Water Systems

Hedstrand Welander, Johan January 2023 (has links)
During the recent prolonged drought in La Guajira, Colombia, the child mortality rate surged to 23.4 per 1000. With the focal point in rural Alta Guajira, a lack of rainfall and wind resulted in an acute potable water scarcity. This paper presents data gathered from interviews conducted with members of the Wayúu indigenous group residing in Alta Guajira and the results surveying in field the solutions already present to the water scarcity. Four potential technological solutions were then devised and evaluated in this context: wind-driven wells, solar-driven wells, solar stills, and reverse osmosis desalination systems. This study shows that reverse osmosis desalination systems are economically unfeasible due to their high initial investment. Solar stills are concluded to be potentially viable for drought emergencies but prohibitively expensive due to their low productivity and area requirements. Solar-driven wells frequently break in the region, likely due to inadequate insulation in underground electrical components, but they represent a crucial yet non-existent complement for water production. Wind-driven wells are the most prominent water source, although relying solely on these creates significant risks. Hence a suggestion for mainly wind-driven production, complemented with solar-driven production, and backed by emergency systems of manual wells and solar stills is suggested.
32

Design and Analysis of Cooling Methods for Solar Panels

Palumbo, Adam M. January 2013 (has links)
No description available.
33

Dimensionering av ett verktygslöst profilsystem för solpaneler / Dimensioning of a tool free profile system for solar panels

Franzén, Sebastian, Ramstedt, Martin January 2016 (has links)
Arbetet dimensionerar ett panelsystem för att motstå yttre påfrestningar som snö och vind, samtidigt som att det ska erbjuda oförstörande av- och påmontering. Hållfasthetsberäkningar har utförts med hjälp av statiska balkfall. Dimensionering av spår, snäppfunktion och låsningar i profilsystemet har utförts. Konstruktionsritningar har utförts, baserade på dimensionering och standarder. Med hjälp av detta arbete går det att tillverka detta system, åtminstone i ett prototypstadie. / This work dimensions a panel system to withstand external loads such as snow and wind, while it will offer non-destructive removing and assembly. Strength calculations have been performed using static beam cases. The design of the track, the snap-fit assembly and locks in the profile system has been changed. Construction drawings have been made, based on the calculated dimensions and required ISO-standards. With the existing work, it is possible to manufacture this system, at least in a prototype stage.
34

Energieffektivisering och energibalansberäkningar samt förbättrings förslag på nyproducerade lägenheter.

Sheibani, Amjad January 2017 (has links)
Syftet: Med arbetet är att utreda en fastighets klimatskal och energiförbrukning med hjälp av energibalansberäkningar. Målet: med rapporten är att upplysa hur fastighetens energiförbrukning kan beskrivas utifrån transmission och ventialtionsberäkningar. Avgränsning: avgränsning till att beräkna energibalanser till en fastighet som består av 46 lägenheter och nästan alla beräkningar är manuella, där energiförbrukningen beräknas. Detta ger en bra överblick över vad som behövs förbättras i dessa lägenheter. Teori: Information om fatigheten samlades in vid ett platsbesök där både in- och utsida undersöktes samt via samtal med företaget PEPA som byggde fastigheten. En ytterligare undersökning gjordes där information om området, byggår, tidigare års energideklarationer och energiberäkningar insamlades samt vilka energibesparingsåtgärder som gjorts i dagsläget. Med hjälp av litteratur, webbaserade källor och artiklar har arbetat granskat och bearbetat till ett sakligt slutresultat. Metod: En studie av litteratur undersökning i ämnet har utförts för att hitta relevant och nödvändig information inom området. För att undersöka fastighetens energianvändning, uppvärmning och konstruktion så har ett flertal fastighetsbesök gjorts. Utförande: Har undersöks fastighetens energiförbrukning och med hjälp av energibalansförbrukningen upplysas fastighetens elanvändning, fjärrvärme, tappvarmvatten, transmissionsförluster och ventilationsförluster etc. Denna studie har gjorts för att utreda investeringskostnader för solceller på fasader och på taket på en byggnad. Dessutom har studien utförs för att se om dessa bidrar till att minska fastighetens årskostnader och energiförbrukning under ett år. Resultat: I resultatdelen visas transmissionsförluster med ett värde på 330 MWh/år och köldbryggor som är 20 % av totala transmissionsförluster. Medan ventilationsförluster är 270 MWh, där luftläckage är 379 W/C. Sammanställningen av U-värde för transmissionsförluster är 0,35 W/m2. C och boverkets krav 0,4 W/m2.C, detta innebär att U-värde uppfyller boverkets krav. Värmeenergi behovet till fastigheten är 647 MWh, medan värmeeffektbehov är 228 kW, där energianvändningen och gränsvärde är 103 kWh/m2.år Diskussion: Syftet med arbetet var att studera och titta närmare på vilka energieffektiviserande åtgärder som finns till huset och vilka åtgärder som kan ge ett bra resultat, för att minska energi förbrukningen och ge besparing. Undersökningen har utförts genom manuella beräkningar, via samtal med personal från HSB på plats i Östersund och Sundsvall. Undersökningen har även utförts genom att samla in alla byggnadsritningar, genom kurslitteratur, Boverket, ISO standard samt genom diskussioner med företag som PEAB som har bidragit med viktig information. Ett schablonblad som erhölls av HSB har används vid beräkningar som exempelvis till dörrar, fönster, ytterdörrar, balkonger samt köldbryggor Slutsats: Transmissionsberäkningarna visar att värmegenomgångskoefficienten har ett rimligt värde, vilket är bra i jämförelse med boverkets krav på 0,4 W/m²·K. Vidare visas det i rapporten att ventilationen som används i fastigheten är bra, då FTX system används och värmeåtervinning sker. En annan åtgärd i rapporten, är en beräkning som visar en sänkning av inomhus temperaturen och är på så sätt lönsam. Den sista åtgärden som har utförts är snålspolande kranar som visar ett bra reslutat på en besparing året runt. Solcellernas beräkningar visar två olika resultat, de som är belägna på taket har en livslängd på 12 år och är mer rimlig än de som är på fasaden som har livslängd på 30 år. / The purpose of the work is to investigate real estate climate scale and energy consumption using energy balance calculations. The goal of the report is to disclose how the energy consumption of the building can be described by transmission, air leakage and ventilation calculations. And where you make an energy balance calculations to the real estate. The work delimited to calculate energy balances for a house consisting of 46 apartments and almost all calculations are manual calculations where energy consumption is calculated which gives a good overview of what is needed to improve in apartments. Information about the real estate was collected at a site visit where both inside and outside were investigated as well as conversations with the company PEPA that built the property. A further survey has been made where information about the area, year of construction, previous year's energy declarations and energy calculations was collected, as well as what energy saving measures have been taken today. With the help of literature, web-based sources and articles have been reviewed and processed into a true final result. Method: A study of literature research on the subject has been conducted to find relevant and necessary information in the field. To investigate the energy use, heating and construction of the property, several property visits have been made. This study has been conducted to investigate investment costs for solar on facades and on roofs of a building. In addition, the study has been conducted to see if these contribute to reducing the property's annual costs and energy consumption over an entire year. Results: Transmission losses are 330 MWh and cold bridges”köldbryggor” which are 20% of total transmission losses. While ventilation losses are 270 MWh, where air leakage is 379 W / C. Compilation of U value for transmission losses is 0.35 W/m2.C and energy agency requirements 0.4 W / m2.C, which means that the U value meets the requirements of the building. Heat energy the need for the property is 647 MWh, while the heat power requirement is 228 kW and energy consumption and limit value is 103 kWh / m2, year.   Discussion: The purpose of the work was to study and look into what energy efficiency measures are available to the house and what measures can provide a good result, to reduce energy consumption and save savings. The survey has been carried out through manual calculations, via talks with HSB staff in place in Östersund and Sundsvall. The survey has also been carried out by collecting all building drawings, through literature and the Boverket, ISO standard and through discussions with companies such as PEAB that have contributed with important information. Conclusion: The transmission calculations show that the heat transfer coefficient is a reasonable value, which is a good in comparison with the requirements of 0.4 W / m². K. Furthermore, the report shows that the ventilation used in the property is good when using FTX systems and heat recovery takes place. Another measure calculation performed in the report is a decrease in indoor temperature, which proves to be profitable. The last measure that has been carried out in the report is the fast-moving cranes that show a good deal of savings all year round. Sun cells calculations show two different results the first one sun cells those located on the roof have a life span of 12 years and are more reasonable while the another one those on the facade that have a life span of 30 years.
35

Estudo do ganho de energia elétrica em painéis fotovoltaicos usando rastreamento solar baseado em sistemas embarcados. / Study of increase in power generation in photovoltaic solar panels using solar tracking based on embedded systems.

Paula, Sérgio Eduardo Alves de 02 July 2015 (has links)
A geração de energia solar fotovoltaica tem crescido anualmente em utilização. Com o aumento dos custos de geração de energia elétrica, fontes renováveis de energia como essa crescem em interesse, até mesmo em aplicações residenciais de microgeração. Este trabalho apresenta o projeto, construção e ensaios de um rastreador solar autônomo, com controle e aquisição de dados de sensoriamento baseado em sistemas embarcados totalmente projetados e produzidos no país, com o objetivo de se aumentar o ganho de energia elétrica gerada a partir de painéis solares de mercado. O projeto do firmware de controle e os algoritmos utilizados foram adaptados continuamente até se atingir os melhores resultados. Foi utilizado um painel solar comum de mercado para realizar os testes, e as placas de circuito impresso projetadas foram confeccionadas localmente. A tomada de dados em diferentes ensaios mostrou que o rastreamento solar de fato aumentou o ganho de energia elétrica com um painel solar comum de mercado, mesmo com alguns problemas a serem corrigidos em uma próxima pesquisa. Assim, a pesquisa realizada confirmou o ganho de energia elétrica para o painel solar escolhido. / Photovoltaic solar generators have grown annually in use. With the increase in electricity generation costs, renewable sources of energy like that grow in interest, even in residential microgeneration applications. This work presents the design, construction and testing of a standalone solar tracker, with control and acquisition of sensors data based on embedded systems totally designed and produced in the country, aiming to increase the power generated from retail solar panels. The firmware design and used algorithms have been continuously adapted to achieve the best results. It was used a standard solar panel to perform the tests, and the designed printed circuit boards were manufactured locally. The data taken in different tests showed that the solar tracking actually increased the power generated with a standard solar panel, even with some problems in the design that have to be corrected in a future implementation. So the project was validated and can be used, including microgeneration in ordinary houses.
36

Projeto de carga eletrônica para caracterização de painéis fotovoltaicos. / Design of an electronic load for photovoltaic module characterization.

Hassem, Moreno Addad 19 May 2015 (has links)
A geração solar fotovoltaica em painéis de silício tem se destacado como uma maneira limpa e renovável de atender à demanda por energia elétrica. Este trabalho apresenta o projeto, construção e testes de um sistema autônomo para obtenção da curva IV e caracterização de painéis fotovoltaicos comerciais instalados em campo. Após um estudo do problema de medição de painéis solares, uma especificação da Solução foi concebida. Com base na especificação, foram realizados o projeto elétrico, a construção de protótipos, a escrita do software de medição e os testes de validação em laboratório. Para validação definitiva do hardware desenvolvido, foram realizados testes em campo utilizando um painel solar comercial. Após a tomada de dados e análise dos resultados, conclui-se que o dispositivo concebido atende aos requisitos especificados e cumpre sua proposta inicial. A metodologia empregada neste trabalho pode ser utilizada para geração de outros instrumentos com finalidade similar ou idêntica. / Photovoltaic solar generators, using silicon panels, have grown popular as a clean and renewable way to supply electrical energy. This work presents the project, construction and testing of an autonomous system for IV curve tracing and characterization of commercial photovoltaic panels deployed in the field. After a study how to properly measure solar panels, a Solution was put in a form of a specification. From specifications, the following phases took place: electrical project, prototype construction, software development and lab testing. To perform final validation of the developed hardware, a field test with a commercial solar panel was performed. After collecting and analyzing data from, it was concluded that the design fulfills the required specifications and intended goals. The methodology employed in this work and be utilized to generate other measuring instruments with similar or identical function.
37

Digital Control Of Solar Photovoltaic Converters

Srinath, R 12 1900 (has links)
A photo-voltaic system consists of solar cells, power converters, battery and the load. The power converter interfaces the solar cells, battery and the load. The battery serves to equalise the energy demand (load) and the energy supply (solar cell). Currently the solar cells and the battery cost nearly 90% of the system cost. A typical photo-voltaic system can adopt various power bus configurations. Battery tied bus is the simplest of the power bus configurations. In this topology, the battery is always attached to the bus. This system is extremely simple in terms of power circuit configuration as well as control. Such systems weigh less and are more reliable. However, the battery tied bus suffers certain disadvantages. The first among them is the poor utilisation of solar panels. The load has to tolerate the full swing of the battery voltage variation. On account of the constraint on the solar panel voltage, the solar panels may not be loaded to the maximum power capacity. Such operating conditions lead to gross under-utilisation of the expensive solar panels. The battery tied bus configuration is designed, built and evaluated experimentally with 4 solar panels rated at 35 W each and a lead acid battery of 12 V 42 AH rating. This thesis explores alternate power architecture to overcome the above limitations. Load regulation and maximum power harvesting from the solar panels are the objectives. In the proposed configuration, a bidirectional power converter is inserted between the bus and the battery. The bidirectional power converter operates in boost mode and charges the battery when the sunlight is available. During eclipse period, it operates in buck mode and meets the load demand. The maximum power is extracted from the panels by controlling the voltage across the solar panels. The bus voltage reference is computed by MPPT block and the bus voltage is regulated to the reference voltage through closed loop control. So the maximum power is extracted from the panels at the expense of extra bidirectional power converter. Even though there is an additional power loss due to the introduction of power converter, this power bus configuration is superior because it increases the output power from the panel itself. The entire control logic implementation is done digitally using dspic30F6010A. The simulation is done by writing script files in C language. The proposed bus configuration is designed, built and evaluated experimentally with the same setup and the results are then compared.
38

Simulering av ett elnät med hänsyn till förnybar energi : En studie av möjliga lösningar på problemet med fler elbilar i elnätet / Simulation of an electric grid with respect to renewable energy : A study of potential solutions to the problem with additional EVs in the electric grid

Maninnerby, Henrik January 2018 (has links)
The purpose of this thesis is to simulate different scenarios where all vehicles are replaced by electric vehicles in the future.   An addition of electric vehicles to the electric grid is not easy to handle, especially not if the consumers choose to charge their vehicles with higher power. As can be seen in the results of this report, flexible demand through power management is a good option to reduce overall power consumption. Of course, customers will have to agree to that their consumption is controlled in this manner.   Using solar cells during the summer works well, but it’s harder wintertime as the largest electric demands arise during the night, when there is close to no sunlight. However, in the case of batteries, they may be helpful. Possibly by letting the solar cells charge the battery during the day and then use it to help charge the electric vehicle during the night. Unfortunately, it was not possible to include this scenario as the used software was unable to handle batteries in that way.   By completely replacing the heat source, in this case with district heating, and thus releasing available power in the transformer, turned out to be the best option. In this way, virtually all predicted amounts of electric cars could be charged with optional charging strength between 3.7 and 11 kW.   As for the T422 transformer, there is no choice but to replace it if a larger number of electric vehicles wants to start charging there. At present, it can handle a maximum of 10-20 electric vehicles that charge at the lowest power as there is only about 50 kW available there winter time. District heating cannot be applied either as the connected customers do not use electric heating. / Detta arbete har till syfte att simulera olika scenarier i ett område där samtliga fordon ersätts av elbilar i framtiden.   En tillkomst av elbilar i elnätet är inte lätt att hantera, speciellt inte om kunderna i nätet väljer att ladda med högre effekt. Vilket kan ses i resultatet i denna rapport, är flexibel förbrukning genom effektstyrning ett bra alternativ för att sänka den totala effektförbrukningen. Fast det gäller då givetvis att kunderna går med på att förbrukningen styrs på detta sätt.   Att använda solceller fungerar bra sommartid, men vintertid är det värre, då det största elbehovet uppstår på natten, när det inte är lika stor solljustillgång. I samband med batterier kan de dock vara till hjälp. Möjligen genom att låta solcellerna ladda upp batteriet under dagen och sedan använda det för att hjälpa till att ladda elbilen under natten. Dessvärre var det inte möjligt att simulera detta scenario på grund av brister i mjukvaran som användes.   Att helt ersätta värmekällan, i detta fall med fjärrvärme, och därmed frigöra effekt i transformatorn visade sig däremot vara det bästa alternativet. På så sätt kunde i stort sett samtliga mängder elbilar laddas med valfri laddningsstyrka mellan 3,7 och 11 kW.   Vad gäller transformator T422, ses inget annat val än att byta ut den om ett flertal elbilar ska börja ladda där. I nuläget klarar den av högst 10-20 elbilar som laddar på lägsta effekt eftersom det endast finns ca 50 kV tillgängligt vintertid. Fjärrvärme kan inte användas där heller som komplement då de tillkopplade kunderna inte använder elektrisk uppvärmning.
39

Les freins sociaux à la diffusion des innovations : le cas des panneaux solaires photovoltaïques en France / The social barriers to the diffusion of innovations : the photovoltaic panels market in France

Lecordier-Ferlay, Marianne 25 June 2012 (has links)
Intérêt du sujet : Dans le domaine de la grande consommation, de nombreuses innovations échouent sur le marché européen. L’innovation étant une des variables clé du modèle économique des sociétés occidentales, l’identification des vecteurs de réussite ou d’échec des produits nouveaux est fondamentale pour le succès des entreprises. Parmi les trois groupes de déterminants de l’acceptation des produits nouveaux (les caractéristiques liées à la personne, au produit ou au système social), nous nous intéressons au dernier, jusque là négligé par la littérature.Objectif : Identifier les freins sociaux qui interviennent dans le processus de diffusion d’une innovation.Contribution attendue : Les apports théoriques attendus de ce travail doctoral sont triples :(1) la prise en compte de la théorie des représentations sociales pour la compréhension du comportement d’achat innovateur; (2) la détermination des éléments de la représentation sociale des panneaux solaires photovoltaïques et la mise en évidence d’une potentielle segmentation par la représentation; (3) et l’identification de freins potentiels à l’acceptation de produits nouveaux.Méthode : Deux études ont été menées : tout d’abord une étude de la représentation sociale des panneaux solaires photovoltaïques au travers de deux méthodes (n=97 et n=205) ; puis une étude des motivations à l’achat de panneaux solaires photovoltaïques par les récits de vie(n=16). Principaux résultats : Ce travail doctoral a permis de mettre en évidence trois freins à la diffusion des panneaux solaires photovoltaïques : (1) le changement social induit par l’acceptation de l’innovation; (2) la potentielle multiplicité des représentations sociales et le problème que cela engendre sur la communication interpersonnelle; (3) et le refus d’appartenance au groupe de référence perçu du produit nouveau. / Topic of interest: in the fast moving consumer good, many innovations fail to introduce the European market. Innovation is a key variable in the economic model of Western societies,therefore identifying the success or the failure antecedents is crucial for the company’s success. Among the three groups of antecedents of the acceptance of new products(personal, product and social characteristics), we will focus on the last one, which has been neglected in the diffusion literature.Objective: Understanding the social barriers which intervene in the innovation diffusion process.Contribution expected: The expected theoretical contributions are threefold: (1) introducing the social representation’s theory to understand the innovative consumer behavior; (2)determining the photovoltaic solar panels’ social representation’s association and highlighting a potential segmentation through the social representation; and (3) identifying the potential barriers to innovation acceptance.Method: Two studies were conducted: first, a study on the social representation of photovoltaic solar panels using two methods (n=97 and n=205); then a study on the motivation in installing photovoltaic solar panel using life stories (n=16)Main results: This doctoral work highlight three barriers to photovoltaic solar panels diffusion: (1) the social change induced by the innovation’s acceptance; (2) the potential multiplicity of the social representations and the way it affects the interpersonal communication;
40

Estudo do ganho de energia elétrica em painéis fotovoltaicos usando rastreamento solar baseado em sistemas embarcados. / Study of increase in power generation in photovoltaic solar panels using solar tracking based on embedded systems.

Sérgio Eduardo Alves de Paula 02 July 2015 (has links)
A geração de energia solar fotovoltaica tem crescido anualmente em utilização. Com o aumento dos custos de geração de energia elétrica, fontes renováveis de energia como essa crescem em interesse, até mesmo em aplicações residenciais de microgeração. Este trabalho apresenta o projeto, construção e ensaios de um rastreador solar autônomo, com controle e aquisição de dados de sensoriamento baseado em sistemas embarcados totalmente projetados e produzidos no país, com o objetivo de se aumentar o ganho de energia elétrica gerada a partir de painéis solares de mercado. O projeto do firmware de controle e os algoritmos utilizados foram adaptados continuamente até se atingir os melhores resultados. Foi utilizado um painel solar comum de mercado para realizar os testes, e as placas de circuito impresso projetadas foram confeccionadas localmente. A tomada de dados em diferentes ensaios mostrou que o rastreamento solar de fato aumentou o ganho de energia elétrica com um painel solar comum de mercado, mesmo com alguns problemas a serem corrigidos em uma próxima pesquisa. Assim, a pesquisa realizada confirmou o ganho de energia elétrica para o painel solar escolhido. / Photovoltaic solar generators have grown annually in use. With the increase in electricity generation costs, renewable sources of energy like that grow in interest, even in residential microgeneration applications. This work presents the design, construction and testing of a standalone solar tracker, with control and acquisition of sensors data based on embedded systems totally designed and produced in the country, aiming to increase the power generated from retail solar panels. The firmware design and used algorithms have been continuously adapted to achieve the best results. It was used a standard solar panel to perform the tests, and the designed printed circuit boards were manufactured locally. The data taken in different tests showed that the solar tracking actually increased the power generated with a standard solar panel, even with some problems in the design that have to be corrected in a future implementation. So the project was validated and can be used, including microgeneration in ordinary houses.

Page generated in 0.0392 seconds