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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.
151

Stambiaplokščių gyvenamųjų namų modernizavimas Vilniaus mieste / The Modernization of Big Panel Residential Houses in the City of Vilnius

Stundžia, Dalius 11 June 2009 (has links)
Didėjant šiluminės energijos ir kuro sąnaudoms, jų taupymas darosi aktualus daugeliui vartotojų. Vis daugiau žmonių domisi energijos taupymo priemonėmis gyvenamuose namuose. Ne tik privačių namų, bet ir privatizuotų butų savininkai daugiabučiuose namuose besikurdami į bendriją, imasi konkrečių veiksmų pastatų šilumos nuostoliams mažinti. Jiems svarbi ne tik finansinė parama, bet ir techninė bei informacinė pagalba. Energijos suvartojimas pastatams šildyti priklauso nuo šalies klimato ypatumų, energetinių resursų įsigijimo galimybių ir kainų, statybos tradicijų ir aplinkosaugos reikalavimų. Energetinių sąnaudų mažinimas gyvenamiesiems pastatams šildyti svarbus ne tik ekonominiu, bet ir ekologiniu požiūriu. Namų modernizavimas pagerina gyvenimo komforto parametrus. Pastato modernizacijos tikslas – padaryti pastatą ekonomiškesnį, komfortiškesnį ir taip pailginti jo eksplotacijos laiką bei padidinti vertę. Šiame darbe pateikiami duomenys apie pastatų atitvarinių konstrukcijų defektus, jų įvertinimo būdus, pastatų šiluminės modernizacijos technologijas ir ekonominę naudą, tyrimų metodus, pastatų konstrukcijose vykstančius šilumos ir masės mainų procesus, įvertinus jų poveikį pastatui. Darbą suraro 97 puslapiai, 55 paveikslai, 11 lentelių, 43 literatūros šaltiniai, priedai. / With the increase of thermal energy and fuel costs, saving is becoming an important issue for many consumers. More and more people are taking an interest in energy – saving measures in their living quarters. Not only owners of private houses but private flat owners in a multi-storey block of flats when setting up a society/community tend to take concrete action to reduce heat losses. They take an interest not only in posssible financial support but also in technical and information assistance. The energy consumption for heating buildings depends on the specific factors of a given country, the possibilities of acquiring energy resources and its price, the building traditions and environmental requirements. Reducing energy costs for heating residential buildings is an important economical and environmental issue. Modernizing houses improves life quality standards. The aim of modernising a building – to make the building more economically efficient, more comfortable and to prolong its lifecycle also to increase its value. This paper presents data on box construction building defects, their assessment methods, thermal modernizing technology and economic benefits, research methods, the heat and mass exchange processes occurring in building constructions, having assessed their impact on the building. Thesis consist of: 97 p. text, 55 pictures, 11 tables, 43 bibliographical entries, references.
152

Combined solar and pellet heating systems for single-family houses : how to achieve decreased electricity usage, increased system efficiency and increased solar gains

Persson, Tomas January 2006 (has links)
In Sweden, there are about 0.5 million single-family houses that are heated by electricity alone, and rising electricity costs force the conversion to other heating sources such as heat pumps and wood pellet heating systems. Pellet heating systems for single-family houses are currently a strongly growing market. Future lack of wood fuels is possible even in Sweden, and combining wood pellet heating with solar heating will help to save the bio-fuel resources. The objectives of this thesis are to investigate how the electrically heated single-family houses can be converted to pellet and solar heating systems, and how the annual efficiency and solar gains can be increased in such systems. The possible reduction of CO-emissions by combining pellet heating with solar heating has also been investigated. Systems with pellet stoves (both with and without a water jacket), pellet boilers and solar heating have been simulated. Different system concepts have been compared in order to investigate the most promising solutions. Modifications in system design and control strategies have been carried out in order to increase the system efficiency and the solar gains. Possibilities for increasing the solar gains have been limited to investigation of DHW-units for hot water production and the use of hot water for heating of dishwashers and washing machines via a heat exchanger instead of electricity (heat-fed appliances). Computer models of pellet stoves, boilers, DHW-units and heat-fed appliances have been developed and the parameters for the models have been identified from measurements on real components. The conformity between the models and the measurements has been checked. The systems with wood pellet stoves have been simulated in three different multi-zone buildings, simulated in detail with heat distribution through door openings between the zones. For the other simulations, either a single-zone house model or a load file has been used. Simulations were carried out for Stockholm, Sweden, but for the simulations with heat-fed machines also for Miami, USA. The foremost result of this thesis is the increased understanding of the dynamic operation of combined pellet and solar heating systems for single-family houses. The results show that electricity savings and annual system efficiency is strongly affected by the system design and the control strategy. Large reductions in pellet consumption are possible by combining pellet boilers with solar heating (a reduction larger than the solar gains if the system is properly designed). In addition, large reductions in carbon monoxide emissions are possible. To achieve these reductions it is required that the hot water production and the connection of the radiator circuit is moved to a well insulated, solar heated buffer store so that the boiler can be turned off during the periods when the solar collectors cover the heating demand. The amount of electricity replaced using systems with pellet stoves is very dependant on the house plan, the system design, if internal doors are open or closed and the comfort requirements. Proper system design and control strategies are crucial to obtain high electricity savings and high comfort with pellet stove systems. The investigated technologies for increasing the solar gains (DHW-units and heat-fed appliances) significantly increase the solar gains, but for the heat-fed appliances the market introduction is difficult due to the limited financial savings and the need for a new heat distribution system. The applications closest to market introduction could be for communal laundries and for use in sunny climates where the dominating part of the heat can be covered by solar heating. The DHW-unit is economical but competes with the internal finned-tube heat exchanger which is the totally dominating technology for hot water preparation in solar combisystems for single-family houses. / <p>QC 20100916</p>
153

Gases combustíveis como alternativas à eletrotermia em aquecimento direto e calor de processo no setor industrial brasileiro / Fuel gases as alternatives to electrothermy in direct heating and process heat in the Brazilian industrial sector

Costa, Fernando Corner da 08 November 2013 (has links)
Este trabalho tem por objetivo analisar as perspectivas dos gases combustíveis como energia final para a obtenção de energia útil, em aquecimento direto (AD) e calor de processo (CP), identificando e quantificando potenciais como alternativa da eletrotermia. São comparados dois panoramas na avaliação das economias de energia primária pela substituição da eletrotermia: o primeiro considerando que a energia substituída oriunda de energéticos do parque gerador; e o segundo levando em conta que a redução se refletiu nas termelétricas. Para atingir este objetivo, o trabalho se inicia com uma revisão bibliográfica, onde são tratados os aspectos necessários para um melhor entendimento do texto, com os conceitos de eletrotermia, calor e termodinâmica, seguindo-se um capítulo destinado aos gases combustíveis, suas características e disponibilidade futura para a conversão. As informações básicas para a análise dos potenciais nos setores foram tomadas a partir do último Balanço de Energia Útil, além de trabalhos desenvolvidos no mercado industrial pelo autor. O trabalho discorre também sobre configurações tecnológicas usadas nas conversões, incluindo os custos envolvidos. Na conclusão, os cálculos mostraram que significativas economias de energia primária podem ser obtidas com a conversão da eletrotermia para gases combustíveis no setor industrial brasileiro, considerando a eletricidade produzida a partir de plantas termelétricas. / This paper aims to analyze the prospects of fuel gases as final energy in order to get useful energy in direct heating and process heat, identifying and qualifying potentials as the alternative of electrothermy. Two panoramas are compared in the evaluation of primary energy displacement: the first one considering the replaced energy coming from energy generating facilities and the second taking into account that the reduction was reflected in thermoelectric power plants. To achieve this goal, the work begins with a literature review which covers the aspects needed for a better understanding of the text, with the concepts of electrothermy, heat and thermodynamics, followed by a chapter intended for fuel gases, their characteristics and future readiness for conversion. The basic information for the analysis of potential sectors were taken for the last Useful Energy Balance, and work undertaken by the author in the industrial market. The paper also discourses about technological configurations used in conversions, including also the costs involved. In conclusion, the calculations showed that significant primary energy savings can be obtained through the conversion of electrothermy by fuel gases in the Brazilian industrial sector, taking into account the electricity produced from thermoelectric power plants.
154

Simulação e projeto de um sistema solar térmico para complemento energético no processo de cura de tabaco

Oliveira, Israel de 09 October 2014 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-03-30T18:22:27Z No. of bitstreams: 1 Israel de Oliveira.pdf: 2249672 bytes, checksum: 651678b57093fe8cfdec97b6e6da1274 (MD5) / Made available in DSpace on 2015-03-30T18:22:27Z (GMT). No. of bitstreams: 1 Israel de Oliveira.pdf: 2249672 bytes, checksum: 651678b57093fe8cfdec97b6e6da1274 (MD5) Previous issue date: 2014-01-31 / JTI Processadora de Tabaco do Brasil Ltda / Programa de Bolsas de Estudo Talentos Tecnosinos / O Brasil é um dos maiores produtores mundiais de tabaco de estufa e a região sul é a maior responsável por essa produção, principalmente o estado do Rio Grande do Sul. Uma das etapas do processo de beneficiamento desse produto é a secagem (cura) das folhas, que utiliza essencialmente lenha como fonte de energia. Esse trabalho apresenta um estudo dos aspectos energéticos que envolvem a cura de tabaco da espécie Virgínia, os resultados e análises das simulações realizadas no software TRNSYS, de um sistema solar térmico com aquecimento de água para complemento energético desse processo de cura. A partir de dados experimentais obtidos em processos de cura, foram definidos os parâmetros mais importantes para a determinação da carga térmica necessária e calculadas as perdas térmicas envolvidas. Os resultados apresentados pelas simulações mostraram que o sistema de energia solar proposto, atuando como fonte auxiliar de energia em uma estufa do tipo bulk, é capaz de atender completamente a carga térmica da primeira fase do processo de cura e contribuir com o aumento da temperatura na estufa necessário à cura dessa espécie de tabaco, gerando reduções no consumo de lenha do processo da ordem de 18 a 39 %, considerando que esse ocorra em um período de sete dias ensolarados no verão, na região de Santa Cruz do Sul-RS. / Brazil is one of the largest barn tobacco producers and the southern region is largely responsible for this production, especially the state of Rio Grande do Sul. One of the steps involved in this product’s processing chain is the leaves drying (curing), which essentially uses firewood as energy source. This work presents a study of the energy aspects involving the curing of Virginia tobacco, the results and analysis of simulations, using the TRNSYS software, of a solar thermal energy system with water heating to complement this curing process. From the experimental data obtained in curing processes, the most important parameters for the determination of thermal load were defined and the heat losses involved were calculated. The results presented by these simulations showed that the proposed solar energy system, acting as an auxiliary power source of a bulk type barn, can completely meet the thermal load of the first phase of the curing process and contribute to the increase of temperature in the barn necessary to cure this kind of tobacco, reducing 18-39 % the firewood consumption in the process, assuming a seven sunny days period during the summer at the region of Santa Cruz do Sul – RS.
155

Estudo numérico de características de escoamento e transferência de calor em coletor solar de tubo evacuado

Souza, Fábio Ricardo de Oliveira de 31 January 2013 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-07-15T13:18:20Z No. of bitstreams: 1 Fábio Ricardo de Oliveira de Souza.pdf: 10103280 bytes, checksum: 4e2fd0c8307348f7e9098749cafe8b73 (MD5) / Made available in DSpace on 2015-07-15T13:18:20Z (GMT). No. of bitstreams: 1 Fábio Ricardo de Oliveira de Souza.pdf: 10103280 bytes, checksum: 4e2fd0c8307348f7e9098749cafe8b73 (MD5) Previous issue date: 2013-01-31 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / Este trabalho apresenta um estudo numérico sobre características de escoamento e transferência de calor em tubo evacuado. A abordagem numérica foi realizada com o software comercial ANSYS-CFX. O modelo numérico adotado é tridimensional e é composto pelas equações da conservação da massa, quantidade de movimento e energia. A malha computacional é do tipo hexaédrica, com refinamento nas regiões de maiores gradientes térmicos e fluidodinâmicos. O modelo implementado foi validado com resultados numéricos da literatura e um estudo de caso foi realizado, considerando variações do ângulo de inclinação do tubo, da variação da taxa de transferência de calor para o tubo e da variação da temperatura da água proveniente do reservatório térmico. Também foram avaliadas duas hipóteses: uma considerando propriedades físicas da água constantes e a outra com propriedades variáveis com a temperatura. Comparações são apresentadas para campos de velocidade e temperatura, vazão mássica e números de Nusselt e de Reynolds. O comparativo entre os resultados obtidos com a hipótese de propriedades constantes, com aqueles obtidos com propriedades variáveis mostra diferenças significativas entre eles, apontando a importância do uso de propriedades variáveis neste tipo de simulação numérica. Os resultados dos estudos paramétricos indicam que o incremento da vazão mássica e da temperatura média de saída do fluido é diretamente proporcional ao incremento do ângulo de inclinação, da taxa de transferência de calor e da temperatura do reservatório térmico. / This work presents a numerical study on characteristics of flow and heat transfer in an evacuated tube. The numerical approach was performed with the commercial software ANSYS-CFX. The numerical model adopted is three-dimensional and consists of the mass, momentum and energy equations. The computational mesh is hexaedrical, with refinement in regions of higher thermal and fluid gradients. The implemented model was validated with numerical results of literature and a case study was conducted considering inclination angle, rate of heat transfer and water temperature from the thermal reservoir. Also were evaluated two hypotheses: one considering constant physical properties of water and the other with properties varying with temperature. Comparisons are presented for velocity and temperature fields, mass flow and Nusselt and Reynolds numbers. The comparison between the results obtained with the hypothesis of constant properties, with those obtained with variable properties, shows significant differences between them, pointing out the importance of using variable properties in this type of numerical simulation. The results of the parametric studies indicate that the increment of the mass flow and average temperature of the fluid is directly proportional to the inclination angle, the rate of heat transfer and the temperature of the thermal reservoir.
156

Simulação de um sistema de refrigeração por absorção com energia solar térmica para locais isolados

Souza, Ronaldo Bueno de 07 April 2015 (has links)
Submitted by Maicon Juliano Schmidt (maicons) on 2015-07-20T14:17:58Z No. of bitstreams: 1 Ronaldo Bueno de Souza.pdf: 1999281 bytes, checksum: 5dd2b3645a9e4750a12f291e30ba6d41 (MD5) / Made available in DSpace on 2015-07-20T14:17:58Z (GMT). No. of bitstreams: 1 Ronaldo Bueno de Souza.pdf: 1999281 bytes, checksum: 5dd2b3645a9e4750a12f291e30ba6d41 (MD5) Previous issue date: 2015-04-07 / CYTED - Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo / Este trabalho apresenta o estudo de um sistema de refrigeração por absorção assistido por energia solar térmica com intuito de ser empregado no arrefecimento de uma pousada de ecoturismo localizada em um local remoto, desprovida de conexão à rede elétrica. Para o estudo do sistema proposto foi utilizado o software de simulações TRNSYS, onde em uma etapa inicial do trabalho foi realizada a comparação dos resultados do software com os resultados dos modelos matemáticos dos componentes do sistema de refrigeração. Foi desenvolvido um modelo computacional, para realização de simulações horárias que permitiu a simulação de três configurações de sistemas de refrigeração por absorção, podendo assim determinar a influência dos componentes e parâmetros utilizados no sistema no uso da energia auxiliar e no atendimento da carga térmica. O primeiro modelo é constituído por um sistema onde a água aquecida pelo coletor solar térmico e é armazenada em um reservatório térmico, sendo a mesma utilizada para a alimentação do chiller de absorção. A água gelada produzida pelo chiller é armazenada em outro reservatório térmico onde fica disponível para o consumo. Neste modelo observa-se que com o uso de 120 m² de coletores de tubo evacuado chega-se a índices de atendimento dos consumos superiores a 87 %. O segundo modelo é similar ao primeiro, com a inclusão de um aquecedor auxiliar para a água de alimentação do chiller de absorção. Neste modelo observou-se que com o uso de 120 m² de coletores de placas planas chega-se a um consumo de energia auxiliar inferior a 195 GJ, e com o uso de 120 m² de coletores de tubo evacuado chega-se a um consumo de energia auxiliar inferior a 150 GJ. O terceiro modelo é similar ao segundo, onde foi acrescentado um sistema para utilização da água de arrefecimento do chiller de absorção, para uso no consumo de água quente para banho, nos chuveiros. Neste modelo observa-se que o aproveitamento da água de arrefecimento não afeta o consumo de energia auxiliar, se comparado com o consumo do segundo modelo. / This paper presents the study of a cooling system for absorption assisted by solar energy with a view to be used in the cooling of an ecotourism lodge located in a remote location, devoid of connection to the grid. To study the proposed system was used TRNSYS simulation software, where in an initial work step of comparing software results with the results of mathematical models of the components of the refrigeration system is performed. A computer model was developed to perform simulations slot which simulated three configurations absorption refrigeration systems and can therefore determine the influence of the components and system parameters used in the auxiliary power usage and meet the thermal load. The first model is made up of a system where the water heated by the solar thermal collector and is stored in a thermal storage tank, being the same used for feeding the absorption chiller. The chilled water produced by the chiller is stored in another thermal reservoir where it is available for consumption. In this model it is observed that with the use of 120 m² evacuated tube collectors comes to fuel consumption attendance rates of over 87 %. The second model is similar to the first, with the inclusion of an auxiliary heater to supply water from the absorption chiller. In this model we found that with the use of 120 m² of flat plate collectors comes to an auxiliary power consumption of less than 195 GJ, and with the use of 120 m² evacuated tube collectors we arrive at a consumption of auxiliary power less than 150 GJ. The third model is similar to the second, which was added to a system using the cooling water from absorption chiller for use in the consumption of hot water for baths, showers on. In this model, it is observed that the use of the cooling water does not affect the auxiliary power consumption compared with the consumption of the second model.
157

Solar Power for Deployment in Populated Areas

Hicks, Nathan Andrew 01 June 2009 (has links)
The thesis presents background on solar thermal energy and addresses the structural challenges associated with the deployment of concentrating solar power fields in urban areas. Two potential structural systems and urban locales of deployment are proposed and investigated to determine whether they have the potential to be a cost-effective renewable energy solution for urban areas. The structural issues explored in the thesis include flutter, the wind loading of open frame structures, performance-based design, and the design of flexibly mounted equipment on a building.
158

Optically Selective Surfaces in low concentrating PV/T systems / Optiskt selektiva ytor i lågkoncentrerande PV/T-system

Morfeldt, Johannes January 2009 (has links)
<p>One of the traditional approaches to reduce costs of solar energy is to use inexpensive reflectors to focus the light onto highly efficient solar cells. Several research projects have resulted in designs, where the excess heat is used as solar thermal energy.</p><p>Unlike a solar thermal system, which has a selective surface to reduce the radiant heat loss, a CPV/T (Concentrating PhotoVoltaic/Thermal) system uses a receiver covered with solar cells with high thermal emittance.</p><p>This project analyzes whether the heat loss from the receiver can be reduced by covering parts of the receiver surface, not already covered with solar cells, with an optically selective coating. Comparing different methods of applying such a coating and the long-term stability of low cost alternatives are also part of the objectives of this project.</p><p>To calculate the heat loss reductions of the optically selective surface coating a mathematical model was developed, which takes the thermal emittances and the solar absorptances of the different surfaces into account. Furthermore, a full-size experiment was constructed to verify the theoretical predictions.</p><p>The coating results in a heat loss reduction of approximately 20 % in such a CPV/T system and one of the companies involved in the study is already changing their design to make use of the results.</p>
159

Utvärdering av energibesparingspotential vid tillämpning av värmepump i diskmaskin : OBS! Sekretessbelagd tills vidare / Evaluation of energy saving potential by the applicatin of a heat pump in a dishwasher

Joensen, Mortan, Nilsson, Maja January 2009 (has links)
<p>För ett genomsnittligt småhus i Sverige idag går ca 5000 kWh till hushållsel. Av dessa 5000 kWh går 7% till att driva diskmaskiner. Effektiviseringen av diskmaskiner har framförallt strävat efter en låg vatten- och energianvändning, en kort processtid samt en effektiv rening av disken.</p><p>Det finns dock gränser för hur effektiva diskmaskinerna kan göras med traditionell teknik. Därför har producenter under de senaste åren börjat se sig om efter mindre traditionella metoder som till exempel bruket av en värmepump för att få ned energiförbrukningen.</p><p>Syftet med det här examensarbetet har varit att ta fram systemlösningar för värmepump i diskmaskin samt att utvärdera energibesparingspotentialen i denna tillämpning.</p><p>Målet har varit att ta fram och beskriva de möjliga systemlösningar som uppstår vid en idégenerering. Att välja ut två lösningar för närmare undersökning, att bestämma en lämplig kompressoreffekt samt att beräkna energibesparingen dessa lösningar ger.</p><p>En litteraturstudie har gjorts av teknik och tillämpningar inom området, som till exempel värmeväxlaranvändning i diskmaskiner samt användandet av värmepumpar i andra vitvaror. Denna litteraturstudie följdes upp av en idégenerering, som tar hänsyn till möjliga värmekällor och –sänkor. Idégenereringen gav upphov till två systemlösningar som modellerades i MATLABs Simulink för att en lämplig kompressoreffekt och storleken på energibesparingen skulle bestämmas.</p><p>De två utvalda lösningarna ifrån idégenereringen var utomhusluftlösningen, där värme hämtas från uteluften och energilagerlösningen, där värme hämtas ur ett energilager. I båda lösningarna överförs värmen till det kalla ingående vattnet.</p><p>Energiåtgången för utomhusluftlösningen var beroende av köldmediets förångningstemperatur och modellering av lösningen visade att energiåtgången var 0,25 kWh vid en förångningstemperatur på -10°C, och 0,18 kWh vid 5°C. Vid modellering av energilagerlösningen påvisades en energiåtgång på 0,23 kWh. Slutsatsen som drogs var att kompressorn vid energilagerlösningen skall leverera en effekt på 240 W till köldmediet.</p> / <p>For an average detached house in Sweden today about 5000 kWh are used for household electricity. Of these 5000 kWh 7% are used to run dishwashers. The streamlining of dishwashers has above all strived for a lower water and energy use, a short process time along with a more efficient cleaning of the dishes.</p><p>There are however limits for how efficient the dishwashers can be made with traditional technology and acceptable costs. Therefore producers have, during recent years, started looking for less traditional methods, for example the use of a heat pump to reduce the energy use.</p><p>The purpose of this examination work has been to find system solutions for an application of a heat pump in a dishwasher and to evaluate the possible energy saving for each solution.</p><p>The goal has been to find and describe possible system solutions, which came up during the idea generation. To choose some of these for a closer investigation, to decide a fitting mechanical power for the compressor and to calculate the energy saving these solutions give rise to.</p><p>The method has consisted of a literature study, an idea generation, which takes the heat sources and sinks in consideration and a modelling in MATLAB’s Simulink of the selected solutions from the idea generation, which has been used to fit a mechanical power for the compressor.</p><p>The result of the idea generation was two solutions, an outdoor air solution, which collects heat from the outdoor air and gives it to the cold water which enters the machine and a energy storage solution, which collect heat from a heat stock to give to the cold entering water. A modelling of these show an energy usage of 0,24 respectively 0,17 kWh for the outdoor air solution, with a heat source temperature at 10 °C respectively 5°C and a energy usage of 0,22 kWh for the energy storage solution for one round.</p><p>The conclusion that was drawn was that the compressor of the energy storage solution should deliver a mechanical power of 240 W to the refrigerant.</p>
160

Study into the Potential and Feasibility of a Standalone Solar-Wind Hybrid Electric Energy Supply System

Bekele, Getachew January 2009 (has links)
The tendency to use renewable energy resources has grown continuouslyover the past few decades, be it due to fear over warnings of globalwarming or because of the depletion and short life of fossil fuels or evenas a result of the interest which has developed among researchers doingscientific research into it. This work can be considered as joining any ofthese groups with an objective of giving electric light to the poorpopulation living in one of the poorest nations in the world.The aim of the work is to investigate supplying electric energy fromsolar-wind hybrid resources to remotely located communities detachedfrom the main grid line in Ethiopia. The communities in mind are one oftwo types; the first is the majority of the poor population residing in thecountryside; and the other is people relocated by the Government fromthe over used and dry regions to relatively productive and fertile ones inline with the long-term poverty reduction plan.The work was begun by investigating wind energy and solar energypotentials at four geographically different locations in Ethiopia bycompiling data from different sources and analyzing it using a softwaretool. The locations are Addis Ababa (09:02N, 038:42E), Mekele (13:33N,39:30E), Nazret (08:32N, 039:22E), and Debrezeit (8:44N, 39:02E).The results related to wind energy potential are given in terms of themonthly Average wind speed, the wind speed probability densityfunction (PDF), the wind speed cumulative density function (CDF), thewind speed duration curve (DC), and power density plots for all fourselected sites. According to the results obtained through the analysis, thewind energy potential, even if it is not exceptional, is irrefutably highenough to be exploited for generating electric energy.The solar energy potential, based on sunshine duration data collectedover a period of 7 - 11 years and radiation data obtained from differentsources, has been calculated using regression coefficients specific to thesites in question. Based on the sunshine duration data, the monthlyaverage daily sunshine amount for each of the places has also beencomputed and given in a form of plot. Through additional work on theresults of the calculations, the solar energy potential has been given inthe form of solar radiation plots for each of the selected sites. Asexpected, the results indicated an abundance of solar energy potential.It is based on the promising findings of these two energy resourcepotentials, wind and solar, that the feasibility study for a standalonesolar-wind hybrid energy supply system has proceeded, targeting thecommunity mentioned earlier. The hybrid system consisted of Windturbine, Photovoltaic panel, diesel generator and a bank of batteries, witha power conditioning converter included in the system.The hybrid standalone supply system is intended to provide electricity toa model community of 200 families with five to six family members ineach. The community is equipped with a primary load, a deferrable load,a community school and a health post. An electric load which includeslighting, water pumping, a radio receiver, and some clinical equipmenthas been suggested. Hybrid Optimization Model for ElectricRenewables, HOMER, software has been used for the analysis. Theaverage wind speed and average solar radiation calculated from the datafor all of the selected sites has been used to input into the software.The hybrid system design is approached in three different ways. The firstapproach is to include within the hybrid system those components whichare locally available, without giving special attention to their efficienciesand proceed with the design work. The second approach is tothoroughly search the market for the best and most efficienttechnological products and to select the best components for theanalysis. A third approach considered in an attempt of cost minimizationis to see if a self-contained type of design can be a better solution. Whatthis means is every household will have its own supply system that mayconsist of any combination of PV and wind turbine including converter,battery and charge controller.After running the simulations, lists of power supply systems have beengenerated, sorted according to their net present cost. Sensitivity variables,such as range of wind speeds, range of radiation levels and diesel pricehave been defined as inputs into the software and the optimizationprocess has been carried out repeatedly for the sensitivity variables andthe results have been refined accordingly. / QC 20100623

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