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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.
81

Оптимизация толщины изоляции теплопровода при канальной прокладке : магистерская диссертация / Optimization of insulation thickness of the heat pipe laid in the channel

Осипов, Р. В., Osipov, R. V. January 2019 (has links)
Диссертация посвящена исследованию проблемы нерационального использования теплоизоляционного слоя при канальной прокладке трубопроводов в непроходных каналах. Определены все термические сопротивления тепловому потоку различных составляющих теплотрассы. Спрогнозированна примерная окупаемость теплоизолируещих слоев различной толщины. Выявлена наиболее оптимальная толщина теплоизолируещего слоя. Для более точного определения теплопотерь трубопроводов в непроходном канале, в программном коплексе ANSYS® построена модель поперечного сечения теплотрассы. Выявлен режим свободной конвекции внутри канала. Смоделированы поля распределения скорости и температуры для сеток различного качества при различных моделях турбулентности. / The thesis is devoted to the study of the problem of the irrational use of the heat-insulating layer in the channel laying of pipelines in impassable channels. All thermal resistance to the heat flux of various components of the heating main are determined. The estimated payback of heat-insulating layers of various thicknesses is predicted. The most optimal thickness of the insulating layer was revealed. To more accurately determine the heat loss of pipelines in a non-passage channel, a cross-sectional model of a heating main has been built in ANSYS®. The mode of free convection inside the channel is revealed. The velocity and temperature distribution fields are simulated for grids of various quality with various turbulence models.
82

Valuation in the energy storage sector - an investor perspective

Vasanoja, Oliver, Volpe, Alessandro January 2023 (has links)
This study will examine a strategy for evaluating energy storage projects by integrating valuation metrics from finance and the energy sector. Uncertainty is one of the key barriers to investment in the energy sector (Shimbar & Ebrahimi, 2017, p. 349) and therefore financial modeling that allows comprehensive valuation of energy investment is necessary (Berrada, 2022, p. 407). The purpose of the study is to propose a strategy for evaluating energy storage projects that applies to investors and decision makers.  LCOS is a necessary component of energy storage project valuation, as it considers both the financial and technical performance of energy storage systems (ESS). Existing research in the field has contradictory opinions regarding the usefulness of LCOS and traditional financial valuation models for investment decisions in the energy storage sector. Few studies have combined modeling from the financial and energy sector. The authors have identified a need to introduce an investor perspective to business research in the energy storage sector. The authors conduct an explorative mixed-method study with an underlying non-positivist philosophical position. The case study design includes creation of five hypothetical energy storage projects to simulate an investment scenario. The authors utilize a point-base system to integrate valuation models from the energy and financial sectors, which include NPV, IRR, payback period, LCOS and technological maturity. Experts in the field provide input for which metrics are emphasized by practitioners. The projects are ranked based on stand-alone metrics, an integrated model and expert opinion. The results indicate that integrating numerous valuation metrics is necessary for analyzing and comparing energy storage investments. The financial viability of projects change based on individual metrics and integrated financial models. Furthermore, the results indicate that LCOS should be reinforced by financial indicators when making investment decisions. The expert input shows that investors emphasize valuation metrics differently, which indicates that the economic attractiveness of energy storage projects varies among investors. IRR is used by practitioners as a primary indicator for profitability. Future research should investigate a method for including sustainability indicators in the valuation process. Furthermore, as data accessibility is an issue in the field of study, future studies should collaborate with practitioners to generate more secondary data sources. Lastly, the impact of discount rates, risk premiums and investor preferences should be researched to better understand investment in the sector.
83

How to reduce the total environmental, economic and social impact of Solar Cell Panels / Möjligheterna att minska de miljömässiga, finansiella och sociala kostnaderna för solcellspaneler

Nilsson, Amanda, Orrenius, Nora January 2021 (has links)
To be able to mitigate the climate change and disasters that will come with it and to ensure economic growth, there is a need for change. A good start is more renewable energy and less harmful emissions. It is known that solar energy is sustainable and made from an endless source, the sun. However, it is not known how much impact the photovoltaic solar panels have through its entire lifecycle, from extraction of raw materials to End of Life management. This study has investigated photovoltaic solar panels' full life cycle to see how sustainable they really are. Including where the biggest opportunities for improvement of environmental, financial and social sustainability within the value chain is found. The results have been obtained by conducting a literature study, interviews with people with expertise of different parts of the value chain and finally calculations have been made to compare and visualize the findings. Two main ways to improve the PV panels’ negative impact in terms of environmental, financial and social sustainability have been established. Firstly, the study suggests the importance of implementing advanced recycling within the value chain. Recycling a high percentage of materials in the PV panel, and reusing the recovered material in production will decrease the energy consumption and harmful emissions significantly, alongside increasing circularity of critical materials and bring both financial and social benefits. Secondly, moving the better part of the production to Europe from China would also decrease the negative impact of the PV panels, especially the environmental and social impact, the study could however not find sufficiently good arguments for financial improvement to move the production to Europe. To be conclusive, this subject would need further studies. / För att kunna lindra klimatförändringar och de medföljande katastroferna och säkerställa den ekonomiska tillväxten finns det ett stort behov av förändring. En bra start är att använda mer förnybar energi och som bidrar till färre skadliga utsläpp. Det är känt att solenergi är hållbart med bränsle från en oändlig källa, solen. Det är emellertid inte känt hur stor påverkan solcellspanelerna har under hela dess livscykel, från utvinning av råvaror till dess panelens liv är över. Denna studie har undersökt solcellspanelernas hela livscykel för att se hur hållbara de egentligen är. Studien har även studerat var de största möjligheterna för förbättring av miljömässig, finansiell och social hållbarhet inom värdekedjan finns. Resultaten har erhållits genom att genomföra en litteraturstudie, intervjuer av personer med expertis inom olika delar av värdekedjan och slutligen har beräkningar gjorts för att jämföra och visualisera resultaten. Två huvudsakliga sätt att förbättra solpanelernas negativa påverkan när det gäller miljömässig, ekonomisk och social hållbarhet har identifierats. För det första föreslår studien vikten av att implementera avancerad återvinning inom värdekedjan. Återvinning av en hög andel material i solcellspanelen och återanvändning av det återvunna materialet i produktionen kommer att minska energiförbrukningen och skadliga utsläpp avsevärt samt förbättra cirkuläriteten av kritiska material och medföra både ekonomiska och sociala fördelar. För det andra skulle förflyttning av den större delen av produktionen till Europa från Kina också minska de negativa effekterna av solcellspaneler, särskilt de miljömässiga och sociala effekterna, studien kunde dock inte hitta tillräckligt med goda argument för att en förflyttning av produktionen till Europa skulle leda till en ekonomisk förbättring. För att detta ska vara avgörande skulle detta ämne behöva ytterligare studier.
84

Counter Rotating Axis Floating Tilting Wind Turbine : Cost and Efficiency analysis of the Secondary electric machine

Nordin, Emelie, Carredano Robertsson, Alicia January 2024 (has links)
Floating offshore wind turbines show great potential within the energy industry, especially for deeper waters where traditional fixed-bottom turbines cannot be used. Offshore locations also offer stronger and more stable winds compared to onshore locations. The study explores the impact of the secondary machine efficiency on the electricity production in a Counter Rotating Axis Floating Tilting (CRAFT) wind turbine. The counter-rotating design holds promise for achieving high overall system efficiency.  MATLAB simulations show that it is possible to maintain a lower secondary machine efficiency without compromising stability. Reviewing two control systems confirms that using a robust control algorithm with optimized TSR ensures system stability in both high and low winds. A decrease in secondary electric machine efficiency from 97% to 93% resulted in a 0.03% reduction in annually generated electricity, whereas a similar decrease in primary electric generator efficiency led to a 1% reduction instead. Decreasing the secondary machine efficiency further to 83% resulted in a 0.1% reduction in annual generated electricity. Thus, the secondary machine's efficiency is shown to be less critical for the electricity production than the primary generator’s efficiency.  Choosing an asynchronous over a synchronous option as the secondary machine is economically advantageous since its lower efficiency of 83% instead of 97% does not significantly affect the electricity production. Moreover, the lower magnet cost for the asynchronous machines positively impacts economic metrics like LCoE, NPVI and payback period, making the asynchronous generator a more favourable economic choice. Further research areas to obtain higher accuracy include integrating differences in maintenance costs and conducting a more in-depth assessment of the investment costs associated with the two types of generators. Additionally, considering airflow losses around turbine blades and airflow interaction amongst the turbines could further enhance the model accuracy.
85

Investeringsbeslut avseende ett Automated Guided Vehicles system : En fallstudie genomförd på Atea Logistics AB angående under vilka förutsättningar det är lönsamt att investera i ett Automated Guided Vehicles System. / Investment decision for an Automated Guided Vehicles system : A case study conducted at Atea Logistics AB regarding the conditions under which it is profitable to invest in an Automated Guided Vehicles System.

Olsson, Astrid, Ivarsson, Aldina January 2024 (has links)
Bakgrund: I och med den ständiga utvecklingen beträffande hanteringen av internaprocesser har automatisering av aktiviteter för lager- och materialhantering ökat. Maskiner som verkar automatiskt benämns som Automated Guided Vehicles, vilket förkortas AGV, därdess utökade användningsområde inom interna processer har ökat avsevärt. Innebörden av AGV-system har genererat omfattande förbättringar av prestanda, däribland produktivitetsförbättringar. Grunden till produktivitetsförbättringarna innefattas av aspektersom att reducering av flaskhalsar samt att nedskärning vid beroende av mänsklig hantering. Syfte: Uppsatsens syfte är att studera möjligheter och utmaningar avseende om det är aktuellt för Atea Logistics AB med en implementering av ett AGV-system för interna processer ideras internlogistikområde. Därutöver är syftet att analysera och presentera vilka förutsättningar som kan påverka lönsamheten för en distributör vid en implementering av ett AGV-system för interna processer i verksamhetens interna logistikområde. Metod: Metodvalen i studien grundar sig i ett kvalitativt tillvägagångssätt till studiensinledande forskningsfråga. Därefter har en kvantitativ forskningsmetod applicerats för att tillämpa uppsatsens andra forskningsfråga. Med avsikt att erhålla en bred omfattning beträffande datainsamlingen har både primär- respektive sekundärdata inhämtats. För att skapa ett välgrundat resultat har det teoretiska materialet studerats i förhållande till det empiriska underlaget. Resultat: Baserat på ett flertal variabler för prestanda diskuteras implementeringen av ett AGV-system hos Atea utifrån lönsamhet. Resultatet visade att det finns flera utmaningar samt möjligheter vid genomförandet av implementeringen, dock visar slutsatsen att det inte är genomförbart för Atea att implementera ett AGV-system med de resurser de har i nuläget. Med utgångspunkt i att studera lönsamheten för liknande distributionsföretag beträffande implementering av ett AGV-system visade det att variabler i form av lönekostnader,investeringskostnaden, transporttid för bingar och väntetid är aspekter som är nödvändigt att ta i beaktning vid investeringen. / Background: With the constant evolution of the management of internal processes, the automation of warehouse and material handling activities has increased. Machines that operate automatically are referred to as Automated Guided Vehicles, abbreviated as AGVs, where their extended use in internal processes has increased significantly. The adoption of AGV systems has generated widespread improvements in performance, including productivity improvements. The basis for productivity improvements includes aspects such as reducing bottlenecks and cutting dependence on human handling.  Purpose: The purpose of the thesis is to study opportunities and challenges regarding whether it is relevant for Atea Logistics AB to implement an AGV system for internal processes in their internal logistics area. In addition, the purpose is to analyze and present the conditions that can affect the profitability of a distributor when implementing an AGV system for internal processes in the company's internal logistics area.  Method: The basis for the methodological choices of the study relates to a qualitative approach to the initial research question of the study. Subsequently, a quantitative research method has been applied to address the second research question of the paper. In order to obtain a broad scope of data collection, both primary and secondary data have been collected. In order to create a well-founded result, the theoretical material has been studied in relation to the empirical data.  Results: Based on several performance variables, the implementation of an AGV-system at Atea is discussed in terms of profitability. The results revealed several challenges and opportunities associated with the implementation. However, the conclusion is that it is not profitable for Atea to implement an AGV-system with the resources they have today.  Based on studying the profitability of similar distribution companies regarding the implementation of an AGV-system, it was found that variables such as labor costs, investment costs, bin transport time and waiting time are aspects that are crucial to consider regarding the investment.
86

Analýza konkrétního investičního projektu - výstavba nové haly a kancelářských prostor / Analysis of a particular investment project - the construction of new buildings and office space

KOLBASKÁ, Lucie January 2010 (has links)
The thesis Analysis of a particular investment project - the construction of new buildings and office space is to evaluate the effectiveness of the investment options elected by the selected evaluation methods. Variants of investments are assessed by the average cost, modified pay-back period and modified the discounted pay-back period. In a further evaluation of options is determined the tax savings of each option and its impact on the total cost of investment. On the basis of all methods and procedures are selected one variant of the investment. Finally, evaluate the sustainability of the investment options selected in the operational phase.
87

Techno Economic study of Citizen Energy Communities among 5 case studies in the EU

Nair, Archana Babu, Boteju, Senali January 2024 (has links)
Energy communities are formed to create integrated regional energy market in EU and non- EU neighboring countries. It attracts investors in generation and energy networks as it comes up with new stable regulations, so that it will ensure the supply is stable and continuous. Five EU countries (Germany, Italy, Sweden, Greece, Austria) with different policies are selected and simulations are done. Economic analysis for the 5 countries is done based on simulation results. The selected 5 EU countries shows a good economic result; therefore, it can be recommended to implement energy communities and cities by developing the directives. By transposition of policies of the energy community and implementing more subsidies or incentive will make a better contribution for the citizen partnership for creating CEC.
88

Solar - Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka

Abeywardana, Asela Janaka January 2016 (has links)
This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel. Solar modules utilize the rooftop area of the building to a valuable application. Linear Fresnel type of solar concentrator is selected considering the requirement of the application and the simplicity of fabrication and installation compared to other technologies. Subsequently, a wood-fired boiler is deployed as the steam generator as well as the balancing power source to recover the effects due to the seasonal variations in solar energy. Bioenergy, so far being the largest primary energy supply in the country, has a good potential for further growth in industrial applications like small hotels.  When a hotel with about 200-guests capacity and annual average occupancy of 65% is considered, the total annual CO2 saving is accounted as 207 tons compared with an entirely fossil fuel (diesel) fired boiler system. The annual operational cost saving is around $ 40,000 and the simple payback period is within 3-4 years. The proposed hybrid system can generate additional 26 employment opportunities in the proximity of the site location area.   This solar-biomass hybrid concept mitigates the weaknesses associated with these renewable technologies when employed separately. The system has been designed in such a way that the total heat demand of hot water and process steam supply is managed by renewable energy alone. It is thus a self-sustainable, non-conventional, renewable energy system. This concept can be stretched to other critical medium temperature applications like for example absorption refrigeration. The system is applicable to many other industries in the country where space requirement is available, solar irradiance is rich and a solid biomass supply is assured.
89

Decisão de investimento: um teste de aderência para franquia no segmento de saúde

Cusnir, Rubens 21 December 2015 (has links)
Made available in DSpace on 2016-04-25T18:40:13Z (GMT). No. of bitstreams: 1 Rubens Cusnir.pdf: 979028 bytes, checksum: 7e9e285f3952b163371bfc28325df8ee (MD5) Previous issue date: 2015-12-21 / The present study aimed to suggest the use of different methods that can help decision makers to evaluate financial investment to be made in the setting up of a particular business venture. The business involves the acquisition, deployment and operation of a health service franchise that is presented to the consumer market in the form of a fitness center oriented and specialized in elderly people. The circumstances offered as investment alternatives in the economic environment that presents real interest rates much lower than those offered to investors in the early 2000s are taken into account, in parallel with the strengthening of the franchises as a thriving productive investment option, with strong growth seen in the last 10 years. The formal and commercial peculiarities of the relationship between franchisees and franchisors, with the possible difficulties and perceived conflicts in the management of these interests are also studied. Medical health market services and the recent awareness for the need for physical activities in all ages are described in addition to the prospect of increased longevity and quality of life in the elderly due to adoption of physical activities. For investment evaluation purposes, methods of Break-Even point, Payback, Net Present Value and Internal Rate of Return are applied, calculated and discussed from a practical case, with real and contemporary data. The study is based on the outcome of these calculations and on their real utility. Suggestions and topics to be addressed in further studies are also provided / O objetivo deste trabalho é sugerir a utilização de diferentes métodos que possam auxiliar um tomador de decisão na avaliação de um investimento financeiro a ser feito na constituição de um empreendimento comercial. O referido empreendimento é composto pela aquisição, implantação e operação de uma franquia de serviços em saúde que se apresenta ao mercado consumidor na forma de uma academia de ginástica voltada e especializada no atendimento do público da terceira idade. São levadas em consideração as circunstâncias atuais oferecidas como alternativas de investimento, num cenário econômico que apresenta taxas de juros reais muito inferiores àquelas oferecidas aos investidores no início dos anos 2.000, em paralelo ao fortalecimento das franquias como uma pujante opção de investimento produtivo, com forte crescimento evidenciado nos últimos 10 anos. Também são estudadas as peculiaridades da relação entre franqueados e franqueadores, do ponto de vista formal e comercial, junto às possíveis dificuldades e conflitos percebidos na gestão desta conjunção de interesses. São descritos o mercado de prestação de serviços em saúde e a recente conscientização a respeito da necessidade de atividades físicas para todas as idades, além da perspectiva do aumento da longevidade e da qualidade de vida dos idosos com a adoção destas práticas esportivas em seu cotidiano. Para efeito de avaliação de investimentos, são descritos os métodos de Ponto de Equilíbrio, Payback, Valor Presente Líquido e Taxa Interna de Retorno, aplicados, calculados e comentados a partir de um caso prático, com dados reais e contemporâneos. O estudo é concluído com base no resultado destes cálculos e a análise da conveniência de suas utilizações, junto a sugestões de aprofundamento dos temas a serem abordados em novos estudos
90

MODELING, SIMULATION AND OPTIMIZATION OF A SUBMERGED RENEWABLE STORAGE SYSTEM INTEGRATED TO A FLOATING WIND FARM : A feasibility case study on the Swedish side of the Baltic sea, based on the geographical and wind conditions

Honnanayakanahalli Ramakrishna, Prajwal January 2019 (has links)
Mathematical modeling and simulations of a submerged renewable storage system integrated to a wind farm, chosen based on the geographical and wind conditions at the Baltic Sea, gives insight on the feasibility of the submerged renewable storage and an approximation of the payback period and profits that could be generated. Genetic Algorithms were used to obtain the optimal number of spheres for a certain depth, based on 2 objective functions I.e. Minimum Life Cycle Cost (LCC) and maximum reduction in wind curtailment. The new arrangement concept shows that the Initial Capital Cost (ICC) could be decreased by 25% to 60% depending upon the number of sphere employed. Based on the inputs considered in the study, the results prove that the submerged renewable storage system would be feasible, and the profits ranging from 15 Million Euro to 29 Million Euro can be achieved at the chosen location, towards the Swedish side of the Baltic sea. Although, in a real life scenario it is assumed that only up to half of the profits obtained in the results would be achievable. The results also show that, the Pump/Turbine with a high turbine efficiency and lower pump efficiency, generated better profits, compared to a Pump/Turbine running with a higher pump efficiency and lower turbine efficiency. An attempt to increase the round-trip efficiency by adding a multi stage submersible pump, resulted in additional ICC and LCC, which saw a decrease in profits.

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