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

Heat demand profiles of buildings' energy conservation measures and their impact on renewable and resource efficient district heating systems

Lundström, Lukas January 2016 (has links)
Increased energy performance of the building stock of European Union is seen as an important measure towards mitigating climate change, increasing resource utilisation efficiency and energy supply security. Whether to improve the supply-side, the demand-side or both is an open issue. This conflict is even more apparent in countries such as Sweden with a high penetration of district heating (DH). Many Swedish DH systems have high share of secondary energy resources such as forest industry residuals, waste material incineration and waste heat; and resource efficient cogeneration of electricity in combined heat and power (CHP) plants. When implementing an energy conservation measure (ECM) in a DH connected building stock, it will affect the operation of the whole DH system. If there are CHP plants and the cogeneration of electricity decreases due to an ECM, and this electricity is valued higher than the fuel savings, the consequences of the ECM would be negative.  These complex relationships are investigated by conducting a case study on the Eskilstuna DH system, a renewable energy supply system with relatively high share of cogenerated electricity. Heat demand profiles of ECMs are determined by building energy simulation, using recently deep energy retrofitted multifamily buildings of the “Million Programme”-era in Eskilstuna as model basis. How implementing ECMs impact on the DH system’s heat and electricity production under different electricity revenue scenarios has been computed and evaluated in terms of resource efficiency and CO2 emissions.  The results show that different ECMs in the buildings impact differently on the DH system. Measures such as improved insulation level of the building’s envelope, that decrease the heat demand’s dependence to outdoor temperature, increase the amount of cogenerated electricity. While measures such as thermal solar panels, which save heat during summer, affects the absolute amount of cogenerated electricity negatively. Revenues from cogenerated electricity influence the amount of cost-effectively produced electricity much more than the impact from ECMs. Environmental benefits of the ECMs, measured in CO2 emissions and primary energy consumption, are quite small in DH systems that have high share of forest residual fuels and electricity cogeneration. The consequences can even be negative if ECMs lead to increased need of imported electricity that is produced resource inefficiently or/and by fossil fuels. However, all studied ECMs increase the relative amount of cogenerated electricity, the ratio between amount of cogenerated electricity and the heat load. This implied that all ECMs increase the overall efficiency of the Eskilstuna DH system.
2

Thermodynamic And Economic Analysis Of A Solar Thermal Powered Adsorption Cooling System

Demirocak, Emre Dervis 01 October 2008 (has links) (PDF)
In this thesis, yearly performance of the solar adsorption cooling system which is proposed to be installed to a residential building in Antalya is theoretically investigated in detail. Firstly, thermodynamic designs of the adsorption cooling cycle for three different types of cycles which are intermittent, heat recovery and heat &amp / mass recovery cycles are presented. Secondly, adsorption characteristics of three adsorbent/adsorbate pairs which are zeolite-water, silica gel-water and activated carbon-methanol are given. Following this, load side (i.e., building) of the system is designed and parameters that should be considered in building design are presented. Then, solar-thermal cooling system design methodology with an emphasis on solar fraction is presented. In addition, system parameters effecting the performance of the adsorption cooling system are analyzed and results are presented. Finally, economic analysis is done in order to understand the economic feasibility of the solar-thermal cooling systems compared to conventional cooling systems. TRNSYS is used for the yearly simulations and an integrated model of the overall system is developed in TRNSYS. Since energy consumption and performance investigations of environment-dependent systems such as building HVAC, refrigeration systems and solar collectors usually require weather information, typical meteorological year (TMY) data for Antalya is also generated in order to be used in the analysis of the system parameters.
3

[en] SOLAR RADIATION RESOURCE ASSESSMENT FOR RIO DE JANEIRO, BRAZIL / [pt] AVALIAÇÃO DA DISPONIBILIDADE DO RECURSO SOLAR NO ESTADO DO RIO DE JANEIRO

FIORELLA DEL CARMEN ALVARO CABRERA 23 November 2018 (has links)
[pt] O potencial da energia solar para a geração de energia elétrica no mundo é sem dúvida o maior dos potenciais das fontes energéticas renováveis, com uma capacidade de produção de eletricidade estimada em 745,8 TWh por ano. Embora não seja responsável por uma parte significativa da matriz elétrica mundial, o crescimento do setor fotovoltaico no mundo é notável. A capacidade instalada mundial de centrais fotovoltaicas cresceu 39 por cento no ano 2013. Os mapas mundiais de radiação solar mostram que aqueles que mais investem em energia solar fotovoltaica não são necessariamente aqueles cujo território recebe a maior quantidade deste recurso. O Brasil, com um grande potencial solar, confirmado por diversos levantamentos, não é um dos principais produtores de eletricidade a partir de sistemas fotovoltaicos. Este setor no Brasil é ainda incipiente, porém, uma das estratégias do país para promover a implementação de sistemas fotovoltaicos é um mecanismo de net metering para mini e micro produtores. Diversos especialistas afirmam que esta estratégia poderia gerar um grande volume de empreendimentos em pequena e média escala nos próximos anos. Este trabalho fornece uma ferramenta de informação sobre a radiação solar no estado do Rio de Janeiro, conformada por mapas de radiação solar global e dados de anos meteorológicos típicos. Com base nos dados gerados, realizaram-se simulações para estimar a radiação solar incidente e a eletricidade produzida por painéis fotovoltaicos em diferentes configurações fixas e com rastreamento. Avaliaram-se os ganhos e perdas ocasionados por cada configuração em relação a configuração horizontal. / [en] Solar energy potential for electricity generation undoubtedly surmounts the potential of all the other renewable energy sources, with an estimated electricity production capacity of 745.8 TWh per year. Albeit solar energy does not account for a significant share of the world electricity matrix, the growth of the photovoltaic market in the world is remarkable: the installed PV capacity increased in 39 percent on 2013. Nevertheless, the world maps of solar radiation show that the countries that invest the most in solar photovoltaic energy are not necessarily the ones that receive the highest solar radiation. Brazil, with an important solar potential, confirmed by diverse assessments, is not one of the main producers of PV-generated electricity. The PV-market in Brazil is still immature, however, one of the strategies of the Government to promote the implementation of PV systems is a net metering mechanism for mini and micro producers. Different specialists claim that this strategy could generate a big volume of new endeavors in small and medium scale in the next years. This study provides information tools about solar radiation in Rio de Janeiro. It comprises maps of global solar radiation in horizontal surfaces and Typical Meteorological Year data sets. Simulations were performed based on the generated data to estimate the incident solar radiation and the electricity produced by PV systems in different fixed and tracking configurations. The gains and losses caused by each configuration with respect to the horizontal configuration were evaluated.
4

Analysis of the Impact of Urban Heat Island on Energy consumption of Buildings in Phoenix

January 2011 (has links)
abstract: The Urban Heat Island (UHI) has been known to have been around from as long as people have been urbanizing. The growth and conglomeration of cities in the past century has caused an increase in the intensity and impact of Urban Heat Island, causing significant changes to the micro-climate and causing imbalances in the temperature patterns of cities. The urban heat island (UHI) is a well established phenomenon and it has been attributed to the reduced heating loads and increased cooling loads, impacting the total energy consumption of affected buildings in all climatic regions. This thesis endeavors to understand the impact of the urban heat island on the typical buildings in the Phoenix Metropolitan region through an annual energy simulation process spanning through the years 1950 to 2005. Phoenix, as a representative city for the hot-arid cooling-dominated region, would be an interesting example to see how the reduction in heating energy consumption offsets the increased demand for cooling energy in the building. The commercial reference building models from the Department of Energy have been used to simulate commercial building stock, while for the residential stock a representative residential model prescribing to IECC 2006 standards will be used. The multiyear simulation process will bring forth the energy consumptions of various building typologies, thus highlighting differing impacts on the various building typologies. A vigorous analysis is performed to see the impact on the cooling loads annually, specifically during summer and summer nights, when the impact of the 'atmospheric canopy layer' - urban heat island (UHI) causes an increase in the summer night time minimum and night time average temperatures. This study also shows the disparity in results of annual simulations run utilizing a typical meteorological year (TMY) weather file, to that of the current recorded weather data. The under prediction due to the use of TMY would translate to higher or lower predicted energy savings in the future years, for changes made to the efficiencies of the cooling or heating systems and thermal performance of the built-forms. The change in energy usage patterns caused by higher cooling energy and lesser heating energy consumptions could influence future policies and energy conservation standards. This study could also be utilized to understand the impacts of the equipment sizing protocols currently adopted, equipment use and longevity and fuel swapping as heating cooling ratios change. / Dissertation/Thesis / M.S. Architecture 2011

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