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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.
31

Moderní metody regulace otopných soustav / Modern methods of control of heating systems

Machala, Martin January 2011 (has links)
The aims of the thesis are modern methods of control of heating systems. Basic principles of regulations are explained and methods of control of heating sources and exchangers are explored. Heating system of family building is projected with two types of control – equithermal regulation with thermostatic heads and individual room control (IRC). Both variants are simulated in program TRNSYS 16.1. From the results are concluded advantages and disadvantages of examined systems of control.
32

Practical evaluation of borehole heat exchanger models in TRNSYS

Thorén, Åsa January 2016 (has links)
Vertical ground source heat pumps are established and still growing on the global market. The modelling of these systems is important for system design and optimization. This is an active field of research, and many models are often built into system simulation software such as TRNSYS. With the intention of having a better sensibility for existing TRNSYS tools, three different cases are simulated with several TRNSYS tools, so called Types. A Thermal Response Test, a large borehole field of an IKEA building complex in Sweden, as well as the Marine Corps Logistic Base in Albany, USA. The vertical ground heat exchanger types 203, 244, 243, 246, 451, 55a and 557b are used. Most of the simulations are investigated and evaluated by comparing them to measured data. The result shows that, for these specific cases, the DTS types 557a and 557b can underestimate the heat transfer early on due to a poor consideration of the thermal capacity inside the borehole. Depending on how the thermal resistance is calculated by a module, the fluid mean temperature simulation is affected by a constant throughout the simulation time. The simulation results indicate that the type 557b, where the borehole resistance is pre-set as an input and known from experimental data, is the most accurate of the types for groundwater filled boreholes. On short term, type 451 provides a good coherence with the measured data, with a relative deviation of 10.3 %. The borehole models that consider the borehole thermal capacity overestimate the short term heat transfer rate, whereas those that neglect the borehole capacity underestimate the short term thermal heat transfer on short term. Existing Types describe successfully the long term behaviour of large borehole fields. Serial versus parallel coupled BHE fields show relatively small differences in performance when simulated with type 557b for a specific study case.
33

District Cooling for Al Hamra Village in Ras Al Khaimah-United Arab Emirates (UAE)

Perera, Withanage Chanaka Sameera January 2011 (has links)
<p>I did my presentation through Centra infron of Professor Bjorn Palm and Dr. Sad Jarall.</p>
34

AN EVALUATION AND ECONOMIC ANALYSIS OF A WATER MAIN GEOTHERMAL SYSTEM IN A RESIDENTIAL SPACE

Kohut, Brian Lee 22 June 2022 (has links)
No description available.
35

Comparison of solar thermal and photovoltaic assisted heat pumps for multi-family houses in Sweden

Andersson, Martin January 2018 (has links)
The building sector account for 40 % of the global energy demand, and an increasingly popular way to supply buildings with heat is through the use of heat pumps. Solar thermal (ST) can either be used as a low temperature energy source in the heat pump or to directly supply the building’s heating demand.  The increasing market of PV has made it a favorite for roof-top solar installation. Its physical integration with buildings and HPs is simpler than that of ST and can supply any available electric load associated with the building and not just the HP system. It can also supply any excess power to the grid.  In order to properly compare these two options, key performance indicators (KPIs) were identified for several system boundaries within the building and HP system. Technical KPIs used were seasonal performance factor (SPF), solar fraction (SF) and self-consumption (SC), while internal rate of return (IRR), net present value (NPV), profitability index (PI) and payback time was used to evaluate their economic performance.  For the thesis a multi-family house was modelled in TRNSYS where different system sizes of either ST or PVs was simulated for a year with three-minute intervals. The ST was connected in a parallel configuration thereby supplying the building’s domestic hot water (DHW) through a separate storage tank. The modelled heat pump was a ground source heat pump (GSHP) which utilizes boreholes as the low temperature energy source. The SPF increased for both the ST and PV integration from the reference scenario (no PV/ST integration) but to a varying degree depending on the analyzed system boundary. The economic results suggested that PVs are the more financially sound option over ST for the simulated MFH. The sensitivity analysis also showed the large impact of economic assumptions on the expected profitability for both the PV and ST systems. Based on the results would the simulated MFH with an existing GSHP benefit more from installing PV instead of ST from both a technical, economic and environmental perspective.  It is reasonable that PVs will most likely be an integral part for future buildings in Sweden with or without HPs because of its financial strength and versatility of demand supply, especially compared to ST. / Byggsektorn står för 40% av det globala energibehovet, och ett alltmer populärt sätt att leverera värme till ett hus är genom användning av värmepumpar. Solvärmefångare kan antingen användas som en lågtemperaturenergikälla i värmepumpen eller för att direkt leverera byggnadens värmebehov.  Den ökande marknaden för solceller har gjort den till en favorit för takmonterad solinstallation. Dess fysiska integration med byggnader är enklare än solvärmefångare och kan leverera el till hea byggnaden och inte bara värmepumpssystemet. Solceller kan också leverera till elnätet om produktionen överstiger byggnadens behov. För att korrekt jämföra dessa två alternativ identifierades viktiga indikatorer för flera systemgränser inom byggnaden och värmepumpssystemet. Tekniska indikatorer som användes var årsvärmefaktor, solfraktion och självförbrukning, medan internränta, nuvärde, lönsamhetsindex och återbetalningstid användes för att utvärdera deras ekonomiska resultat. För uppsatsen modellerades ett flerbostadshus med tillgänglig takyta i TRNSYS där olika systemstorlekar (i kvadratmeter) av antingen solvärmefångare eller solceller var simulerade i ett år med tre minuters intervall. Solvärmefångaren var ansluten i en parallell konfiguration med värmepumpen, varigenom byggnadens varmvatten levereras genom en separat lagertank. Den modellerade värmepumpen var en bergvärmepump som utnyttjar borrhål som lågtemperaturenergikälla. Årsvärmefaktorn ökade för både solvärmefångar- och solcells-integrationen från referensscenariot (ingen solteknisk-integration) men i varierande grad, beroende på den analyserade systemgränsen. De ekonomiska resultaten visade att solceller är det mer ekonomiskt sunda alternativet över solvärmefångare för det simulerade flerbostadshuset. Känslighetsanalysen visade också på den stora effekten av ekonomiska antaganden på den förväntade lönsamheten för både solceller och solvärmefångare. Baserat på resultaten skulle det simulerade flerbostadshuset med en befintlig bergvärmepump dra nytta av att installera solceller istället för solvärmefångare från ett tekniskt, ekonomiskt och miljömässigt perspektiv. Det är troligt att solceller kommer vara en del i framtida byggnader i Sverige med eller utan värmepumpar på grund av den ekonomiska styrkan och möjligheten att tillgodose både byggnaden och elnätet vid överproduktion.
36

Etudes expérimentales et numériques de systèmes de micro cogénération couplés aux bâtiments d’habitation et au réseau électrique / Experimental and numerical studies of micro combined heat and power systems coupled to dwelling buildings and to the power grid

Bouvenot, Jean-Baptiste 27 November 2015 (has links)
La micro cogénération désigne la génération simultanée de deux types d’énergie à faible puissance. En énergétique, ce terme désigne en pratique la production simultanée d’électricité et de chaleur : le principe reposant sur la récupération de la chaleur fatale induite par la production électrique. Deux bancs d’essais ont d’abord été réalisés sur deux prototypes de micro cogénérateurs : un moteur Stirling à gaz et un moteur à vapeur à granulés de bois. Une campagne expérimentale a été menée pour caractériser chaque système au niveau énergétique et environnemental. Les résultats expérimentaux ont abouti sur deux modèles numériques dynamiques et semi-physiques de micro cogénérateurs programmés dans l’environnement numérique TRNSYS où une plateforme numérique de simulation a été développée. Celle-ci intègre principalement des modèles de systèmes de stockage d’énergie, des générateurs stochastiques de fichiers de besoins énergétiques et des stratégies innovantes de pilotage des systèmes et des charges selon des critères de précision et de réalisme.Cette plateforme a permis d’évaluer la pertinence énergétique, environnementale et économique de micro cogénérateurs couplés aux bâtiments d’habitation et au réseau électrique selon différentes configurations. / Micro combined heat and power (µCHP) or cogeneration means the simultaneous generation of two energy types. In energetic fields, this term refers usually to the simultaneous production of electricity and heat: the principle being based on the recovering of the fatal heat induced by the electricity production processes.Firstly, two test benches were carried out on two µCHP prototypes: a gas Stirling engine and a wood pellets steam engine. Experimental investigations were conducted to characterize each system at energy and environmental levels. The experimental results led two dynamic and semi physical numerical models of µCHP systems programmed in the numerical tool TRNSYS where a numerical platform has been developed. This platform integrates mainly energy storage systems models, stochastic energy needs file generators and innovative management strategy of systems and energy loads according to precision and realism criteria.This platform allows assessing realistic energy, environmental and economic relevance of µCHP systems coupled with dwelling buildings and the power grid according to different configurations.
37

Ein Beitrag zur Optimierung der Betriebsweise heizungs- und raumlufttechnischer Anlagen

Felsmann, Clemens 07 June 2002 (has links)
Im Rahmen der vorliegenden Arbeit wird gezeigt, wie ein Gebäude- und Anlagensimulationsprogramm mit bekannten Optimierungsalgorithmen gekoppelt und zur theoretischen Lösung optimaler Steuer- und Regelprobleme in der Gebäudetechnik eingesetzt werden kann. Theoretische Optimallösungen erlauben im Sinne eines optimalen Vergleichsprozesses die Bewertung praktisch anderweitig umsetzbarer Steuerungs- und Regelungsmechanismen. Die im Hinblick auf ein gewähltes Gütekriterium erforderliche Notwendigkeit zur Verbesserung von vorhandenen Steuerungs- und Regelungsszenarien sowie die theoretisch maximal erreichbaren Extremwerte lassen sich leicht abschätzen.
38

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.
39

Simulação do sistema de aquecimento de ar de um secador solar híbrido de produtos agroalimentícios usando o TRNSYS

Basso, Diego Morello January 2017 (has links)
O presente trabalho tem por objetivo principal apresentar a avaliação térmica, energética e financeira para um sistema de aquecimento de ar de um secador solar híbrido de produtos agroalimentícios, o qual utiliza como fonte de energia a energia solar e uma fonte de energia auxiliar. Dois tipos de fonte de energia auxiliar são utilizados, uma fonte utiliza biomassa como combustível e a outra utiliza energia elétrica. O sistema é composto por um coletor solar térmico, tipo placa plana de exposição indireta, uma fonte de energia auxiliar. O software TRNSYS é utilizado como ferramenta para executar as simulações, tendo como meta alcançar a temperatura do ar de 70°C na entrada da câmara de secagem. Os resultados são apresentados em função das temperaturas da placa absorvedora, do ar de saída do coletor solar e do ar de entrada na câmara de secagem e em função da quantidade de energia, por hora, fornecida para o ar de secagem pelo coletor solar (ganho de energia útil) e pela fonte de energia auxiliar. Calcula-se o custo horário da energia considerando a utilização da biomassa e da energia elétrica, resultando no custo da biomassa equivalente a 42,5% do custo da energia elétrica.Embora os custos com insumos sejam mais baratos para a utilização do sistema com biomassa, a implementação desse sistema é mais cara, sendo viável apenas em longo prazo. O retorno do investimento para o sistema com biomassa ocorre no quarto ano, enquanto que o sistema com energia elétrica obtém retorno no primeiro ano. / This work aim to perform thermal, energy and financial analysis for an air heating system of a hybrid solar dryer for agricultural products, which uses as energy source a combination of solar energy and an auxiliary power source. Two types of external auxiliary power source for energy are used, biomass and electric power. The dryer is composed by an indirect flat plate flat plate collector, an external energy source and a drying chamber. The software TRNSYS is used to run the hybrid solar dryer simulations. The simulations goal is for the system to achieve 70°C air temperature at the drying chamber inlet. The results are showed as a function of the absorber flat plate temperature, the solar thermal collector outlet air temperature and the drying chamber inlet air temperature as a function of the energy amount per hour supplied to the drying air by the solar collector (useful energy gain) and by the external auxiliary power source. The energy cost per hour is calculated by assuming each one of the sources, biomass and electric power. It resulted that biomass costs 42.5% of the electrical power total costs. Although the source material costs are cheaper for biomass usage, it implies higher implementation costs, thus requiring long range usage analysis to prove practicable. The biomass system return of investment occurs at the fourth year while at the electrical power system return of investment occurs at the first year.
40

Solar-hydrogen Stand-alone Power System Design And Simulations

Uluoglu, Arman 01 May 2010 (has links) (PDF)
In this thesis, solar-hydrogen Stand-Alone Power System (SAPS) which is planned to be built for the emergency room of a hospital is designed. The system provides continuous, off-grid electricity during the whole period of a year without any external electrical power supply. The system consists of Photovoltaic (PV) panels, Proton Exchange Membrane (PEM) based electrolyzers, PEM based fuel cells, hydrogen tanks, batteries, a control mechanism and auxiliary equipments such as DC/AC converters, water pump, pipes and hydrogen dryers. The aim of this work is to investigate the optimal system configuration and component sizing which yield to high performance and low cost for different user needs and control strategies. TRNSYS commercial software is used for the overall system design and simulations. Numerical models of the PV panels, the control mechanism and the PEM electrolyzers are developed by using theoretical and experimental data and the models are integrated into TRNSYS. Overall system models include user-defined components as well as the default software components. The electricity need of the emergency room without any shortage is supplied directly from the PV panels or by the help of the batteries and the fuel cells when the solar energy is not enough. The pressure level in the hydrogen tanks and the overall system efficiency are selected as the key design parameters. The major component parameters and various control strategies affecting the hydrogen tank pressure and the system efficiency are analyzed and the results are presented.

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