Dissertations / Theses: 'Simulation of Stirling cycle'

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Blaha, Josef. "Stirlingův motor." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228037.

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This dissertation discusses Stirling’s cycle and its contribution using different approaches. There are calculation of Schmidt’s theory and distinctiveness between ideal and real cycle described. Based on my previous research, this work provides a detailed summary of different methods which are used to stimulate Stirling’s cycles as well as the motor as a whole. Attention is particularly dedicated to current utilization of this machine which is not broadly known within general public.

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Ozbay, Sercan. "Thermal Analysis Of Stirling Cycle Regenerators." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613541/index.pdf.

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Stirling cycle cryocoolers are used widely in military applications. The regenerator is the key element of Stirling cycle cryocoolers. It is known that performance of the regenerator directly affects the cryocooler performance. Therefore, any improvement on the regenerator will lead to a more efficient cryocooler. Thus, it is essential to have an idea about regenerator parameters and their effects on the system. In this study Stirling engine regenerator, which is constructed by wire mesh screens, is accepted as a porous medium. Using energy balance and continuity equation, matrix and fluid thermal equations are derived. Simplified versions of these equations are obtained for not only the ideal case, but also two other cases which take into account the effects of longitudinal conduction and the effects of regenerator wall. A computer code is developed in Matlab to solve these equations using finite difference method. The developed code is validated by using Sage. Afterwards, effects of all regenerator parameters on regenerator performance are investigated in detail and results are presented. To make this investigation easier, a graphical user interface is also built (in Matlab) and used.

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Wills, James Alexander. "Exergy analysis of a Stirling cycle." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26865.

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In this dissertation the analysis of the Stirling engine is presented, this research topic falls within the category of thermal energy conversion. The research that was conducted is presented in three chapters of which the topics are: the effects of allocation of volume on engine performance, the GPU-3 (Ground Power Unit - developed by GM) Stirling engine analysis, and the optimisation of a 1000 cm³ Stirling engine with finite heat capacity rates at the source and the sink. The Stirling engine has many advantages over other heat engines, as it is extremely quiet, has multi-fuel capabilities and is highly efficient. There is also significant interest in using Stirling engines in low to medium temperature solar thermal applications, and for waste heat recovery. To develop high-performance engines that are also economically viable, advanced mathematical models that accurately predict performance and give insight into the different loss mechanisms are required. This work aims to use and adapt such a model to analyse the effects of different engine parameters and to show how such a model can be used for engine optimisation using the Implicit Filtering algorithm. In the various analyses that are presented, the dynamic second order adiabatic numerical model is used and is coupled to equations that describe the heat and mass transfer in the engine. The analysis shows that the allocation of volume has a significant effect on engine performance. It is shown that in high-temperature difference (HTD) engines, increasing dead-volume ratio increases efficiency and decreases specific work output. In the case of low-temperature difference (LTD) and medium-temperature difference (MTD) engines, there is an optimal dead-volume ratio that gives maximum specific work output. It was also found that there are optimal swept volume ratios and that the allocation of heat exchanger volume has a negligible effect on engine performance - so long as the dead-volume ratio is optimal. The second order model with irreversibilities included was used to perform an exergy analysis of the GPU-3 Stirling engine. This model compared well with experimental results and the results from other models found in the literature. The results of the study show the two different approaches in modelling the engine losses and the effect that the various engine parameters have on the GPU-3 power output and efficiency. The optimisation of the 1000 cm³ Stirling engine was performed using a model with finite heat capacity rates at the source and the sink, fixed number of heater and cooler tubes, and four different regenerator mesh types. The engine geometry was optimised for maximum work output using the implicit filtering algorithm, and the results show the dominant effect that the regenerator has on engine performance and the geometry that gives maximum work output. The critical insights obtained from this research are the importance of the dead-volume ratio in engine analysis, the merits of the novel Second law Stirling engine model, and the importance of regenerator mesh choice and geometry. The Implicit filtering algorithm is also shown to be a suitable choice of optimisation algorithm to use with Stirling engine mathematical models.

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Liang, Hua. "Viability of stirling-based combined cycle distributed power generation." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176484842.

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DRUMOND, CARLO CESAR. "NUMERICAL SIMULATION OF A ROTARY STIRLING ENGINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30089@1.

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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
O presente trabalho estuda um motor de deslocamento positivo Stirling rotativo. Dois modelos de simulação para este motor Stirling rotativo são desenvolvidos. O primeiro modelo utiliza o método isotérmico, mediante o qual a câmara de expansão/compressão do motor está à mesma temperatura do reservatório térmico com que troca calor. O segundo modelo utiliza o método de volumes de controle, no qual o motor é dividido em cinco volumes de controle: as câmaras de expansão e compressão, o aquecedor, o resfriador e o compartimento rotativo. Para cada volume de controle aplicam-se as equações de conservação de massa e energia e de equações de estado do gás. O sistema de equações diferenciais ordinárias resultantes do segundo modelo, é integrado, permitindo obter-se a variação no ângulo do eixo para todas as variáveis termodinâmicas do motor (pressão, temperatura, etc.). Dadas as condições de operação e a geometria do motor rotativo em estudo, os modelos preveem resultados globais e transientes ângulo a ângulo. Os resultados dos modelos são confrontados com resultados teóricos disponíveis na literatura.
The present work studies a positive displacement rotary Stirling engine. Two simulation models for this rotary Stirling engine are developed. The first model applies the isothermal method, in which the gas at the engine expansion / compression chamber has the same temperatures of the thermal reservoir. The second model uses the control volume method, in which the engine is divided into five control volumes: the expansion and compression chambers, the heater, the chiller and the rotary chamber. For each control volume the equations of conservation of mass and energy and the equation of state, are applied. The system of ordinary differential equations resulting from the second model is integrated allowing to obtain the variation in the axis angle for all thermodynamic variables of the motor (pressure, temperature, etc.). Given the operating conditions and geometry of the rotating motor under study, the models provide global and transient results from angle to angle. Results from two models are confronted with theoretical results available in the literature.

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Chen, Mingfei. "Computer simulation of Ringbom stirling engine with solar pond." Ohio University / OhioLINK, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1182285925.

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Hering, Klaus. "Parallel Cycle Simulation." Universität Leipzig, 1996. https://ul.qucosa.de/id/qucosa%3A34504.

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Parallelization of logic simulation on register-transfer and gate level is a promising way to accelerate extremely time extensive system simulation processes for whole processor structures. In this report parallel simulation realized by means of the functional simulator parallel- TEXSIM based on the clock-cycle algorithm is considered. Within a corresponding simulation, several simulator instances co-operate over a loosely-coupled processor system, each instance simulating a part of a synchronous hardware design. Therefore, in preparation of parallel simulation, partitioning of hardware models is necessary, which is essentially determining e±ciency of the following simulation. A framework of formal concepts for an abstract description of parallel cycle simulation is developed. This provides the basis for partition valuation within partitioning algorithms. Starting from the definition of a Structural Hardware Model as special bipartite graph Sequential Cycle Simulation is introduced as sequence of actions. Following a cone-based partitioning approach a Parallel Structural Hardware Model is defined as set of Structural Hardware Models. Furthermore, a model of parallel computation called Communicating Processors is introduced which is closely related to the well known LogP Model. Together with the preceding concepts it represents the basis for determining Parallel Cycle Simulation as sequence of action sets.

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Hugh, Mark A. "The effects of regenerator porosity on the performance of a high capacity stirling cycle cryocooler." Ohio : Ohio University, 1993. http://www.ohiolink.edu/etd/view.cgi?ohiou1175707790.

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Pfeiffer, Jens [Verfasser]. "Unsteady Analytical Model for Appendix Gap Losses in Stirling Cycle Machines / Jens Pfeiffer." München : Verlag Dr. Hut, 2016. http://d-nb.info/109781811X/34.

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Deetlefs, Ivan Niell. "Design, simulation, manufacture and testing of a free-piston Stirling engine." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95922.

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Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: The aim of this study was to design and manufacture an experimentally testable free-piston Stirling engine (FPSE), including a linear electric generator; to develop and validate a theoretical simulation model; to identify problem areas pertaining to its manufacture; and finally to assess the work undertaken, to lay out the groundwork for the future development of a 3 kWe FPSE suitable for incorporation in a solar Stirling dish power generator. A redesigned version of the Beale B- 10B demonstrator engine was manufactured to overcome design diffculties and to simplify testing. The design made use of an electric generator designed at the Department of Electrical and Electronic Engineering at Stellenbosch University. Experimental measurements included piston and displacer motions, hot side and cold side temperatures, working space pressure, electric generator output, as well as heat rejection via a water jacket. Experimental measurements were taken prior to and subsequent to the addition of the electric generator. Indicated power was calculated as 0,659 W at a frequency of 10,99 Hz prior to the addition of the electric generator. The addition of the electric generator was unsuccessful since it was not well matched with the engine. The indicated power calculated was between 0,138 W and 0,144 W for different loads on the electric generator, while the electrical output power ranged from 1,23 mWe to 1,79 mWe. The addition of the electric generator produced non-continuous motion caused by magnetic forces instead of engine pressure variations. The major manufacturing diffculty was the attachment of magnets for the electric generator, but this was overcome with the manufacture of a special assembly jig. The theoretical simulation model was a combination of a third-order and dynamic analysis. Working space values were solved by the application of the conservation of mass, momentum and energy equations for a one-dimensional discretised model of the engine, while the motion of the piston and displacer was determined by applying the equations of motion. The majority of experimental measurements were predicted more accurately when higher heat transfer coeficients were used between the working space and wall temperatures. The theoretical simulation model was used to gain insight into the effect of input parameters on engine operation. The displacer rod diameter was shown to have implications on output power and stability, while it was shown that there is a natural tendency to deliver constant output power at a near-constant frequency over a range of piston loads for an FPSE. It was also shown that the design of an FPSE is complex and that the design of all components should be done in parallel. The control of an FPSE was seen to be both a necessity and can be used to exploit the advantages of the uncoupled nature of an FPSE.
AFRIKKANSE OPSOMMING: Die doel van hierdie studie was om 'n eksperimentele toetsbare vrye-werksuier Stirling enjin te vervaardiging, wat 'n lineêre elektriese kragopwekker insluit; om 'n teoretiese simulasie model te ontwikkel en te yk; om vervaardiging probleme te identi seer; en om die ondernemende werk te assesseer om 'n fondasie te lê vir die toekomstige ontwikkeling van 'n 3 kWe vrye-werksuier Stirling enjin wat by 'n Stirling sonskottel ingelyf kan word. 'n Herontwerpte weergawe van die Beale B-10B demonstrasie enjin was vervaardig om ontwerp probleme te bowe te kom en om die toets daarvan te vereenvoudig. Die ontwerp het gebruik gemaak van 'n elektriese kragopwekker wat by die Departement Elektriese en Elektroniese Ingenieurswese aan die Universiteit van Stellenbosch ontwerp is. Eksperimentele metings het die werksuier en verplaser bewegings ingesluit, sowel as die warm kant en koue kant temperature, die werkruimte druk, die elektriese uitset van die kragopwekker, sowel as die hitteuitruiling wat met 'n water verkoelingskringloop gepaard gaan. Eksperimentele metings was geneem voor en na die byvoeging van die elektriese kragopwekker. Kraglewering was bereken op 0,659 W teen 'n frekwensie van 10,99 Hz voordat die elektriese kragopwekker bygevoeg is. Die byvoeging van die elektriese kragopwekker was onsuksesvol omdat die nie gepas was vir die enjin nie. Die kraglewering is bereken op vlakke wat gewissel het tussen 0,138 W en 0,144 W vir die verskillende belastings op die elektriese kragopwekker, terwyl die elektriese uitset gewissel het tussen 1,23 mWe en 1,79 mWe. Die byvoeging van die elektriese kragopwekker het 'n nie-aaneenlopende beweging veroorsaak weens die magnetiese kragte wat dit beinvloed het in plaas van enjindruk variasies. Die belangrikste ontwerpuitdagings was die ontwerp van 'n werksuier en verplaser wat 'n klein toleransie passing kon handhaaf om sodoende 'n seël te verseker terwyl dit aan temperatuur variasies blootgestel was. Die grootste vervaardigingsprobleem was die aanheg van magnete vir die elektriese kragopwekker, maar dit is te bowe gekom deur 'n spesiale voeg te vervaardig. Die teoretiese simulasie model was 'n kombinasie van 'n derde-orde en 'n dinamiese analise. Werkruimte waardes was opgelos deur die toepassing van die behoud van massa, momentum en energie vergelykings vir 'n een-dimensionele gediskretiseerde model van die enjin, terwyl die beweging van die werksuier en verplaser bepaal was deur die toepassing van die bewegingvergelykings. Die meerderheid van die eksperimentele metings was meer akkuraat voorspel wanneer hoër warmteoordrag koë siënte tussen die werkruimte en muurtemperature gebruik was. Die teoretiese simulasie model was gebruik om insig in terme van die e ek van invoer veranderlikes op die enjin gedrag te toon. Daar was getoon dat die verplaserstaaf diameter implikasies het op kragoplewering en stabiliteit, terwyl die natuurlike tendens van 'n vrye-werksuier Stirling enjin gewys was om 'n konstante kraguitvoer te lewer op 'n naby-konstante frekwensie oor 'n reeks werksuier laste. Daar was ook gewys dat die ontwerp van 'n vryewerksuier Stirling enjin kompleks is en dat die ontwerp van alle komponente in parallel gedoen moet word. Die beheer van 'n vrye-werksuier Stirling enjin was gewys om beide noodsaaklik te wees, sowel as gebruik kan word om die unieke voordele van 'n vrye-werksuier Stirling enjin se ongekoppelde natuur te ontgin.

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Seres, Sandu. "Life cycle assessment of hybrid systems for rural electrification in Bolivia." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299637.

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Bolivia is a developing country in South America. Many rural communities still lack access to electricity. The extension of the National Grid System to all rural communities is not feasible due to economic and topographic challenges as well as the environmental problems that may arise. To tackle these problems, Off-grid solutions are implemented. Photovoltaic (PV) panels combined with batteries are a viable option for areas located close to the equator and high altitudes such as Bolivia. Almost always a controlled source of energy such as Diesel generators must complement the PV system due to the stochastic nature of solar energy. The use of fossil fuel can be detrimental to the environment and more environmentally friendly solutions are being investigated. The use of wood pellets in Stirling engines is a viable replacement for Diesel generators. The purpose of this study is to investigate and compare the environmental impacts caused by two Off-grid hybrid systems. The first one is composed of a Diesel generator, PV panels, and batteries. The second one is composed of a Stirling engine, PV panels, and batteries. The study area chosen for this work is the community El Carmen, Pando, in Bolivia. A Life Cycle Assessment (LCA) model is carried out for the systems according to the 4 phases of the LCA methodology. First, individual LCA models for all midpoint impact categories are generated. Secondly, a comparative LCA between the two systems, both at midpoint and endpoint, is created. Finally, a sensitivity analysis is conducted to determine the robustness of the models. The individual midpoint analysis of both systems showed that the controlled part of the electricity production (i.e., the Diesel generator and the Stirling engine) generated the greatest impact in the categories Global warming, Stratospheric ozone depletion, Ionizing radiation, Ozone formation, Fine particulate matter formation, Terrestrial acidification, Human carcinogenic toxicity, Land use, Fossil fuel scarcity, and Water consumption. All the processes related to the PV panels generated a greater impact in all Ecotoxicity categories (terrestrial, marine, and freshwater), Eutrophication (freshwater and marine), and Human non-carcinogenic toxicity. The midpoint results of the comparative LCA are inconclusive. Each system received higher scores in certain categories and lower scores in others. No firm conclusion could be drawn regarding the identification of the more environmentally friendly alternative. The Diesel/PV/Batteries system dominated the Global warming, Tropospheric ozone formation, Fine particulate matter formation, Terrestrial acidification, and Fossil resource scarcity categories. The Stirling/PV/Batteries system showed a greater impact on Stratospheric ozone depletion, Ecotoxicity, Eutrophication, Human carcinogenic toxicity, Human non- carcinogenic toxicity, and Mineral resource scarcity. The endpoint damage assessment showed that the emissions and midpoint categories described had a greater impact on Human health and Resource scarcity in the case of the Diesel/PV/Batteries system. On the other hand, the Stirling/PV/Batteries system caused greater damage to the Ecosystem category. The sensitivity analysis was conducted in two scenarios for each system. In the first scenario, alteration of fuel transport distance, no significant changes were detected in all endpoint categories. In the second scenario, alteration of Diesel/Stirling Contribution, the model showed an increasing trend (~30% for the first system and ~25% for the second one) in all categories when the contribution of the controlled part of the electricity production was increased.
Bolivia är ett utvecklingsland i Sydamerika där många landsbygdssamhällen fortfarande saknar tillgång till elektricitet. En anslutning till det nationella kraftsystemet är inte genomförbar på grund av de ekonomiska och topografiska svårigheterna samt miljöproblemen som kan uppstå. För att ta itu med problemet måste decentraliserade lösningar hittas. Solcellspaneler i kombination med batterier utgör ett möjligt alternativ för avlägsna områden som befinner sig nära ekvatorn och vid höga höjder. Ett sådant system behöver dock ytterligare en kontrollerad energikälla för att tillgodose efterfrågan på grund av den ojämna tillgången på solenergi. Det vanligaste alternativet är dieselgeneratorer. Men förbränning av fossila bränslen påverkar klimatet och mer miljövänliga lösningar undersöks. Stirlingmotorer som använder träpellets skulle kunna ersätta dieselgeneratorn i kampen för en bättre miljö. Syftet med denna studie är att undersöka och jämföra miljöpåverkan av två hybridsystem. Det ena systemet består av en dieselgenerator, PV-paneler och batterier medan det andra systemet består av en Stirlingmotor, PV-paneler och batterier. Det utvalda studieområdet är samhället El Carmen, Pando, i Bolivia. En livscykelanalys (LCA) utförs för de två systemen enligt LCA-metodiken. Först, utförs individuella LCA för vardera system för alla påverkanskategorier vid midpoint. Sedan utförs en jämförande LCA mellan de två systemen för alla påverkanskategorier både vid midpoint och endpoint. Slutligen, utförs en känslighetsanalys för att testa systemens robusthet. Den individuella analysen vid midpoint för båda systemen påvisade att den kontrollerade delen av elproduktion, det vill säga dieselgeneratorn och Stirlingmotorn, genererade den största miljöpåverkan i kategorierna Global uppvärmning, Uttunning av ozonskiktet, Joniserande strålning, Bildning av marknära ozon, Bildning av partiklar, Försurning, Cancerframkallande humantoxicitet, Landanvändning, Brist på fossila resurser och Vattenförbrukning. Alla processerna kopplade till PV-elproduktionen genererade en större miljöpåverkan i kategorierna Ecotoxicitet (mark, söt- och havsvatten), Övergödning (såväl söt- som havsvatten) och Icke cancerframkallande humantoxicitet. Resultaten vid midpoint för den jämförande LCA är inte övertygande. Vardera system fick högre poäng i vissa kategorier men lägre poäng i andra. Ingen tydlig slutsats kunde dras angående identifieringen av det mer miljövänliga alternativet. Diesel/PV/Batteri-systemet dominerar kategorierna Global uppvärmning, Bildning av marknära ozon, Bildning av partiklar, Försurning och Brist på fossila bränslen medan Stirling/PV/Batteri-systemet påvisade större miljöpåverkan i kategorierna Uttunning av ozonskiktet, Ekotoxicitet, Övergödning, Cancerframkallande humantoxicitet och Brist på mineraltillgångar. Skadebedömningen vid endpoint påvisade att de redovisade utsläppen och midpoint- katergorierna har en större påverkan på människors hälsa och resursbrist i Diesel/PV/Batteris fall. Däremot påvisade det Stirling/PV/Batteri-systemet en större påverkan på ekosystemet. Känslighetsanalysen utfördes i två scenarier. I det första scenariot ändrades avståndet för bränsletransport. Ingen signifikant skillnad påvisades i någon av de tre endpoint- kategorierna. I det andra scenariot, Diesel/Stirling insats, påvisades en ökande trend (~30% för första systemet och ~25% för det andra) i alla endpoint-kategorier med ökandet av insatsen från den kontrollade delen av elproduktion.

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Marin, Andreea. "Optimizarea exergoeconimică a unei centrale solare termice." Thesis, Paris 10, 2014. http://www.theses.fr/2014PA100054.

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Dans le contexte économique et énergétique actuel, la mise en œuvre de technologies à l'aide de l'énergie renouvelable comme source de chauffage offre un double avantage: la réduction de la pollution et des coûts de carburant. Il y a un besoin de promouvoir les sources renouvelables d'énergie comme les sources significatives de production d'énergie pour les systèmes décentralisés. Une première étude bibliographique a été fait sur les technologies existantes pour la production d'énergie électrique à partir du solaire. Cette étude consiste dans la recherche d’une nouvelle solution de conversion de l’énergie solaire pour la production d’électricité de faible puissance. L'un des objectifs de cette thèse a été la construction d'un moteur Stirling de type gamma fonctionnant à basse différence de température, adapté à un circuit solaire (capteur plan). Le moteur Stirling a été testé en vue de comparer les résultats expérimentales avec les résultats d’un model Schmidt, fait dans le logiciel, Matlab. Un autre cycle thermodynamique étais étudie dans cette travail, le Cycle Organique Rankine (ORC). Un modèle mathématique a été développé et vérifie dans les logiciels, Thermoptim et EES (Engineering Equation Solver) avec les résultats expérimentaux pour étudier les performances d'installation avec des différentes températures de fonctionnement. La méthode exergétique et la méthode du Pincement sont utilisée pour évaluer les performances du système comme irréversibilité, destruction d’exergie et phénomènes qui se produisent dans toutes les composantes du système ORC pour améliorer son fonctionnement
In the current economic and energy context, implementation of technologies using renewable energy as heat source has two advantages: reducing pollution and fuel costs. There is a need to promote renewable energy sources such as significant sources of power generation for decentralized systems. In the first part, it was made a literature review on existing technologies for the production of electricity with solar energy. One of the objectives of this thesis was to build a Stirling engine gamma type suitable to use solar energy (flat plate collator). The Stirling engine was tested to compare the experimental results with the results of Schmidt model, realized in the software, Matlab. Another thermodynamic cycle was studied in this work, the Organic Rankine Cycle (ORC). A mathematical model was developed and verified in software, Thermoptim and EES (Engineering Equation Solver) with experimental results to study the installation performance function of different operating temperatures. The entire system and each subsystem are analyzed according to the first and the second law of thermodynamics. The exergy method and Pinch analysis are used to evaluate the performance of the system like irreversibility and exergy destruction, phenomenon that occurs in all components of the ORC system. This analysis is to improve the operation

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Howard, Dustin F. "Modeling, simulation, and analysis of grid connected dish-stirling solar power plants." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34832.

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The percentage of renewable energy within the global electric power generation portfolio is expected to increase rapidly over the next few decades due to increasing concerns about climate change, fossil fuel costs, and energy security. Solar thermal energy, also known as concentrating solar power (CSP), is emerging as an important solution to new demands for clean, renewable electricity generation. Dish-Stirling (DS) technology, a form of CSP, is a relatively new player in the renewable energy market, although research in the technology has been ongoing now for nearly thirty years. The first large plant utilizing DS technology, rated at 1.5 MW, came online in January 2010 in Peoria, AZ, and plants rated for several hundred MW are in the planning stages. Increasing capacity of this technology within the utility grid requires extensive dynamic simulation studies to ensure that the power system maintains its safety and reliability in spite of the technological challenges that DS technology presents, particularly related to the intermittency of the energy source and its use of a non-conventional asynchronous generator. The research presented in this thesis attempts to fill in the gaps between the well established research on Stirling engines in the world of thermodynamics and the use of DS systems in electric power system applications, a topic which has received scant attention in publications since the emergence of this technology. DS technology uses a paraboloidal shaped dish of mirrors to concentrate sunlight to a single point. The high temperatures achieved at the focal point of the mirrors is used as a heat source for the Stirling engine, which is a closed-cycle, external heat engine. Invented by the Scottish clergyman Robert Stirling in 1816, the Stirling engine is capable of high efficiency and releases no emissions, making it highly compatible with concentrated solar energy. The Stirling engine turns a squirrel-cage induction generator, where electricity is delivered through underground cables from thousands of independent, autonomous 10-25 kW rated DS units in a large solar farm. A dynamic model of the DS system is presented in this thesis, including models of the Stirling engine working gas and mechanical dynamics. Custom FORTRAN code is written to model the Stirling engine dynamics within PSCAD/EMTDC. The Stirling engine and various other components of the DS system are incorporated into an electrical network, including first a single-machine, infinite bus network, and then a larger 12-bus network including conventional generators, loads, and transmission lines. An analysis of the DS control systems is presented, and simulation results are provided to demonstrate the system's steady state and dynamic behavior within these electric power networks. Potential grid interconnection requirements are discussed, including issues with power factor correction and low voltage ride-through, and simulation results are provided to illustrate the dish-Stirling system's capability for meeting such requirements.

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Cakil, Semih. "Computational Analysis For Performance Prediction Of Stirling Cryocoolers." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612738/index.pdf.

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Stirling cryocoolers are required for a wide variety of applications, especially in military equipment, due to their small size, low weight, long lifetime and high reliability considering their efficiency. Thus, it is important to be able to investigate the operating performance of these coolers in the design stage. This study focuses on developing a computer program for simulating a Stirling cryocooler according to the second order analysis. The main consideration is to simulate thermodynamic, fluid dynamic and heat transfer behavior of Stirling cryocoolers. This goal is achieved by following the route of Urieli (1984), which was focused on Stirling cycle engines. In this research, a simulation for performance prediction of a Stirling cryocooler is performed. In addition to that, the effects of system parameters are investigated. This attempt helps to understand the real behavior of Stirling cryocoolers using porous regenerator material. Results implied that first order analysis methods give optimistic predictions where second order method provides more realistic data compared to first order methods. In addition to that, it is shown that regenerator porosity has positive effect on heat transfer characteristics while affecting flow friction negatively. As a conclusion, this study provides a clear understanding of loss mechanisms in a cryocooler. Performed numerical analysis can be used as a tool for investigation of effects of system parameters on overall performance.

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Diallo, Alpha Dassimou. "Contribution à la conception et à la réalisation d'une micro-machine thermique à cycle de Stirling." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD035.

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En France, on estime que plus de 27 TWh de chaleur à une température comprise entre 100 et 200°C sont perdus chaque année. La récupération de cette chaleur perdue est donc un enjeu important pour réduire la consommation globale d'énergie. La récupération de la chaleur peut se faire à l'aide de machines de Stirling, qui sont des machines thermodynamiques réversibles convertissant la chaleur en mouvement mécanique - lequel pourrait ensuite être converti en électricité - à partir de deux sources de température suffisamment différentes. La récupération de la chaleur produite par les systèmes électroniques pourrait être faite avec une machine de Stirling miniaturisée capable de produire de l'électricité à partir de n'importe quelle source de chaleur. Une telle micro-machine peut aussi fonctionner en mode "réfrigérateur" (transport de la chaleur d'une source chaude vers une source froide grâce à un travail mécanique) et pourrait être utilisée pour refroidir des composants électroniques. Le rendement énergétique des machines Stirling peut atteindre 38% (avec une source chaude à 200°C) et leur entretien est réputé être minimal. Cependant, aucune machine Stirling n'a encore été démontrée avec un volume inférieur à un centimètre cube. En 2015, une architecture de micromachine Stirling triphasée pouvant être miniaturisée grâce aux technologies MEMS a été proposée et testée avec succès en macro-volume (avec une taille d'une vingtaine de centimètres). Le présent travail de thèse a été consacré à la miniaturisation de ce nouveau concept de micromachine Stirling pour la récupération de chaleur entre 50 et 200°C, en utilisant les technologies MEMS. Cette approche permettrait la production simultanée de grandes quantités de micro-machines et donc la création éventuelle de réseaux de micromachines à faible coût par watt d'électricité produite. Les micromachines sont constituées d'un empilement de tranches de silicium et de verre. Leurs défis de conception ont été étudiés en détail et leur puissance mécanique de sortie attendue a été estimée. Les procédés de fabrication nécessaires ont été développés et la caractérisation de chaque élément a été effectuée avant l'assemblage. Elles comportent notamment des membranes hybrides de 5 mm de diamètre et de 200 microns d'épaisseur qui jouent le rôle des pistons en micro-volumes et sont des éléments clés de la micro-machine. Ces membranes sont constituées de pièces en silicium (spirales et disques) noyées dans une membrane souple en élastomère de silicone dont les propriétés mécaniques ont donc été étudiées en détail. Des simulations numériques du comportement mécanique et dynamique de ces membranes hybrides ont été présentées. L'accord entre les simulations numériques et les caractérisations a été considéré comme très satisfaisant. Ces membranes se sont révélées très robustes et le déplacement de leur centre peut atteindre 1 à 2 mm sans dommage. Leurs fréquences de résonance vont de 850 Hz à 2800 Hz et il a été montré qu'elles peuvent fonctionner à 200°C sans vieillissement. De plus, l'optimisation d'un procédé d'assemblage par thermocompression d'or (Au) a permis d’obtenir des contraintes de rupture en traction d'environ 20 à 30 MPa, parmi les meilleures rapportées dans la littérature. Des prototypes de micromachines triphasées de 20x20x8mm ont été assemblés, mais leur fonctionnement en mode moteur n'a pas pu être observé, même pour une différence de température de 100 °C. Cependant, en insérant des aimants pour provoquer le déplacement des membranes par excitation électromagnétique, il a été possible d'observer un effet de refroidissement encourageant. Grâce aux travaux réalisés, les principaux éléments de base sont maintenant disponibles et devraient permettre des optimisations ultérieures dans des conditions beaucoup plus favorables
In France, it is estimated that more than 27 TWh of heat at a temperature between 100 and 200°C is lost each year. The recovery of this lost heat is therefore an important issue in reducing overall energy consumption. Heat recovery can be done using Stirling machines, which are reversible thermodynamic machines that convert heat into mechanical motion, which could then be converted into electricity from two sufficiently different temperature sources. The recovery of the heat produced by electronic systems could be done with a miniaturized Stirling machine capable of producing electricity from any heat source. Such a micro-machine can also operate in "refrigerator" mode (transporting heat from a hot source to a cold source through mechanical work) and could be used to cool electronic components. The energy efficiency of Stirling machines can reach 38% (with a hot source at 200°C) and their maintenance is considered minimal. However, no Stirling machine has yet been demonstrated with a volume of less than one cubic centimeter. In 2015, a three-phase Stirling micromachine architecture that can be miniaturized using MEMS technologies has been proposed and successfully tested in macro-volume (with a size of about twenty centimeters). The present thesis work was devoted to the miniaturization of this new Stirling micromachine concept for heat recovery between 50 and 200°C, using MEMS technologies. This approach would allow the simultaneous fabrication of large quantities of micro-machines and thus the possible creation of micromachine networks at low cost per watt of electricity produced. The studied micromachines are made up of a stack of silicon and glass wafers. Their design challenges have been studied in detail and their expected mechanical output power has been estimated. The necessary manufacturing processes were developed and the characterization of each element was carried out prior to assembly. In particular, they include hybrid membranes 5 mm in diameter and 200 microns thick that act as micro-volume pistons and are key elements of the machine. These membranes are made up of silicon parts (spirals and discs) embedded in a flexible silicone elastomer membrane whose mechanical properties have therefore been studied in detail. Numerical simulations of the mechanical and dynamic behavior of these hybrid membranes were presented. The agreement between the numerical simulations and the characterizations was considered to be very satisfactory. These membranes proved to be very robust and the displacement of their center can reach 1 to 2 mm without damage. Their resonance frequencies range from 850 Hz to 2800 Hz and it was shown that they can operate at 200°C without aging. In addition, the optimization of a gold thermocompression assembly process has resulted in tensile breaking stresses of about 20-30 MPa, among the best reported in the literature. Prototype of 20x20x8mm three-phase micromachines were assembled, but their operation in motor mode could not be observed, even for a temperature difference of 100°C. However, when magnets were inserted to induce the displacement of the membranes by electromagnetic excitation, it was possible to observe an encouraging cooling effect. As a result of the work carried out, the main basic elements are now available and should allow further optimization under much more favorable conditions

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Tang, Kuo-Chiang. "Development of computer simulation package for a stirling cryocooler with multiple expansion stages." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1173276031.

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Riabzev, Sergey. "Simulation and development of linear single-piston balanced compressor in Stirling cryogenic cooler." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/33722.

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The linear compressor in a Stirling cooling engine is well known as a source of significant vibration, causing a harmful jitter of equipment, wherein it is employed. Some equipment operates typically in harsh airborne environment, i.e. broadband vibrations, quasi-static accelerations and shocks. Under such excitations, the state-of-the-art approaches to a vibration control, either passive or active, are often failed to meet simultaneously the specified performance, reliability and price.

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Cruz, Vinicius Guimarães da. "Desenvolvimento experimental de um motor stirling tipo gama." Universidade Federal da Paraíba, 2012. http://tede.biblioteca.ufpb.br:8080/handle/tede/5341.

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Made available in DSpace on 2015-05-08T14:59:44Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2663529 bytes, checksum: 5f0d6dec066e59a555afa41866bdae84 (MD5) Previous issue date: 2012-09-06
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The current paper develops an experimental Stirling engine Gama type. Different settings of this type of engine are presented (alpha, beta and gamma), along with the Stirling Cycle Definition and the mathematical modeling for each setting. It´s been Proceed a mathematical analysis based on the Stirling Theory, which is the method based upon the isothermical compression and expansion of an ideal gas, put to analysis by a computer software, determining the dependency between the engine s construction and functioning parameters. Bibliography used takes over the main Stirling engine settings and various working conditions, fed by a numerous types of fuels. The experimental part of the paper is assembling of a Stirling engine gamma type containing no regenerator, therefore, having the air as its working fluid, using electrical resistances as heat source, also a water jet at ambiance temperature to cool down the compression and heat exchanger. Engine tests were performed at atmospheric pressure, temperatures from 100 to 600 °C, 100 to 400 rpm rotations. The results are presented in graphics and are questioned.
O presente trabalho consiste no desenvolvimento experimental de um motor Stirling tipo gama. São apresentadas inicialmente as diferentes configurações deste tipo de motor (alfa, gama e beta), a definição do ciclo de Stirling e a modelagem matemática para cada configuração. Uma análise matemática é feita através da teoria de Schmidt, que é um método baseado na compressão e expansão isotérmica de um gás ideal, implementada em programa computacional permitindo determinar a dependência entre os parâmetros construtivos e de funcionamento do motor. A revisão bibliográfica contempla as principais configurações de motores Stirling e várias condições de funcionamento, alimentados por diversos tipos de combustíveis. A parte experimental do trabalho é a montagem de um protótipo de motor Stirling tipo gama sem regenerador tendo o ar como fluido de trabalho, utilizando resistências elétricas como fonte de calor e um fluxo de água a temperatura ambiente para o resfriamento do trocador de calor de compressão. Os testes do motor serão realizados a pressão atmosférica, para temperaturas de 100 a 600 °C e rotações de 100 a 400 rpm, os resultados são apresentados em gráficos e discutidos.

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19

Su, C.-C. "An enquiry into the mechanism of the pressure drop in the regenerator of the Stirling cycle machine." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377258.

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Martaj, Nadia. "Modélisation énergétique et exergétique, simulation et optimisation des moteurs Stirling à faible différence de températures : confrontations avec l'expérience." Paris 10, 2008. http://www.theses.fr/2008PA100184.

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"Les moteurs alternatifs de type Stirling, sont des moteurs à "air chaud" qui ont la particularité d'être à apport de chaleur externe. Capables d'une grande souplesse d'adaptation et d’utiliser des sources de chaleur variées, ils constituent, dans l'optique du développement durable, une alternative à prendre en compte pour une conversion efficace des chaleurs perdues, de l’énergie solaire et des bio-énergies en travail mécanique. En plus de leur rendement théorique égal à celui de Carnot, ils sont capables de fonctionner avec une faible différence des températures de leurs deux réservoirs de chaleur (Low Temperature Differential : LTD). Ils peuvent ainsi récupérer et convertir en travail les chaleurs perdues dans les procédés industriels ou dans les machines thermiques. Leur configuration géométrique peut être très simple : 2 volumes variables reliés par une conduite. Cette thèse porte sur l’étude des moteurs Stirling à faible différence des températures, en particulier leur modélisation, leur simulation à 0, 1 ou 2 dimensions, leur optimisation et la comparaison avec les résultats de l’expérience. L’étude a été décomposée comme suit : - une analyse énergétique du cycle moteur de Stirling, selon la thermodynamique à échelle finie (TEF), avec des réservoirs infinis (températures constantes des sources, chaude et froide) a été entreprise et a débouché sur la mise en évidence de grandeurs caractéristiques, dimensionnées ou non, et sur une optimisation sous contraintes physiques (pmax, Vmax, Tmax, …). - une analyse énergétique, entropique et exergétique des échangeurs chaud et froid, séparément, puis globale du moteur a été présentée. Cette nouvelle analyse a été réalisée toujours selon la TEF mais en considérant des réservoirs finis (températures variables au niveau des sources). Des modèles d’optimisation du fonctionnement du moteur ont été développés, avec une contrainte sur la surface totale d’échange de chaleur des échangeurs. L’approche utilisée a permis de montrer l’influence de la surface finie et des capacités finies des échangeurs sur l’optimum de fonctionnement de la machine et de définir la distribution optimale de la surface d’échange entre les échangeurs de chaleur. - un modèle numérique 0-D décrivant l’évolution des variables (pression, volumes, masses, énergies échangées, irréversibilités…) en fonction de l’angle de vilebrequin dans le cas d’un moteur LTD a été développé en respectant les hypothèses de Schmidt : températures constantes dans les espaces chaud et froid et pression instantanée uniforme du gaz de travail. Ce modèle fournit les bilans énergétique, entropique et exergétique, dans les espaces chaud (détente), froid (compression) et de régénération. - une simulation dynamique 1-D satisfaisante a été faite à l’aide d’un logiciel du commerce (AMESim), mais cette fois-ci sans aucune hypothèse réductrice sur les températures et les pressions. - une simulation 2-D plus complète des transferts d'énergies, de quantité de mouvement et de masse des écoulements compressibles a été réalisée avec un logiciel multiphysique à maillage mobile (COMSOL) dans le cas de ce même moteur LTD, en supposant la régénération nulle. Cette simulation nous a permis d'obtenir les valeurs instantanées des variables locales en régime établi : pression, température, vitesse et volume. - une confrontation des résultats des modèles 0-D, 1-D et 2-D avec les résultats expérimentaux obtenus sur un moteur réel de notre laboratoire nous a permis de conclure à une bonne corrélation entre ces résultats, en particulier avec ceux du modèle 1-D. De plus, l’existence de 2 régimes de transfert de chaleur en fonction de la vitesse de rotation a été mise en évidence et des équations représentatives ont été proposées. "
Stirling engines are "hot air" engines to which heat is provided from an outside source. Able of great flexibility and of any heat source use, they are an alternative, to be taken into account within the sustainable development perspective, for the effective conversion of waste heat or solar- or bio- energies into mechanical work. Their theoretical efficiency equal to Carnot efficiency and their ability to work with small temperature differences between their two heat reservoirs (“Low Temperature Differential”, LTD) enable them to recover and convert waste heat issued from industrial processes and thermal machines into mechanical work. Their geometrical configuration can be very simple : 2 variable closed volumes only connected by a duct. The aim of this thesis is the study of the LTD Stirling engine, particularly its modeling, its simulation (0-D, 1-D or 2-D), its optimization and the comparison with the experimental results. This study was decomposed as follows : - an energy analysis of the cycle of the Stirling engine with infinite reservoirs (constant temperatures of the hot source and cold sink), accordingly to the finite scale thermodynamics (FScT) methods, was carried out and extended to an optimization with physical constraints (pmax, Vmax, Tmax, …). Characteristic numbers, dimensioned or not, were put to evidence. - an energy, entropy and exergy analysis of the heat exchangers, hot and cold separately, and, then, of the whole engine is presented. This new analysis was carried out, once more accordingly to the finite scale thermodynamics methods, by considering finite reservoirs. Models for the engine optimization are developed, with a constraint on the total heat transfer surface of the exchangers. The used approach makes it possible to highlight the influence of the finite surface and finite capacities of the exchangers on the optimum of the engine operation characteristics and on the optimal distribution of the heat- transferring surface between the heat exchangers. - a 0-D numerical model describing the evolution of the internal variables (pressure, volumes, masses, exchanged energies, irreversibilities…) as function of the crankshaft angle was developed, in the case of an LTD engine, in accordance to Schmidt assumptions : constant temperature in hot and cold volumes and instantaneous uniform gas pressure. This model gives the energy-, entropy- and exergy balance in the three spaces : hot expansion volume, cold compression volume and regenerator. - a satisfying 1-D dynamic modeling was done with the help of a commercial software (AMESim), and, this time, without any restrictive assumption on the temperatures and pressures. - a more complete 2-D simulation of energy-, mass- and momentum transfer of the compressible working-gas flow was carried out using a multiphysics software (COMSOL) for this LTD Stirling engine assuming a null regeneration. This analysis enabled us to obtain the instantaneous values of the local variables in steady-state operation mode : pressure, temperature, speed and volume. - the results of the 0-D, 1-D and 2-D models were compared with the experimental results obtained from an actual engine of our laboratory. We thus concluded there is a good correlation between the results obtained from these models, particularly the 1-D model, and those of the experiments. Furthermore, 2 heat transfer regimes were detected depending on the speed of revolution and equations were proposed to represent them

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Boart, Patrik. "Life cycle simulation support for functional products /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/20.

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Petre, Camelia Feidt Michel Petrescu Stoian. "Utilisation de la thermodynamique à vitesse finie pour l'étude et l'optimisation du cycle Carnot et des machines de Stirling." Nancy : Université de Nancy 1, 2007. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2007_0115_PETRE.pdf.

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Thèse de doctorat : Mécanique, Energétique : Nancy 1 : 2007. Thèse de doctorat : Mécanique, Energétique : Université Politehnica de Bucarest : 2007.
Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr.

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Petre, Camelia. "Utilisation de la thermodynamique à vitesse finie pour l’étude et l’optimisation du cycle Carnot et des machines de Stirling." Thesis, Nancy 1, 2007. http://www.theses.fr/2007NAN10115/document.

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Le sujet choisi a nécessité une étude bibliographique pour les études de recherche publiées dans les domaines de la Thermodynamique à Vitesse Finie (TVF) et Thermodynamique en Temps Fini (TTF), et pas seulement. Le premier chapitre est dédié à l’état de l’art bibliographique en ce qui concerne le sujet. Une synthèse des aspects énergétiques du Monde, les principales considérations sur les machines de Stirling, les principales méthodes d’analyse et optimisation thermodynamique sont présentés. La comparaison entre la TVF et TTF est présentée, car le développement original s’appuie sur deux méthodes, une de la TVF et l’autre de la TTF, ou plutôt en Dimension Finie. Le deuxième chapitre est dédié aux contributions originales dans le domaine de la TVF: l’adaptation de la Méthode Directe à l’étude et optimisation des machines à cycle inverse avec des irréversibilités internes et externes; amélioration de la méthode de Schmidt en considérant la cinématique effective de la machine considérée ; présentation d’une étude de sensibilité qui permet de séparer les irréversibilités par causes et analyser les effets séparément ; adaptation de la Méthode Directe à l’étude et optimisation de moteurs de Stirling solaires et des ensembles solaire récepteur – concentrateur - moteur Stirling solaire- générateur électrique ; validation de schéma par la comparaison avec les données expérimentales; mise en valeur de la recherche par une application pratique: système de génération d’énergie électrique à partir de l’énergie solaire et hydrogène comme vecteur d’énergie. Le troisième chapitre est dédié aux contributions originales dans le domaine de la TTF. Un modèle thermodynamique pour l’étude et optimisation des machines thermiques est proposé et appliqué pour le cycle de Carnot, pour plusieurs cas, pour des lois de transfert de chaleur linéaires et non linéaires convectif et radiatif. L‘existence des données expérimentales a fait possible la simulation du fonctionnement avec le modèle analytique et la validation. Les conclusions générales et perspectives attendues sont présentées
The stated subject needed an important bibliographic research for the publications in the field of Thermodynamics with Finite Speed (TFS) and Thermodynamics in Finite Time (TFT), and more than that. The first chapter is dedicated to the current status in the chosen subject. A synthesis of worldwide energetic aspects, main considerations on Stirling machines, main methods for analysis and optimization are presented. An important paragraph is the comparison between TFS and TFT, since the original contributions represent two methods, one from TFS and the other one from TFT. The second chapter is dedicated to the original contributions in the field of TFS: adjustment of the Direct Method to the study and optimization of reverse cycle machines with internal and external irreversibilities; correction of the Schmidt method by considering the effective kinematics of the studied machine; development of a sensitivity study to analyze the effects of each irreversibility; adaptation of the Direct Method to the study and optimization of Stirling solar engines and solar assemblies receiver – concentrator - Stirling engine - electric generator; validation of the proposed scheme par comparison with experimental data; research practical utilization: a proposed solar system for electric energy and hydrogen (as an energy career) production. The third chapter is dedicated to the original contributions in the field of TFT. A thermodynamic model pour for the study and optimization of thermal machines is proposed and applied to the Carnot cycle, for more cases, for linear and non linear convective and radiative heat transfer laws. Existence of experimental data allowed the operating simulation and validation of the model. The general conclusions and perspectives are presented

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Cortes, Francisco O’Neill. "An endogenous business cycle model : theory and simulation." Master's thesis, Instituto Superior de Economia e Gestão, 2016. http://hdl.handle.net/10400.5/12830.

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Mestrado em Economia Monetária e Financeira
Esta dissertação tem como objectivos principais, partindo dos modelos de ciclos económicos endógenos existentes na literatura, em primeiro lugar construir um novo modelo e em segundo lugar determinar a sua capacidade para gerar ciclos e em que medida os valores dos parâmetros afectam os resultados. O modelo-base que foi usado foi o modelo da capacidade utilizada de Leão (2016), complementado com o modelo "profit squeeze" de Sherman (1991). Depois de terem sido feitas simulações usando, tanto quanto possível, valores plausíveis para os parâmetros, concluiu-se que o modelo é de facto capaz de gerar ciclos económicos que satisfazem a maior parte dos factos estilizados e cuja forma depende dos parâmetros. Contudo, fica por fazer a estimação dos parâmetros do modelo para situações económicas concretas. Em suma, os resultados obtidos sugerem que a resposta do investimento a desvios da capacidade utilizada face ao seu valor desejável, o principal mecanismo em que o modelo se baseia, tem um papel relevante na explicação de como os ciclos económicos se desenrolam em economias reais.
This dissertation has as its main objectives, taking the models for endogenous business cycles existing in the literature, firstly to build a new model and secondly to determine its actual capability to generate cycles and how different parameter values can change the results. The base model used was the capacity utilization model by Leão (2016), complemented with the profit squeeze model by Sherman (1991). After we had run simulations using, as much as possible, plausible values for the parameters, it was found that the model can indeed generate business cycles that satisfy most stylized facts and whose shape depends on the parameters. However, the next step of estimating the parameters of the model for concrete real world situations remains still to be done. Overall, our results suggest that the response of investment to deviations of capacity utilization from its desirable level, which is the main mechanism on which the model is based, plays a significant role in the explanation of how business cycles develop in real economies.
N/A

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Mabrouk, Mohamed Tahar. "Production optimale d’énergie pour une communauté à petite échelle : application à l’optimisation d’une centrale solaire hybride produisant électricité et chaleur." Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0163/document.

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Ce travail traite la modélisation et l'optimisation des centrales solaires thermodynamiques à concentration produisant de l'électricité pour l'électrification des zones rurales isolées et mal raccordées au réseau électrique. D’abord, un modèle optique et thermique détaillé des concentrateurs solaires cylindro-paraboliques est présenté permettant l'identification de capteurs existants et la création de corrélations qui peuvent être injectées dans un modèle plus global. Dans un second temps, un modèle original d'un stock de chaleur stratifié de type « lit de roche » est développé. Le nouveau modèle proposé permet de déterminer analytiquement le profil de température dans le stock à n'importe quel instant dans le cas d'une température d'entrée régulée. Ensuite, deux alternatives de bloc moteur sont modélisées : le moteur Stirling et le Cycle Organique de Rankine (ORC acronyme anglais pour Organic Rankine Cycle). Concernant le moteur Stirling, une revue critique des modèles existants a été effectuée. Certains de ces modèles ont été implémentés et complétés par des modèles originaux des pertes par fuite de matière et par effet navette. Le cycle organique de Rankine, lui, est modélisé par un modèle orientée vers l'optimisation. Enfin, une optimisation mono et multicritère d’une centrale solaire est effectuée. La configuration étudiée est équipée d’un stock de chaleur et d’une chaudière d’appoint. Elle est optimisée selon trois critères : le coût moyen actualisé de l'électricité (LCOE acronyme anglais pour Levelized Cost Of Electricity), le rendement énergétique de la centrale et la quantité de CO2 émise par Kilowatt heure d'électricité produite
This work deals with the modelling and the optimization of thermodynamic solar power plants intended to supply electricity to isolated locations. Firstly, a state of the art of solar collectors is achieved and a model for parabolic trough collectors is proposed. This model is used for actual collectors identification. It is used also to propose correlations to be introduced in the whole system model. In a second time, a state of the art of energy storage technologies is conducted and an original model of a packed bed storage tank is proposed. This model gives an explicit solution of the temperature inside the tank without using a time step based numerical resolution. Two alternatives for the power block are given: Stirling engines and Organic Rankine Cycles. For Stirling engines, a critical review of existing models is performed. Some losses occurring in Stirling engines are not well documented in the literature as leakage losses at the power piston and displacer gap losses. Therefore, original models are proposed to estimate these losses. When compared to former models in the literature, the new model of the displacer gap losses demonstrates clearly that it is very important to use decoupled models with caution. Concerning the ORC, an optimization-oriented model is proposed. Finally, a mono and multi-objective optimization of a solar power plant is performed. The optimized system is composed of a solar field, a packed bed heat storage, a power block and an auxiliary fired heater. Objective functions used in this study are: the Levelized Cost of Electricity (LCOE), the energetic efficiency of the power plant and CO2 emission per kilowatt hour of electricity

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Hickman, David Matthew. "The simulation of spark ignition engine behaviour under drive cycle and off-cycle operating conditions." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395491.

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François, Pierre. "Contribution à la modélisation électromagnétique d’un générateur linéaire à induction appliquée à un micro-cogénérateur Stirling à piston libre." Thesis, Cachan, Ecole normale supérieure, 2011. http://www.theses.fr/2011DENS0003.

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Cette thèse porte sur le développement d’un cogénérateur résidentiel constitué d’un générateur linéaire asynchrone entraîné par deux moteurs Stirling fonctionnant en mode ‘piston libre double effet’. Les critères caractérisant un tel cogénérateur sont décrits ainsi que ses différents modes d’utilisation dans le domaine résidentiel. Les différentes technologies sont passées en revue.Les équations de la mécanique sur lesquelles se fondent le contrôle du couplage thermoélectrique du cogénérateur et sa stabilité y sont définies. Le générateur électrique est modélisé en vue de calculer les grandeurs électriques des équations à bobines couplées et les grandeurs du schéma électrique équivalent, ce schéma permet d’inverser le modèle.Les résultats des modèles analytiques sont validés par des mesures faites sur des maquettes spécialement conçues. Une étude paramétrique de la structure du générateur a permis d’optimiser ses performances. Les équations de la mécanique et le modèle électrique sont utilisés pour poser les bases d’une optimisation ‘système’ du cogénérateur
This thesis focuses on the development of a residential cogenerator which consists of a linear induction generator driven by two Stirling engines, free-piston double-acting operating mode. The criteria characterizing such cogenerator are described and its various modes of use in the residential sector. The various technologies are reviewed.The equations of mechanics that underlie the control of the coupling of thermoelectric cogeneration and stability are defined.The electric generator is modeled to calculate the electrical coil coupled equations and the magnitudes of the equivalent circuit, this scheme allows us to reverse the pattern. The results of analytical models are validated by measurements on specially designed models. A parametric study of the structure of the generator has optimized its performances. The equations of mechanical and electrical model are used to lay the groundwork for optimization of all the cogenerator, considered as a system

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Posadas, Sergio. "Stochastic simulation of a Commander's decision cycle (SSIM CODE)." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA392113.

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Thesis (M.S. in Operations Research) Naval Postgraduate School, June 2001.
Thesis advisor(s): Paulo, Eugene P. ; Olson, Allen S. "June 2001." Includes bibliographical references (p. 111-115). Also available in print.

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Nyoni, Bothwell. "Simulation of the sulphur iodine thermochemical cycle / Bothwell Nyoni." Thesis, North-West University, 2011. http://hdl.handle.net/10394/6685.

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The demand for energy is increasing throughout the world, and fossil fuel resources are diminishing. At the same time, the use of fossil fuels is slowly being reduced because it pollutes the environment. Research into alternative energy sources becomes necessary and important. An alternative fuel should not only replace fossil fuels but also address the environmental challenges posed by the use of fossil fuels. Hydrogen is an environmentally friendly substance considering that its product of combustion is water. Hydrogen is perceived to be a major contender to replace fossil fuels. Although hydrogen is not an energy source, it is an energy storage medium and a carrier which can be converted into electrical energy by an electrochemical process such as in fuel cell technology. Current hydrogen production methods, such as steam reforming, derive hydrogen from fossil fuels. As such, these methods still have a negative impact on the environment. Hydrogen can also be produced using thermochemical cycles which avoid the use of fossil fuels. The production of hydrogen through thermochemical cycles is expected to compete with the existing hydrogen production technologies. The sulphur iodine (SI) thermochemical cycle has been identified as a high-efficiency approach to produce hydrogen using either nuclear or solar power. A sound foundation is required to enable future construction and operation of thermochemical cycles. The foundation should consist of laboratory to pilot scale evaluation of the process. The activities involved are experimental verification of reactions, process modelling, conceptual design and pilot plant runs. Based on experimental and pilot plant data presented from previous research, this study presents the simulation of the sulphur iodine thermochemical cycle as applied to the South African context. A conceptual design is presented for the sulphur iodine thermochemical cycle with the aid of a process simulator. The low heating value (LHV) energy efficiency is 18% and an energy efficiency of 24% was achieved. The estimated hydrogen production cost was evaluated at $18/kg.
Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

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Mapamba, Liberty Sheunesu. "Simulation of the copper–chlorine thermochemical cycle / Mapamba, L.S." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7052.

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The global fossil reserves are dwindling and there is need to find alternative sources of energy. With global warming in mind, some of the most commonly considered suitable alternatives include solar, wind, nuclear, geothermal and hydro energy. A common challenge with use of most alternative energy sources is ensuring continuity of supply, which necessitates the use of energy storage. Hydrogen has properties that make it attractive as an energy carrier. To efficiently store energy from alternative sources in hydrogen, several methods of hydrogen production are under study. Several literature sources show thermochemical cycles as having high potential but requiring further development. Using literature sources, an initial screening of thermochemical cycles was done to select a candidate thermochemical cycle. The copper–chlorine thermochemical cycle was selected due to its relatively low peak operating temperature, which makes it flexible enough to be connected to different energy sources. Once the copper–chlorine cycle was identified, the three main copper–chlorine cycles were simulated in Aspen Plus to examine which is the best configuration. Using experimental data from literature and calculating optimal conditions, flowsheets were developed and simulated in Aspen Plus. The simulation results were then used to determine the configuration with the most favourable energy requirements, cycle efficiency, capital requirements and product cost. Simulation results show that the overall energy requirements increase as the number of steps decrease from five–steps to three–steps. Efficiencies calculated from simulation results show that the four and five–step cycles perform closely with 39% and 42%, respectively. The three–step cycle has a much lower efficiency, even though the theoretical calculations imply that the efficiency should also be close to that of the four and five–step cycles. The five–step reaction cycle has the highest capital requirements at US$370 million due to more equipment and the three–step cycle has the lowest requirement at US$ 275 million. Payback analysis and net present value analysis indicate that the hydrogen costs are highest for the three–step cycle at between US$3.53 per kg for a 5–10yr payback analysis and the five–step cycle US$2.98 per kg for the same payback period.
Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

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Garcia, Alberto A. "Improving life cycle management through simulation and efficient design." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Sept/08Sep%5FGarcia.pdf.

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Thesis (M.S. in Operations Research)--Naval Postgraduate School, September 2008.
Thesis Advisor(s): Lucas, Thomas W. "September 2008." Description based on title screen as viewed on November 6, 2008. Includes bibliographical references (p. 89-90). Also available in print.

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Biglione, Jordan. "Simulation et optimisation du procédé d'injection soufflage cycle chaud." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0079/document.

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Le procédé d'injection soufflage est rendu accessible aux presses d'injection standard à travers le procédé d'injection soufflage cycle chaud, sans stockage puis réchauffe de la préforme. Le but étant de rendre accessible la production de petites séries de pièces creuses à des entreprises possédant un parc machine de presse à injecter. Les pièces sont réalisées en polypropylène et sont soufflées juste après avoir été injectées. Ce processus implique que la préforme se doit d'être suffisamment malléable pour être soufflée mais suffisamment visqueuse pour éviter de se rompre durant la phase de soufflage. Ces contraintes conduisent à une fenêtre de mise en oeuvre réduite, comprise entre la température de fusion du polymère et la température de cristallisation, soit le domaine ou le polypropylène est à l'état amorphe et suffisamment froid pour avoir une viscosité conséquente sans cristalliser. Ce procédé cycle chaud implique des gradients de température, de grands taux d'étirages et d'importantes cinétiques de refroidissement. Des mesures de rhéométrie à l'état fondu sont réalisées pour identifier le comportement de la matière dans la plage de température du procédé, de même que des tests de calorimétrie différentielle. L'observation du procédé et l'étude de la cristallisation du matériau permettent de supposer que ce dernier reste à l'état fondu durant la phase de soufflage. Un modèle rhéologique de Cross est utilisé, avec la dépendance thermique prise en compte par une loi d'Arrhénius. Le procédé est simulé à l'aide d'un logiciel de calcul par éléments finis dédié aux écoulements de fluides complexes (POLYFLOW) dans l'espace de travail ANSYS Workbench. La géométrie autorise une approche axisymétrique, facilitant ainsi la modélisation. Le calcul transitoire est lancé sous conditions anisothermes et l'auto-échauffement est considéré. Des études de sensibilité sont réalisées et révèlent l'influence de paramètres procédé tels que le comportement du matériau, la pression de soufflage et le champ de température initial. Des mesures d'épaisseurs sont réalisées en utilisant une méthode de traitement d'image permettant l'analyse des images numérisées de pièces découpées et des images issues de tomographie X des pièces. Les résultats simulés sont comparés aux mesures expérimentales. Le modèle présente les mêmes tendances que les mesures. L'existence de déformations élongationnelles, mais aussi par cisaillement lors du soufflage après contact avec le moule, est discutée. Une boucle d'optimisation est mise en place afin de déterminer numériquement la géométrie optimale de préforme. Des points de contrôle sont placés le long de la préforme et l'algorithme d'optimisation modifie les épaisseurs à ces points
Single stage injection blow molding process, without preform storage and reheat, could be run on a standard injection molding machine, with the aim of producing short series of specific hollow parts. The polypropylene bottles are blown right after being injected. The preform has to remain sufficiently malleable to be blown while being viscous enough to avoid being pierced during the blow molding stage. These constraints lead to a small processing window, and so the process takes place between the melting temperature and the crystallization temperature, where the polypropylene is in his molten state but cool enough to enhance its viscosity without crystallizing. This single stage process introduces temperature gradients, molecular orientation, high stretch rate and high cooling rate. Melt rheometry tests were performed to characterize the polymer behavior in the temperature range of the process, as well as Differential Scanning Calorimetry. A viscous Cross model is used with the thermal dependence assumed by an Arrhenius law. The process is simulated through a finite element code (POLYFLOW) in the Ansys Workbench framework. The geometry allows an axisymmetric approach. The transient simulation is run under anisothermal conditions and viscous heating is taken into account. Thickness measurements using image analysis are done and the simulation results are compared to the experimental ones. The experimental measurements are done by analizing tomography datas. The simulation shows good agreements with the experimental results. The existence of elongational strain as well as shear strain during the blowing after contact with the mold is discussed. An optimization loop is run to determine an optimal initial thickness repartition by the use of a Predictor/Corrector method to minimize a given objective function. Design points are defined along the preform and the optimization modifies the thickness at these locations. This method is compared to the Downhill Simplex Method and shows better efficiency

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Sathya, Santhana. "Fabrication of a thin film resistance heater." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175624104.

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Ucer, Deniz. "Life Cycle Assessment Of Masonry Wall Types Using Simulation Technique." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614373/index.pdf.

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This is the report of a Life Cycle Assessment (LCA) study on some masonry wall types. As the starting point, literature on masonry materials, techniques and possible end-of-life scenarios were examined that are needed for the formulation of a LCA study. Prevalent masonry types were detected as fired clay brick, AAC block, natural stone, mud brick as well as prevalent end-of-life cases as landfill, reuse and recycling. Additionally, an overview of the literature on Environmental Impact Assessment (EIA) was presented in order to detect a framework for the structure of a LCA study. After the collection of all needed information, several possible life cycle scenarios were formulated in a realistic manner for each stated masonry type. Obtained information was applied to a LCA evaluation software product named SimaPro life cycle inventory software (PRé
Consultants, 2012). By means of the software product, general scores of environmental impact for all alternatives were obtained. Besides analyzing and comparing the scores, basic reasons behind the results were discussed in terms of similarity and difference. The results reveal that when the requirements shaping the wall are clearly described, the most and the least environmental friendly wall types are detectable. During the study two main scopes, such as commonly used wall thicknesses and thicknesses for thermal insulation were described and several types of walls with life cycle alternatives were labeled as the most or the least harmful to nature. To conclude, although it is not reasonable to point out one type of masonry as the least harmful one for any cases, the conditions of each case detect the most and the least v harmful type of masonry walls. Nevertheless, the relatively low environmental impact of mud brick masonry is striking. Therefore the environmental friendly aspect of mud brick masonry is underlined &ndash
one more time- by the results of this study.

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Sazdanoff, Nick. "Modeling and simulation of the algae to biodiesel fuel cycle." Connect to resource, 2006. http://hdl.handle.net/1811/5981.

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Thesis (Honors)--Ohio State University, 2006.
Title from first page of PDF file. Document formattted into pages: contains vii, 60 p.; also includes graphics. Includes bibliographical references (p. 59-60). Available online via Ohio State University's Knowledge Bank.

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Ny, Henrik. "Strategic Life-Cycle Modeling and Simulation for Sustainable Product Innovation." Doctoral thesis, Karlskrona : Blekinge Institute of Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00441.

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Many specific methods and tools have been developed to deal with sustainability problems. However, without a unifying theory it is unclear how these relate to each other and how they can be used strategically. A Framework for Strategic Sustainable Development (FSSD) is being developed to cover this need for clarity and structure. It includes backcasting from a principled definition of sustainability as a key feature. The aim of this thesis is to study how this framework can guide the use and improvement of detailed methods and tools, in particular to support sustainable product innovation (SPI). First, a new strategic life-cycle management approach is presented, in which the selection of aspects to be considered are not based on typical down-stream impact categories, but on identified major violations of sustainability principles. Ideas of how this approach can inform various specific methods and tools are also presented, as a basis for an integrated “toolbox” for SPI. As part of such, a new “template” approach for sustainable product development (TSPD) is developed through a sustainability assessment case study of TVs. That study indicates that this approach can create a quick and strategically relevant overview of critical sustainability aspects of a product, as well as facilitate communication between top management, product developers and external stakeholders. Based on such an assessment, it is sometimes necessary to go deeper into details, including the use of specific engineering methods and tools. To facilitate a coordinated assessment of sustainability aspects and technical aspects, an introductory procedure for sustainability-driven design optimization is suggested trough a water jet cutting case study. Equally important, to get a breakthrough for SPI, it is essential to integrate sustainability aspects into the overall decision-making process at different levels in companies. An approach to assessing sustainability integration in strategic decision systems is therefore also developed through a case study involving several companies. Finally, the integration between the FSSD and general systems modeling and simulation (SMS) is discussed and tested in another water jet cutting case study. It is shown feasible to start with the FSSD to create lists of critical flows and practices, ideas of long term solutions and visions, and a first rough idea about prioritized early investments. After that, SMS can be applied to study the interrelationships between the listed items, in order to create more robust and refined analyses of the problems at hand, possible solutions and investment paths, while constantly coupling back to the sustainability principles and guidelines of the FSSD. This research shows that the combination of the FSSD with detailed methods and tools cohesively provides decision-makers with both a robust overview and, when needed, a more coordinated and effective detailed support. To utilize its full potential, this approach should now be integrated into decision processes, software and manuals for SPI.

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Freikamp, Frank. "Towards multi-cycle simulation of in-cylinder flow and combustion /." Göttingen : Cuvillier, 2008. http://d-nb.info/991710207/04.

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HERRERIA, ERNESTO JAVIER RUANO. "SIMULATION OF AN ORGANIC RANKINE CYCLE POWERED BY SOLAR ENERGY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21796@1.

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FUNDAÇÃO DE APOIO À PESQUISA DO ESTADO DO RIO DE JANEIRO
Esta simulação considera um ciclo Rankine que utiliza um fluido de trabalho orgânico, com a particularidade que a fonte de energia de entrada ao sistema será solar. Esta energia renovável que provem do potencial do Sol é aproveitada com a utilização de coletores concentradores lineares parabólicos. Estes dois circuitos: do ciclo Rankine orgânico e do conjunto de coletores interatuam termicamente mediante um trocador de calor chamado de gerador de vapor. Adicionalmente, existe um sistema de armazenamento térmico que permite acumular parte da energia solar coletada para ser utilizada em períodos sem radiação solar ou com níveis baixos da mesma. A primeira parte deste trabalho mostra os aspectos teóricos introdutórios e as considerações para trabalhar com um ciclo Rankine de tipo orgânico, o tipo de coletores escolhido e a utilização de armazenamento térmico. O segundo capítulo mostra o modelo matemático apropriado para simular um sistema de geração de potência de baixa capacidade (50 kW) e os componentes de cada circuito: ciclo (bomba, expansor, condensador, recuperador, gerador de vapor), coletores (cobertura, refletor, absorvedor, etc.) e armazenamento (tanques, etc.). A simulação foi desenvolvida no software EES. O terceiro analisa os parâmetros do modelo, seus possíveis valores físicos, a sensibilidade da sua variação e sua seleção adequada com o objetivo de efetuar uma simulação bastante similar à realidade e as incertezas presentes. No capítulo final se apresentam os resultados em base as condições de desenho consideradas.
This simulation considers a Rankine cycle that works with an organic fluid, but has the particularity of using solar power as the font of input energy. This renewable energy that comes from the sun’s potential is taken with the use of parabolic trough collectors. These two circuits: that of the organic Rankine cycle (ORC) and the other of collector’s ensemble interact termically in a heat exchanger called as vapor generator. Adicionally there’s a thermal storage system that allows accumulating part of the collected solar energy to be used for periods of time when there’s no solar radiation or with very low levels of it. The first part of this work shows the introductory theoretical aspects and the considerations to work with an organic Rankine cycle (ORC), the type of chosen collector and the use of heat storage. The second chapter shows the appropriate mathematic model to simulate a system of power generation of low capacity (50 kW) and the components of each circuit: ORC (pump, expander, condenser, recuperator, vapor generator), collectors (glass cover, reflector mirror, absorber tube, etc.) and thermal storage (storage tanks, etc.). The simulation was developed using EES software. The third chapter analyzes the parameters of the model, specially its values and possible variations to approach the simulation to the reality. In the final chapter, some results are presented based on some considered design conditions.

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Aben, Frans. "Experimental simulation of the seismic cycle in fault damage zones." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAU012/document.

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Les séismes le long de grandes failles crustales représentent un danger énorme pour de nombreuses populations. Le mécanique de ces failles est influencé par des zones endommagées qui entourent le coeur de faille. La fracturation dans ces zones contrôle chaque étape du cycle sismique. En effet, cette zone contrôle la mécanique de la rupture sismique, elle est un conduit pour les fluides, réagit chimiquement sous l'effet de fluides réactifs, et facilite la déformation pendant les périodes post- et inter-sismiques. Dans cette thèse de doctorat, des expériences de laboratoire ont été réalisées pour mieux comprendre 1) la façon dont l'endommagement est généré pendant le chargement transitoire co-sismique, 2) comment l'endommagement permet de mieux contraindre le chargement co-sismique le long de grandes failles, et iii) comment les fractures peuvent se cicatriser au fil du temps et contrôler l'évolution de la perméabilité et de la résistance mécanique de la faille.L'introduction de la thèse propose une revue critique de la littérature sur la génération de dommages co-sismiques et en particulier sur la formation des roches pulvérisées. Le potentiel de ces roches comme marqueur des déformations co-sismiques est discuté. Bien que ces roches pulvérisées soient prometteuses pour ces aspects, plusieurs questions restent ouvertes.L'une de ces questions concerne les conditions de chargement transitoire nécessaires pour atteindre la pulvérisation. Le seuil de taux de deformation pour atteindre la pulvérisation peut être réduit par des endommagemments progressifs, au cours de ruptures sismiques successives. Des barres de Hopkinson ont été utilisées pour effectuer des chargements dynamique successifs d'une roche cristalline (monzonite). Les résultats montrent que le seuil pour atteindre la pulvérisation est réduit d'au moins 50% lorsque des chargements successives sont imposés. Cette thèse discute aussi pourquoi les roches pulvérisées sont presque toujours observées dans des roches cristallines et peu dans des roches sédimentaires poreuses. Pour comprendre cette observation, des expériences à haute vitesse de déformation ont été effectuées sur des grès de Rothbach. Les résultats montrent que la pulvérisation des grains eux mêmes ne se produit pas dans les grès. L'endommagement reste se produit principalement à une échelle supérieure à celle grains, et des bandes de compaction sont observées. La compétition entre l'endommagement inter- et intra-granulaire est expliquée par les paramètres microstructuraux en combinant deux modèles micromécaniques classiques. Les microstructures observées dans les grès peuvent se former dans le régime quasi-statiques et aussi dans le régime dynamique. Par conséquent, il est recommandée d'être prudent lors de l'interprétation du mécanisme de deformation dans les roches sédimentaires proches de la surface. La dernière question abordée durant la thèse est la cicatrisation post-sismique de fractures co-sismiques. Des expériences ont été réalisées pour cicatriser des fissures par précipitation de calcite. Le but est l'étude du couplage entre l'augmentation de résistance mécanique de la roche fissurée et l'évolution de la perméabilité. Les échantillons fracturées ont été soumis à des conditions de pression et températures similaires de la croûte supérieure et à une percolation d'un fluide sursaturé en calcite pendant plusieurs mois. Ce couplage non-existe dans les premières étapes de la cicatrisation. Il est révélé par l'imagerie par tomographie aux rayons X que le scellement naissant des fractures se produit dans les porosités situées en aval de barrières d'écoulement, et donc dans des régions qui ne touchent pas les principales voies d'écoulement du fluide. Le découplage entre l'augmentation de résistance de la roche et la perméabilité suggère que les zones d'endommagement peu profondes dans les failles actives peuvent rester des conduits actifs pour les fluides plusieurs années après un séisme
Earthquakes along large crustal scale faults are a huge hazard threatening large populations. The behavior of such faults is influenced by the fault damage zone that surrounds the fault core. Fracture damage in such fault damage zones influences each stage of the seismic cycle. The damage zone influences rupture mechanics, behaves as a fluid conduit to release pressurized fluids at depth or to give access to reactive fluids to alter the fault core, and facilitates strain during post- and interseismic periods. Also, it acts as an energy sink for earthquake energy. Here, laboratory experiments were performed to come to a better understanding of how this fracture damage is formed during coseismic transient loading, what this fracture damage can tell us about the earthquake rupture conditions along large faults, and how fracture damage is annihilated over time.First, coseismic damage generation, and specifically the formation of pulverized fault damage zone rock, is reviewed. The potential of these pulverized rocks as a coseismic marker for rupture mechanisms is discussed. Although these rocks are promising in that aspect, several open questions remain.One of these open questions is if the transient loading conditions needed for pulverization can be reduced by progressively damaging during many seismic events. The successive high strain rate loadings performed on quartz monzonites using a split Hopkinson pressure bar reveal that indeed the pulverization strain rate threshold is reduced by at least 50%.Another open question is why pulverized rocks are almost always observed in crystalline lithologies and not in more porous rock, even when crystalline and porous rocks are juxtaposed by a fault. To study this observation, high strain rate experiments were performed on porous Rothbach sandstone. The results show that pervasive pulverization below the grain scale, such as observed in crystalline rock, does not occur in the sandstone samples for the explored strain rate range (60-150 s-1). Damage is mainly occurs at a scale superior to that of the scale of the grains, with intragranular deformation occurring only in weaker regions where compaction bands are formed. The competition between inter- and intragranular damage during dynamic loading is explained with the geometric parameters of the rock in combination with two classic micromechanical models: the Hertzian contact model and the pore-emanated crack model. In conclusion, the observed microstructures can form in both quasi-static and dynamic loading regimes. Therefore caution is advised when interpreting the mechanism responsible for near-fault damage in sedimentary rock near the surface. Moreover, the results suggest that different responses of different lithologies to transient loading are responsible for sub-surface damage zone asymmetry.Finally, post-seismic annihilation of coseismic damage by calcite assisted fracture sealing has been studied in experiments, so that the coupling between strengthening and permeability of the fracture network could be studied. A sample-scale fracture network was introduced in quartz monzonite samples, followed exposure to upper crustal conditions and percolation of a fluid saturated with calcite for several months. A large recovery of up to 50% of the initial P-wave velocity drop has been observed after the sealing experiment. In contrast, the permeability remained more or less constant for the duration of the experiment. This lack of coupling between strengthening and permeability in the first stages of sealing is explained by X-ray computed micro tomography. Incipient sealing in the fracture spaces occurs downstream of flow barriers, thus in regions that do not affect the main fluid flow pathways. The decoupling of strength recovery and permeability suggests that shallow fault damage zones can remain fluid conduits for years after a seismic event, leading to significant transformations of the core and the damage zone of faults with time

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Jun, Jong Brian. "A Visual Simulation Life-Cycle Of The Queston Physician Network." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/10030.

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This research develops a discrete-event simulation model of the Queston Physician Network using the Visual Simulation Environment (VSE), an object-oriented simulation software program. The Queston Physician Network, a subsidiary of Biological & Popular Culture, Inc., attempts to centralize the administrative, financial, and telecommunication needs of a network of primary care physicians located throughout the United States. The VSE, running on the NeXTSTEP operating system, is a discrete event simulation software package with the capability to tackle the complexities associated with such a network design. The advantages of VSE over other simulation languages include its visualization of objects, domain independence, and object-oriented design and modeling. The objective of the Queston simulation model is to addresses the performance capabilities of the physician network operationally centralized in the Queston Information Center. Additionally, the model could be used to analyze a physician-patient encounter of a generic clinic to identify recommended staffing and scheduling schemes. Object-oriented programming allows the objects in the model to be instantiated at the time of execution. This feature permits the creation of one flexible generic clinic that can be reused to produce several identical clinics at program execution. In this model, one generic, family practice clinic and the Queston Information Center are created. Input data provided by both medical experts and a time study are used. Verification and validation techniques are applied in all phases of the modeling effort. Results using different configurations are presented and recommendations for future research are discussed
Master of Science

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Green, Lilian. "Dynamic simulation for whole life appraisal." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325206.

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Moradi, Mohammed Hasan. "New modelling and control methods with application to combined cycle power plants." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21157.

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This thesis reports the analysis and modelling required to build a software simulation of combine cycle power plants. A new MIMO PID controller tuning method and a novel predictive PID controller design method for MIMO systems are also described in the thesis. The emphasis of this work is on simulation; identification and controller design methods. The thesis begins with an account of the combined cycle power plant modelling and simulation development. This culminates in a library of different blocks and subsystems of combined cycle power plants. The simulation development shows how the steady state and dynamic behaviour of combined cycle power plants can be simulated and implemented in the SMULINK and MATLAB environment using per unit models, which are suitable for control design. In the identification stage, the relay identification method is used to identify the critical points of the system for a newly defined criterion at bandwidth frequency. Then, the identified critical points are used to tune PID controllers. The thesis then outlines multivariable PID tuning methods and makes a comparison between these methods and the new relay identification method concerning their robustness for MIMO systems. The last two chapter of thesis are concerned with a new predictive PID controller design method for both SISO and MIMO systems. This methodology is concerned with the design of PID controllers, which have similar features to the model-based predictive controller. Generalized Predictive Control (GPC) design principles are used to develop the PID control with predictive capabilities for both SISO and MIMO systems. The combined cycle power plant simulation, especially the boiler subsystem, is used as an example throughout the thesis.

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Reinecke, Isabel [Verfasser]. "Mathematical modeling and simulation of the female menstrual cycle / Isabel Reinecke." Berlin : Freie Universität Berlin, 2009. http://d-nb.info/102366514X/34.

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Lewis, William I. "Simulation to determine the impacts of life-cycle manning on lieutenants." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Jun%5FLewis%5FW.pdf.

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Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2005.
Thesis Advisor(s): Paul J. Sanchez, Samuel E. Buttrey. Includes bibliographical references (p. 57-58). Also available online.

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Butko, Anastasiia. "Techniques de simulation rapide quasi cycle-précise pour l'exploration d'architectures multicoeur." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS144/document.

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Le calcul intensif joue un rôle moteur de premier plan pour de nombreux domaines scientifiques. La croissance en puissance crête des supercalculateurs a évolué du téraflops au pétaflops en l'espace d'une décennie. Toutefois, la consommation d'énergie associée extrêmement élevée ainsi que le coût associé ont motivé des recherches vers des technologies plus efficaces énergétiquement comme l'utilisation de processeurs issus du domaine des systèmes embarqués à faible puissance.Selon les prévisions, les systèmes multicœurs émergents seront constitués de centaines de cœurs d'ici la fin de la décennie. Cette évolution nécessite des solutions efficaces pour l'exploration de l'espace de conception et le débogage. Les simulateurs industriels et académiques disponibles à ce jour diffèrent en termes de compromis entre vitesse de simulation et précision. Leur adoption est généralement définie par le niveau d'exploration souhaité. Les simulateurs quasi cycle-précis sont populaires et attrayants pour l'exploration architecturale. Alors que la vitesse de simulation est trivialement observée, le niveau de précision de ces simulateurs reste souvent flou. En outre, bien que permettant une évaluation flexible et détaillée de l'architecture, les simulateurs quasi cycle-précis entraînent des vitesses de simulation lentes ce qui limite leur champ d'application pour des systèmes avec des centaines de cœurs. Cela exige des approches alternatives capables de fournir des simulations rapides tout en préservant une précision élevée ce qui est cruciale pour l'exploration architecturale.Dans cette thèse, des modèles d'architectures multicœurs complexes ont été développés et évalués en utilisant des systèmes de simulation quasi cycle-précis pour l'exploration de la performance et de la puissance. Sur cette base, une approche hybride orientée traces d'exécution a été proposée pour permettre une exploration rapide, flexible et précise des architectures multicœurs à grande échelle. Sur la base de l'environnement de simulation proposé, plusieurs configurations de systèmes manycoeurs ont été construites et évaluées en évaluant le passage à l'échelle des performances. Enfin, des configurations alternatives d'architectures multicœurs hétérogènes ont été proposées et ont montré des améliorations significatives en termes d'efficacité énergétique
Since the computational needs precipitously grow each year, HPC technology becomes a driving force for numerous scientific and consumer areas. The most powerful supercomputer has been progressing from TFLOPS to PFLOPS throughout the last ten years. However, the extremely high power consumption and therefore the high cost pushed researchers to explore more energy-efficient technologies, such as the use of low-power embedded SoCs.The evolution of emerging manycore systems, forecasted to feature hundreds of cores by the end of the decade calls for efficient solutions for the design space exploration and debugging. Available industrial and academic simulators differ in terms of simulation speed/accuracy trade-offs. Cycle-approximate simulators are popular and attractive for architectural exploration. Even though enabling flexible and detailed architecture evaluation, cycle-approximate simulators entail slow simulation speeds, thereby limiting their scope of applicability for systems with hundreds of cores. This calls for alternative approaches capable of providing high simulation speed while preserving accuracy that is crucial to architectural exploration.In this thesis, we evaluate cycle-approximate simulation techniques for fast and accurate exploration of multi- and manycore architectures. Expecting to significantly reduce simulation time still preserving the accuracy at the cycle-approximate level, we propose a hybrid trace-oriented approach to enable flexible manycore architecture simulation. We design a set of simulation techniques to overcome the main weaknesses of the trace-oriented approach. The trace synchronization technique aims to manage control and data dependencies arising from the abstraction of processor cores. The trace replication technique is proposed to simulate manycore architectures using a finite set of pre-collected traces. The computation phase scaling technique is designed to enable flexible switching between multiple processor models without considering microarchitectural difference but taking into account the computation speed ratio. Based on the proposed simulation environment, we explore several manycore architectures in terms of performance and energy-efficiency trade-offs

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Silva, Rodney Busquim e. "Simulation of the nuclear fuel cycle with recycling : options and outcomes." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44794.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2008.
Includes bibliographical references (p. 202-204).
A system dynamics simulation technique is applied to generate a new version of the CAFCA code to study the mass flow in the nuclear fuel cycle, and the impact of different options for advanced reactors and fuel recycling facilities on the accumulation of the transuranics (TRU) inventory. Several aspects of the nuclear fuel cycle are studied for the US and for Brazil. This includes the impact of advanced nuclear technologies' introduction, under a prescribed industrial construction capacity, on uranium resources, the need for uranium enrichment, demand for fuel reprocessing facilities, and total cost of electricity over the next one hundred years. Introduction of fuel recycling can reduce the growing demand for uranium, and the long-term need for storage of radioactive spent fuel. However, the timing of introduction of recycling is important for proper technology development, and that is reflected in the assessments. The nuclear fuel cycle is modeled as a high level structure diagram, which provides an overview of the interconnections among its blocks without showing all the details, and as a structure-policy diagram which details the decision rules applied to the structure. The high level structure diagram represents the nuclear fuel cycle; the fleet of thermal and fast reactors; the separation and reprocessing plants; the waste repository; the spent fuel storage; and the paths for the fuel and waste mass transfer. In addition, an economic model is added to study different cases under the same assumptions. The economic model is based on the forecasted need for advanced reactors and recycling facilities, assuming that all costs are recovered within the nuclear energy system.
(cont.) Different recycling technology options are included in the code: (1) Thermal recycling in LWRs using Combined Non-Fertile and UO₂ Fuel (CONFU), (2) Recycling of TRU in fertilefree fast cores of Actinide Burner Reactors (ABR); and (3) Fast recycling of TRU with UO₂ in self-sustaining Gas-cooled Fast Reactors (GFR). Case studies for different advanced technology introduction dates and for distinct TRU depletion rates are examined. In particular, the code is equipped to simulate the introduction of two recycling technology options with a prescribed allocation of the TRU supply between them. The simulation results show that early introduction of the GFR recycling scheme leads to the most significant reduction in uranium consumption, and enrichment requirements, thus delaying the depletion date of uranium ore. The GFR technology requires less uranium resources due to U recycling and near unity fissile conversion ratio. However, in a non-breeding reactor system, the consumption of U continues to grow, and the TRU needed to start fast reactors will be growing at a constrained rate. On the other hand, the CONFU recycling scheme keeps the TRU inventory in the entire system well below other schemes, and guarantees equilibrium between the generation and consumption of transuranics without investments in fast reactors. Also, it reduces the TRU sent to the repository for disposal by orders of magnitude. The ABR scheme does the same but requires the introduction of fast reactors. Nevertheless, the CONFU and ABR schemes have no significant impact on the amount of uranium resources consumption or enrichment requirements. CONFU incinerates more TRU than the GFR and ABR schemes during the simulation period. Economic analysis indicates that the CONFU technology is more attractive at current uranium prices, and that fast recycling becomes as attractive as thermal recycling at higher uranium prices.
(cont.) The results also show that if a nuclear fuel cycle state/reactor state collaboration with Brazil is started, there will be a significant impact on the U.S. cumulative TRU inventory at interim storage, enrichment requirements, uranium consumption, and number of advanced fuel facilities. The results show that a nuclear partnership without the introduction of advanced nuclear technologies would not have advantages for the U.S. Furthermore, a nuclear collaboration allows a higher ratio of fast reactors to total installed nuclear electric capacity in the U.S.
by Rodney Busquim e Silva.
S.M.

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VanDoorne, Rick. "Stochastic rail life cycle cost maintenance modeling using Monte Carlo simulation." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/61343.

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The objective of this study was to quantify and determine trends in the uncertainty in the life cycle cost (LCC) associated with the maintenance and renewal (M&R) of the rail of a railway track under a fixed set of input parameters and conditions. Rail maintenance models were identified in the literature which use the mean or expected value of the input distributions to determine a corresponding mean or expected LCC. Although these models display important trends with regard to input parameters such as inspection intervals, they provide no means to quantify the uncertainty related to maintenance and renewal decisions. Thus, a numerical model was developed and programmed using MATLAB which allows the quantification of the uncertainty in the LCC estimated for a given set of conditions. The model uses Monte Carlo simulation to determine the LCC associated with the installation, maintenance and renewal of the rail. The model incorporates imperfect inspections, a hazard function for rail fatigue defects modelled using the Weibull probability distribution and a P-F interval for rail fatigue defects modelled using an exponential probability distribution. The model also allows the modelling of maintenance as either perfect or minimal maintenance as well as the use of either flash butt or alumino-thermic welds to conduct the maintenance. This allowed the development of a method to assess which weld type to use to minimise the minimum attainable mean LCC. The developed model was validated against a similar stochastic rail maintenance model from the literature. However, the model from the literature considers only the expected LCC and does not show any uncertainty related thereto. The novelty in this study therefore lies in the fact that the LCC uncertainty can be quantified in the form of a probability distribution at any given renewal tonnage for a given set of conditions. It was found that the distribution of the LCC at a given renewal tonnage followed a lognormal probability distribution. The standard deviation of the lognormal distributions fitted using the method of maximum likelihood was used as a metric to quantify the uncertainty related to the life cycle cost at a given renewal tonnage. The LCC uncertainty was found to increase with an increase in inspection interval length. Furthermore, the uncertainty was also found to increase with a respective increase in renewal tonnage. For varying inspection interval lengths it was found that the uncertainty of combined maintenance costs (planned plus unplanned maintenance costs) tended more strongly towards the uncertainty in the planned maintenance costs for smaller inspection intervals and more strongly towards the uncertainty in unplanned maintenance costs for larger inspection intervals. A critical cost ratio was found of flash butt weld cost to alumino-thermic weld cost at which the minimum attainable mean LCC was equal. It is more economical to use flash butt welding for maintenance if the cost of flash butt welding maintenance produces a cost ratio lower than the critical cost ratio. The developed model could allow railway operators to assess the risk associated with renewal of the rail at varying renewal tonnages for given conditions such as inspection interval lengths, detectability of rail fatigue defects and the arrival rate of rail fatigue defects.
Dissertation (MEng)--University of Pretoria, 2017.
Civil Engineering
MEng
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Bullich, Adrien. "Simulation efficace d’architectures opérationnelles." Nantes, 2014. http://www.theses.fr/2014NANT2053.

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Le travail de cette thèse s’inscrit dans le contexte des systèmes embarqués temps réel. Ces systèmes exigent d’importants efforts pour leur validation et leur vérification. Dans le cadre de cette thèse, nous nous intéressons plus particulièrement à la validation par simulation. Celle-ci peut se faire à de nombreux niveaux d’abstraction, depuis le haut niveau du modèle de l’application jusqu’au code binaire. Nous nous situons dans ce dernier cas, seul capable de donner des résultats précis au cycle près. HARMLESS est un langage de description d’architectures. Il permet de générer un simulateur fonctionnel (ISS) et un simulateur temporel précis au cycle près (CAS). Dans le cadre des systèmes temps réel, c’est ce deuxième type de simulateurs qui nous intéresse. Relativement à l’ISS, un CAS présente l’inconvénient majeur de se montrer très lent à l’exécution. Un moyen d’améliorer la rapidité d’exécution est d’utiliser la simulation compilée. On distingue deux grands types d’implantation de la simulation : la simulation interprétée et la simulation compilée. Si un simulateur interprété se comporte comme un interpréteur du programme à exécuter, un simulateur compilé nécessite une phase de compilation du programme. Il permet une meilleure vitesse d’exécution, au détriment de la souplesse dans la chaîne de développement. C’est cette technique que nous introduirons dans le cadre des CAS. Couplé à une technique d’abstraction du programme, nous montrerons que l’on peut améliorer la vitesse de simulation de plus de 50% en comparaison du CAS interprété
The work of this thesis lies in the context of real-time embedded systems. These systems require significant effort for validation and verification. As part of this thesis, we are particularly interested in validation through simulation. This can be done at many levels of abstraction, from high-level model of the application to binary code. We are in the latter case, only able to give accurate results close to the processor cycle. HARMLESS is a Hardware Architecture Description Language (HADL). It generates a functional simulator (ISS) and a temporal simulator cycle-accurate (CAS). As part of real-time systems, it is this second type of simulators that interests us. With respect to the ISS, CAS has the major drawback to be very slow at runtime. One way to improve the speed of execution is to use the compiled simulation. There are two main types of implementation of the simulation: interpreted simulation and compiled simulation. If interpreted simulator behaves as an interpreter for the program to run, a compiled simulator requires a compilation phase of the program. It allows a better execution speed to the detriment of flexibility in the development chain. It is this technique that we introduce in the context of CAS. Coupled with a technique of abstraction of the program, we will show that we can improve the simulation speed by more than 50% compared to the interpreted CAS

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Guidosh, Jacob A. "The use of life cycle assessment through an objective framework constructed by simulation /." Connect to resource online, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1252941644.

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Horkeby, Kristofer. "Simulation of Heat Recovery Steam Generator in a Combined Cycle Power Plant." Thesis, Linköpings universitet, Institutionen för systemteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75836.

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This thesis covers the modelling of a Heat Recovery Steam Generator (HRSG) in a Combined Cycle Power Plant(CCPP). This kind of power plant has become more and more utilized because of its high efficiency and low emissions. The HRSG plays a central role in the generation of steam using the exhaust heat from the gas turbine. The purpose of the thesis was to develop efficient dynamic models for the physical components in the HRSG using the modelling and simulation software Dymola. The models are then to be used for simulations of a complete CCPP.The main application is to use the complete model to introduce various disturbances and study their consequences inthe different components in the CCPP by analyzing the simulation results. The thesis is a part of an ongoingdevelopment process for the dynamic simulation capabilities offered by the Solution department at SIT AB. First, there is a theoretical explanation of the CCPP components and control system included in the scope of this thesis. Then the development method is described and the top-down approach that was used is explained. The structure and equations used are reported for each of the developed models and a functional description is given. Inorder to ensure that the HRSG model would function in a complete CCPP model, adaptations were made and tuning was performed on the existing surrounding component models in the CCPP. Static verifications of the models are performed by comparison to Siemens in-house software for static calculations. Dynamic verification was partially done, but work remains to guarantee the validity in a wide operating range. As a result of this thesis efficient models for the drum boiler and its control system have been developed. An operational model of a complete CCPP has been built. This was done integrating the developed models during the work with this thesis together with adaptations of already developed models. Steady state for the CCPP model is achieved during simulation and various disturbances can then be introduced and studied. Simulation time for a typical test case is longer than the time limit that has been set, mainly because of the gas turbine model. When using linear functions to approximate the gas turbine start-up curves instead, the simulation finishes within the set simulation time limit of 5 minutes for a typical test case.

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Dissertations / Theses on the topic 'Simulation of Stirling cycle'

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