Le couple zéolite/H2O, qui présente une densité énergétique importante et remplit les conditions d’innocuité requises pour un système de stockage de chaleur pour l’habitat, est mis en œuvre dans réacteur modulaire à lit fixe. Un modèle monodimensionnel de transferts couplés de masse et de chaleur dans un lit fixe de grains de zéolite parcourus par un flux d'air humide été élaboré. Ce dernier a été conçu de façon à pouvoir intégrer rapidement des données sur de nouvelles générations de matériaux et coupler le réacteur à d’autres modèles : bâtiment/sous-station/quartier. L'étape de validation expérimentale montre que le modèle permet une estimation satisfaisante de l'autonomie, la durée d'amorçage et la puissance moyenne fournie en phase de décharge ainsi que la durée de charge. Ce modèle est donc un bon outil de dimensionnement et de pilotage du réacteur. L'analyse de sensibilité a montré que l'amélioration des prévisions du modèle requiert une évaluation plus précise de la chaleur complémentaire de sorption et de la porosité du lit. Après avoir estimé les besoins de chauffage d'une maison BBC deux dimensionnements ont été proposés afin d'effacer soit l'hyper-pointe de 18h - 20h soit la semaine la plus froide. Si la première stratégie aboutit à un système de stockage plus compact, la seconde permet de réduire le nombre de cycles marche/arrêt. Pour un îlot de 50 maisons BBC, la notion de foisonnement est considérée lors de l'estimation des besoins en chauffage pendant la semaine la plus froide. La phase de charge du système de stockage se ferait par le biais de la chaleur fatale récupérée dans l'industrie. Pour des stratégies d'effacement similaires (semaine la plus froide en hiver), un volume équivalent de 544 litres par maison dans l'îlot suffit pour répondre aux besoins de chauffage à Nancy contre 580 litres pour une maison BBC seule. / Heat storage systems for residential house heating could contribute to smoothing the load curve and would help prevent the use of the most polluting power plants or electricity imports during consumption peaks. Thermochemical heat storage systems are suitable for the intended application since they have high energy densities and low thermal losses. This thesis focuses on the design of an adsorption heat storage system that would be used to shed the load curve of the heating device of a house or residential district during the winter peak consumption periods. The zeolite/H2O pair, which has interesting features such as a high energy density and meets the conditions of safety required for a heat storage system for housing, is implemented in a modular fixed bed reactor. A 1D pseudo-homogeneous model was developed in order to simulate the performance of a fixed bed of zeolite during the adsorption and desorption of water. The latter was designed so as to facilitate the integration of data on new generations of materials and model couplings. The need to obtain data on the sorption properties of the zeolite/H2O pair to have reliable simulation results has been demonstrated, particularly at low partial pressures of water vapor and under the operating conditions selected. The experimental validation phase shows that the pseudo-homogeneous model provides a satisfactory estimate of criteria such as the autonomy, the responsiveness and the average power delivered during the discharging phase and the charging time. The model is thus a good sizing and management tool of the reactor. A sensitivity analysis, with the method of Morris, showed that improved model estimates require a more accurate assessment of the additional heat of sorption and porosity of the bed. After assessing the heating needs of the LEB house with a thermal model of the latter in cold climate conditions, two heat storage reactors were sized in order to shed the heating system's load curve either between 6 and 8pm or during the coldest week of the year. While the first strategy results in a more compact storage system, the second makes it possible to reduce the number of on/off cycles. The need for predictive control for monitoring the storage system was highlighted. As for the residential district of 50 LEB houses, diversity is considered when estimating the heating needs of the latter during the coldest week in Nancy. The heat source during the charging phase of the container would be industrial waste heat. During the coldest week, two sizings are suggested. For similar load shedding strategies, the comparison of the equivalent storage volume per house in the district with the storage volume for a single house serves highlights the importance of taking into account diversity. In order to meet the heating needs in Nancy, an equivalent volume of 544 liters per house in the district is sufficient whereas 580 liters are needed for a LEB house.

Le travail présenté dans ce manuscrit concerne le développement d’un système de stockage thermique par chaleur latente pour les centrales solaires à concentration utilisant la génération directe de vapeur, et s’attache plus particulièrement la sélection et l’étude du matériau à changement de phase (MCP). Cette thèse a été réalisée dans le cadre du projet Stockage Thermique Appliqué à l’extension de pRoduction d’énergie Solaire thermodynamique (STARS) porté par le consortium composé d’AREVA Renouvelables, la société Hamon d’Hondt, l’institut CEA liten et les laboratoires IPNO, LPCS et LaTEP. Ce projet est accompagné par l’ADEME dans le cadre du programme énergies décarbonnées des investissements d’avenir.Le premier chapitre de ce manuscrit situe le contexte de l’étude en dressant un état de l’art des différents systèmes solaires à concentration existants et des différents moyens de stocker l’énergie pour ce type de technologie. Le projet STARS est ensuite présenté. Ce chapitre se termine par un descriptif des objectifs du travail de thèse. L’intégralité du processus de sélection du MCP, incluant le recensement des matériaux dans la littérature, la définition des critères de sélection et la caractérisation par calorimétrie différentielle à balayage des candidats les plus pertinents, est détaillée dans le chapitre II. À l’issue de ce travail, le choix du consortium se porte sur le nitrate de sodium, un sel inorganique possédant une température de fusion adaptée à la technologie d’AREVA et une densité de stockage importante. La poursuite de l’étude, concernant la stabilité thermique du MCP durant son utilisation en conditions industrielles, fait l’objet du chapitre III. Cette étude comporte une partie bibliographique permettant de mettre en évidence les problématiques liées à la dégradation thermique du matériau et à son comportement vis-à-vis des matériaux métalliques avec lesquels il sera amené à être en contact (échangeur de chaleur, cuve de stockage). La principale conséquence des phénomènes mis en évidence étant la réduction du nitrate de sodium en nitrite de sodium, l’étude de l’impact du taux de nitrite de sodium sur les propriétés thermiques du MCP a été réalisée. Les résultats de cette campagne expérimentale ont montré une diminution significative de la température de fusion et de la chaleur latente du MCP lorsque la proportion de nitrite de sodium croît. Afin d’étudier l’évolution de composition du MCP dans des conditions réelles de fonctionnement, un dispositif a été conçu spécifiquement pour reproduire des conditions de cyclage thermique en présence de métaux. L’étude menée à l’aide de ce dispositif a permis d’analyser la cinétique de réduction du nitrate de sodium en nitrite de sodium. Les résultats montrent que l’évolution de composition du MCP dans les conditions opératoires du projet est négligeable, garantissant la stabilité des propriétés thermiques de celui-ci au cours de son utilisation.Enfin, le dernier chapitre est consacré à l’étude de l’amélioration des transferts thermiques au sein du MCP. En effet, le nitrate de sodium possède une conductivité thermique faible, pouvant limiter la puissance des échanges de chaleur dans le système de stockage. En premier lieu, un état de l’art des solutions d’intensification des transferts dans le domaine du stockage par chaleur latente est dressé. Ce travail a permis de mettre en évidence que l’utilisation de composites à base de mousses métalliques constitue une voie pertinente d’amélioration des transferts. Ainsi une campagne expérimentale visant à évaluer les performances de tels composites a permis de mettre en évidence le potentiel de ce type de configuration. / The work presented in this manuscript concerns the development of a latent heat thermal energy storage system adapted to concentrated solar power plant using direct steam generation, and more particularly on the selection and the study of the Phase Change Material (PCM) used in this system. This thesis was performed within the framework of the STARS project (Stockage Thermique Appliqué à l’extension de pRoduction d’énergie Solaire thermodynamique) carried by the consortium of AREVA Renouvelables, Hamon d’Hondt company, CEA institute liten and laboratories IPNO, LPCS and LaTEP. This project is accompanied by ADEME under the énergies décarbonnées des investissements d’avenir program. The first chapter of this manuscript sets up the context of this study by drawing a state of art of different existing CSP technologies and various ways to store energy for this kind of systems. The STARS project is then described. This chapter ends with a description of the thesis objectives. The entire PCM selection process, including identification of materials in literature, definition of various criteria and thermal characterization by differential scanning calorimetry (DSC) of the most relevant candidates, is detailed in chapter II. This work leads to the selection of sodium nitrate by the consortium, an inorganic salt with a suitable melting temperature considering AREVA’s technology and a large storage density. The following work, concerning the thermal stability of the PCM under thermal cycling, is then presented in chapter III. This part includes a bibliographic study allowing to highlight issues related to thermal degradation of the PCM and its behavior regarding to metallic material with which it will have to be in contact (heat exchanger, storage tank). The main consequence of these phenomena is the reduction of sodium nitrate into sodium nitrite, and thus the impact of sodium nitrite fraction on the thermal properties of the PCM was studied. The results of this experimental work shows a significant reduction of the melting temperature and the latent heat as the fraction in sodium nitrite increases. To study the evolution of the PCM composition under real operating situation, a specific device was designed to replicate thermal cycling conditions in the presence of metals. This device was used to analyze the kinetics of reducing sodium nitrate into sodium nitrite. The results show that the changes in composition of the PCM in the project’s operating conditions are negligible, ensuring the stability of its thermal properties during its lifetime. The last chapter is devoted to the improvement of heat transfers within the PCM. Indeed, sodium nitrate has a low thermal conductivity which may limit the power of the heat exchange in the storage system. A state of art of available solutions for the intensification of thermal transfers concerning latent heat storage was done. This study highlighted that the use of composites based on metallic foams constitutes an effective way of improvement. Thus an experimental campaign was conducted to evaluate the performances of such composites, allowing to show the potential of this kind of configuration.

Ce travail porte sur le développement d’un système de stockage de chaleur en vue d’assurer le confort thermique de l’habitacle d’un véhicule électrique. Ce dispositif, appelé batterie thermique, se présente comme un réservoir composé d’un lit fixe de matériaux à changement de phase (MCP). Ce type de matériau a la propriété d’emmagasiner de fortes quantités de chaleur (latente) sous de faibles volumes, permettant d’envisager un système très compact. A l’échelle du matériau, une investigation sur la cinétique des transferts thermiques au sein de plusieurs MCPs a été évaluée. Une expression phénoménologique décrivant l’évolution temporelle de la température d’un MCP en phase de solidification a été proposée. Elle permet d’estimer la durée de solidification du matériau en fonction de ses caractéristiques géométriques et thermiques. A l’échelle du système, un prototype de batterie thermique a été réalisé et la dynamique des transferts en phase de stockage et déstockage a été étudiée. Les durées de stockage et déstockage suivent des lois de puissance avec le débit imposé ; les pertes de charges s’avèrent insignifiantes. En parallèle, un modèle numérique simulant le comportement dynamique et thermique d’un lit fixe de particules de MCP a été développé et validé sur les données expérimentales. Il pourra être utilisé pour le dimensionnement du futur prototype et servira également d’outil pour optimiser les performances de la batterie en ajustant les paramètres de contrôle / This study focuses on the development of a heat storage system used to ensure passenger compartment thermal comfort in an electric vehicle. This device, called a thermal battery, is a packed bed latent heat tank filled with phase change materials (PCM). This type of material has the property of storing large amounts of latent heat in small volumes, allowing a very compact system. At the material scale, an investigation on heat transfer dynamics within several PCM was studied. A phenomenological expression which depicts the temporal evolution of the PCM temperature for a solidification phase was suggested. This allows the estimation of the material solidification duration in terms of geometric and thermal characteristics. At the system scale, a thermal battery prototype was set up and the thermal transfer dynamics during the charging and discharging phases were studied. The charging and discharging durations are fitted by power laws in terms of the flow rate; the pressure drops are insignificant. Simultaneously, a numerical model which simulates the dynamic and thermal behavior of a PCM particle fixed bed was developed and validated with the experimental data. It can be used for future prototype sizing and will also serve as a tool to optimize the performance of the battery by setting the control parameters

Ice based Cool Thermal Energy Storage (CTES) systems have attracted much attention during last few decades. The reasons are mainly of economical and environmental nature. Compared to conventional refrigeration and air-conditioning systems without cool thermal energy storage, implementation of CTES will increase environmental standards and overall efficiency of the energy systems as it contributes to the phase-out of synthetic refrigerants and reduces peak loads in electricity grids. For the application of a cool thermal energy storages in refrigeration installations and HVAC systems in industry and building sector, it is necessary to have appropriate design tools in order to sufficiently accurate predict their performance. In this thesis theoretical and experimental investigations of two ice based cool thermal energy storage systems, namely static, indirect, external melt, ice-on-coil, i.e. ice bank system and dynamic, ice slurry cool thermal energy storage system are carried out. An ice bank storage technology for cooling purposes is known for a long time. The main drawbacks which are hindering its wider use are the system complexity, high first costs, system efficiency which is highly dependant on design, control and monitoring of the system, etc. On the other hand, ice slurry technology was not well studied until recently, while in the current scientific literature there are still differences between results and conclusions reported by different investigators. The aim of the present thesis is to extend the knowledge in the field of ice based CTES systems, thereby contributing in the development and wider utilization of those systems. In the first part of the thesis a computer application, named “BankaLeda” is presented. It enables simulation of an ice bank system performance. In order to verify developed simulation model an experimental evaluation has been performed. Field measurements have been conducted on a two module silo which was installed as a part of the refrigeration system in dairy and cheese factory “Antun Bohnec” in the city of Ludbreg in Croatia. Experimental findings were compared to the simulation model. The software „BankaLeda“ presents a strong optimization tool for designers and engineers in the field by providing a high degree of freedom in defining particular system design and operating parameters. It offers a basis for assessment and testing of a new energy efficient system arrangements and measures. Besides it will give decisionmakers the ability to test potential solutions in the process of CTES system design. In the second part of the thesis ice slurry pressure drop and heat transfer in horizontal straight tubes have been experimentally investigated. In particular a mixture of 10.3 % of ethanol and water with an initial freezing point of -4.4 °C was considered. It was found that the behaviour of ice slurry flow is changing with time and that ice slurry pressure drop is generally higher than for single phase flow. However for ice concentrations of 15 % and higher, for certain velocities ice slurry pressure drop is found to be of a similar value as for single phase fluid. Moreover, if ice slurry is to be used as a energy transport media it is recommended to keep the ice mass fraction at a level of 20 %. With tube geometry and thermophysical properties of a carrier fluid the heat transfer of ice slurry is generally a function of ice mass fraction and velocity. The imposed heat flux has no or has just minor influence on the heat transfer coefficient. Up to ice mass fraction between 10-15 % the mean heat transfer coefficient shows only slight (laminar flow) or no increase (turbulent flow) in comparison to single phase flow. Beyond that ice mass fraction the heat transfer coefficient is increasing significantly. The test data for pressure drop and heat transfer in laminar and turbulent regime was compared to several correlations from the literature. A new correlations for ice slurry pressure drop and heat transfer in the laminar flow regime, for 10.3 % ethanol and water mixture, were derived based on the present experimental data. The correlation for pressure drop predicts 82 % of the experimental data with ±15 % accuracy, while the correlation for heat transfer predicts 75 % of the data with the same accuracy. In order to investigate advantages and disadvantages of a dynamic, ice slurry system over a static, indirect, external melt, ice-on-coil CTES system and to assess their differences from economical aspects, a theoretical simulation model of an ice slurry CTES have been developed. It was found that the ice slurry based CTES systems posses higher economic and energy saving potential than static type systems. In the best case scenario the total energy consumption of dynamic CTES system was found to be approximately 25 % lower than for a static CTES system. / QC 20100715

Examining methods for controlling the electricity demand in Kuwait was the main objective and motivation of this researchp roject. The extensiveu se of air-conditioning for indoor cooling in office and large commercial buildings in Kuwait and the Gulf States represents a major part of the power and electricity consumption in such countries. The rising electricity generation cost and growing rates of consumption continuously demand the construction new power plants. Devising and enforcing Demand-SideM anagemen(t DSM) in the form of energye fficient operations trategies was the response of this research project to provide a means to rectify this situation using the demand-side management technique known as demand levelling or load shifting. State of the art demand-sidem anagementte chniquesh ave been examined through the developmenot f a model basedp redictive control optimisations trategyf or an integrateda ndm odulara pproachto the provisiono f ice thermals torage. To evaluate the potential of ice-storage assisted air-conditioning systems in flattening the demand curve at peak times during the summer months in Kuwait, a model of a Heating, Ventilation, and Air-conditioning (HVAC) plant was developed in Matlab. The model engaged the use of model based predictive control (MPQ as an optimisation tool for the plant as a whole. The model with MPC was developed to chose and decide on which control strategy to operate the integrated ice-storage HVAC plant. The model succeeded in optimising the operation of the plant and introduced encouraging improvement of the performance of the system as a whole. The concept of the modular ice-storage system was introduced through a control zoning strategy based on zonal orientation. It is believed that such strategy could lead to the modularisation of ice-storage systems. Additionally, the model was examined and tested in relation to load flattening and demonstrated promising enhancement in the shape of the load curve and demonstrated flattened demand curves through the employed strategy. When compared with measured data from existing buildings, the model showed potential for the techniques utilised to improve the load factor for office buildings.

Cette étude concerne la compréhension des mécanismes de transfert de chaleur et le développement d’un système de stockage pour la valorisation de la chaleur fatale industrielle. L’utilisation de Matériaux à Changement de Phase (MCP) permet d’atteindre une densité énergétique élevée et de restituer la chaleur à température constante. Cependant, leur faible conductivité thermique impose d’améliorer les transferts thermiques, notamment par l’utilisation d’échangeurs à surface augmentée. Le but est de comprendre le comportement de tels échangeurs en régime transitoire au contact de MCP. Une étude expérimentale à basse température, où quatre échangeurs de type tube-calandre ont été testés avec différentes orientations (horizontale/verticale) et injections (haut/bas), a mis en évidence des phénomènes de transfert thermique importants, comme la convection naturelle à la charge et la contraction volumique à la décharge. Ces observations ont été validées par un modèle CFD tridimensionnel. Une méthode de comparaison des performances basée sur un calcul d’énergie par le biais d’un maillage expérimental est proposée et permet de sélectionner un échangeur selon les critères de densités énergétiques, de temps caractéristique et de coût. Trois MCP, envisagés pour l’application, ont alors été testés à température réelle (100-200 °C) au contact d’un échangeur tube inox à ailettes transverses en aluminium pour évaluer leur cyclabilité et comparer leur comportement. Le mélange de sels, H105 (Tfusion = 122 °C), n’est pas retenu pour l’application à cause de sa faible densité énergétique (≈ 56 kWh/m3) et sa plage de fusion trop étalée. L’acide sébacique (Tfusion = 132 °C) a un comportement répétable au cours des cycles et une densité énergétique plus élevée (≈ 66 kWh/m3). L’alcool de sucre, l’érythritol (Tfusion = 118 °C), présente de bonnes thermo-physiques (128 kWh/m3) mais la maîtrise de sa cristallisation est un point clé pour l’utiliser en tant que MCP. / This PhD thesis deals with the understanding of the heat transfer mechanisms and with the development of thermal energy storage system for the industrial waste heat recovery application. The use of Phase Change Materials (PCM) is attractive for its high storage density and its possibility to deliver heat at constant temperature. However, the PCM low thermal conductivity leads to develop heat transfer improvement methods, such as heat exchangers with increased heat transfer surface. The goal is to characterize the behavior of such heat exchangers An experimental study, where four several heat exchangers have been tested with different orientations (horizontal/vertical) and injection types (upward/downward), highlighted the impact of natural convection during the melting process and the volume contraction one during the solidification. These results have been validated through a 3D numerical model. A performance comparison method based on an energy calculation through an experimental mesh is proposed and enables to select a heat exchanger on criteria such as the storage density, the characteristic time and the cost. Three PCM, adapted to our application, have been tested at the intended temperature (100-200 °C) by integrating them into a storage system made of a stainless steel tube with aluminum circular fins. Their ability to resist to repeated cycles has been assessed and their behavior has been compared. The salts mixture, H105 (Tmelting = 122 °C), is not selected for the application because of it low storage density (≈ 56 kWh/m3) and its large melting area. The sebacic acid (Tmelting = 132 °C) has a repeatable behavior with cycles and a higher storage density (≈ 66 kWh/m3) and is appropriate as storage material. The sugar alcohol, erythritol (Tmelting = 118 °C), has good thermo-physical properties (128 kWh/m3) but the crystallization control is a key point to use it as a PCM.

The focus of this thesis work was the development of an approachto couple a previosly existing Thermal Energy Storage (TES) modelwritten in C++ with a Simulink/Simscape plant model to simulate anAdvanced Adiabatic Compressed Air Energy Storage (AA-CAES) plant.After the creation and validation of such tool, the complete modelwas used to run simulations, with the aim of assessing the AA-CAESplant's performance under multiple patterns of charge anddischarge.Most of the works found in the literature only provide values ofstorage efficiency obtained from analytical approaches, whilethose that use simulation tools provide average values ofefficiencies when the plant is performing a series of identicalcycles of charge and discharge. During this thesis project,instead, simulations were performed for consecutive irregularcycles determined as the plant response to the electric grid powerrequest. The average efficiency values obtained provide thereforea better representation of how the plant would perform in realapplications.The results show that, under the assumptions made, the AA-CAESplant's overall storage efficiency is influenced very weakly byalterations of the charge-discharge patterns, and that goodperformances can be expected not only for identical chargedischargeconsucutive cycles, but for any pattern that observesthe cavern pressure limits, as long as the thermal energy storageis sized wisely.In addition, a sensitivity analysis was performed in order toassess the influence of turbomachinery efficiency on overallstorage efficiency, for a specified plant layout. The results showthat the turbine efficiency is the most affecting parameter to theplant's performance, while the impact of the main compressors'sinefficiency is mitigated by the thermal recovery that takes placein the TES.The present work confirms that AA-CAES is a promising technologyand that storage efficiencies above 70% can be achieved even inrealistic production scenarios.Finally, future steps for more accurate simulations of plants'performances and more detailed energy production scenarios areproposed.MSc ET 18007Examinator: Joakim WidénÄmnesgranskare: Ane HåkanssonHandledare:

Examining methods for controlling the electricity demand in Kuwait was the main objective and motivation of this researchp roject. The extensiveu se of air-conditioning for indoor cooling in office and large commercial buildings in Kuwait and the Gulf States represents a major part of the power and electricity consumption in such countries. The rising electricity generation cost and growing rates of consumption continuously demand the construction new power plants. Devising and enforcing Demand-SideM anagemen(t DSM) in the form of energye fficient operations trategies was the response of this research project to provide a means to rectify this situation using the demand-side management technique known as demand levelling or load shifting. State of the art demand-sidem anagementte chniquesh ave been examined through the developmenot f a model basedp redictive control optimisations trategyf or an integrateda ndm odulara pproachto the provisiono f ice thermals torage. To evaluate the potential of ice-storage assisted air-conditioning systems in flattening the demand curve at peak times during the summer months in Kuwait, a model of a Heating, Ventilation, and Air-conditioning (HVAC) plant was developed in Matlab. The model engaged the use of model based predictive control (MPQ) as an optimisation tool for the plant as a whole. The model with MPC was developed to chose and decide on which control strategy to operate the integrated ice-storage HVAC plant. The model succeeded in optimising the operation of the plant and introduced encouraging improvement of the performance of the system as a whole. The concept of the modular ice-storage system was introduced through a control zoning strategy based on zonal orientation. It is believed that such strategy could lead to the modularisation of ice-storage systems. Additionally, the model was examined and tested in relation to load flattening and demonstrated promising enhancement in the shape of the load curve and demonstrated flattened demand curves through the employed strategy. When compared with measured data from existing buildings, the model showed potential for the techniques utilised to improve the load factor for office buildings.

Made available in DSpace on 2014-12-17T14:58:19Z (GMT). No. of bitstreams: 1 PedroSGM_DISSERT.pdf: 2326508 bytes, checksum: 0470d41afc69c7b0199856916c484045 (MD5) Previous issue date: 2012-12-17 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Cada vez mais o mundo est? adotando uma matriz energ?tica limpa e sustent?vel, com o uso da agricultura para produ??o de agroenergia e combust?veis verdes, como bioetanol e biodiesel. A produ??o do biodiesel gera um coproduto, a glicerina, em que as usinas produtoras t?m dificuldades com o destino do seu excedente. V?rias pesquisas est?o sendo desenvolvidas para nortear diferentes usos do glicerol (glicerina pura). O glicerol possui total solubilidade com a ?gua e pode ser usado como aditivo anticongelante aplicado como fluido refrigerante secund?rio, em sistemas de refrigera??o indireta e com termoacumula??o. Tamb?m, o glicerol ? uma mat?ria-prima alternativa na produ??o de propilenoglicol, um ?lcool de grande aplicabilidade industrial inclusive como anticongelante. Por?m, o melhor ?lcool anticongelante ? o etilenoglicol, um ?lcool t?xico derivado do petr?leo. As solu??es ?gua-glicerol (AG) e ?gua-propilenoglicol (AP) possuem propriedades termof?sicas de qualidade inferior e desequilibradas se comparadas ?s solu??es ?gua-etilenoglicol (AE). Desta forma, esta pesquisa inovadora teve como prop?sito o desenvolvimento e a caracteriza??o de solu??es tern?rias ?gua-glicerol-propilenoglicol (AGP) como fluidos secund?rios, com propriedades termof?sicas desej?veis e competitivas com as solu??es ?gua-etilenoglicol. Equa??es preditivas simplificadas foram usadas para prever o comportamento das solu??es AGP, onde as seguintes propriedades termof?sicas foram avaliadas e estimadas teoricamente: ponto de congelamento, massa espec?fica, calor espec?fico e condutividade t?rmica. As concentra??es para definir o ponto de congelamento das solu??es AGP foram definidas a partir da Lei de Raoult das propriedades coligativas. A an?lise matem?tica inicial mostrou que as solu??es AGP possuem propriedades mais equilibradas que as solu??es AG e AP e competitiva com a solu??o AE. A comprova??o experimental das solu??es AGP foi feita a partir de ensaios para verificar suas propriedades (massa espec?fica, condutividade t?rmica e viscosidade din?mica), comparando com as solu??es de refer?ncia AG e AP. Os resultados experimentais comprovaram as expectativas iniciais e viabilidade t?cnica do novo fluido secund?rio tern?rio. A grande vantagem dos fluidos AGP ? que s?o at?xicos e derivam de fontes renov?veis

Comme les autres technologies liées aux énergies renouvelables, le solaire à concentration souffre des problèmes liés à l’intermittence de la ressource. La technologie thermocline est une solution prometteuse qui réduirait le coût du stockage thermique dans les centrales solaires de ce type. Cependant, aucune étude n’a jusqu’ici porté sur l’impact de la variation de la température en sortie du réservoir de stockage de type thermocline sur les autres composants de la centrale. Ce travail de thèse a pour but d’améliorer les connaissances sur ce sujet, grâce à l’utilisation d’une mini boucle solaire cylindro parabolique intégrant un stockage thermocline.En premier lieu, la compatibilité entre le fluide de transfert de la centrale (huile synthétique) et les potentiels matériaux de garnissage de la cuve de stockage (Cofalit, briques de cendres volantes, alumine) est vérifiée. Puis les performances de chacun des composants de la centrale (cuve de stockage, collecteurs solaires, générateur de vapeur) sont analysées expérimentalement et numériquement. Enfin, le comportement du système global est étudié, avec un accent porté sur l’impact de la variation de la température de sortie de la cuve thermocline sur les autres composants.Il a été montré qu’avec un dimensionnement et une stratégie de contrôle appropriés, la technologie thermocline diminue très peu les performances de la centrale solaire par rapport à la technologie conventionnelle à deux cuves (maximum 3 4 % de diminution de la production électrique). / Like other renewable energy technologies, concentrated solar power (CSP) suffers from resource intermittence. Thermocline technology is a promising solution to decrease cost of thermal energy storage in CSP plants. Thermocline behavior has thoroughly been studied in the past years and its behavior is considered well known. However no study treated of thermocline tanks integrated in CSP plants. Thus, the impact of the varying outlet temperature of the thermocline storage has not been assessed yet. This work aims to fill this lack of knowledge by studying a mini parabolic trough power plant integrating a thermocline tank as storage.First, the compatibility between the heat transfer fluid of the plant (synthetic oil) and various potential filler materials (Cofalit, coal fly ash bricks, alumina) of the storage tank is verified. Then, some performance studies are performed on the three main components of the power plant (energy storage tank, solar collectors, steam generator). Finally, the behavior of the whole system is assessed, with a focus on the impact of the varying fluid temperature at the outlet of the thermocline tank on the other components.It has been shown that, with a proper sizing and an appropriate control strategy, thermocline technology induces very low decrease of the solar power plant performance in comparison to the conventional two tank technology (maximum 3-4% of electrical power production difference).