<p>Due to climatic change, increasing thermal loads inbuildings and rising living standards, comfort cooling inbuildings is becoming increasingly important and the demand forcomfort cooling is expanding very quickly around the world. Theincreased cooling demand results in a peak in electrical powerdemand during the hottest summer hours. This peak presents newchallenges and uncertainties to electricity utilities and theircustomers.</p><p>Cool thermal storage systems have not only the potential tobecome one of the primary solutions to the electrical powerimbalance between production and demand, but also shift coolingenergy use to off-peak periods and avoid peak demand charges.It increases the possibilities of utilizing renewable energysources and waste heat for cooling generation. In addition, acool storage can actually increase the efficiency of combinedheat and power (CHP) generation provided that heat drivencooling is coupled to CHP. Then, the cool storage may avoidpeaks in the heat demand for cooling generation, and this meansthat the CHP can operate at design conditions in most oftime.</p><p>Phase Change Materials (PCMs) used for cool storage hasobtained considerable attention, since they can be designed tomelt and freeze at a selected temperature and have shown apromising ability to reduce the size of storage systemscompared with a sensible heat storage system because they usethe latent heat of the storage medium for thermal energystorage.</p><p>The goal of this thesis is to define suitable PCM candidatesfor comfort cooling storage. The thesis work combines differentmethods to determine the thermophysical properties oftetradecane, hexadecane and their binary mixtures, anddemonstrates the potential of using these materials as PCM forcomfort cooling storage. The phase equilibrium of the binarysystem has been studied theoretically as well asexperimentally, resulting in the derivation of the phasediagram. With knowledge of the liquid-solid phase equilibriumcharacteristics and the phase diagram, an improvedunderstanding is provided for the interrelationships involvedin the phase change of the studied materials. It has beenindicated that except for the minimum-melting point mixture,all mixtures melt and freeze within a temperature range and notat a constant temperature, which is so far often assumed in PCMstorage design. In addition, the enthalpy change during thephase transition (heat of fusion) corresponds to the phasechange temperature range; thus, the storage density obtaineddepends on how large a part of the phase change temperaturerange is valid for a given application.</p><p>Differential Scanning Calorimetery (DSC) is one frequentlyused method in the development of PCMs. In this thesis, it hasbeen found that varying results are obtained depending on theDSC settings throughout the measurements. When the DSC runs ata high heating/cooling rate it will lead to erroneousinformation. Also, the correct phase transition temperaturerange cannot be obtained simply from DSC measurement. Combiningphase equilibrium considerations with DSC measurements gives areliable design method that incorporates both the heat offusion and the phase change temperature range.</p><p>The potential of PCM storage for peak shaving in differentcooling systems has been demonstrated. A Computer model hasbeen developed for rapid phase equilibrium calculation. The useof phase equilibrium data in the design of a cool storagesystem is presented as a general methodology.</p><p><b>Keywords:</b>Comfort cooling, peak shaving, PCM, coolthermal storage system, DSC, phase change temperature range,the heat of fusion, phase equilibrium, phase diagram. Language:English</p>

The demand for clean and environmentally benign energy resources has been a great concern in the last two decades. To alleviate the associated environmental problems, reduction of the use of fossil fuels by developing more cost-effective renewable energy technologies becomes more and more significant. Among various types of renewable energy sources, solar energy and bioenergy take a great proportion. This dissertation focuses on the heat transfer and flow in solar energy and bioenergy systems, specifically for Thermal Energy Storage (TES) systems in Concentrated Solar Power (CSP) plants and open-channel algal culture raceways for biofuel production. The first part of this dissertation is the discussion about mathematical modeling, numerical simulation and experimental investigation of solar TES system. First of all, in order to accurately and efficiently simulate the conjugate heat transfer between Heat Transfer Fluid (HTF) and filler material in four different solid-fluid TES configurations, formulas of an effective heat transfer coefficient were theoretically developed and presented by extending the validity of Lumped Capacitance Method (LCM) to large Biot number, as well as verifications/validations to this simplified model. Secondly, to provide design guidelines for TES system in CSP plant using Phase Change Materials (PCM), a general storage tank volume sizing strategy and an energy storage startup strategy were proposed using the enthalpy-based 1D transient model. Then experimental investigations were conducted to explore a novel thermal storage material. The thermal storage performances were also compared between this novel storage material and concrete at a temperature range from 400 °C to 500 °C. It is recommended to apply this novel thermal storage material to replace concrete at high operating temperatures in sensible heat TES systems. The second part of this dissertation mainly focuses on the numerical and experimental study of an open-channel algae culture raceway for biofuel production. According to the proposed flow field design of ARID-HV algal raceway, experiments and numerical simulation have been conducted to understand the enhancement of flow mixing in the flow field of ARID-HV raceway by cutting slots on top of the dam near the dead zones. A new method was proposed to quantitatively evaluate the flow mixing by using the statistics of temporal and spatial distribution of the massless fluid particles (centered in each cell at the inlet surface) in the raceway collecting the data of path-lines of fluid particles from CFD results. It is hoped that this method can be applied to assist the algal raceway flow field design as well as other engineering applications. The third part introduces the details about the construction work of a high temperature molten salt test loop. Because of the limited operating temperature of conventional synthetic oils, in order to obtain higher energy conversion efficiency, higher operating temperature is always desirable in a CSP plant which leads to the requirement of new generation of HTF. Currently, a halide salt eutectic mixture (NaCl-KCl-ZnCl₂) as a potential HTF for future CSP applications has been proposed by a multi-institute research team, led by University of Arizona. The thermophysical properties of the halide eutectic salt have been measured. However, this new developed halide eutectic salt has not been tested in a circulating loop at a high operating temperature for the measurement of heat transfer coefficient. It is a significant effort to build such a test system due to extremely high operating temperature. As a consequence, in the third part of this dissertation, details about the design of the lab-scale test system and all the equipment items will be introduced. The investigations included in this dissertation for the heat transfer and flow in solar energy and bioenergy systems are of particular interest to the renewable energy engineering community. It is expected that the proposed methods can provide useful information for engineers and researchers.

[pt] Um sistema térmico de armazenamento da energia com pasta de cristais de gelo foi desenvolvido para aplicações de condicionamento de ar e resfriamento de processos. O sistema usa um evaporador orbital de haste, um trocador de calor vertical do tipo tubo e carcaça com intensificação mecânica de transferência de calor. A pasta de gelo é produzida continuamente sem acumulação no evaporador e é compatível com unidades condensadoras convencionais, tanques de armazenamento e bombas. Soluções aquosas diluídas ou soluções inorgânicas de salmoura promovem a formação de cristais de gelo, e o gelo líquido resultante pode ser bombeado ou por gravidade alimentar um tanque de armazenamento. O circuito hidráulico de refrigeração (carga térmica) pode ser desacoplado da produção do gelo utilizando-se o tanque de armazenamento. O armazenamento de gelo líquido fornece temperaturas consistentemente baixas à medida que se derrete o gelo, que por sua forma pode ser derretido também muito rapidamente. Com suas altas temperaturas características de evaporação e elevados fluxos do calor, os sistemas de geração de gelo líquido apresentam potencial para reduzir significativamente os custos de capital inicial e operação, quando comparados com tecnologias de sistemas estáticos de gelo ou ice harvesting. / [en] New ice crystal slurry thermal energy storage (TES) system has been developed for both HVAC and process cooling applications. The system uses an orbital rod evaporator (ORE), a vertical shell-and-tube heat exchanger with mechanical heat transfer augmentation, as a dynamic ice maker to generate liquid ice. Ice forms continuously without accumulation in the ORE and is compatible with conventional condensing units, storage tanks, and pumps. Dilute glycol or inorganic brine solutions promote formation of ice crystals, and the resulting liquid ice may be pumped or gravity fed to a storage tank. The cooling load circuit can be hydraulically decoupled from ice production at the storage tank. Stored liquid ice provides consistently low solution supply temperatures over significant portions of the ice melt period and may be melted very rapidly. With its characteristic high evaporator temperatures and high heat fluxes, ORE TES systems have the potential for significantly lower capital and operating costs than static ice or ice harvesting technologies.

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

Distributed power generation through renewable sources of energy has the potential of meeting the challenge of providing electricity access to the off-grid population, estimated to be around 1.2 billion residing across the globe with 300 million in India, in a sustainable way. Technological solutions developed around these energy challenges often involve thermal systems that convert heat available from sources like solar, biomass, geothermal or unused industrial processes into electricity. Conventional steam based thermodynamic cycle at distributed scale (< 1 MWe) suffers from low efficiency driving scientific research to develop new, scalable, efficient and economically viable power cycles. This PhD work conducts one such study which provides a database of thermal power blocks optimized for the lowest initial investment cost to developers of distributed power plants. The work is divided in two steps; a) feasibility study of various thermodynamic cycles for distributed power generation covering different operating temperature regimes and b) perform their detailed thermo-economic modelling for the heat sources mentioned above. Thermodynamic cycles are classified into three temperature domains namely, low (< 450 K), medium (< 600 K) and high (< 1000 K) T cycles. Any fluid whose triple point temperature is below the typical ambient temperatures is a potential working fluid in the power cycle. Most of the organic and the inorganic fluids satisfy this criterion and can be perceived as potential power cycle fluids. The general notion is that organic fluids are more suited for low or medium temperature cycles whereas inorganic fluids for high temperature ones. Organic fluids can further be classified into hydrofluorocarbon and hydrocarbon. While the former has high global warming potential (GWP), the latter is flammable in nature. Their mixture in certain compositions is found to obviate both the demerits and perform equally well on thermodynamic scales for low T cycles. On the similar lines, mixture of HCs and inorganic fluids, such as propane+CO2 and isopentane+CO2 are found to be more appropriate for medium T applications if the issues like pinch temperature in the regenerator arising due to temperature glide are taken care of. In the high temperature domain, high efficiency Brayton cycle (supercritical CO2) and transcritical condensing cycles are studied with the latter being 2 % more efficient than the former. However, application of the condensing cycle is limited to low temperature ambient locations owing to low critical temperature of CO2 (304 K). In the same cycle configuration, mixture of CO2 and propane (52 and 48%) with a critical temperature of ~ 320 K is observed to retain the thermodynamic performance with the increased heat rejection temperature matched to the tropical ambient conditions. However, these cycles are plagued by the high operating pressures (~300 bar) calling for high temperature steel making the power block uneconomical. In this regard, the advanced CO2 cycles are developed wherein the optimum operating pressures are limited to 150 bar with an increased cycle efficiency of 6 % over the S-CO2 cycle. Feasibility study carried out on these cycles in the Indian context indicates the low and medium T cycles to be better suited for distributed power generation over the high T cycles. In the second part of work, a comprehensive study is performed to optimize the low and the medium T cycles on a thermo-economic basis for the minimum specific investment cost ($/We). Such a study involves development of component level models which are then integrated to form the system of interest, thus, following a bottom-up approach. A major emphasis is given on the development of scroll expander and low cost pebble bed thermal energy storage system that are the reported in the literature as the areas with high uncertainties while connecting them to the system. Subsequently, the key design parameters influencing the specific cost of power from an air-cooled ORC are identified and used to formulate a 7-dimensional space to search for the minimum costs for applications with a) geothermal/waste or biogas heat sources and b) solar ORCs. Corresponding maps of operating parameters are generated to facilitate distributed power engineers in the design of economic systems within constraints such as available heat source temperatures, maximum expander inlet pressures imposed, etc. Further, the effect of power scaling on these specific costs is evaluated for ORC capacities between 5 and 500 kWe.

Cette étude concerne un système de stockage d’électricité basé sur le stockage thermique. Le principe est de convertir de l’électricité issue d’énergies renouvelables en chaleur lorsque la production est supérieure à la demande, de conserver cette chaleur puis de la reconvertir en électricité lorsqu’un besoin se présente. Le système proposé s’appuie sur une technologie de stockage sensible à haute température : le stockage régénératif gaz/solide. Ce stockage est associé à une boucle de charge et à un cycle thermodynamique de restitution électrique. Dans cette étude, deux architectures sont étudiées pour ce dernier : la première est basée sur un cycle gaz, la seconde sur un cycle combiné Joule/Rankine. Un modèle global du système est développé sur la base d’une modélisation de chaque composant à un niveau de détail approprié. Sur la base de ce modèle, une analyse thermodynamique est menée. Celle-ci identifie le rendement exergétique global du procédé, proche de celui d’un cycle à combustion. Une analyse exergétique détaillée du stockage identifie les principaux postes d’irréversibilités dans ce composant. Elle montre qu’il est possible d’optimiser de manière relativement simple ses performances en jouant sur son dimensionnement. Par la suite, une analyse économique montre qu’en dépit de ses performances inférieures, le cycle gaz est associé à des coûts d’investissement limités qui rendent son utilisation pertinente. En termes de coût du stockage, le système étudié est compétitif avec des solutions comme les batteries. / This study concerns an electricity storage system based on thermal energy storage. Its overall purpose is to convert electricity produced by renewable energies into heat when the supply exceeds the demand. This heat is stored for a few hours and converted back to electricity when there is a need for it. The proposed system relies on a high temperature sensible thermal energy storage technology known as the gas/solid packed bed thermal storage. This storage comes with a charging loop and a thermodynamic cycle to carry out the heat to electricity conversion. In this study, two main architectures are considered for this cycle: a simple gas cycle and a Joule/Rankine combined cycle. Each component is modeled with an appropriate level of detail in order to create a global model of the system. This model is used to carry out a thermodynamic analysis. This study calculates the global exergy efficiency of the whole process, which is close to exergy efficiency of a combustion cycle. A detailed exergy analysis of the storage allows to identify the main phenomena behind the availability losses of this component. It shows that it is possible to increase the efficiency of the storage by modifying its sizing. Apart from this study, an economic analysis shows that regardless of its low energy and exergy efficiencies, the gas cycle comes with limited investment costs which insure an interesting profitability. In terms of storage cost, the proposed system is close to other electricity storage solutions like batteries.

Ces dernières décennies ont vu le développement exponentiel des technologies de stockage, du fait des contraintes de plus en plus fortes sur le secteur énergétique et les ressources fossiles, suscitant un intérêt croissant de la part des chercheurs et des industriels. Ces technologies trouvent en effet de multiples applications, par exemple en combinaison avec des sources d’énergie renouvelable pour pallier leur intermittence, ou en récupération de chaleur fatale sur les procédés industriels. De nombreux concepts ont été développés à ce jour, et parmi eux la solution thermocline dual-media, qui consiste à stocker l’énergie sous forme thermique dans un réservoir contenant le mélange d’un fluide et d’une matrice solide.C’est sur cette technologie que s’est focalisé le projet Therm’Stock, porté par le groupe CNIM et soutenu par les Investissements d’Avenir de l’ADEME. Ce projet, débuté en 2015, associe cette entreprise à trois laboratoires, dont le Laboratoire de Thermique Energétique et Procédés (LaTEP) de l’Université de Pau et des Pays de l’Adour. La contribution du LaTEP dans le projet a été centrée sur l’étude des matériaux de stockage à utiliser pour le système thermocline envisagé, avec un focus sur les huiles thermiques comme fluide caloporteur.Dans un premier temps, un recensement des huiles disponibles commercialement a été réalisé, afin de sélectionner les fluides répondant aux contraintes du projet Therm’Stock, et notamment à la gamme de température de fonctionnement visée. Les huiles sélectionnées ont ensuite été caractérisées à l’aide du matériel disponible au laboratoire, afin de définir un ordre de priorité pour leur étude. L’huile Jarytherm® DBT s’étant démarquée, c’est ce fluide qui a été choisi pour la suite des analyses.Ces analyses ont porté sur deux aspects d’intérêt pour le stockage thermocline dual-media : le vieillissement du fluide caloporteur, et sa compatibilité avec le matériau de stockage solide. Les études réalisées ont permis d’évaluer l’influence de différents paramètres sur le vieillissement de l’huile (température, durée), ainsi que sa compatibilité avec plusieurs familles de matériaux. Au total, ce sont 15 combinaisons huiles/solides qui ont été testées, sur 18 campagnes d’essai.Deux matériaux solides ont montré une compatibilité intéressante avec l’huile Jarytherm® DBT : l’acier et le verre soda-lime. Afin de compléter l’étude réalisée au laboratoire, ces deux combinaisons ont été introduites et testées dans un pilote de stockage thermocline dual-media, développé et exploité par Bertin Technologies, filiale du groupe CNIM. Certains des résultats obtenus ont été communiqués au LaTEP, et ont permis une étude à échelle pilote des performances du stockage avec les matériaux sélectionnés. Cette analyse a par la suite été complétée par une étude numérique, au travers du développement d’un modèle spécifique de stockage thermique. L’utilisation de ce modèle a permis de confirmer et d’étendre les résultats expérimentaux obtenus sur le pilote de Bertin Technologies, mais également d’intégrer les données de vieillissement générées sur le banc d’essai du laboratoire. / These last decades, stronger constraints on the energy sector and fossil sources depletion have pushed towards an increased development of storage technologies, which benefited from a renewed interest from researchers and industrialists. These technologies can be implemented in various applications, for example in combination with renewable energy sources or for waste heat recovery in industrial processes. Several concepts have been developed so far, and among them the dual-media thermocline, which consists in storing thermal energy in a single tank, containing a fluid in direct contact with a solid matrix.Therm’Stock project, led by the CNIM group and supported by the “Investissements d’Avenir” program from ADEME, has focused on this dual-media thermocline system. This project started in 2015, gathering the leading company and three laboratories, including the Laboratory for Thermal, Energy and Process engineering (LaTEP) from the University of Pau (UPPA). LaTEP contribution to the project has been focused on storage material selection and characterization, and more particularly on thermal oils as heat transfer fluids.The study began with a screening of commercial thermal oils, in order to select the ones that could match the constraints linked to Therm’Stock project, and especially the temperature range chosen, between 100 and 350°C. The identified oils have then been characterized using the devices available at LaTEP, to define a priority order for their evaluation for thermal storage. Jarytherm® DBT oil showed promising properties, and this fluid was chosen for the following analyses.These analyses focused on two main aspects, of interest for dual-media thermocline systems: oil ageing, and its compatibility with solid storage medium. The influence of temperature and time on oil ageing has been evaluated, along with the importance of the solid in direct contact with the fluid. In total, 15 oils/solids combinations have been considered, with 18 test campaigns. Two solids have shown promising compatibility with Jarytherm® DBT oil: steel and soda-lime glass. In order to complete the laboratory-scale tests, these two combinations have been introduced and tested in a pilot-scale dual-media thermocline, developed and exploited by Bertin Technologies, a CNIM group affiliate. Some of these experimental data have been shared with LaTEP, and allowed for a pilot-scale study of storage performance with the selected materials. This analysis was then complemented by a numerical study, through the development of a specific one-dimensional storage model. Using this model, experimental data generated on Bertin Technologies pilot could be confirmed and extended. Integrating data from laboratory-scale ageing tests, the influence of heat transfer fluid degradation on storage performance has also been evaluated.

Dans les années récentes, des politiques visant à promouvoir l’efficacité énergétique ont été instaurées en réponse aux obligations réglementaires européennes et internationales. Le stockage d’énergie thermique s’est révélé être une technologie qui permet une amélioration de l’efficacité énergétique, en particulier celle des installations techniques pour le conditionnement d’air, le chauffage et l’eau chaude sanitaire pour le bâtiment. Parmi les différents types existants, le stockage thermique par chaleur sensible est le plus ancien et le plus répandu sur le marché. Or, l’intégration du ballon de stockage dans les installations énergétiques s’avère délicate tant dans la phase de conception que de l’exploitation de ces installations. Par ailleurs, il convient d’évaluer – pour les systèmes et équipements techniques du bâtiment – leurs consommations énergétiques annuelles (ou saisonnières). Pour répondre à l’ensemble de ces exigences, le recours à la modélisation et simulation dynamique des composants et systèmes énergétiques devient indispensable. Le travail de la présente thèse présente une approche de modélisation et de simulation dynamique d’un ballon de stockage d’eau par chaleur sensible qui répond aux contraintes particulières suivantes : assurer une modélisation fine à partir de la résolution des équations de Navier-Stokes d’un composant – le ballon de stockage – dans lesquels les mécanismes de transfert et d’écoulement sont complexes et réaliser une modélisation dynamique d’un système thermique associant des divers composants techniques d’un circuit et ceci avec des temps de calcul raisonnables, compatibles avec les pratiques courantes des bureaux d’étude spécialisés en conception d’installations . Le travail réalisé associe donc une analyse fine du comportement dynamique du ballon grâce au développement d’un modèle CFD, la détermination d’un modèle réduit à partir de ce modèle – qui permet la construction d’un champ dynamique de température – et enfin une modélisation sous Modelica adaptée à la simulation d’un système énergétique complexe. Dans les différentes phases de cette étude, les résultats issus de la simulation sont alors confrontés aux résultats déduits de divers travaux expérimentaux. La validation de la démarche suite à cette confrontation calculs/expériences permet d’envisager l’application des outils présentés à des projets techniques notamment au projet « PV cooling » de climatisation des bâtiments avec une ressource solaire photovoltaïque, projet réalisé en parallèle de ce projet de thèse et porté par les acteurs industriels qui soutiennent cette recherche. / In recent years, policies to promote energy efficiency have been introduced in response to European and International regulatory obligations. Thermal Energy Storage has proven to be a technology that improves energy efficiency, particularly for the air conditioning, heating and domestic hot water utilities in buildings. Among the existing types, sensible heat storage is the oldest and most widespread on the market. The integration of the storage tank into energy installations may be tricky in both the design and operation phases of these installations. Moreover, the annual (or seasonal) energy consumption of the building's technical systems and equipment should be evaluated. To meet all these requirements, dynamic modeling and simulation of energy components and systems becomes essential. The work of this thesis presents a dynamic modeling and simulation approach of a sensible heat water storage tank which respond to the following particular constraints: To ensure a fine modeling based on the resolution of the Navier-Stokes equations of a component – the storage tank – in which the flow and transfer mechanisms are complex, and to carry out a dynamic modeling and simulation, with reasonable computational time, of a thermal energy system associating various technical components of a circuit and compatible with the usual practices of the specialized system design offices. Thus, the carried out work combines a detailed analysis of the dynamic behavior of the storage tank through the development of a CFD model, the development of a reduced model from the previous CFD model that allows the construction of temperature dynamic fields and finally a Modelica modeling adapted to the simulation of a complex energy system. In the different phases of this study, the results from the simulation are compared to the results deduced from various experimental works. The validation of the approach following this comparison between calculations and experimental results makes it possible to consider the application, of the presented tools, in technical projects and in particular the project “PV cooling” for buildings air conditioning with a photovoltaic solar resource, a project that is carried out in parallel with this thesis by the industrial players supporting this research.

Les travaux présentés dans cette thèse concernent le développement d’un procédé de stockage d’énergie thermique haute température par voie thermochimique en vue d’une application dans une centrale solaire à concentration. Un état de l’art des technologies de stockage d’énergie thermique haute température par voie thermochimique a permis de définir le couple réactionnel et la technologie les mieux adaptés au procédé. Ainsi, la réaction réversible Ca(OH)2(s) = CaO(s) + H2O(g) est mise en oeuvre dans un réacteur à lit fluidisé. Une étude expérimentale a permis de démontrer la faisabilité du procédé en stockant et en déstockant l’énergie à une même température et en mettant en oeuvre 50 cycles de charge/décharge de l’énergie sans perte de réversibilité. L’utilisation d’un modèle monodimensionnel couplant les phénomènes chimiques, thermiques et hydrodynamiques à l’intérieur du réacteur a permis de mettre en évidence l’influence des conditions opératoires sur les performances du système. Les premiers pas vers une extrapolation industrielle font l’objet de la dernière partie de ces travaux, en présentant l’analyse énergétique d’une centrale solaire à concentration intégrant le procédé de stockage développé et en présentant une étude expérimentale mettant en oeuvre un solide de type industriel dans le réacteur. / This PhD thesis concerns the development of a high temperature thermochemical heat energy storage process for an application in concentrated solar power plants. A literature review allows the identification of both the best reaction couple and technology to operate the process. Thus, the Ca(OH)2(s) = CaO(s) + H2O(g) reversible reaction is carried out in a fluidized bed reactor. The experimental study demonstrated the process feasibility. Thermal energy has been charged and discharged at the same temperature and 50 cycles have been performed without any loss of reversibility. A 1D model coupling the chemical, thermal and hydrodynamic phenomena inside the reactor has been developed to study the operating parameter effects on the process performance. The last section of this work deals with the first steps towards an industrial scale-up. An energetic analysis of a concentrated solar power plant integrating the developed storage process is detailed as well as the reactions implementation with an industrial solid.

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T16:52:08Z No. of bitstreams: 0 / Made available in DSpace on 2016-11-11T16:52:08Z (GMT). No. of bitstreams: 0 / Esta dissertação tem por objetivo reportar dados relativos às características elétricas e microestruturais de eletrodos aplicadas em dispositivos armazenadores de energia, especificamente supercapacitores constituídos por eletrodos de carvão ativado. Os parâmetros elétricos estudados foram a resistência em série equivalente obtida pelo método da interrupção de corrente (ESR(Inst)) (sendo que a sigla ESR é oriunda do termo inglês Equivalent Series Resistance), a resistência em paralelo equivalente (EPR(Dep)) obtida pelo método do valor dependente (sendo que a sigla EPR é oriunda do termo inglês Equivalent Parallel Resistance) e a capacitância (C(DC)) obtida pelo método da corrente contínua (sendo que a sigla DC oriunda do termo inglês Direct Current). Tais parâmetros foram escolhidos devido ao impacto que causam no tempo de vida útil, na capacidade de armazenamento de cargas elétricas, na velocidade de carga e descarga, na perda por efeito termoiônico nos processos de carga e descarga e na perda de cargas armazenadas devido à autodescarga em supercapacitores. Os dados microestruturais reportam por meio de imagens a homogeneidade da porosidade e por meio de valores correlacionados a composição química e eventuais contaminações presentes nos eletrodos. Os dados e valores coletados possuem a intenção de servir como referência comparativa de qualidade e apontar qual parâmetro afeta mais a qualidade do supercapacitor. Para tanto foram realizados testes a fim de coletar valores de C(DC), ESR(Inst) e EPR(Dep) após a exposição de supercapacitores de 1F/5,5V a temperaturas de 50ºC, 75ºC, 100ºC e 125ºC por 672 horas, sendo os dados coletados ao inicio dos testes, à temperatura ambiente, e posteriormente a cada 168 horas. Feitos os experimentos concluiu-se que o parâmetro que sofreu maior deterioração com o acréscimo de energia térmica foi a EPR(Dep), em seguida a C(DC), que de fato pouco sofreu alteração e a ESR(Inst), em que a mudança dentro do erro de medição foi imperceptível. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP