Dissertations / Theses: 'TES (Thermal energy storage)'

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Ruiz-Cabañas, F. Javier. "Corrosion evaluation of molten salts thermal energy storage (TES) systems in concentrated solar power plants (CSP)." Doctoral thesis, Universitat de Lleida, 2020. http://hdl.handle.net/10803/671680.

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El protagonisme creixent de la tecnologia solar termoelèctrica entre el ventall de les energies renovables es centra en la seva capacitat d’adaptar la seva producció a la demanda energètica exigida. La gestionabilitat d’aquest tipus de centrals s’ha aconseguit amb la integració de sistemes d’emmagatzematge tèrmic en les mateixes. La major part dels sistemes d’emmagatzematge tèrmic, ja sigui els que s’utilitzen a nivell comercial com aquells que es troben en fase de desenvolupament proposen l’ús de sals inorgàniques foses com a medi d’emmagatzematge. Aquestes sals presenten l’inconvenient de la seva alta corrosivitat a altes temperatures. Per un costat, s’han analitzat els fenòmens de corrosió associats a les sals solars utilitzades a la planta pilot TES-PS10 mitjançant la instal·lació de racks de testimonis de corrosió als tancs de sals. A més, al finalitzar l’operació de la instal·lació pilot s’ha dut a terme un estudi post-mortem dels seus. Finalment, amb l’objectiu d’abaratir el cost de l’inventari de sals, s’ha analitzat a nivell de laboratori la corrosivitat de diferents mescles de nitrats de baixa puresa. El segon bloc de la tesi es centra en els sistemes d’emmagatzematge tèrmic en calor latent. Concretament, s’analitza la corrosió associada a la mescla peritèctica 46% LiOH-54% KOH proposta com a material de canvi de fase en un mòdul d’evaporació d’instal·lacions termoelèctriques de generació directa de vapor. D’aquesta forma, s’han dut a terme una sèrie d’assajos a nivell de laboratori amb l’objectiu d’avaluar el comportament envers la corrosió de diferents materials en contacte amb aquests hidròxids. El creciente protagonismo de la tecnología solar se centra en su capacidad para adaptar su producción a la demanda energética exigida. La gestionabilidad de este tipo de centrales se ha conseguido mediante la integración de sistemas de almacenamiento térmico en sales fundidas. El uso de sales fundidas en sistemas de almacenamiento térmico presenta el hándicap de su corrosividad a alta temperatura. El primer bloque de la Tesis analiza los fenómenos de corrosión asociados a las sales solares en la planta piloto TES-PS10 mediante la instalación de racks de corrosión en los tanques de sales. Además, se ha llevado a cabo un estudio post-mortem de componentes de la instalación. Finalmente, se ha analizado a nivel de laboratorio la corrosividad de distintas mezclas de nitrato de baja pureza. El segundo bloque de la tesis se centra en los sistemas de almacenamiento en calor latente. En concreto, se analiza la corrosión asociada a la mezcla peritéctica 46% LiOH-54% KOH propuesta como material de cambio de fase en el módulo de evaporación en plantas de generación directa de vapor. De este modo, se han llevado a cabo ensayos de corrosión a nivel de laboratorio para evaluar el comportamiento a corrosión de distintos materiales en contacto con los hidróxidos. The growing of concentrated solar power (CSP) within the different renewable energies is due to its ability to adapt the production to the required energy demand. The dispatchability of this type of plants has been achieved through the integration of molten salts thermal storage systems (TES). Molten salts have a handicap associated to their corrosiveness at high temperature. First block of this Thesis analyzes the corrosion phenomena associated with solar salts used in TES-PS10 pilot plant by installing corrosion racks in the salt tanks. Moreover, a postmortem study of different components was performed after facility shut down. Finally, in order to reduce the cost of the salt inventory in TES systems, the corrosivity of different low purity nitrates mixtures has been analyzed at laboratory scale. The second block of the Thesis focuses on latent heat storage systems. Specifically, it has been analyzed the corrosion associated with the proposed 46% LiOH-54% KOH peritectic mixture as a phase change material in the evaporation module of direct steam generation (DSG) CSP plants. Thus, corrosion tests have been performed at laboratory level to evaluate the corrosion performance of several materials in contact with such hydroxides.

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Egersand, Anton, and Emil Fransson. "THE POTENTIAL OF A LATENT HEAT THERMAL ENERGY STORAGE : An Investigation on Rocklunda's Sport Facilities." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55539.

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The world is ever increasing in its energy usage, making energy that is sustainable and secure harder to achieve. To fulfil the Paris agreement to limit global warming, the world needs to transition from fossil fuels toward more renewable energy sources, like wind and solar, but these sources have fluctuation in supply which often create a mismatch with demand. To combat this issue, thermal energy storage can be utilized, and one such technology is latent heat thermal energy storage. This study aimed to investigate the potential of latent heat thermal energy storage by developing a simple model of such a system and studying its impact on Rocklunda’s sport facilities. The model was developed by using MATLAB, primarily using the photovoltaic overproduction of the facilities to store as energy for the latent heat thermal energy storage. The implemented storage, based on the model’s result, had overall positive impact on the facilities. The optimized storage capacity was about 510 kWh, which throughout the storage’s lifetime would save ~4 989 MWh worth of heat by using the best performing phase change material: aluminium-silicon. The storage would also be able to utilize ~82% of the annual photovoltaic overproduction that would otherwise be unused/sold as well as reducing the heat demand by ~12% by using the heat stored via the storage. The implementation also proved to have beneficial effects on the environment as the saved heat was the equivalent of mitigating ~304 ton of CO2 emissions. Furthermore, there is a profit of ~236 000 SEK. Reduction and Reuse of energy with interconnected Distribution and Demand (R2D2)

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PISTACCHIO, STEFANO. "Experimental measurement of the Molten Salts (MS) Thermal Conductivity and verification of the Thermocline stability in Thermal Energy Storage (TES) system." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2015. http://hdl.handle.net/2108/202929.

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A Thermal conductivity probe fo rhigh temperature(HT-TCP) has been built and tested. Its design and construction procedure are adapted from the ambient temperature ther- mal conductivity probe(AT-TCP) due to the good performance softhislast.The construction procedure and the preliminary tests are accurately described.The probe contains a PtwireasheaterandatypeKthermocouple(K-TC)as temperature sensor, and its size are so small (diameter0.6mmandlength60mm) to guaranteea length to diameter ratioofabout100.Calibration tests with glycerolfor temperatures between 0C and 60C have shown a good Agreement with literature data,within3%.First tests on aternarysalt(18%inmassof NaNO3, 52% KNO3, and30% LiNO3) at120C and 150C , have given good results:an Agreement was found with the Thermal conduc- tivity of the standard solar salt(60% NaNO3, 40% KNO3), even if the data for this last have been extrapolated,being it solidat those temperatures. Unfortunately, at the higher temperaturetested(200C), the viscosityof the salt highly decreases,and free convection starts, making the measurements unreliable. A numerica linvestigation of the performance of the storage and evolution of the ther- mocline for theOPTSFull scaleconguration and for the OPTSsystem of theEnea Casaccia facility is carriedon.The full scale conguration has a tankheightinthe order of12m,because this choice allow stop operate the systeminnatural convection regime forlow charge fraction softh e storage.In order to obtainnumerical results in a time scalesuitable with computer resources and activities, the adoption of anaxisym- metric simplication of the geometriesis pursuit. The code OpenFOAMversion2.2.0 is used to perform the simulations. Code and model settings together with the adopted computational grids,initia land boundary conditionsare described in the following sec- tions. A summary of the simulation results is then given. A steady-state numerical investigation of the MSHeatExchanger prototype developed in ENEA Casaccia is presented.This component is realized to perform the heat exchange between moltensalts(aternarymixture ) and adiathermicoil and with a moderate tem- peraturegap(38C). In order to optimize the heate xchangereciency and toobtain the greatest contact are a between uids the pipe line series of diathermicoil is designed with anhelical geometry.The moltensaltsside is aconvectionalcy lindricalgeome- try with the Greater diameter in the region where pipe line series are located while the other portion of the heater has a diameter lower than the length of the cylinder.The codeOpenFOAMversion2.2.0 is use d to perform the simulations for the discharging phase. Code and model settings together with the adopted computational grids, initial and boundary conditions are described in the following sections and summary of the simulation results is then given.

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Rossi, Espagnet Alberto. "Techno-Economic Assessment of Thermal Energy Storage integration into Low Temperature District Heating Networks." Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191485.

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Thermal energy storage (TES) systems are technologies with the potential to enhance the efficiency and the flexibility of the coming 4th generation low temperature district heating (LTDH). Their integration would enable the creation of smarter, more efficient networks, benefiting both the utilities and the end consumers. This study aims at developing a comparative assessment of TES systems, both latent and sensible heat based. First, a techno-economic analysis of several TES systems is conducted to evaluate their suitability to be integrated into LTDH. Then, potential scenarios of TES integration are proposed and analysed in a case study of an active LTDH network. This is complemented with a review of current DH legislation focused on the Swedish case, with the aim of taking into consideration the present situation, and changes that may support some technologies over others. The results of the analysis show that sensible heat storage is still preferred to latent heat when coupled with LTDH: the cost per kWh stored is still 15% higher, at least, for latent heat in systems below 5MWh of storage size; though, they require just half of the volume. However, it is expected that the cost of latent heat storage systems will decline in the future, making them more competitive. From a system perspective, the introduction of TES systems into the network results in an increase in flexibility leading to lower heat production costs by load shifting. It is achieved by running the production units with lower marginal heat production costs for longer periods and with higher efficiency, and thus reducing the operating hours of the other more expensive operating units during peak load conditions. In the case study, savings in the magnitude of 0.5k EUR/year are achieved through this operational strategy, with an investment cost of 2k EUR to purchase a water tank. These results may also be extended to the case when heat generation is replaced by renewable, intermittent energy sources; thus increasing profits, reducing fuel consumption, and consequently emissions. This study represents a step forward in the development of a more efficient DH system through the integration of TES, which will play a crucial role in future smart energy system. Thermal energy storage (TES) eller Termisk energilagring är en teknologi med potentialen att öka effektivitet och flexibilitet i den kommande fjärde generationens fjärrvärme (LTDH). Studien har som mål att kartlägga en komparativ uppskattning av TES systemen, baserad både på latent och sensibel värme. Resultaten visar att lagring av sensibel värme är att föredra före latent värme när den kopplas med LTDH: pris per lagrade kWh kvarstår som 15% högre än för latent värme i system under 5 MWh av lagringsutrymme; dock fordrar de endast hälften av volymen. Utifrån systemperspektiv innebär introduktionen av TES system i nätverket en ökning av flexibilitet vilket leder till reducerade värmeproduktionskostnaderna i mindre belastning. I fallstudien nås en sparnivå av femhundra euro per år genom denna operativa strategi, med en investering av 2000 euro för inköp av vattentank. Resultaten kan också vidgas till en situation där värmeproduktionen ersätts av förnybara, intermittenta energikällor; till detta medföljer högre vinster, lägre bruk av bränsle vilket skulle innebära lägre utsläpp. Studien kan ses som ett steg framåt mot skapandet av en mer effektiv DH system genom integrationen av TES, vilket kommer att spela en betydande roll i framtida smarta energisystem.

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Gunasekara, Saman Nimali. "Phase Equilibrium-aided Design of Phase Change Materials from Blends : For Thermal Energy Storage." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-212440.

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Climate change is no longer imminent but eminent. To combat climate change, effective, efficient and smart energy use is imperative. Thermal energy storage (TES) with phase change materials (PCMs) is one attractive choice to realize this. Besides suitable phase change temperatures and enthalpies, the PCMs should also be robust, non-toxic, environmental-friendly and cost-effective. Cost-effective PCMs can be realized in bulk blends. Blends however do not have robust phase change unless chosen articulately. This thesis links bulk blends and robust, cost-effective PCMs via the systematic design of blends as PCMs involving phase equilibrium evaluations. The key fundamental phase equilibrium knowledge vital to accurately select robust PCMs within blends is established here. A congruent melting composition is the most PCM-ideal among blends. Eutectics are nearly ideal if supercooling is absent. Any incongruent melting composition, including peritectics, are unsuitable as PCMs. A comprehensive state-of-the-art evaluation of the phase equilibrium-based PCM design exposed the underinvestigated categories: congruent melting compositions, metal alloys, polyols and fats. Here the methods and conditions essential for a comprehensive and transparent phase equilibrium assessment for designing PCMs in blends are specified. The phase diagrams of the systems erythritol-xylitol and dodecane-tridecane with PCM potential are comprehensively evaluated. The erythritol-xylitol system contains a eutectic in a partially isomorphous system unlike in a non-isomorphous system as previous literature proposed. The dodecane-tridecane system forms a probable congruent minimum-melting solid solution, but not a maximum-melting liquidus or a eutectic as was previously proposed. The sustainability aspects of a PCM-based TES system are also investigated. Erythritol becomes cost-effective if produced using glycerol from bio-diesel production. Olive oil is cost-effective and has potential PCM compositions for cold storage. A critical need exists in the standardization of methods and transparent results reporting of the phase equilibrium investigations in the PCM-context. This can be achieved e.g. through international TES collaboration platforms. Energi är en integrerad del av samhället men energiprocesser leder till miljöbelastning, och klimatförändringar. Därför är effektiv energianvändning, ökad energieffektivitet och smart energihantering nödvändigt. Värmeenergilagring (TES) är ett attraktivt val för att bemöta detta behov, där ett lagringsalternativ med hög densitet är s.k. fasomvandlingsmaterial (PCM). Ett exempel på ett billigt, vanligt förekommande PCM är systemet vatten-is, vilket har använts av människor i tusentals år. För att tillgodose de många värme- och kylbehov som idag uppstår inom ett brett temperaturintervall, är det viktigt med innovativ design av PCM. Förutom lämplig fasförändringstemperaturer, entalpi och andra termofysikaliska egenskaper, bör PCM också ha robust fasändring, vara miljövänlig och kostnadseffektiv. För att förverkliga storskaliga TES system med PCM, är måste kostnadseffektivitet och robust funktion under många cykler bland de viktigaste utmaningarna. Kostnadseffektiva PCM kan bäst erhållas från naturliga eller industriella material i bulkskala, vilket i huvudsak leder till materialblandningar, snarare än rena ämnen. Blandningar uppvisar dock komplexa fasförändringsförlopp, underkylning och/eller inkongruent smältprocess som leder till fasseparation. Denna doktorsavhandling ger ny kunskap som möjliggör att bulkblandningar kan bli kostnadseffektiva och robusta PCM-material, med hjälp av den systematiskutvärdering av fasjämvikt och fasdiagram. Arbetet visar att detta kräver förståelse av relevanta grundläggande fasjämviktsteorier, omfattande termiska och fysikalisk-kemiska karakteriseringar, och allmänt tillämpliga teoretiska utvärderingar. Denna avhandling specificerar befintlig fasjämviktsteori för PCM-sammanhang, men sikte på att kunna välja robusta PCM blandningar med specifika egenskaper, beroende på tillämpning. Analysen visar att blandningar med en sammansättning som leder till kongruent smältande, där faser i jämvikt har samma sammansättning, är ideala bland PCM-blandningar. Kongruent smältande fasta faser som utgör föreningar eller fasta lösningar av ingående komponenter är därför ideala. Eutektiska blandningar är nästan lika bra som PCM, så länge underkylning inte förekommer. Därmed finns en stor potential för att finna och karakterisera PCM-ideala blandningar som bildar kongruent smältande föreningar eller fasta lösningar. Därigenom kan blandningar med en skarp, reversibel fasändring och utan fasseparation erhållas – egenskaper som liknar rena materialens fasändringsprocess. Vidare kan man, via fasdiagram, påvisa de blandningar som är inkongruent smältande, inklusive peritektiska blandningar, som är direkt olämpliga som PCM. Denna avhandling ger grundläggande kunskap som är en förutsättning för att designa PCM i blandningar. Genom en omfattande state-of-the-art utvärdering av fas-jämviktsbaserad PCM-design lyfter arbetet de PCM-idealiska blandningarna som hittills inte fått någon uppmärksamhet, såsom kongruenta smältande blandningar, och materialkategorierna metallegeringar, polyoler och fetter. Resultatet av arbetet visar dessutom att vissa PCM-material som ibland föreslås är direkt olämpliga då fasdiagram undersöks, bl a pga underkylning och även peritektiska system med fasseparation och degradering av kapaciteten (t ex Glauber-salt och natriumacetat-trihydrat). Denna avhandling specificerar och upprättar grundläggande teori samt tekniker, tillvägagångssätt och förhållanden som är nödvändiga för en omfattande och genomsynlig fasjämviktsbedömning, för utformning av PCM från blandningar för energilagering. Med detta som bas har följande fasdiagramtagits fram fullständigt: för erytritol-xylitol och för dodekan-tridekan, med PCM-potential för låg temperaturuppvärmning (60-120 °C) respektive frysning (-10 °C till -20 °C) utvärderas fullständigt. Erytritol-xylitol systemet har funnits vara eutektiskt i ett delvis isomorft system, snarare än ett icke-isomorft system vilket har föreslagits tidigare litteratur. Dodekan-tridekan systemet bildar ett system med kongruent smältande fast lösning (idealisk som en PCM) vid en minimumtemperatur, till skillnad från tidigare litteratur som föreslagt en maximumtemperatur, eller ett eutektiskt system. Teoretisk modellering av fasjämvikt har också genomförts för att komplettera det experimentella fasdiagrammet för systemet erytritol-xylitol. Efter granskning av de metoder som använts tidigare i PCM-litteraturen har här valts ett generiskt tillvägagångssätt (CALPHAD-metoden). Denna generiska metod kan bedöma vilken typ av material och fasändring som helst, till skillnad från en tidigare använda metoder som är specifika för materialtyper eller kemiska egenskaper. Denna teoretiska studie bekräftar termodynamiskt solvus, solidus, eutektisk punkt och erytritol-xylitol fasdiagrammet i sin helhet. Vad gäller hållbarhetsaspekter med PCM-baserad TES, lyfter denna avhandling fokus på förnybara och kostnadseffektiva material (t.ex. polyoler och fetter) som PCM. Som exempel har här undersökts erytritol och olivolja, med förnybart ursprung. Erytritol skulle kunna bli ett kostnadseffektivt PCM (163 USD/kWh), om det produceras av glycerol vilket är en biprodukt från biodiesel/bioetanolframställning. Olivolja är ännu ett kostnadseffektivt material (144 USD/kWh), och som här har påvisats innehålla potentiella PCM sammansättningar med lämpliga fasändringsegenskaper för kylatillämpningar. En övergripande slutsats från denna avhandling är att det finns ett behov av att standardisera tekniker, metoder och transparent resultatrapportering när det gäller undersökningar av fasjämvikt och fasdiagram i PCM-sammanhang. Internationella samarbetsplattformar för TES är en väg att koordinera arbetet. QC 20170830

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Barreneche, Güerisoli Camila. "Development and characterization of new materials incorporating phase change materials (PCM) for thermal energy storage (TES) applications in buildings." Doctoral thesis, Universitat de Lleida, 2013. http://hdl.handle.net/10803/123749.

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Actualment, la demanda d'energia per satisfer el confort tèrmic en edificació és un dels majors reptes per a les administracions. Per tant, l'eficiència dels diferents sistemes d'emmagatzematge d'energia s està investigant intensament per la comunitat científica. Una alternativa viable és l'ús de materials de canvi de fase (PCM). Les parafines han estat molt utilitzades com PCM per la seva alta capacitat d'emmagatzematge de calor (al voltant de 100-130 kJ·kg-1) i la seva baixa temperatura de fusió la qual és molt estable. A més, el consum d'energia i les oscil·lacions de la temperatura internes d'edificis es poden reduir quan un PCM s'incorpora en evolvents. L'objectiu principal d'aquesta tesi és el desenvolupament de nous materials que continguin PCM basant-se en l'estudi del procés per obtenir la correcta introducció del PCM dins el material. A més, les propietats termofísiques d'aquests nous materials s'han de conèixer i per tant caracteritzar a nivell de laboratori. Aquesta tesi doctoral se centra en els treballs publicats en revistes científiques amb alt factor d'impacte indexats al camp de l Energia els quals reflecteixen treball realitzat. D'altra banda, aquesta tesi conté una revisió de l'estat de l'art destacant els requisits per a un PCM i llista tots els tipus de PCM disponibles al mercat i utilitzats en investigació. D'altra banda, un nou concepte de material compost que incorpora PCM ha estat desenvolupat en aquesta tesi. Aquest compost té la matriu polimèrica, i inclou un residu del procés de reciclatge de l acer. D'aquesta manera s'obtenen làmines denses que es poden modelar. La fabricació d'aquest material podria considerar-se un mètode per a la reutilització d'aquest residu. D'altra banda, aquest tipus de residus conté òxids de metalls pesants que augmenten les propietats d'aïllant acústic de la làmina aconseguint millorar el resultat final de la solució constructiva. A més, el comportament termofísico dels materials compostos utilitzats en edificis és difícil de caracteritzar i l'anàlisi tèrmica dels PCM és un pas necessari per al disseny dels mateixos. Les dues primeres caracteritzacions termofísiques estudiades en aquesta tesi es van realitzar mitjançant corbes calorimètriques que és una de les tècniques més potents disponibles actualment. tres estudis més van ser van realitzar amb dispositius desenvolupats per diferents grups d'investigació a Espanya per tal de mesurar les propietats termofísiques dels materials compostos o materials multicapa que incorporen PCM. Hoy en día, la demanda de energía para satisfacer el confort térmico en edificación es uno de los mayores desafíos para las administraciones. Por lo tanto, la eficiencia de los diferentes sistemas de almacenamiento de energía está siendo intensamente investigado por la comunidad científica. Una alternativa viable es el uso de materiales de cambio de fase (PCM). La parafina ha sido muy usada como PCM debido a su alta capacidad de almacenamiento de calor (alrededor de 100-130 kJ·kg-1) y a su baja temperatura de fusión la cual es muy estable. Además, el consumo de energía y las oscilaciones de la temperatura internas se pueden reducir cuando un PCM se incorpora en envolventes de edificios. El objetivo principal de esta tesis es el desarrollo de nuevos materiales que contengan PCM basándose en el estudio del proceso para obtener la correcta introducción del PCM. Además, las propiedades termofísicas de estos nuevos materiales se debe conocer y por tanto caracterizar a nivel de laboratorio. Esta tesis doctoral se centra en los trabajos publicados en revistas científicas con alto factor de impacto indexados en el campo de Energía los cuales reflejan el trabajo realizado. Por otra parte, esta tesis contiene una revisión del estado del arte destacando los requisitos para un PCM y lista todos los tipos de PCM comercializados y utilizados en investigación. Por otra parte, un nuevo concepto de material compuesto que incorpora PCM ha sido desarrollado en esta tesis. Este compuesto tiene la matriz polimérica, e incluye un residuo del proceso de reciclaje de acero. De este modo se obtienen láminas densas moldeables. La fabricación de este material podría considerarse un método para la reutilización de este residuo. Por otra parte, este tipo de residuos contiene óxidos de metales pesados que aumentan las propiedades de aislante acústico de la lámina consiguiendo mejorar el resultado final de la solución constructiva. Además, el comportamiento termofísico de los materiales compuestos utilizados en edificios es difícil de caracterizar y el análisis térmico de los PCM es un paso necesario para el diseño de los mismos. Las dos primeras caracterizaciones termofísicas estudiadas en esta tesis se realizaron mediante calorimetría diferencial de barrido que es una de las técnicas más potentes disponibles actualmente. tres estudios más fueron realizaron con dispositivos desarrollados por diferentes grupos de investigación en España con el fin de medir las propiedades termofísicas de los materiales compuestos o materiales multicapa que incorporan PCM. Nowadays, energy demand to satisfy thermal comfort in buildings is one of the major challenges for governments and administrations. Therefore, energy storage system efficiency is being studied by the international scientific community. A feasible alternative is the use of phase change materials (PCM). Paraffin waxes have been used as PCM because of their high heat storage capacity (around 100-130 kJ·kg"1) and their low and stable melting temperature. Furthermore, the energy consumption and indoor oscillations temperature may be reduced when PCM is incorporated in building envelopes and the thermal inertia increment when PCM is combined with thermal insulation was widely studied. The main objective of this thesis is the development of new materials containing PCM based on the study of process to get the correct PCM introduction. In addition, thermophysical properties of these new materials must be characterized. In order to perform the characterization, it was used several developed devices. This PhD thesis is based on papers published in scientific journals with high impact factor in the Energy field and one patent that reflect the work performed. This thesis contains a review of the state of the art highlighting the requirements order to a certain PCM and lists and sorts all PCM available in the market and used in research. On the other hand, a new concept of composite material incorporating PCM is developed in this thesis. This composite has polymeric matrix and includes one waste from the steel recycling process obtaining mouldable dense sheets. The manufacture of this material is considered a way to reuse the waste. Furthermore, this waste contains heavy metals oxides which add acoustic insulation properties to the final constructive system. One patent and two papers are the main result. Moreover, thermophysical behaviour of composite materials used in buildings envelopes is difficult to characterize. In addition, PCM thermal analysis is a necessary step of building design as well as it will be a key point in the final thermal results of the envelope. The first two thermophysical characterizations studied in this thesis were performed using differential scanning calorimetry which is one of the most powerful techniques. Three more studies were performed using devices developed by different research groups in Spain in order to measure thermophysical properties of composite materials or multilayered materials incorporating PCM.

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Prieto, Cristina. "Advanced thermal energy storage research in demo plants for commercial systems." Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/399235.

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La present tesis s’enmarca en el camp/sector de l’emmagatzematge d’energia tèrmica, concretament en el procès de disseny i optimització que comporta el desenvolupament d’una tecnologia d’emmagatzematge tèrmic. Per aquest fi s’han dissenyat, construit, operat i analitzat dues plantes prototip, la primera d’elles situada a la Universitat de Lleida amb una capacitate de 66 kWhth i la segona situada a la plataforma Solcar d’Abengoa, amb 8m5 MWhth. Al llarg d’aquesta tesis, es mostra el procès d’anàlisi, estudi i optimització realitzat per permetre desenvolupar els sistemes d’emmagatzematge tèrmic amb sals foses desde la seva etapa inicial de desenvolupament y la seva extrapolació a dissenys comercials, permetent el desenvolupament de tecnologies d’emmagatzematge tèrmic que ajudin a reduir els costs i a augmentar l’eficiència de les plantes de generació de concentració solar amb un objectiu clar: que l’electricitat d’origen solar sigui competitiva enfront a les plantes fòssils en l’horitzó 2020. La presente tesis se encuadra en el campo del almacenamiento de energía térmica, en concreto en el proceso de diseño y optimización que conlleva el desarrollo de una tecnología de almacenamiento térmico. Para ello se han diseñado, construido, operado y analizado dos plantas prototipos, la primera de ellas sita en la Universidad de Lleida con una capacidad de 66 kWhth y la segunda sita en la plataforma Solucar de Abengoa, con 8,5 MWhth. A lo largo de esta tesis, se muestra el proceso de análisis, estudio y optimización realizado para permitir desarrollar los sistemas de almacenamiento térmico con sales fundidas desde su etapa inicial de desarrollo hasta su etapa de demostración y su extrapolación a diseños comerciales, permitiendo el desarrollo de tecnologías de almacenamiento que ayuden a reducir costes y a aumentar la eficiencia de las plantas de generación de concentración solar con un objetivo claro: que la electricidad de origen solar sea competitiva frente a las plantas fósiles en el horizonte 2020. This thesis is framed in the field of thermal energy storage, particularly in the design and optimization process needed for the development of a thermal storage technology. For this purpose we have been designed, built, operated and analyzed two prototypes, the first one located at the University of Lleida with a capacity of 66 kWhth and the second one located at the Solucar Platform Abengoa, with 8,5 MWhth. Throughout this thesis, the process of analysis, study and optimization done allow developing thermal storage systems with molten salt from its initial stage of development to demonstration stage and their extrapolation to commercial designs. This development of the storage technologies helps to reduce costs and increase the efficiency of solar power plants concentration with a clear objective: solar electricity is competitive with fossil plants in 2020.

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Ghashami, Bahman. "A New Power Storage, Cooling Storage, and Water Production Combined Cycle (PCWCC)." Thesis, Högskolan i Gävle, Energisystem, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-22725.

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Fresh water shortage and hot weather are common challenges in many countries of the world. In the other hand, the air conditioning systems which are used for indoor cooling cause peak electricity demand during high temperatures hours. This peak hour demand is very important since it is more expensive and mainly is supplied by fossil fuel power plants with lower efficiencies compare to base load fossil fuel or renewable owe plants. Moreover, these peak electricity load fossil fuel power plants cause higher green house gas emission and other environmental effects. So, all these show that any solution for these problems could make life better in those countries and all over the world.In this thesis, a new idea for a Power storage, Cooling storage, and Water production Combined Cycle (PCWCC) is introduced and reviewed. PCWCC is combination of two thermal cycles, Ice Thermal Energy Storage (ITES) and desalination by freezing cycle, which are merged together to make a total solution for fresh water shortage, required cooling, and high peak power demand. ITES is a well known technology for shifting the electricity demand of cooling systems from peak hours to off-peak hours and desalination by freezing is a less known desalination system which is based on the fact that the ice crystals are pure and by freezing raw water and melting resulted ice crystals, pure water will be produced. These two systems have some common processes and equations and this thesis shows that by combining them the resulted PCWCC could be more efficient than each of them. In this thesis, the thermodynamic equations and efficiencies of each PCWCC sub-systems are analyzed and the resulted data are used in finding thermodynamics of PCWCC itself. Also, by using reMIND software, which uses Cplex to find the best combinations of input/output and related processes, the cost of produced fresh water and cooling from PCWCC is compared with total cost of fresh water and cooling produced by each sub-systems of PCWCC in three sample cities all over the world, Kerman, Dubai, and Texas. These cities are chosen since they have similar ambient temperature trend with different electricity and fresh water tariff's. The results show that, the PCWCC is economical where there is a significant electricity price difference between ice charging and ice melting hours, off-peak and peak hours, of the day or when the fresh water price is high compare to electricity price. The results also show that how the revenue from fresh water could cover the used electricity cost and make some income as well.

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NIRMALANANDHAN, VICTOR SANJIT. "HEAT TRANSFER AUGMENTATION FOR EXTERNAL ICE-ON-TUBE TES SYSTEMS USING POROUS COPPER MESH TO INCREASE VOLUMETRIC ICE PRODUCTION." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100796827.

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Santo, Luca. "AA-CAES physical modelling: integration of a 1D TES code and plant performance analysis." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-360448.

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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:

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Navarro, Farré Lidia. "Thermal energy storage in buildings through phase change materials (PCM) incorporation for heating and cooling purposes." Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/398840.

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La reducció del consum energètic dels sistemes de calefacció i refrigeració dels edificis és un repte fonamental per assolir els objectius marcats per l’Horitzó 2020. Noves aplicacions d'emmagatzematge d'energia tèrmica en edificis es mostren prometedores per reduir aquest elevat consum energètic. Un dels objectius d'aquesta tesi doctoral és revisar les aplicacions passives i actives d'emmagatzematge d'energia que es troben en la literatura, especialment aquelles que utilitzen materials de canvi de fase (PCM). En aplicacions passives els requeriments de confort i les condicions climàtiques són els principals paràmetres que s’han tingut en compte fins ara. Per això s'estudia la influència de càrregues internes en el aplicacions passives de PCM. D'altra banda, es presenta un sistema innovador que actua com una unitat d'emmagatzematge tèrmic i alhora com un sistema de calefacció i refrigeració. El rendiment tèrmic d'aquest sistema es testeja sota condicions reals i s'avalua el seu potencial de reducció del consum d'energia. La reducción del consumo energético de calefacción y refrigeración de los edificios es un reto para lograr los objetivos marcados por el Horizonte 2020. Nuevas aplicaciones de almacenamiento de energía térmica en edificios se muestran prometedoras para reducir este elevado consumo energético. Uno de los objetivos de esta tesis doctoral es revisar aplicaciones pasivas y activas de almacenamiento de energía que se encuentran en la literatura, especialmente aquellas con materiales de cambio de fase (PCM). En aplicaciones pasivas los requerimientos de confort y las condiciones climáticas son los principales parámetros que se han tenido en cuenta hasta ahora. Se estudia la influencia de cargas internas en aplicaciones pasivas de PCM. También, se presenta un sistema innovador que actúa como una unidad de almacenamiento térmico y como calefacción y refrigeración. El rendimiento térmico de este sistema se testea bajo condiciones reales y evalúa su potencial de reducción del consumo energético. Reducing the energy consumption of heating and cooling systems of buildings is a key challenge to achieve the targets set for the Horizon 2020. New applications of thermal energy storage in buildings are promising to reduce the high energy consumption. One of the objectives of this PhD is to review passive and active applications of thermal energy storage in buildings found in the literature, especially those that use phase change materials (PCM). In passive applications comfort requirements and climatic conditions are the main parameters that have been considered so far. For this study, the influence of internal loads has been taken into account in passive PCM applications. Moreover, an innovative system which acts as a storage unit and a heating and cooling supply is presented. The thermal performance of this system is studied and the potential in reducing the energy consumption of heating and cooling is evaluated.

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Miró, Laia. "Industrial waste heat: mapping, estimations and recovery by means of TES." Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/399633.

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En l’actual context energètic, l'ús de la calor residual industrial (CRI) representa una oportunitat atractiva de substituir el consum d'energia primària per un mitjà amb baix nivell d'emissions i baix cost. Aquesta calor es pot recuperar i reutilitzar en altres processos, ser transformada en electricitat o calor.Tot i el seu prometedor potencial, aquest CRI no s’utilitza. L'objectiu d'aquesta tesi doctoral és el de superar algunes de les barreres tecnològiques i d'informació actuals que dificulten l’ús d’aquesta fot d’energia. En primer lloc, s’ha identificat el potencial mundial actual de CRI a escala de. En segon lloc, es va generar noves avaluacions d’estimació del potencial de CRI: a la indústria de la manufactura espanyola i en la indústria de minerals no metàl•lics Europea. Finalment, es va tractar la recuperació i reutilització d'aquesta calor mitjançant l’emmagatzematge d’energia tèrmica i es va avaluar exhaustivament els casos pràctics on aquesta tecnologia ha estat implementada. En el actual contexto energético, el uso del calor residual industrial (CRI) representa una oportunidad atractiva de sustituir el consumo de energía primaria por un medio de bajo nivel de emisiones y de bajo coste. Este calor se puede recuperar y reutilizar en otros procesos, ser transformado en electricidad o en calor. A pesar de su prometedor potencial, este CRI está actualmente en desuso. El objetivo de esta tesis doctoral es el de superar algunas de las barreras tecnológicas y de información que existen actualmente en la utilización de esta fuente de energía. En primer lugar, se ha identificado el potencial mundial actual de CRI a escala de país. En segundo lugar, se generaron nuevas evaluaciones de estimación del potencial de CRI: en la industria de la manufactura española y en la industria de minerales no metálicos Europea. Finalmente, se trató la recuperación y reutilización de este calor mediante almacenamiento de energía térmica y se evaluó exhaustivamente los casos prácticos donde esta tecnología ha sido implementada. In the current energy context, the use of industrial waste heat (IWH) provides an attractive opportunity to substitute primary energy consumption by a low-emission and low-cost energy carrier. Despite its potential, IWH is largely untapped. This heat can be recovered and reused in other processes, transformed into electricity or heat. The aim of this PhD is to overcome some of the current technological and information barriers and to provide the literature and the researchers with more knowledge of the topic and supporting its widespread development. First, current IWH potential worldwide at country scale was identified. Second, new assessments to estimate the regional IWH potential were generated: in the Spanish manufacture industry as well as in the European non-metallic mineral industry. Finally, its reuse by means of thermal energy storage (TES) was analysed and an exhaustive research of current case studies was performed.

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Ximenes, Naves Alex. "Whole Life Sustainability Assessment at the Building Industry and Constructed Assets, through the Whole Life Costing Assessment and Life Cycle Costing Assessment evaluating the economic and financial aspects." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/670202.

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Els edificis d’energia neta poden ser entesos com a edificis, que durant un temps determinat generen tanta energia com consumeixen. Ja sigui des del punt de vista de l’oferta o el consum, la disponibilitat d’energia està relacionada amb alguns aspectes bàsics, com ara la font (s), la conversió, la distribució, l’ús, el malbaratament, l’optimització, l’eficiència i l’autonomia. Aquests temes revelen la complexitat del tema de l'energia i justifiquen l'atenció especial que li dóna la comunitat acadèmica. Per obtenir resultats tangibles en l'anàlisi d'aquests sistemes, en el nostre estudi ens centrem en la modelització i optimització de solucions energètiques aplicades a edificis o sistemes similars. D'altra banda, el període de temps dels objectes analitzats es va estendre fins al seu període de cicle de vida previst. Es van establir els objectius principals com: - Verificar i analitzar l’estat de la tecnologia de les energies renovables per a edificis i actius construïts i l’aplicabilitat de l’anàlisi de costos del cicle de vida a aquests temes; - Configurar models reproductibles d’edificis i les seves principals càrregues elèctriques, mitjançant eines d’enginyeria de processos assistits per ordinador, per procedir a simulacions i optimització, considerant-se com a font d’energia primària l’energia solar; - Quantificar, utilitzant estudis de casos reals i hipotètics, els beneficis de les solucions proposades, amb l'objectiu de realitzar tota l'avaluació de la sostenibilitat de la vida mitjançant la reducció de tot el cost del cicle de vida; Los edificios de energía de red cero pueden entenderse como edificios, que durante un tiempo dado generan tanta energía como consumen. O bien, desde el punto de vista del suministro o el consumo, la disponibilidad de energía está relacionada con algunos problemas básicos, como las fuentes, la conversión, la distribución, la utilización, el desperdicio, la optimización, la eficiencia y la autonomía. Estos problemas revelan la complejidad del tema de la energía y justifican la atención especial que le presta la comunidad académica. Para obtener resultados tangibles en el análisis de estos sistemas, en nuestro estudio nos centramos en el modelado y la optimización de soluciones energéticas aplicadas a edificios o sistemas similares. Por otro lado, el período de tiempo de los objetos analizados se extendió a su período de ciclo de vida esperado. Los objetivos principales se establecieron como: - Verificar y analizar el estado de la técnica de las soluciones de energía renovable para edificios y activos construidos y la aplicabilidad del análisis de costos de ciclo de vida a estas cuestiones; - Configure modelos reproducibles de edificios y sus principales cargas eléctricas, a través de herramientas de Ingeniería de Procesos Asistidos por Computadora, para proceder a simulaciones y optimización, considerando como fuente de energía primaria la energía solar; Net-zero energy buildings can be understood as buildings, that for a given time, generate as much energy as they consume. Either, from the point of view of supply or consumption, energy availability is related to some basic issues such as source (s), conversion, distribution, utilization, waste, optimization, efficiency and autonomy. These issues reveal the complexity of the subject of energy and justify the special attention given to it by the academic community. To obtain tangible results in the analysis of these systems, in our study we focus on the modelling and optimization of energy solutions applied to buildings or similar systems. On the other hand, the time frame of the analysed objects was extended to their expected life cycle period. The main objectives were stablished as: - Verify and analyse the state-of-the-art of renewable energy solutions for buildings and constructed assets and the applicability of life cycle costing analysis to these issues; - Configure reproducible models of buildings and their main electrical loads, via Computer Aided Process Engineering tools, to proceed simulations and optimization, considering as primary energy source solar energy; - Quantify, using real-life and hypothetical case studies, the benefits of the proposed solutions, aiming the whole life sustainability assessment through the reduction of the whole life cycle costing; and - Guarantee the reproducibility of the models and main general results of this study and make them public, to contribute with their applicability and further researches.

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Xu, Ben. "Heat Transfer and Flow in Solar Energy and Bioenergy Systems." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/578616.

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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.

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Silva, Tiago Manuel Rodrigues da. "Análise numérica e experimental para o desenvolvimento de uma proteção solar com incorporação de materiais de mudança de fase." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17346.

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Doutoramento em Sistemas Energéticos e Alterações Climáticas O sector dos edifícios é o maior consumidor final de energia na União Europeia. O maior consumo de energia neste sector está associado principalmente ao recurso de sistemas ativos para a climatização dos espaços interiores – aquecimento e arrefecimento. Atualmente, o desenho arquitectónico exterior de escritórios e de edifícios comerciais recorre sistematicamente ao uso de vãos envidraçados e de soluções translúcidas, que aumenta significativamente as perdas térmicas nestas zonas. Os sistemas de armazenamento de energia térmica, utilizando materiais de mudança de fase nos edifícios, é um tema atualmente muito investigado e com rápido desenvolvimento tecnológico. A incorporação de materiais de mudança de fase é atualmente uma solução avançada que permite melhorar o desempenho térmico do edifício, inclusive na aplicação em vãos envidraçados e soluções de proteção solar. O presente trabalho apresenta e analisa a campanha experimental e simulação numérica de um sistema de proteção solar que incorpora materiais de mudança de fase. A campanha experimental é composta por dois compartimentos lado a lado, e cada um deles tem duas proteções solares – um dos compartimentos com a incorporação de materiais de fase e no outro sem. Ambos os compartimentos foram sujeitos a condições climatéricas exteriores similares numa região de clima mediterrânio durante a estação de verão e de inverno. A fachada orientada a sul é um vão envidraçado, o qual tem aplicado o sistema de proteção solar. De acordo com os critérios de validação analisados, os resultados do modelo numérico foram considerados calibrados e validados. Os resultados obtidos provam o potencial dos materiais de mudança de fase na regulação térmica e na otimização da eficiência energética dos espaços interiores dos edifícios. The building sector is the largest final end-use consumer of energy in the European Union. The large energy consumption of the building sector is mainly resourcing to active systems for cooling and heating of indoor spaces. Presently, the external envelopes of offices and commercial buildings are systematically composed by large glazed areas, which lead to substantial heat losses through these zones. Thermal Energy Storage systems (TES), using phase change materials (PCM) in buildings, are widely investigated technologies and a fast developing research area. The use of phase change materials (PCMs) is presently an advanced solution to improve the energy performance of building components, namely the glazing and window shutter protections solutions. The present work presents and discusses a numerical and experimental testing of a thermal energy system that contains phase change materials. The testing apparatus is composed by two side-by-side compartments that have two similar windows shutters, one containing PCMs and the other considered as a reference solution, without PCMs. The internal compartments were submitted to similar weather conditions in a Mediterranean climate during the summer and winter season, and the south oriented facade is a glazed area that incorporates the window protection systems. According the used acceptance criteria, the results of the numerical model presented a good agreement and reliability and were considered calibrated with well prediction data. The results reveal the PCM potential for the thermal regulation of indoor spaces as well as improving the energy efficiency of indoor building spaces.

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Tomasetta, Camilla <1983&gt. "Life Cycle Assessment of Underground Thermal Energy Storage Systems: Aquifer Thermal Energy Storage verus Borehole Thermal Energy Storage." Master's Degree Thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/3476.

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Underground Thermal Energy Storage (UTES) systems are energy conservation systems used to buffer the difference between energy supply and energy demand and therefore represent an interesting alternative to energy depletion. At the same time they contribute to cut CO2 emissions by a reduction of energy demand from traditional heating/cooling systems. Even though UTES are relatively environmental friendly solutions they are not completely free of impacts on the underground. They have possible hydro(geo)logical, chemical, thermal or microbiological impacts that are obviously strongly interrelated. The risks of UTES to groundwater quality are insufficiently known, and policies to address this uncertainty are still lacking. In order to improve the understanding and knowledge of UTES techniques, this study aimed to perform a Life Cycle Analysis (LCA) on two different UTES systems: Aquifer Thermal Energy Storage (ATES) and Borehole Thermal Energy Storage (BTES). Even if at present LCA has been mainly performed on products of the industrial and building sector it can be a useful instrument to determine the sustainability of these two possible alternatives of underground exploitation.

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Hongois, Stéphanie. "Stockage de chaleur inter-saisonnier par voie thermochimique pour le chauffage solaire de la maison individuelle." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00665612.

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Les actions conjointes en faveur d'une meilleure isolation du bâti et de l'expansion des énergies renouvelables dans l'habitat jouent un rôle de premier plan dans la politique de réduction des gaz à effet de serre et la recherche d'une plus grande efficacité énergétique. La présente thèse vise à développer un système de stockage de chaleur par voie thermochimique dédié au chauffage solaire d'une maison individuelle. A cet effet, un matériau de stockage spécifique à été mis au point, à base de zéolithe et de sulfate de magnésium. Le principe, reposant sur un phénomène mixte d'adsorption physique de vapeur d'eau et de réaction chimique d'hydratation, est à caractère inter-saisonnier : en été, la chaleur issue de capteurs solaires thermiques à air est stockée par le matériau, qui se déshydrate selon une réaction endothermique ; en hiver, l'exothermicité de la réaction inverse est exploitée afin de chauffer l'habitat. Après un état de l'art des technologies de stockage thermique, un protocole de préparation de ce matériau composite innovant est établi. Des travaux de caractérisation sont alors entrepris à l'échelle micro et macroscopique. A partir de ces données expérimentales macroscopiques, le système de stockage est dimensionné en fonction des besoins en chaleur pour le chauffage d'une maison individuelle de type Bâtiment Basse Consommation. A l'issue de cette étude, un modèle de réacteur de stockage thermique est élaboré, afin d'interpréter les transferts couplés de matière et de chaleur intervenant dans le lit de matériau et d'optimiser le réacteur de stockage en conséquence. La validité du modèle est ensuite testée et discutée à la lumière des résultats expérimentaux.

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Ranjith, Adam. "Thermal Energy Storage System Construction." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264530.

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In the framework of 2020 PUPM HEAT project three different types of thermal energy storage (TES) systems are being constructed and analyzed at a demonstration site set up at the power plant IREN in Moncalieri, Italy. KTH will assist this project by setting up a validation rig where three TES systems in smaller dimensions will be constructed and analyzed for its performance, to use as guideline for the demonstration site rig. The first TES system that is being constructed is the submerged parallel spiral heat exchanger which is a completely new version of latent heat storage to be tested. For this idea, parallel layers of spiral copper coils will fill up a tank shell which in turn will be filled with phase change material. By injecting high temperature heat transfer fluid, phase change material will change its state and energy will be stored in the system. When injecting low temperature heat transfer fluid, the energy will be extracted. This BSc thesis will present detailed design solutions for the tank shell and the spiral copper coils that will be used for the heat exchanger. Presented solutions are then used to order parts needed to initiate the construction phase. Inom ramverket för 2020 PUPM HEAT projektet kommer tre olika typer av värmeenergilagrings enheter tillverkas och analyseras vid energikraftverket IREN i Moncalieri, Italien. KTH kommer att assistera detta projekt genom att sätta upp en anläggning med tre liknande värmeenergilagrings enheter i mindre dimensioner som kommer konstrueras och analyseras. Dess data kommer sedan användas som riktlinje för att tillverka de större värmeenergilagringsenheterna i IREN. Den första enheten som tillverkas är en värmeväxlare som bygger på en ny version av latent energilagring. Den kommer att bestå av parallella lager av spiral formade koppar rör som fyller en tank. Tomrummet som blir över kommer att fyllas upp av fasändrings material (PCM). Genom att injicera varmt vatten i systemet kommer PCM:et att byta fas, vilket resulterar i att värmeenergin lagras i systemet. När sedan kallt vatten injiceras kan den sparade energin bli utvunnen. Den här rapporten kommer att presentera designen till tank kåpan såväl som den inre strukturen med kopparrör som behövs till värmeväxlaren. Resultatet ska möjliggöra beställning av alla delar som behövs för att konstruera värmeväxlaren.

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Desrues, Tristan. "Stockage massif d'électricité sous forme thermique." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00627054.

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Les travaux présentés dans cette thèse concernent un nouveau procédé de stockage d'électricité à échelle industrielle, sous forme de stockage de chaleur sensible. La chaleur est stockée dans deux échangeurs gaz-solide de grande taille appelés régénérateurs qui sont reliés à une paire de turbomachines (compresseur et turbine) formant ainsi un cycle thermodynamique. Selon le sens d'écoulement du fluide caloporteur, ce cycle est de type " pompe à chaleur " en stockage ou " moteur thermique " en déstockage. La modélisation complète du procédé a permis de caractériser son comportement dans un cas industriel, et de mettre en évidence les tendances principales du système. Les performances prévues se rapprochent de celles des installations existantes les plus adaptées au stockage massif d'électricité, telles que le stockage hydraulique gravitaire. Une étude CFD a permis l'optimisation d'une géométrie de canal à obstacles destinée à intensifier l'échange thermique dans les régénérateurs et qui sera testée expérimentalement à la suite de cette thèse. Les préparatifs de cette expérience sont abordés et ses objectifs sont explicités.

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Hedkvist, Måns. "Expansion av Fjärrvärmeproduktion ur ett Ekonomiskt Perspektiv : En Numeriskt Modellerad Fallstudie." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-183869.

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Fjärrvärme i dagens Sverige är ett väletablerat sätt att leverera värme för både industriell och privat användning. Med nästa generations fjärrvärmesystem vid horisonten kan förändringar av existerande fjärrvärmenät komma att bli vanligt förekommande. Trots att det inte är fullt aktuellt med den typen av renoveringar ännu så måste fjärrvärmenät ibland byggas ut för att hantera nya situationer som kan uppstå. För att få en god uppskattning om vad de nya situationerna kommer kräva, och potentiellt kosta, så är simuleringsmodeller ett användbart verktyg. Den här studien har granskat en kommande ökning av effektbehovet och en konsekvent ökning av den producerade värmen angående fjärrvärmesystemet lokaliserat i Malå. Granskningen genomfördes via etablering av en simuleringsmodell som baserats på metoder från tillgänglig litteratur. Empiriska värden användes både som indata till modellen och för feluppskattning. Två hypotetiska scenarier undersöktes där effektbehovet hos en industrikund antas dubbleras, ett som systemet ser ut idag och det andra med ett termiskt energilager i form av en ackumulatortank inkluderat. Simuleringssvaren gav en uppskattning av hur mycket effekt en ny produktionsenhet behöver kunna producera för att nå ett eftersökt mål. Dessa visade på att en ny produktionsenhet med en effekt av minst 10.50 MW är nödvändigt. Vidare så indikerade resultaten att installation av ett sådant energilager med den valda styrningen inte reducerar effektmagnituden hos en ny produktionsenhet. De visade dock på att införande av energilagret kan medföra en reduktion i antalet effektsvängningar som förekommer i systemet. Beroende på övrig konfiguration så minskades förekomsten av antalet effektsvängningar mellan 0.2 till 25.5 procent med ett energilager av den minsta undersökta volymen infört. District heating in Sweden is a well established way of delivering heat for both industrial and private applications. With the next generation of district heating on the doorstep, changes of existing district heating networks may become a regular occurrence. Despite the fact that these kinds of reconstructions are not quite applicable yet, refurbishments of existing district heating networks are still sometimes necessary in order to deal with new prerequisites that may appear. In order to achieve a good estimation of what these new prerequisites will require and possibly cost, the usage of tools such as models for simulation are valuable. This study has evaluated a future increase of power demand and the subsequent expansion of the produced heat concerning the district heating network located in the city of Malå. The evaluation was carried forth by establishment of a simulation model which was based on present literature. Empirical data was used both as input and for error estimation. Two hypothetical scenarios were examined in which the power demand of an industrial customer is assumed to be doubled. The first represented the system as it is defined presently, while the other introduced a tank thermal energy storage to the system. The results of the simulation yielded an estimate of how much heat a new plant needs to produce in order to attain a set goal. These suggested that the necessary heat production in the new plant needs to be at least 10.50 MW. Furthermore, the results indicated that the inclusion of a thermal energy storage of this kind and with the defined priorities will not reduce the required size of a new production plant. However, they did indicate that the defined thermal energy storage may contribute to a reduction in the number of power fluctuations occurring in the system. Depending on other configurations, the frequency of the power fluctuations were reduced between 0.2 to 25.5 percent with the inlcusion of the smallest examined thermal energy storage.

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Bembry, Walter T. IV. "Emergency thermal energy storage: cost & energy analysis." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/13086.

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Master of Science Department of Mechanical Engineering Donald Fenton The need to store and access electronic information is growing on a daily basis as more and more people conduct business and personal affairs through email and the internet. To meet these demands, high energy density data centers have sprung up across the United States and around world. To ensure that vital data centers run constantly, proper cooling must be maintained to prevent overheating and possible server damage from occurring. Emergency cooling systems for such systems typically utilize traditional batteries, backup generator, or a combination thereof. The electrical backup provides enough power to support cooling for essential components within the data centers. While this method has shown to be reliable and effective, there are several other methods that provide reliable emergency cooling at a fraction of the cost. This paper address the lack of information regarding the initial, operation, and maintenance costs of using Thermal Energy Storage (TES) tanks for emergency cooling. From research and various field examples, five emergency cooling system layouts were designed for various peak cooling loads. Looking at the different cooling loads, components, and system operations an economic evaluation of the system over a 20 year period was conducted. The economic analysis included the initial and maintenance costs of each system. In an effort to better understand power consumption of such systems and to help designer’s better estimate the long term costs of TES tanks systems, five layouts were simulated through a program called TRNSYS developed for thermal systems. To compare against current systems in place, a benefit to cost ratio was done to analyze TES versus a comparable UPS. The five simulated systems were one parallel pressurized tank, one parallel and one series atmospheric tank, one parallel low temperature chilled water, and one series ice storage tank. From the analysis, the ice storage and pressurized systems were the most cost effective for 1 MW peak cooling loads. For 5 MW peak cooling loads the ice storage and chilled water systems were the most cost effective. For 15 MW peak loads the chilled water atmospheric TES tanks were the most cost effective. From the simulations we concluded that the pressurized and atmospheric systems consumed the least amount of power over a 24 hour period during a discharge and recharge cycle of the TES tank. From the TRNSYS simulations, the ice storage system consumed 22 – 25% more energy than a comparable chilled water system, while the low temperature storage system consumed 6 – 8% more energy than the chilled water system. From the benefit-cost-ratio analysis, it was observed that all systems were more cost effective than a traditional battery UPS system of comparable size. For the smaller systems at 1 MW the benefit-cost-ratio ranged between 0.25 to 0.55, while for larger systems (15 MW) the ratio was between 1.0 to 3.5 making TES tanks a feasible option for providing emergency cooling for large and small systems.

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Ugur, Burcu. "Thermal Energy Storage in Adsorbent Beds." Thesis, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24362.

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Total produced energy in the world is mostly consumed as thermal energy which is used for space or water heating. Currently, more than 85% of total thermal energy consumption is supplied from fossil fuels. This high consumption rate increases the depletion risk of fossil fuels as well as causing a tremendous release of hazardous gases such as carbon dioxide, carbon monoxide, sulfur oxides, nitrogen oxides and particulate matter that effects both environment and human health. Those drawbacks force humankind to search for new technologies, like renewables, to reduce fossil fuel dependency on thermal energy production. Thermal energy storage in adsorbent beds is one of the resulting technologies. Adsorption is an exothermic process in which a fluid (adsorbate) diffuses into the pores of a porous solid material (adsorbent) and trapped into the crystal lattice. In this system, exothermic adsorption of water vapor from air is carried out by using hybrid adsorbent of activated alumina and zeolite. In previous studies, through literature review, this adsorbent was selected to be the most efficient adsorbent for this process due to its high water adsorption capacity, high heat of adsorption, and stability [Dicaire and Tezel, 2011]. In this study, previous studies started on this project was confirmed and pursued by trying to increase the efficiency of the process and confirm the feasibility and applicability of this system in larger scales. In this thesis, various zeolite and activated alumina hybrid adsorbents with varying zeolite compositions were screened to find the most efficient adsorbent for thermal energy storage process that gives the highest energy density. Then, existing small column was replaced with a new one, which is 16 times bigger in volume, in order to confirm the feasibility of this process at larger scales. Applicability of on-off heat release in adsorption process was also investigated by conducting several on-off experiments at different on-off time periods. Moreover, exothermic adsorption process was modeled by doing mass and energy balances in the column, water accumulation balance in the pellets, and energy balance in the column wall. Validity of this model was confirmed by comparing it with experimental results at different column volumes, and at different volumetric flow rates. Finally, an overall plant design, capital cost and thermal energy price estimations were done for adsorption thermal energy storage plants for different storage capacities and payback periods.

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Berglund, Simon. "Rock cavern as thermal energy storage." Thesis, Luleå tekniska universitet, Energivetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79596.

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In the fall of 2019, a comprehensive idea study was conducted on heat storage in two rock caverns located at Näsudden in Skelleftehamn and was part of the project course "Energiteknik, huvudkurs" at Luleå University of Technology. This idea study investigated the conditions of using waste heat from Boliden AB:s copper smeltery (Rönnskär) and storing this waste heat in two rock caverns and use them as seasonal thermal storage tanks, with the purpose of using the heat in the nearby district heating network, thus replacing some of the oil burned at Rönnskär. To investigate this, the authors of the idea study looked at two different storage cycles of seasonal storage and modeled this in ANSYS Fluent to simulate the heat storage and the heat losses. The results from this idea study showed promising results for using these caverns as heat storage and this work is therefore a continuation of the idea study. Since the study provided a good understanding of the conditions for seasonal storage, some questions arose about how the rock caverns will behave during an intermittent operation, which is the planned mode of operating the caverns in case of deployment. In this thesis, intermittent operation of these caverns are explored and how this effects the temperature in the caverns and its surrondings, the charge/discharge speed, how insulated walls affect the operation and how much oil is replaced. At the beginning of this project a review of the idea study and similar projects was done to gain deeper knowledge about the subject, but also to get a wider grasp on the different problems that could arise during the thesis. Relevant data for the caverns was collected and acquired to get a deeper understanding of its geometry, layout and what kind of modifications are really possible. Further data from the district heating networks of Boliden AB and Skellefteå Kraft was acquired. The available waste heat from Rönnskär was examined and used to calculate the chargeable energy by hour for the caverns, with the limits of Skelleftehamn district heating network in mind. By examining the different steam boiler patterns, the discharge pattern could be calculated. Using CFD, the unknown global heat transfer coefficient between the cavern water and the cavern wall can be determined. This data was then used with a set of differential equations to model the behavior of the caverns in Simulink. This allowed to determine the behavior for the caverns during normal operation, such as how the heat losses evolve, how the temperatures fluctuate, how much heat the caverns can be charged with and how much they can discharge. The results from the simulations showed that the caverns discharge a higher amount of energy when operating intermittently than when operating seasonally. Depending on how the caverns are utilized, different amounts of discharged energy are obtained. This range from 2224,7MWh to 7846,1MWh for the different discharging patterns. The usage also affects the efficiency of the cavern giving the efficiency a range between 19% to 53,9%. The heat losses range from around 20kW to 1000kW, depending on operation. Insulating the cavern walls reduces on average the heat losses by a factor of 5. Operating the caverns intermittently would on average remove a total of 29 ktonne CO2 and 88,74 tonne NOx for its expected lifespan of 30 years. Economically, the rock caverns have good economic potential as they would save about 80 million SEK during their lifetime just from buying less oil. Hösten 2019 genomfördes en omfattande idéstudie om värmelagring i två bergrum vid Näsudden i Skelleftehamn och var en del av projektkursen "\textit {Energiteknik, huvudkurs}" vid Luleå tekniska universitet. Denna idéstudie undersökte villkoren för att använda spillvärme från Boliden AB:s kopparsmältverk (Rönnskär) och lagra denna värme i bergrummen och använda dem som säsongslagrade ackumulatortankar. Syftet med detta var att använda värmen i det närliggande fjärrvärmenätverket och därmed ersätta en del av den förbrända oljan hos Rönnskär. Författarna utforskade detta genom att undersöka två olika lagringscykler för säsongslagring och modellerade detta i ANSYS Fluent för att simulera värmelagring och värmeförluster. Resultaten från idéstudien visade lovande resultat för säsongsbaserad värmelagring i dessa bergrum och detta arbete är därför en fortsättning av idéstudien. Eftersom studien gav en god förståelse för förhållandena för säsongslagring, uppstod några frågor om hur bergrummen kommer att bete sig under en intermittent drift, vilket är den planerade driften av bergrummen vid en framtida användning. I detta projekt undersöks intermittent drift av dessa bergrum och hur detta påverkar temperaturen i bergrummen och dess omgivning, laddnings- / urladdningshastigheten, hur isolerade väggar påverkar driften och hur oljeförbrukningen reduceras. I början av detta projekt gjordes en genomgång av idéstudien och liknande projekt för att få djupare kunskap om ämnet, men också för att få ett bredare grepp om de olika problem som kan uppstå under arbetets gång. Relevant data för bergrummen samlades in och anskaffades för att få en djupare förståelse för dess geometri, layout och vilken typ av ändringar som verkligen är möjliga. Ytterligare data från fjärrvärmenätverket för Boliden AB och Skellefteå Kraft förvärvades. Den tillgängliga spillvärme från Rönnskär undersöktes och användes för att beräkna den urladdningsbara energin per timme för bergrummen, med begränsningarna i Skelleftehamns fjärrvärmenät i åtanke. Genom att undersöka de olika ångpannmönstren kan urladdningsmönstret beräknas. Med hjälp av CFD kan den okända globala värmeöverföringskoefficienten mellan bergrumsvattnet och bergväggen bestämmas. Denna data användes sedan med en uppsättning differentialekvationer för att modellera driften av bergrummen i Simulink. Detta gjorde det möjligt att bestämma beteendet för bergrummen under normal drift, till exempel hur värmeförlusterna utvecklas, hur temperaturen fluktuerar, hur mycket värme bergrummen kan laddas med och hur mycket de kan ladda ur. Resultaten från simuleringarna visade att bergrummen kan ladda ur en större mängd energi än vid en säsongsbetonad drift. Beroende på hur grottorna utnyttjas erhålls olika mängder urladdad energi. Detta sträcker sig från 2224,7MWh till 7846,1MWh för de olika urladdningsmönstren. Användningen påverkar också grottans effektivitet vilket ger en effektivitet mellan 19% och 53,9%. Värmeförlusterna sträcker sig från cirka 1000 kW till 20kw, beroende på drift. Isolering av bergväggarna minskar i genomsnitt värmeförlusten med en faktor 5. Att använda grottorna intermittent skulle i genomsnitt ersätta totalt 29 kton CO2 och 88,74 ton NOx för den förväntade livslängden på 30 år. Bergrummen har även god ekonomisk potential eftersom de skulle spara cirka 80 miljoner SEK under sin livstid bara från minskade oljekostnader.

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Ohannessian, Roupen. "Thermal Energy Storage Potential in Supermarkets." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-140647.

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The objective of this research is to evaluate the potential of thermal energy storage in supermarkets with CO2 refrigeration systems. Suitable energy storage techniques are investigated and the seasonal storage technology of boreholes is chosen to be the focus of the study. The calculations are done for five supermarket refrigeration systems with different combinations of heating systems and borehole thermal energy storage control strategies. The two heating systems analyzed are the ground source heat pump and the heat recovery from the supermarket’s refrigeration system. The simulation results show that the introduction of thermal energy storage in the scenarios with heat pump can reduce the annual total energy by 6.3%. It is also shown that increasing the number of boreholes can decrease the life cycle cost of the system. Moreover, it is established that a supermarket system with heat recovery consumes 8.1% less energy than the one using heat pump and adding thermal energy storage on the heat recovery system further improves the energy consumption by 3.7% but may become costly.

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Alfasfos, Rami. "Cavern Thermal Energy Storage for District Cooling. Feasibility Study on Mixing Mechanism in Cold Thermal Energy Storage." Thesis, KTH, Kraft- och värmeteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219932.

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Bugaje, Idris M. "Thermal energy storage in phase change materials." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335920.

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Basgall, Lance Edgar. "Thermal energy storage design for emergency cooling." Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/4637.

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Master of Science Department of Mechanical and Nuclear Engineering Donald L. Fenton Emergency cooling systems are applied to any application where the loss of cooling results in damage to the product, loss of data, or equipment failure. Facilities using chilled water for cooling that experience an electrical power outage, even a small one, would cause the chiller to shut down for 20 minutes or more. If emergency cooling is not available, temperatures would continue to increase to dangerous levels, potentially damaging the facility. Examples of facilities that could be protected by having emergency cooling systems are data centers, hospitals, banks, control rooms, laboratories, clean rooms, and emergency shelters among others. This project addresses the current lack of information and methods needed to correctly design emergency cooling systems. Three application uses were investigated for the possible benefits of having emergency cooling systems. The software TRNSYS was used to simulate five typical emergency cooling systems for each of the three applications. The characteristics and differences of the systems developed from the simulations were then analyzed and documented. The five systems simulated include a pressurized chilled water tank (parallel), atmospheric chilled water tank (parallel and series), low temperature chilled water tank (parallel), and ice storage tank (series). Simulations showed that low temperature chilled water tanks were less stratified than regular chilled water tanks by approximately 10%. Simulations also showed that the differences between atmospheric and pressurized tanks were negligible. Each tank discharged energy in the same manner and managed to replenish itself in the same amount of time. Examination of the different system configurations showed that tanks in series with the thermal load have issues with recharging due to its inability to isolate itself from the thermal load. It was also observed that while low temperature chilled water and ice storage tanks had the potential of reducing the storage tank volume, the amount of time ragged cooling will last is decreased by at least a factor of two. The examination of the five systems produced the desired design methodologies needed to address the lack of information on emergency cooling systems. With the reported information designers can effectively engineer systems to meet their needs.

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Oliver, David Elliot. "Phase-change materials for thermal energy storage." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/17910.

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There is a current requirement for technologies that store heat for both domestic and industrial applications. Phase-change materials (PCMs) represent an important class of materials that offer potential for heat storage. Heat-storage systems are required to undergo multiple melt/freeze cycles without any change in melting-crystallisation point and heat output. Salt hydrates are attractive candidates on account of their high energy densities, but there are issues associated with potential crystallisation of lower-hydrates, long-term stability, and reliable nucleation. An extensive review of the PCMs in the literature, combined with an evaluation of commercially available PCMs led to the conclusion that many of the reported PCMs, lack at least one of the key requirements required for use as a heat-storage medium. The focus of this research was therefore to identify and characterise new PCM compositions with tailored properties. New PCM compositions based of sodium acetate trihydrate were developed, which showed improved properties through the use of selective polymers that retard the nucleation of undesirable anhydrous sodium acetate. Furthermore, the mechanism of nucleation of sodium acetate trihydrate by heterogeneous additives has been investigated using variable-temperature powder X-ray diffraction. This study showed that when anhydrous Na2HPO4 was introduced to molten sodium acetate trihydrate at 58°C the hydrogenphosphate salt is present as the dihydrate. On heating to temperatures in the range 75-90°C the dihydrate was observed to dehydrate to form anhydrous Na₂HPO4. This result explains the prior observation that the nucleator is deactivated on heating. The depression of melting point of sodium acetate trihydrate caused by the addition of lithium acetate dihydrate has also been investigated using differential scanning calorimetry and powder X-ray diffraction. It has been possible to tune the melting point of sodium acetate trihydrate thereby modifying its thermal properties. Studies of the nucleation of sodium thiosulfate pentahydrate, a potential PCM, led to the structural characterisation of six new hydrates using single crystal Xray diffraction. All of these hydrates can exist in samples with the pentahydrate composition at temperatures ranging from 20°C to 45°C. These hydrates are: α-Na₂S₂O₃·2H₂O, which formed during the melting of α-Na₂S₂O₃·5H₂O; two new pentahydrates, β-Na₂S₂O₃·5H₂O and γ-Na₂S₂O₃·5H₂O; Na₂S₂O₃·1.33 H₂O, β-Na₂S₂O₃·2H₂O and Na₂S₂O₃·3.67 H₂O, which formed during the melting of β- Na₂S₂O₃·5H₂O. Furthermore, new PCMs in the 75-90°C range were identified. The commercial impact and route to market of several of the PCMs are discussed in the final chapter.

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McTigue, Joshua. "Analysis and optimisation of thermal energy storage." Thesis, University of Cambridge, 2016. https://www.repository.cam.ac.uk/handle/1810/263019.

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The focus of this project is the storage of thermal energy in packed beds for bulk electricity storage applications. Packed beds are composed of pebbles through which a heat transfer fluid passes, and a thermodynamic model of the heat transfer processes within the store is described. The packed beds are investigated using second law analysis which reveals trade-offs between several heat transfer processes and the importance of various design parameters. Parametric studies of the reservoir behaviour informs the design process and leads to a set of design guidelines. Two innovative design features are proposed and investigated. These features are segmented packed beds and radial-flow packed beds respectively. Thermal reservoirs are an integral component in a storage system known as Pumped Thermal Energy Storage (PTES). To charge, PTES uses a heat pump to create a difference in internal energy between two thermal stores; one hot and one cold. The cycle reverses during discharge with PTES operating as a heat engine. The heat pumps/engines require compression and expansion devices, for which simple models are described and are integrated with the packed bed models. The PTES system behaviour is investigated with parametric studies, and alternative design configurations are explored. A multi-objective genetic algorithm is used to undertake thermo-economic optimisations of packed-bed thermal reservoirs and PTES systems. The algorithm generates a set of optimal designs that illustrate the trade-off between capital cost and round-trip efficiency. Segmentation is found to be particularly beneficial in cold stores, and can add up to 1% to the round-trip efficiency of a PTES system. On the basis of the assumptions made, PTES can achieve efficiencies and energy densities comparable with other bulk electricity storage systems. However, the round-trip efficiency is very sensitive to the efficiency of the compression–expansion system. For designs that utilised bespoke reciprocating compressors and expanders, PTES might be expected to achieve electricity-to-electricity efficiencies of 64%. However, using compression and expansion efficiencies typical of off-theshelf devices the round-trip efficiency is around 45%.

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Al, Edhari Ahmed J. "Thermal Energy Storage Using Natural Porous Media." Thesis, California State University, Fullerton, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10275441.

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Heat transfer and fluid flow through porous media have received great attention due to its wide applications in engineering fields, such as acoustics, filtrations, and thermal energy storage. Thermal energy storage (TES) is a technique to stock thermal energy for later use in many applications, such as district heating. TES is used to store solar thermal energy and excessive heat from non-natural sources to provide a reliable, stable, and cheap thermal energy. The present study considers a simple and inexpensive design which can easily be constructed using readily available porous media that are commonly found in nature. The applications of the present study can aid in decreasing the expenditures of heating spaces by reducing energy consumption and peak demand. The present study experimentally investigated the effect of grains size of used porous media (sand, gravel, and rocks) on the heat transfer through TES. Also, the experimental study was used to validate the numerical model which was implemented to investigate the effect of the design parameters, such as pipes burial depth and pipes spacing and the permeability of porous media, on the performance of TES during the charging and discharging processes. The present study showed that a shallow burial depth and placing pipes close together resulted in the maximized performance of TES. Moreover, the stored thermal energy can last longer during thermal discharging process when the used storage medium has low permeability. An experimental model can be used for future studies to optimize the performance during the discharging process to save time and money.

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Edwards, Jacob N. "Thermal energy storage for nuclear power applications." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/36238.

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Master of Science Department of Mechanical and Nuclear Engineering Hitesh Bindra Storing excess thermal energy in a storage media that can later be extracted during peak-load times is one of the better economical options for nuclear power in future. Thermal energy storage integration with light water-cooled and advanced nuclear power plants is analyzed to assess technical feasibility of different storage media options. Various choices are considered in this study; molten salts, synthetic heat transfer fluids, and packed beds of solid rocks or ceramics. In-depth quantitative assessment of these integration possibilities are then analyzed using exergy analysis and energy density models. The exergy efficiency of thermal energy storage systems is quantified based on second law thermodynamics. The packed bed of solid rocks is identified as one of the only options which can be integrated with upcoming small modular reactors. Directly storing thermal energy from saturated steam into packed bed of rocks is a very complex physical process due to phase transformation, two phase flow in irregular geometries and percolating irregular condensate flow. In order to examine the integrated physical aspects of this process, the energy transport during direct steam injection and condensation in the dry cold randomly packed bed of spherical alumina particles was experimentally and theoretically studied. This experimental setup ensures controlled condensation process without introducing significant changes in the thermal state or material characteristics of heat sink. Steam fronts at different flow rates were introduced in a cylindrical packed bed and thermal response of the media was observed. The governing heat transfer modes in the media are completely dependent upon the rate of steam injection into the system. A distinct differentiation between the effects of heat conduction and advection in the bed were observed with slower steam injection rates. A phenomenological semi-analytical model is developed for predicting quantitative thermal behavior of the packed bed and understanding physics. The semi-analytical model results are compared with the experimental data for the validation purposes. The steam condensation process in packed beds is very stable under all circumstances and there is no effect of flow fluctuations on thermal stratification in packed beds. With these experimental and analytical studies, it can be concluded that packed beds have potential for thermal storage applications with steam as heat transfer fluid. The stable stratification and condensation process in packed beds led to design of a novel passive safety heat removal system for advanced boiling water reactors.

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38

Fredi, Giulia. "Multifunctional polymer composites for thermal energy storage and thermal management." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/265328.

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Thermal energy storage (TES) consists in storing heat for a later use, thereby reducing the gap between energy availability and demand. The most diffused materials for TES are the organic solid-liquid phase change materials (PCMs), such as paraffin waxes, which accumulate and release a high amount of latent heat through a solid-liquid phase change, at a nearly constant temperature. To avoid leakage and loss of material, PCMs are either encapsulated in inert shells or shape-stabilized with porous materials or a nanofiller network. Generally, TES systems are only a supplementary component added to the main structure of a device, but this could unacceptably rise weight and volume of the device itself. In the applications where weight saving and thermal management are both important (e.g. automotive, portable electronics), it would be beneficial to embed the heat storage/management in the structural components. The aim of this thesis is to develop polymer composites that combine a polymer matrix, a PCM and a reinforcing agent, to reach a good balance of mechanical and TES properties. Since this research topic lacks a systematic investigation in the scientific literature, a wide range of polymer/PCM/reinforcement combinations were studied in this thesis, to highlight the effect of PCM introduction in a broad range of matrix/reinforcement combinations and to identify the best candidates and the key properties and parameters, in order to set guidelines for the design of these materials. The thesis in divided in eight Chapters. Chapter I and II provide the introduction and the theoretical background, while Chapter III details the experimental techniques applied on the prepared composites. The results and discussion are then described in Chapters IV-VII. Chapter IV presents the results of PCM-containing composites having a thermoplastic matrix. First, polyamide 12 (PA12) was melt-compounded with either a microencapsulated paraffin (MC) or a paraffin powder shape-stabilized with carbon nanotubes (ParCNT), and these mixtures were used as matrices to produce thermoplastic laminates with a glass fiber fabric via hot-pressing. MC was proven more suitable to be combined with PA12 than ParCNT, due to the higher thermal resistance. However, also the MC were considerably damaged by melt compounding and the two hot-pressing steps, which caused paraffin leakage and degradation, as demonstrated by the relative enthalpy lower than 100 %. Additionally, the PCM introduction decreased the mechanical properties of PA12 and the tensile strength of the laminates, but for the laminates containing MC the elastic modulus and the strain at break were not negatively affected by the PCM. Higher TES properties were achieved with the production of a semi-structural composite that combined PA12, MC and discontinuous carbon fibers. For example, the composite with 50 wt% of MC and 20 wt% of milled carbon fibers exhibited a total melting enthalpy of 60.4 J/g and an increase in elastic modulus of 42 % compared to the neat PA. However, the high melt viscosity and shear stresses developed during processing were still responsible for a not negligible PCM degradation, as also evidenced by dynamic rheological tests. Further increases in the mechanical and TES properties were achieved by using a reactive thermoplastic matrix, which could be processed as a thermosetting polymer and required considerably milder processing conditions that did not cause PCM degradation. MC was combined with an acrylic thermoplastic resin and the mixtures were used as matrices to produce laminates with a bidirectional carbon fabric, and for these laminates the melting enthalpy increased with the PCM weight fraction and reached 66.8 J/g. On the other hand, the increased PCM fraction caused a rise in the matrix viscosity and so a decrease in the fiber volume fraction in the final composite, thereby reducing the elastic modulus and flexural strength. Dynamic-mechanical investigation evidenced the PCM melting as a decreasing step in ’; its amplitude showed a linear trend with the melting enthalpy, and it was almost completely recovered during cooling, as evidenced by cyclic DMA tests. Chapter V presents the results of PCM-containing thermosetting composites. A further comparison between MC and ParCNT was performed in a thermosetting epoxy matrix. First, ParCNT was mixed with epoxy and the mixtures were used as matrices to produce laminates with a bidirectional carbon fiber fabric. ParCNT kept its thermal properties also in the laminates, and the melting enthalpy was 80-90 % of the expected enthalpy. Therefore, ParCNT performed better in thermosetting than in thermoplastic matrices due to the milder processing conditions, but the surrounding matrix still partially hindered the melting-crystallization process. Therefore, epoxy was combined with MC, but the not optimal adhesion between the matrix and the MC shell caused a considerable decrease in mechanical strength, as also demonstrated by the fitting with the Nicolais-Narkis and Pukanszky models, both of which evidenced scarce adhesion and considerable interphase weakness. However, the Halpin-Tsai and Lewis-Nielsen models of the elastic modulus evidenced that at low deformations the interfacial interaction is good, and this also agrees with the data of thermal conductivity, which resulted in excellent agreement with the Pal model calculated considering no gaps at the interface. These epoxy/MC mixtures were then reinforced with either continuous or discontinuous carbon fibers, and their characterization confirmed that the processing conditions of an epoxy composite are mild enough to preserve the integrity of the microcapsules and their TES capability. For continuous fiber composites, the increase in the MC fraction impaired the mechanical properties mostly because of the decrease in the final fiber volume fraction and because the MC phase tends to concentrate in the interlaminar region, thereby lowering the interlaminar shear strength. On the other hand, a small amount of MC enhanced the mode I interlaminar fracture toughness (Gic increases of up to 48 % compared to the neat epoxy/carbon laminate), as the MC introduced other energy dissipation mechanisms such as the debonding, crack deflection, crack pinning and micro-cracking, which added up to the fiber bridging. Chapter VI introduces a fully biodegradable TES composite with a thermoplastic starch matrix, reinforced with thin wood laminae and containing poly(ethylene glycol) as the PCM. The wood laminae successfully acted as a multifunctional reinforcement as they also stabilized PEG in their inner pores (up to 11 wt% of the whole laminate) and prevent its leakage. Moreover PEG was proven to increase the stiffness and strength of the laminate, thereby making the mechanical and TES properties synergistic and not parasitic. Finally, Chapter VII focused on PCM microcapsules. The synthesis of micro- and nano-capsules with an organosilica shell via a sol-gel approach clarified that the confinement in small domains and the interaction with the shell wall modified the crystallization behavior of the encapsulated PCM, as also evidenced by NMR and XRD studies and confirmed by DSC results. In the second part of Chapter VII, a coating of polydpamine (PDA) deposited onto the commercial microcapsules MC. The resulting PDA coating was proven effective to enhance the interfacial adhesion with an epoxy matrix, as evidenced by SEM micrographs. XPS demonstrated that the PDA layer was able to react with oxirane groups, thereby evidencing the possibility of forming covalent bond with the epoxy matrix during the curing step.

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39

Fredi, Giulia. "Multifunctional polymer composites for thermal energy storage and thermal management." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/265328.

Full text

Abstract:

Thermal energy storage (TES) consists in storing heat for a later use, thereby reducing the gap between energy availability and demand. The most diffused materials for TES are the organic solid-liquid phase change materials (PCMs), such as paraffin waxes, which accumulate and release a high amount of latent heat through a solid-liquid phase change, at a nearly constant temperature. To avoid leakage and loss of material, PCMs are either encapsulated in inert shells or shape-stabilized with porous materials or a nanofiller network. Generally, TES systems are only a supplementary component added to the main structure of a device, but this could unacceptably rise weight and volume of the device itself. In the applications where weight saving and thermal management are both important (e.g. automotive, portable electronics), it would be beneficial to embed the heat storage/management in the structural components. The aim of this thesis is to develop polymer composites that combine a polymer matrix, a PCM and a reinforcing agent, to reach a good balance of mechanical and TES properties. Since this research topic lacks a systematic investigation in the scientific literature, a wide range of polymer/PCM/reinforcement combinations were studied in this thesis, to highlight the effect of PCM introduction in a broad range of matrix/reinforcement combinations and to identify the best candidates and the key properties and parameters, in order to set guidelines for the design of these materials. The thesis in divided in eight Chapters. Chapter I and II provide the introduction and the theoretical background, while Chapter III details the experimental techniques applied on the prepared composites. The results and discussion are then described in Chapters IV-VII. Chapter IV presents the results of PCM-containing composites having a thermoplastic matrix. First, polyamide 12 (PA12) was melt-compounded with either a microencapsulated paraffin (MC) or a paraffin powder shape-stabilized with carbon nanotubes (ParCNT), and these mixtures were used as matrices to produce thermoplastic laminates with a glass fiber fabric via hot-pressing. MC was proven more suitable to be combined with PA12 than ParCNT, due to the higher thermal resistance. However, also the MC were considerably damaged by melt compounding and the two hot-pressing steps, which caused paraffin leakage and degradation, as demonstrated by the relative enthalpy lower than 100 %. Additionally, the PCM introduction decreased the mechanical properties of PA12 and the tensile strength of the laminates, but for the laminates containing MC the elastic modulus and the strain at break were not negatively affected by the PCM. Higher TES properties were achieved with the production of a semi-structural composite that combined PA12, MC and discontinuous carbon fibers. For example, the composite with 50 wt% of MC and 20 wt% of milled carbon fibers exhibited a total melting enthalpy of 60.4 J/g and an increase in elastic modulus of 42 % compared to the neat PA. However, the high melt viscosity and shear stresses developed during processing were still responsible for a not negligible PCM degradation, as also evidenced by dynamic rheological tests. Further increases in the mechanical and TES properties were achieved by using a reactive thermoplastic matrix, which could be processed as a thermosetting polymer and required considerably milder processing conditions that did not cause PCM degradation. MC was combined with an acrylic thermoplastic resin and the mixtures were used as matrices to produce laminates with a bidirectional carbon fabric, and for these laminates the melting enthalpy increased with the PCM weight fraction and reached 66.8 J/g. On the other hand, the increased PCM fraction caused a rise in the matrix viscosity and so a decrease in the fiber volume fraction in the final composite, thereby reducing the elastic modulus and flexural strength. Dynamic-mechanical investigation evidenced the PCM melting as a decreasing step in ’; its amplitude showed a linear trend with the melting enthalpy, and it was almost completely recovered during cooling, as evidenced by cyclic DMA tests. Chapter V presents the results of PCM-containing thermosetting composites. A further comparison between MC and ParCNT was performed in a thermosetting epoxy matrix. First, ParCNT was mixed with epoxy and the mixtures were used as matrices to produce laminates with a bidirectional carbon fiber fabric. ParCNT kept its thermal properties also in the laminates, and the melting enthalpy was 80-90 % of the expected enthalpy. Therefore, ParCNT performed better in thermosetting than in thermoplastic matrices due to the milder processing conditions, but the surrounding matrix still partially hindered the melting-crystallization process. Therefore, epoxy was combined with MC, but the not optimal adhesion between the matrix and the MC shell caused a considerable decrease in mechanical strength, as also demonstrated by the fitting with the Nicolais-Narkis and Pukanszky models, both of which evidenced scarce adhesion and considerable interphase weakness. However, the Halpin-Tsai and Lewis-Nielsen models of the elastic modulus evidenced that at low deformations the interfacial interaction is good, and this also agrees with the data of thermal conductivity, which resulted in excellent agreement with the Pal model calculated considering no gaps at the interface. These epoxy/MC mixtures were then reinforced with either continuous or discontinuous carbon fibers, and their characterization confirmed that the processing conditions of an epoxy composite are mild enough to preserve the integrity of the microcapsules and their TES capability. For continuous fiber composites, the increase in the MC fraction impaired the mechanical properties mostly because of the decrease in the final fiber volume fraction and because the MC phase tends to concentrate in the interlaminar region, thereby lowering the interlaminar shear strength. On the other hand, a small amount of MC enhanced the mode I interlaminar fracture toughness (Gic increases of up to 48 % compared to the neat epoxy/carbon laminate), as the MC introduced other energy dissipation mechanisms such as the debonding, crack deflection, crack pinning and micro-cracking, which added up to the fiber bridging. Chapter VI introduces a fully biodegradable TES composite with a thermoplastic starch matrix, reinforced with thin wood laminae and containing poly(ethylene glycol) as the PCM. The wood laminae successfully acted as a multifunctional reinforcement as they also stabilized PEG in their inner pores (up to 11 wt% of the whole laminate) and prevent its leakage. Moreover PEG was proven to increase the stiffness and strength of the laminate, thereby making the mechanical and TES properties synergistic and not parasitic. Finally, Chapter VII focused on PCM microcapsules. The synthesis of micro- and nano-capsules with an organosilica shell via a sol-gel approach clarified that the confinement in small domains and the interaction with the shell wall modified the crystallization behavior of the encapsulated PCM, as also evidenced by NMR and XRD studies and confirmed by DSC results. In the second part of Chapter VII, a coating of polydpamine (PDA) deposited onto the commercial microcapsules MC. The resulting PDA coating was proven effective to enhance the interfacial adhesion with an epoxy matrix, as evidenced by SEM micrographs. XPS demonstrated that the PDA layer was able to react with oxirane groups, thereby evidencing the possibility of forming covalent bond with the epoxy matrix during the curing step.

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40

Delhomme, Baptiste. "Couplage d'un réservoir d'hydrure de magnésium avec une source externe de chaleur." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00767941.

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L'objectif de la thèse était d'étudier la faisabilité d'un couplage thermique entre un réservoir d'hydrure métallique et une source externe de chaleur. L'évolution des propriétés de composites à base d'hydrure de magnésium (MgH2) a été étudiée en fonction du nombre de cycles d'hydruration. On observe une très bonne stabilité de la capacité massique d'absorption sur le long terme (600 cycles réalisés). Les premiers cycles sont néanmoins marqués par une évolution importante de la microstructure qui dépend de la proportion et/ou de la nature de l'additif utilisé lors de la mécano-synthèse des poudre d'hydrure. Cette évolution est associée à une augmentation de la conductivité thermique, mais également à une légère dégradation des cinétiques intrinsèques de réaction ainsi qu'à une expansion volumique des composites. Nos mesures montrent que l'amplitude des contraintes mécaniques engendrées sur les parois d'un réservoir se stabilisent après une cinquantaine de cycles. Un réservoir contenant 10 kg de MgH2, et capable de stocker 6500 Nl d'hydrogène en 35 minutes a ensuite été développé au laboratoire. L'énergie des réactions d'absorption et de désorption est échangée avec une source externe de chaleur via un fluide caloporteur. Ce système permet de représenter l'intégration thermique d'un réservoir d'hydrure dans un système de cogénération. Un modèle numérique a été développé afin de mieux appréhender le comportement de ce réservoir. Des essais de couplage entre un réservoir de taille plus modeste et une pile à combustible haute température (SOFC) développant une puissance électrique de 1 kW ont également été réalisés au Politecnico di Torino.

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41

Renaldi, Renaldi. "Modelling and optimisation of energy systems with thermal energy storage." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31214.

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One of the main challenges in the implementation of renewable energy is the mismatch between supply and demand. Energy storage has been identified as one of the solutions to the mismatch problem. Among various storage technologies, thermal energy storage (TES) is foreseen to have a significant role to achieve a low carbon energy systems because of the large share of thermal energy demand and its relatively low cost. However, integrating TES into energy systems requires careful design and implementation since otherwise potential financial and environmental savings may not be achieved. Computational-based design tools are ubiquitous in the design process of modern energy systems and can be broadly categorised into two methodologies: optimisation and simulation. In both cases, designing an energy system with storage technology is significantly more complicated than those without, mainly due to the coupling of variables between time steps. This thesis is concerned with two facets of the application of TES in energy systems. First, the role of TES in improving the performance of renewable-based domestic heating systems. Second, the implementation of optimisation and simulation tools in the design of energy systems with integrated TES. They are addressed by examining two case studies that illustrate the spatial and temporal variance of energy systems: a single dwelling heat pump system with a hot water tank, and a solar district heating system with a borehole thermal energy storage. In the single dwelling case study, the technical and financial benefits of TES installation in a heat pump system are illustrated by the optimisation model. A simulation model which utilises the optimisation results is developed to assess the accuracy of the optimisation results and the potential interaction between the two methodologies. The solar district heating case study is utilised to highlight the potential of a time decomposition technique, the multiple time grids method, in reducing the computational time in the operational optimisation of the system. Furthermore, the case study is also employed to illustrate the potential of installing a similar system in the UK. The latter study was performed by developing a validated simulation model of the solar district heating system. The findings of the analyses reported in this thesis exemplify the potential of TES in a domestic and community-level heating system in the UK. They also provide a basis for recommendations on the improved use of optimisation and simulation tools in the design process of energy systems.

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42

Meroueh, Laureen. "Electrically charged thermal energy storage systems for grid-level electricity storage." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115660.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. Cataloged from PDF version of thesis. Includes bibliographical references (pages 155-171). Unlike most other commodities, electricity produced at any given time must match the electricity being consumed or the stability of the electric grid is jeopardized. Electricity demand changes throughout the day result in required generation ramp-ups that strain power plants, reduce cycle efficiency and increase CO2 emissions. This problem is exacerbated when renewable sources such as wind and solar are integrated into the grid, due to their intermittency. A change in methods of energy production globally that allows synergistic coupling of renewable and fossil fuels is needed. Currently, pumped hydroelectric and compressed air energy storage are the two most common methods of storage, but are highly geographic dependent systems and thus of limited applicability. There exists a strong demand for grid-scale energy storage that are cost-effective and without geographic constraints. In this thesis, storage systems that are charged by electricity and discharged to produce electricity at times of high demand, are theoretically evaluated. Various types of storage such as chemical, thermal, and mechanical, are reviewed to determine the most ideal method for grid-level energy storage. Thermal energy storage systems using phase change materials are most attractive on a cost and energy density basis. Two system designs are evaluated that can couple to both existing and future power plants since they are electrically charged, via joule heating for example, and later discharged to produce electricity using the plant's turbomachinery. Described within is a novel system in which silicon is used as the storage medium and energy release is predominantly through radiative heat transfer. Another design based on the eutectic alloy Al0.88 Si0.12 and other sensible energy storage materials is also evaluated. As an example, the energy storage systems are coupled to a power plant operating according to a supercritical Rankin cycle, and their performance is compared to that of a boiler. Additionally, system cost is compared to existing storage technologies. Although storing electricity as heat and back to electricity is thermodynamically unfavorable, we present an analysis to show that this approach can be cost competitive and provides a segue from fossil fuels to renewable energy. by Laureen Meroueh. S.M.

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43

Arnold, David. "Thermal characteristics of encapsulated ice storage." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280954.

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44

Glos, Jan. "Modelování a řízení toků elektrické a tepelné energie v plně elektrických automobilech." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-433039.

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Systematické řízení tepelných a elektrických toků v plně elektrických automobilech se stává velmi důležitým, protože v těchto typech automobilů není k dispozici dostatek odpadního tepla pro vytápění kabiny. Aby v zimním období nedocházelo ke snížení dojezdu, je nutné použití technologií, které umožní snížení spotřeby energie nutné k vytápění kabiny (např. tepelné čerpadlo, zásobník tepla). Je také zapotřebí vytvořit řídicí algoritmy pro tato zařízení, aby byl zajištěn jejich optimální provoz. V letním období je nezbytné řídit tepelné toky v rámci elektromobilu tak, aby nedocházelo k nadměrnému vybíjení baterie kvůli chlazení kabiny a dalších částí. Tato práce řeší jak návrh řídicích algoritmů, tak i vývoj rozhodovacího algoritmu, který zajistí směřování tepelných toků.

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45

Tarragona, Roig Joan. "Smart control techniques for thermal energy storage systems." Doctoral thesis, Universitat de Lleida, 2021. http://hdl.handle.net/10803/671420.

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Augmentar l’ús d’energia provinent de fonts renovables és important en la lluita contra el canvi climàtic. No obstant, la seva implantació planteja reptes importants deguts a la manca de continuïtat en la seva generació i al desajust que existeix amb els perfils de consum. La present tesi doctoral s’emmarca en dues propostes per incrementar el rendiment dels panells fotovoltaics en l’àmbit dels sistemes de calefacció per edificis. Per una banda, el sistema integra un tanc d'emmagatzematge d'energia tèrmica, que permet emmagatzemar l'energia generada pels panells durant el dia, a fi de poder-la consumir a les hores amb més demanda. D'altra banda, el sistema també compta amb una estratègia de control predictiu, que permet pronosticar les condicions meteorològiques i les demandes de calefacció futures, per tal d'ajustar el funcionament de tot el conjunt d'elements, considerant aquesta informació. El sistema proposat ha demostrat ser efectiu en diferents tipus de clima i habitatges. Aumentar el uso de energía procedente de fuentes renovables es importante en la lucha contra el cambio climático. No obstante, su implantación plantea retos importantes debidos a la falta de continuidad en su generación y al desajuste que existe con los perfiles de consumo. La presente tesis doctoral se enmarca en dos propuestas para incrementar el rendimiento de los paneles fotovoltaicos en el ámbito de los sistemas de calefacción para edificios. Por un lado, el sistema integra un tanque de almacenaje de energía térmica, que permite almacenar la energía generada por los paneles durante el día, a fin de poderla consumir a las horas con más demanda. Por otro lado, el sistema también cuenta con una estrategia de control predictivo, que permite pronosticar las condiciones meteorológicas y las demandas de calefacción futuras, para ajustar el funcionamiento de todo el conjunto de elementos, considerando esta información. El sistema propuesto demostró ser efectivo en distintos tipos de climas y viviendas. To increase the use of energy that comes from renewables is important to fight against climate change. However, their deployment leads to significant challenges due to the intermittence in their generation and the mismatch between energy demand and supply. In that sense, this PhD thesis is framed in two proposals to increase the performance of photovoltaic panels in heating systems integrated in the building sector. On the one hand, the system considers a thermal energy storage tank, which allows to store the energy produced by the panels during the solar hours, in order to consume it along the peak demand periods. On the other hand, the system also takes into account a model predictive control strategy, which enables to forecast weather conditions and future heating demands, to adjust the operation of all the elements. The proposed system demonstrated a good and effective behaviour in different climate conditions and buildings.

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46

Jaconelli, Livio, and Anton Pettersson-Thurfjell. "Numerical Verification of Mobile Thermal Energy Storage Performance." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-216157.

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47

Al-Mosawi, Alaa Liaq Hashem. "Thermal energy storage for building-integrated photovolaic components." Thesis, University of Strathclyde, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549422.

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48

Cho, Eugene N. (Eugene Nammyoung). "Understanding and engineering azobenzene for thermal energy storage." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111320.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017. Cataloged from PDF version of thesis. Includes bibliographical references (pages 135-146). This thesis focuses on the understanding and engineering of a molecule known as azobenzene which holds unique properties for thermal storage applications. The azobenzene molecule undergoes structural change into a metastable state which has the ability to store energy. This thesis utilizes the energy storage and structural change properties of this molecule to develop new materials for thermal energy storage. The first is through a concept called solar thermal fuel which is storing the solar energy in rearranged bonds of the azobenzene and later releasing that energy in the form of heat. The second approach is through the structural property difference of its two states in order to moderate the phase change temperature of organic phase change materials. Essentially, the molecule azobenzene was modified and engineered to be used as a thermal battery as well as to mediate thermal energy storage in other materials. The first chapter will give a brief introduction on the concept and past examples of solar thermal fuel. Chapter 2, 3, 4 will discuss about the development of solar thermal fuel while chapter 5 discusses about a recently developed concept of using azobenzene to moderate phase change temperature. Chapter 2 shows the first demonstration of using solar thermal fuel in the solid state through functionalizing azobenzene on a polymer template. The polymer platform allows fabrication of a thin film of this material which enabled charging, discharging, and heat release using optically chargeable molecules all within the solid-state. A demonstration of solid state application was shown by constructing a macroscopic device which resulted in heat release bringing a temperature increase of as high as 10 OC. Next in chapter 3, azobenzene was engineered on the molecular lever with bulky aromatic groups (phenyl, biphenyl, and tert-butyl phenyl groups). The molecules were designed and synthesized for the purpose of increasing energy stored while promoting solid state solar thermal fuels. The design allowed fabrication of molecular based thin film, which was able to be charged with light, a great improvement from the original azobenzene, which crystallized preventing switching in the solid state. Molecular engineering proved to be a powerful and effective method in improving other solar thermal fuel properties, such as energy storage in STFs, chargeability, and also the thermal stability of the molecular thin film. In chapter 4, new diacetylene derivatives with azobenzene moieties and with varied alkyl spacers and linkers were synthesized to show photocontrolled self-assembly and disassembly of photon energy storage materials. This azobenzene decorated diacetylenes not only allowed solar energy storage but also demonstrated phase change characteristic of organic materials can be a parameter to consider in terms of designing high energy density photon energy storage materials. Chapter 5 discusses azobenzene based dopants in organic phase change material to photomoderate the phase change temperature. Three different types, 8 in total, organic phase change materials were tested to show the possibilty of this concept in a wide variety of phase change materials. A deep understanding was developed giving parameters to achieve a large phase change temperature difference in the organic phase change materials using the structual difference of the trans and the cis state of azobenzene. by Eugene N. Cho. Ph. D.

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Kotze, Johannes Paulus. "Thermal energy storage in metallic phase change materials." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/96049.

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Thesis (PhD) -- Stellenbosch University, 2014. ENGLISH ABSTRACT: Currently the reduction of the levelised cost of electricity (LCOE) is the main goal of concentrating solar power (CSP) research. Central to a cost reduction strategy proposed by the American Department of Energy is the use of advanced power cycles like supercritical steam Rankine cycles to increase the efficiency of the CSP plant. A supercritical steam cycle requires source temperatures in excess of 620°C, which is above the maximum storage temperature of the current two-tank molten nitrate salt storage, which stores thermal energy at 565°C. Metallic phase change materials (PCM) can store thermal energy at higher temperatures, and do not have the drawbacks of salt based PCMs. A thermal energy storage (TES) concept is developed that uses both metallic PCMs and liquid metal heat transfer fluids (HTF). The concept was proposed in two iterations, one where steam is generated directly from the PCM – direct steam generation (DSG), and another where a separate liquid metal/water heat exchanger is used – indirect steam generation, (ISG). Eutectic aluminium-silicon alloy (AlSi12) was selected as the ideal metallic PCM for research, and eutectic sodium-potassium alloy (NaK) as the most suitable heat transfer fluid. Thermal energy storage in PCMs results in moving boundary heat transfer problems, which has design implications. The heat transfer analysis of the heat transfer surfaces is significantly simplified if quasi-steady state heat transfer analysis can be assumed, and this is true if the Stefan condition is met. To validate the simplifying assumptions and to prove the concept, a prototype heat storage unit was built. During testing, it was shown that the simplifying assumptions are valid, and that the prototype worked, validating the concept. Unfortunately unexpected corrosion issues limited the experimental work, but highlighted an important aspect of metallic PCM TES. Liquid aluminium based alloys are highly corrosive to most materials and this is a topic for future investigation. To demonstrate the practicality of the concept and to come to terms with the control strategy of both proposed concepts, a storage unit was designed for a 100 MW power plant with 15 hours of thermal storage. Only AlSi12 was used in the design, limiting the power cycle to a subcritical power block. This demonstrated some practicalities about the concept and shed some light on control issues regarding the DSG concept. A techno-economic evaluation of metallic PCM storage concluded that metallic PCMs can be used in conjunction with liquid metal heat transfer fluids to achieve high temperature storage and it should be economically viable if the corrosion issues of aluminium alloys can be resolved. The use of advanced power cycles, metallic PCM storage and liquid metal heat transfer is only merited if significant reduction in LCOE in the whole plant is achieved and only forms part of the solution. Cascading of multiple PCMs across a range of temperatures is required to minimize entropy generation. Two-tank molten salt storage can also be used in conjunction with cascaded metallic PCM storage to minimize cost, but this also needs further investigation. AFRIKAANSE OPSOMMING: Tans is die minimering van die gemiddelde leeftydkoste van elektrisiteit (GLVE) die hoofdoel van gekonsentreerde son-energie navorsing. In die kosteverminderingsplan wat voorgestel is deur die Amerikaanse Departement van Energie, word die gebruik van gevorderde kragsiklusse aanbeveel. 'n Superkritiese stoom-siklus vereis bron temperature hoër as 620 °C, wat bo die 565 °C maksimum stoor temperatuur van die huidige twee-tenk gesmelte nitraatsout termiese energiestoor (TES) is. Metaal fase veranderingsmateriale (FVMe) kan termiese energie stoor by hoër temperature, en het nie die nadele van soutgebaseerde FVMe nie. ŉ TES konsep word ontwikkel wat gebruik maak van metaal FVM en vloeibare metaal warmteoordrag vloeistof. Die konsep is voorgestel in twee iterasies; een waar stoom direk gegenereer word uit die FVM (direkte stoomopwekking (DSO)), en 'n ander waar 'n afsonderlike vloeibare metaal/water warmteruiler gebruik word (indirekte stoomopwekking (ISO)). Eutektiese aluminium-silikon allooi (AlSi12) is gekies as die mees geskikte metaal FVM vir navorsingsdoeleindes, en eutektiese natrium – kalium allooi (NaK) as die mees geskikte warmteoordrag vloeistof. Termiese energie stoor in FVMe lei tot bewegende grens warmteoordrag berekeninge, wat ontwerps-implikasies het. Die warmteoordrag ontleding van die warmteruilers word aansienlik vereenvoudig indien kwasi-bestendige toestand warmteoordrag ontledings gebruik kan word en dit is geldig indien daar aan die Stefan toestand voldoen word. Om vereenvoudigende aannames te bevestig en om die konsep te bewys is 'n prototipe warmte stoor eenheid gebou. Gedurende toetse is daar bewys dat die vereenvoudigende aannames geldig is, dat die prototipe werk en dien as ŉ bevestiging van die konsep. Ongelukkig het onverwagte korrosie die eksperimentele werk kortgeknip, maar dit het klem op 'n belangrike aspek van metaal FVM TES geplaas. Vloeibare aluminium allooie is hoogs korrosief en dit is 'n onderwerp vir toekomstige navorsing. Om die praktiese uitvoerbaarheid van die konsep te demonstreer en om die beheerstrategie van beide voorgestelde konsepte te bevestig is 'n stoor-eenheid ontwerp vir 'n 100 MW kragstasie met 15 uur van 'n TES. Slegs AlSi12 is gebruik in die ontwerp, wat die kragsiklus beperk het tot 'n subkritiese stoomsiklus. Dit het praktiese aspekte van die konsep onderteken, en beheerkwessies rakende die DSO konsep in die kollig geplaas. In 'n tegno-ekonomiese analise van metaal FVM TES word die gevolgtrekking gemaak dat metaal FVMe gebruik kan word in samewerking met 'n vloeibare metaal warmteoordrag vloeistof om hoë temperatuur stoor moontlik te maak en dat dit ekonomies lewensvatbaar is indien die korrosie kwessies van aluminium allooi opgelos kan word. Die gebruik van gevorderde kragsiklusse, metaal FVM stoor en vloeibare metaal warmteoordrag word net geregverdig indien beduidende vermindering in GLVE van die hele kragsentrale bereik is, en dit vorm slegs 'n deel van die oplossing. ŉ Kaskade van verskeie FVMe oor 'n reeks van temperature word vereis om entropie generasie te minimeer. Twee-tenk gesmelte soutstoor kan ook gebruik word in samewerking met kaskade metaal FVM stoor om koste te verminder, maar dit moet ook verder ondersoek word.

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Kolesnik, Lindgren Julian. "Aquifer Thermal Energy Storage : Impact on groundwater chemistry." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232110.

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Groundwater is potentially a useful source for storing and providing thermal energy to the built environment. In a nordic context, aquifer thermal energy storage, (ATES) has not been subject to a wider extent of research concerning environmental impact. This thesis intends to study the impact on groundwater chemistry from an ATES that has been operational since 2016 and is located in the northern part of Stockholm, on a glaciofluvial deposit called the Stockholm esker. Analysis of groundwater sampling included a period of 9 months prior to ATES operation as well as a 7 month period after operation and sampling was conducted in a group of wells in vicinity of the installation and within the system as ATES operation began. Means of evaluation constituted a statistical approach which included Kruskal-Wallis test by ranks, to compare the ATES wells with the wells in the surroundings and principal component analysis, (PCA), to study the chemical parameters that could be related to ATES. In addition, a geophysical survey comprising 2D-resistivity and induced polarization, (IP) was done to elucidate whether the origin of high salinity could be traced to nearby possible sources. The analysis was based on foremost the cycle of cold energy storage. The results showed large variations in redox potential, particularly at the cold wells which likely was due to the mixing of groundwater considering the different depths of groundwater being abstracted/injected from different redox zones. Arsenic, which has shown to be sensitive to high temperatures in other research showed a decrease in concentration compared to surrounding wells. There were found to be a lower specific conductivity and total hardness at the ATES well compared to their vicinity. That indicates that they are less subject to salinization and that no accumulation has occurred to date. It is evident that the environmental impact from ATES is governed by the pre-conditions in soil- and groundwater.

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Dissertations / Theses on the topic 'TES (Thermal energy storage)'

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