Thèses : « THERMAL ENERGY STORAGE SYSTEM (TES) »

1

Darkwa, K. « Thermal energy storage (TES) systems involving thermochemical reactions ». Thesis, Cranfield University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309836.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

2

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

3

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Egersand, Anton, et 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.

Texte intégral

Résumé :

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)

Styles APA, Harvard, Vancouver, ISO, etc.

5

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.

Texte intégral

Résumé :

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

Styles APA, Harvard, Vancouver, ISO, etc.

6

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

7

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.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

8

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.

Texte intégral

Résumé :

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:

Styles APA, Harvard, Vancouver, ISO, etc.

9

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

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Gravoille, Pauline. « CASE STUDY OF ACTIVE FREE COOLING WITH THERMAL ENERGY STORAGE TECHNOLOGY ». Thesis, KTH, Kraft- och värmeteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-77778.

Texte intégral

Résumé :

May 25, 2011, Reuters’ headline read: "New York State is prepared for summerelectricity demand". The NY operator forecasts for next summer a peak of 33GW, close to therecord ever reached. With soaring cooling demands, the electricity peak load represents a substantialconcern to the energy system. In the goal of peak shaving, research on alternative solutions based onThermal Energy Storage (TES), for both cooling and heating applications, has been largely performed.This thesis addresses thermal comfort applications with use of active free cooling through implementationof latent heat based TES. Active free cooling is based on the use of the freshness of a source, the outsideair for example, to cool down buildings. This work conceptualizes the implementation of TES basedcooling system with use of Phase Change Material in an in-house-built model. The principle of PhaseChange Material, or Latent Heat TES (LHTES), lies on latent energy which is the energy required for thematerial to change phase. In order to properly size this cooling system, a multi-objective optimization isadopted. This optimization, based on minimization of multi-objective functions, led to optimal designconfigurations. In parallel, the electrical consumption of the system and the volume uptake of the systemwere also considered. Through the obtained optimization studies, we identified non-linearinterdependency between the two objective functions: the cost of the system and the acceptable remainingcooling needs. By remaining cooling needs, we mean the cooling needs that the system cannot meet. As amatter of fact, sizing the system according to these cooling needs would imply a very high cost. It wasfound that for a certain amount of remaining cooling needs, the PCM-based cooling system reveals to bean interesting solution compared to conventional air conditioning in terms of electrical consumption andoverall system cost.
Best Master Thesis Award, granted by French Academic Institute
Cold Thermal Energy Storage

Styles APA, Harvard, Vancouver, ISO, etc.

11

Oró, Prim Eduard. « Thermal energy storage (TES) using phase change materials (PCM) for cold applications ». Doctoral thesis, Universitat de Lleida, 2013. http://hdl.handle.net/10803/110542.

Texte intégral

Résumé :

L’objectiu d’aquesta tesis doctoral és el desenvolupament d’un sistema d’emmagatzematge d’energia tèrmica (TES) mitjançant la utilització de materials de canvi de fase (PCM) per aplicacions a baixa temperatura, en particular, per a congeladors comercials. Es provarà tant experimental com numèricament la millora de les condicions de l’emmagatzematge i també la millora de la qualitat dels aliments emmagatzemats/transportats. També inclou la investigació de nous PCMs, estudiant la modificació de la temperatura de canvi de fase i analitzant velocitats de degradació i corrosió amb els materials recipients. Els resultats obtinguts a les diferents aplicacions estudiades demostren el clarament el benefici de la utilització de PCM, reduint les fluctuacions i les caigudes de temperatura tant al interior dels sistemes com del producte, i per tant millorant la qualitat d’aquests.
El objetivo de esta tesis doctoral es el desarrollo de un sistema de almacenamiento de energía térmica (TES) mediante la utilización de materiales de cambio de fase (PCM) para aplicaciones a baja temperatura, en particular, para los congeladores comerciales. Se probará experimental y numéricamente la mejora de las condiciones de almacenamiento, y también la mejora de la calidad de los alimentos almacenados/transportados. También incluye la investigación de nuevos PCM, estudiando la modificación de la temperatura de cambio de fase y analizando velocidades de degradación y corrosión con los materiales contenedores. Los resultados obtenidos en las diferentes aplicaciones demuestran el beneficio de usar PCM, reduciendo las fluctuaciones y las caídas de temperatura tanto del interior de los sistemas como del producto almacenado y por tanto la mejoría de la calidad de éstos.
The aim of this PhD thesis is to develop a thermal energy storage (TES) system using phase change materials (PCM) for cold temperature applications in particular for commercial freezers testing experimentally and numerically the improvement of its thermal performance and the food quality stored. This thesis also includes the research on PCM with attractive properties for low temperature applications such as controllable phase change temperature and low corrosion and degradation rate. The results obtained in the proposed applications have proved the benefit of using PCM in the proposed cold applications based on reduction of the interior/product temperature fluctuations and

Styles APA, Harvard, Vancouver, ISO, etc.

12

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Saffari, Tabalvandani Mohammad. « Simulation-based optimization of thermal energy storage (TES) materials for building and industry applications ». Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/459304.

Texte intégral

Résumé :

Una quantitat substancial d'energia s'utilitza en els sectors de l'edificació i de la indústria per als propòsits de la calefacció i de la refrigeració. Els materials d'emmagatzematge d'energia tèrmica (TES) poden oferir importants beneficis energètics i econòmics als edificis residencials, comercials i industrials. Els materials de TES tenen el potencial per reduir les demandes de refredament i de l'electricitat màxima en sectors de l'edificació i de la indústria; però, per tal d'implementar adequadament aquesta tecnologia per maximitzar els beneficis econòmics, es necessiten tècniques de simulació i optimització numèrica. La important contribució original que emergeix de la present tesi és l'ús de mètodes de simulació numèrica i optimització per avançar l'aplicació de la tecnologia TES en els sectors residencials i industrials. Per a això, es presentarà una revisió pel que fa a l'ús d'eines de simulació d'energia per al desenvolupament d'edificis per analitzar passivament els materials realçats amb TES.
Una cantidad substancial de energía se utiliza en los sectores de la edificación y de la industria para los propósitos de la calefacción y de la refrigeración. Los materiales de almacenamiento de energía térmica (TES) pueden ofrecer importantes beneficios energéticos y económicos a los edificios residenciales, comerciales e industriales. Los materiales de TES tienen el potencial para reducir las demandas de enfriamiento y de la electricidad máxima en sectores de la edificación y de la industria; sin embargo, con el fin de implementar adecuadamente esta tecnología para maximizar los beneficios económicos, se necesitan técnicas de simulación y optimización numérica. La importante contribución original que emerge de la presente tesis es el uso de métodos de simulación numérica y optimización para avanzar la aplicación de la tecnología TES en los sectores residenciales e industriales.
A substantial amount of energy is used in building and industry sectors for heating and cooling purposes. Thermal energy storage (TES) materials can offer important short-term and long-term energy, economic, and comfort benefits to residential, commercial, and industrial buildings. TES materials have the potential to reduce the cooling and peak electricity demands in building and industry sectors, however, in order to properly implement this technology to maximize the economic benefits, numerical simulation and optimization techniques are necessary. The significant original contribution emerges from the present thesis is the use of numerical simulation and optimization methods to advance the application of TES technology in the industrial and building sector. To achieve this, a review will be presented regarding the use of whole-building energy simulation tools to analyse buildings passively enhanced with TES materials.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Raud, Ralf. « Optimized salt selection for solar thermal latent heat energy storage ». Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/116429/1/Ralf_Raud_Thesis.pdf.

Texte intégral

Résumé :

This thesis contributes to the state of the art of Concentrating Solar Thermal by rigorously examining the selection process for the thermal storage medium. An optimized process is developed and then applied to the local constraints to optimize the technoeconomic performance of the storage media for the ongoing Australian Solar Thermal Research Initiative.

Styles APA, Harvard, Vancouver, ISO, etc.

15

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Ferrer, Muñoz Gerard. « Characterization, equation formulation and enhancement of phase change materials (PCM) for thermal energy storage (TES) ». Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/399901.

Texte intégral

Résumé :

L’edificació, la indústria i el transport són els tres principals sectors consumidors d’energia, representant el 96 % de l’energia final consumida a la Unió Europea, i essent responsable de gairebé la totalitat de les emissions de CO2. El programa Horizon 2020 de la Comissió Europea expressa la necessitat de reduir el consum d’energia i les emissions d’efecte hivernacle en un 20 % per l’any 2020. L’emmagatzematge d’energia és un dels principals camps considerats i desenvolupats per reduir les emissions, doncs permet emparellar la demanda i el subministrament d’energia amb sistemes simples i eficients. Els sistemes d’emmagatzematge d’energia tèrmica (TES) permeten emmagatzemar densitats d’energia elevades per poder variar la demanda d’energia i facilitat l’ús d’energia renovables. Aquesta tesi està principalment enfocada en l’emmagatzematge de calor latent, una tecnologia què, tot i que ha estat àmpliament estudiada, encara necessita millores i presenta buits importants.
La edificación, la industria i el transporte son los tres principales sectores consumidores de energía, representando el 96 % de la energía total consumida en la Unión Europea, y siendo responsables de casi la totalidad de las emisiones de CO2. El programa Horizon 2020 de la Comisión Europea expresa la necesidad de reducir el consuma de energía i las emisiones de efecto invernadero en un 20 % para el año 2020. El almacenaje de energía es uno de los principales campos considerados y desarrollados para reducir las emisiones, pues permite emparejar la demanda y el subministro de energía con sistemas simples y eficientes.Los sistemas de almacenaje de energía térmica (TES) permiten almacenar densidades de energía elevadas para poder variar la demanda de energía y facilitar el uso de energías renovables. Esta tesis está principalmente enfocada en el almacenaje de calor latente, una tecnología que, aunque ha sido ampliamente estudiada, aún necesita mejoras y presenta vacíos importantes.
Buildings, industry and transport are the three main energy consuming sectors, representing the 96 % of the final energy consumption in the European Union, and being responsible of almost the totality of the CO2 emissions. The horizon 2020 program of the European Commission expresses the need to reduce by 20 % the energy consumption and greenhouse emissions by the year 2020Energy storage is one of the main fields considered and developed to reduce emissions, allowing to match energy demand and supply with simple and efficient systems.Thermal energy storage (TES) systems allow the storage of high energy densities in order to shift the energy demand and ease the use of renewable energies. This thesis is mainly focused in latent energy storage, a technology that despite having been widely studied, still requires improvements and presents important gaps.

Styles APA, Harvard, Vancouver, ISO, etc.

17

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

18

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

19

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Hinke, Themba D. « Hot thermal storage in a variable power, renewable energy system ». Thesis, Monterey, California : Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42645.

Texte intégral

Résumé :

Approved for public release; distribution is unlimited
This thesis outlines the design of a renewable energy heat generation system with thermal storage for DOD facilities. The DOD is seeking to implement an increased percentage of renewable energy systems at its facilities in order to improve energy security and reduce energy costs. The intermittent nature of renewable energy generation, however, presents a major challenge to full implementation. This shortfall can be overcome by targeted facility-scale energy storage that allows for increased use of renewable-only systems. Since a large percentage of the electric energy used in both residential and commercial facilities is for space and water heating, thermal storage is a viable solution. Presented in this thesis is a method for designing, analyzing, and sizing a facility-scale thermal storage system. The results demonstrate thermal storage is a more cost-effective option when compared to alternatives like battery storage. In addition to being cheaper, thermal storage systems are safer, more reliable, and have a longer life cycle.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Maidadi, Mohaman Bello. « Packed-bed rock thermal energy storage for concetrated solar power : enhancement of storage time and system efficiency ». Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020914.

Texte intégral

Résumé :

Solar thermal energy harvesting is a promising solution to offset the electricity demands of a growing population. The use of the technology is however still limited and this can most likely be attributed to the capital cost and also the intermittent nature of solar energy which requires incorporation of a storage system. To make the technology more attractive and effective, cheap means of harvesting solar energy and the development of efficient and inexpensive thermal energy storage devices will improve the performance of solar energy systems and the widespread use of solar energy. Heat storage in a packed-bed rock with air as the working fluid presents an attractive and simple solution for storing solar thermal energy and it is recommended for solar air heaters. A packed-bed rock storage system consists of rocks of good heat capacity packed in a storage tank. The working fluid (air) flows through the bed to transfer its energy. The major concern of the design for a packed-bed rock thermal storage system is to maximize the heat transfer and minimise the pressure drop across the storage tank and hence the pumping power. The time duration the stored energy can be preserved and the air flow wall effect through the bed are the common complications encountered in this system. This study presents an experimental and analytical analysis of a vacuum storage tank with the use of expanded perlite for high temperature thermal energy storage in a packed-bed of rocks. Dolerite rocks are used as the storage medium due to their high heat capacity and as they are locally available. To minimise the pressure drop across the tank, moderate rock sizes are used. The tank contains baffles, allowing an even spread of air to rock contact through the entire tank, therefore improving heat transfer. There is a good correlation between the predicted and the actual results (4 percent) which implies that the baffles incorporated inside the vacuum tank forces the air through the entire tank, thereby resulting in an even lateral temperature distribution across the tank. The investigation of heat loss showed that a vacuum with expanded perlite is a viable solution to high temperature heat storage for an extended period. The research also focuses on the investigation of a proposed low cost parabolic trough solar collector for an air heating system as shown in Figure (1.3). The use of a standard solar geyser evacuated tube (@R130 each) has cost benefits over the industry standard solar tubes normally used in concentrating solar power systems. A mathematical was developed to predict the thermal performance of proposed PTC and it was found that the measured results compared well with the predictions. The solar energy conversion efficiency of this collector is up to 70 percent. This research could impact positively on remote rural communities by providing a source of clean energy, especially for off-grid applications for schools, clinics and communication equipment. It could lead to a significant improvement in the cost performance, ease of installation and technical performance of storage systems for solar heating applications.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Niaparast, Shervin. « ENERGY ANALYSIS OF A SOLAR BLIND CONCEPT INTEGRATED WITH ENERGY STORAGE SYSTEM ». Thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131419.

Texte intégral

Résumé :

The use of an attached sunspace is one of the most popular passive solar heating techniques. One of the main drawbacks of the sunspace is getting over heated by the sun energy during the hot season of the year. Even in northern climates overheating could be problematic and there is a considerable cooling demand. Shading is one of the most efficient and cost effective strategies to avoid overheating due to the high irradiation especially in the summer. Another strategy is using ventilation system to remove the excess heat inside the sunspace. However this rejected energy can be captured and stored for future energy demands of the sunspace itself or nearby buildings. Therefore the Solar blind system has been considered here for the shielding purpose in order to reduce the cooling demand. By considering the PV/T panels as the solar blind, the blocked solar energy will be collected and stored for covering part of the heating demand and the domestic hot water supplies of the adjacent building. From a modeling point of view, the sunspace can be considered as a small-scale closed greenhouse. In the closed greenhouse concept, available excess heat is indeed utilized in order to supply the heating demand of the greenhouse itself as well as neighboring buildings. The energy captured by PV/T collectors and the excess heat from the sunspace then will be stored in a thermal energy storage system to cover the daily and seasonal energy demand of the attached building. In the present study, a residential building with an attached sunspace with height, length and width of 3, 12 and 3.5 meters respectively has been assumed located in two different locations, Stockholm and Rome. Simulations have been run for the Solar blind system integrated with a short-term and a long-term TES systems during a year to investigate the influence of the sunspace equipped with a PV/T Solar blind on the thermal behavior of the adjacent building. The simulated results show that the Solar blind system can be an appropriate and effective solution for avoiding overheating problems in sunspace and simultaneously produce and store significant amount of thermal energy and electricity power which leads to saving considerable amount of money during a year.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Zhou, Zexing. « Engineering design of thermochemical energy storage system to provide hot water suitable for membrane distillation operation ». Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/208079/1/Zexing_Zhou_Thesis.pdf.

Texte intégral

Résumé :

This thesis used Computational Fluid Dynamic Software Ansys Fluent to evaluate the design of a Zeolite 13X based Thermochemical Energy Storage System. The system is designed to provide constant hot water supply during night-time for a solar Membrane Distillation (MD) system. It overcomes the intermittent nature of solar energy to provide a sustainable energy solution for mining water treatment in Australia. The utilization of CFD also proposed a method to predict the performance of a designed TES which estimated the critical configurations such as optimal charging/discharging flow rate, temperature, relative humidity, and pipe arrangement configuration, etc.

Styles APA, Harvard, Vancouver, ISO, etc.

24

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Xiang, Yetao. « Experimental and computational investigation of building integrated PV thermal air system combined with thermal storage ». Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42743/.

Texte intégral

Résumé :

Issues from global warming with increased CO2 emissions have been to a main concern over world. As an example in the UK, the energy demand in the domestic sector has risen by 17% in 2010 compared with that of 1970. Applying renewable energy is widely agreed to be the most effective and promising way to solve the problem where solar energy and photovoltaic technology have been greatly developing from the last century. Photovoltaic combines with Phase Change Material (PV/PCM) system is a hybrid solar system which uses phase change material to reduce the PV temperature and to store energy for other applications. This thesis aims to investigate the performance of a designed building integrated photovoltaic thermal system (BIPVT) with PCM as thermal storage for building applications. The research objectives are to increase the building integrated photovoltaic (BIPV) efficiency by incorporating PCM while utilising the stored heat in PCM for controlling indoor conditions and reduce the total building energy consumption. The research starts with solar energy convection technologies including solar thermal and solar photovoltaic. Then a combined technology named photovoltaic thermal system (PVT) was introduced and discussed. Research work on a different type of PVT using water and air as thermal energy medium was further reviewed and discussed. An analytical approach investigation was presented on a PVT system and the results were used to design the experiment work on PV/PCM configuration. Experiments have been carried out on a prototype PV/PCM air system using monocrystalline photovoltaic modules. Transient simulations of the system performance have also been performed using a commercial computational fluid dynamics (CFD) package based on the finite volume method. The results from simulation were validated by comparing with experimental results. The results indicated that PCM is effective in limiting temperature rise in PV device and the heat from PCM can enhance night ventilation and decrease the building energy consumption to achieve indoor thermal comfort for certain periods of time. An entire building energy simulation with designed PV/PCM air system was also carried out under real weather condition of Nottingham, UK and Shanghai, China. The result also shows a market potential of PV/PCM system and a payback time of 11 years in the UK condition if using electrical heater.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Tabassum, Tonny. « A numerical study of a double pipe latent heat thermal energy storage system ». Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=87015.

Texte intégral

Résumé :

Solar energy is an intermittent supply source of energy. To efficiently utilize this free renewable energy source some form of thermal energy storage devices are necessary. Phase change materials (PCMs), because of their high energy density storage capacity and near isothermal phase change characteristics, have proven to be promising candidates for latent heat thermal energy storage (LHTES) devices. Among the various LHTES devices for low temperature residential heating and cooling applications, the shell-and-tube type heat exchanging devices are the most simple to operate and can be easily fabricated. This work numerically investigates the buoyancy driven heat transfer process during melting (charging) of a commercial paraffin wax as PCM filling the annulus of a horizontal double pipe heat exchanger. The heated working fluid (water) is passing through the central tube of the annulus at a sufficiently high flow-rate and thereby maintaining an almost isothermal wall temperature at the inner pipe which is higher than the melting temperature of the PCM. The transient, two-dimensional coupled laminar momentum and energy equations for the model are suitably non-dimensionalized and are solved numerically using the enthalpy-porosity approach. Time-wise evolutions of the flow patterns and temperature distributions are presented through velocity vector fields and isotherm plots. In this study, two types of PCM filled annuli, a plain annulus and a strategically placed longitudinal finned annulus, are studied. The total energy stored, the total liquid fraction and the energy efficiency at different melting times are evaluated for three different operating conditions and the results are compared between the plain and finned annuli. The present study will provide guidelines for system thermal performance and design optimization of the shell-and-tube LHTES devices.
L'énergie solaire est une source d'alimentation d'énergie intermittente. Pour utiliser efficacement cette source gratuite d'énergie renouvelable, une certaine forme de dispositifs de stockage d'énergie thermique est nécessaire. Les matériaux à changement de phase (PCMs) en raison de leur capacité d'énergie à haute densité de stockage et les caractéristiques quasi isothermes de changement de phase se sont révélés être des candidats prometteurs pour les dispositifs de stockage de la chaleur latente de l'énergie thermique (LHTES). Parmi les différents dispositifs LHTES pour le chauffage résidentiel à basse température et les utilisations possibles comme refroidissant, les dispositifs d'échange de chaleur du type à tubes et calandre et les dispositifs de type à tubes sont les plus simples à faire fonctionner et peuvent être facilement fabriqués. Ce travail étudie numériquement le processus de flottabilité piloté par le transfert de chaleur lors de la fusion (stockage de la chaleur) d'une cire de paraffine commerciale utilisée comme PCM remplissant l'espace annulaire d'un échangeur de chaleur horizontal à double conduit. Le fluide chauffé (de l'eau) faisant action passe par le conduit central de l'espace annulaire à un débit suffisamment élevé et maintient ainsi une température quasi isotherme de la paroi du conduit intérieur qui est supérieure à la température de fusion du PCM. La dynamique laminaire couplée à deux dimensions et les équations énergétiques transitoires du modèle sont convenablement dédimensionnées et sont résolues numériquement en utilisant l'approche enthalpie-porosité. Les évolutions selon le facteur temps des modèles d'écoulement et des distributions de température sont présentées par des champs vectoriels de vitesse et des courbes isothermiques. Dans cette étude, deux types d'espaces annulaires remplis de PCM, un espace annulaire simple et un espace annulaire longitudinal à ailettes s

Styles APA, Harvard, Vancouver, ISO, etc.

27

Garay, Rosas Ludwin. « System Simulation of Thermal Energy Storage involved Energy Transfer model in Utilizing Waste heat in District Heating system Application ». Thesis, KTH, Kraft- och värmeteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-161726.

Texte intégral

Résumé :

Nowadays continuous increase of energy consumption increases the importance of replacing fossil fuels with renewable energy sources so the CO2 emissions can be reduced. To use the energy in a more efficient way is also favorable for this purpose. Thermal Energy Storage (TES) is a technology that can make use of waste heat, which means that it can help energy systems to reduce the CO2 emissions and improve the overall efficiency. In this technology an appropriate material is chosen to store the thermal energy so it can be stored for later use. The energy can be stored as sensible heat and latent heat. To achieve a high energy storage density it is convenient to use latent heat based TES. The materials used in this kind of storage system are called Phase Change Materials (PCM) and it is its ability of absorbing and releasing thermal energy during the phase change process that becomes very useful. In this thesis a simulation model for a system of thermal energy transportation has been developed. The background comes from district heating systems ability of using surplus heat from industrials and large scale power plants. The idea is to implement transportation of heat by trucks closer to the demand instead of distributing heat through very long pipes. The heat is then charged into containers that are integrated with PCM and heat exchangers. A mathematical model has been created in Matlab to simulate the system dynamics of the logistics of the thermal energy transport system. The model considers three main parameters: percentage content of PCM in the containers, annual heat demand and transport distance. How the system is affected when these three parameters varies is important to visualize. The simulation model is very useful for investigation of the economic and environmental capability of the proposed thermal energy transportation system. Simulations for different scenarios show some expected results. But there are also some findings that are more interesting, for instance how the variation of content of PCM gives irregular variation of how many truck the system requires, and its impact on the economic aspect. Results also show that cost for transporting the heat per unit of thermal energy can be much high for a small demands compared to larger demands.

Styles APA, Harvard, Vancouver, ISO, etc.

28

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Wong, Kin-chuen, et 黃健全. « Optimization of building cooling system based on genetic algorithms and thermal energy storage ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B45701416.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

30

Kota, Krishna. « DESIGN AND EXPERIMENTAL STUDY OF AN INTEGRATED VAPOR CHAMBER – THERMAL ENERGY STORAGE SYSTEM ». Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2816.

Texte intégral

Résumé :

Future defense, aerospace and automotive technologies involve electronic systems that release high pulsed waste heat like during high power microwave and laser diode applications in tactical and combat aircraft, and electrical and electronic systems in hybrid electric vehicles, which will require the development of an efficient thermal management system. A key design issue is the need for fast charging so as not to overheat the key components. The goal of this work is to study the fabrication and technology implementation feasibility of a novel high energy storage, high heat flux passive heat sink. Key focus is to verify by theory and experiments, the practicability of using phase change materials as a temporary storage of waste heat for heat sink applications. The reason for storing the high heat fluxes temporarily is to be able to reject the heat at the average level when the heat source is off. Accordingly, a concept of a dual latent heat sink intended for moderate to low thermal duty cycle electronic heat sink applications is presented. This heat sink design combines the features of a vapor chamber with rapid thermal energy storage employing graphite foam inside the heat storage facility along with phase change materials and is attractive owing to its passive operation unlike some of the current thermal management techniques for cooling of electronics employing forced air circulation or external heat exchangers. In addition to the concept, end-application dependent criteria to select an optimized design for this dual latent heat sink are presented. A thermal resistance concept based design tool/model has been developed to analyze and optimize the design for experiments. The model showed that it is possible to have a dual latent heat sink design capable of handling 7 MJ of thermal load at a heat flux of 500 W/cm2 (over an area of 100 cm2) with a volume of 0.072 m3 and weighing about 57.5 kg. It was also found that with such high heat flux absorption capability, the proposed conceptual design could have a vapor-to-condenser temperature difference of less than 10 0C with a volume storage density of 97 MJ/m3 and a mass storage density of 0.122 MJ/kg. The effectiveness of this heat sink depends on the rapidness of the heat storage facility in the design during the pulse heat generation period of the duty cycle. Heat storage in this heat sink involves transient simultaneous laminar film condensation of vapor and melting of an encapsulated phase change material in graphite foam. Therefore, this conjugate heat transfer problem including the wall inertia effect is numerically analyzed and the effectiveness of the heat storage mechanism of the heat sink is verified. An effective heat capacity formulation is employed for modeling the phase change problem and is solved using finite element method. The results of the developed model showed that the concept is effective in preventing undue temperature rise of the heat source. Experiments are performed to investigate the fabrication and implementation feasibility and heat transfer performance for validating the objectives of the design i.e., to show that the VCTES heat sink is practicable and using PCM helps in arresting the vapor temperature rise in the heat sink. For this purpose, a prototype version of the VCTES heat sink is fabricated and tested for thermal performance. The volume foot-print of the vapor chamber is about 6"X5"X2.5". A custom fabricated thermal energy storage setup is incorporated inside this vapor chamber. A heat flux of 40 W/cm2 is applied at the source as a pulse and convection cooling is used on the condenser surface. Experiments are done with and without using PCM in the thermal energy storage setup. It is found that using PCM as a second latent system in the setup helps in lowering the undue temperature rise of the heat sink system. It is also found that the thermal resistance between the vapor chamber and the thermal energy storage setup, the pool boiling resistance at the heat source in the vapor chamber, the condenser resistance during heat discharging were key parameters that affect the thermal performance. Some suggestions for future improvements in the design to ease its implementation and enhance the heat transfer of this novel heat sink are also presented.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering PhD

Styles APA, Harvard, Vancouver, ISO, etc.

31

Kota, Krishna M. « Design and experimental study of an integrated vapor chamber thermal energy storage system ». Orlando, Fla. : University of Central Florida, 2008. http://purl.fcla.edu/fcla/etd/CFE0002332.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Hallqvist, Karl. « Högtempererat borrhålslager för fjärrvärme ». Thesis, Uppsala universitet, Naturresurser och hållbar utveckling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-231586.

Texte intégral

Résumé :

The district heating load is seasonally dependent, with a low load during periods of high ambient temperature. Thermal energy storage (TES) has the potential to shift heating loads from winter to summer, thus reducing cost and environmental impact of District Heat production. In this study, a concept of high temperature borehole thermal energy storage (HT-BTES) together with a pellet heating plant for temperature boost, is presented and evaluated by its technical limitations, its ability to supply heat, its function within the district heating system, as well as its environmental impact and economic viability in Gothenburg, Sweden, a city with access to high quantities of waste heat. The concept has proven potentially environmentally friendly and potentially profitable if its design is balanced to achieve a good enough supply temperature from the HT-BTES. The size of the heat storage, the distance between boreholes and low borehole thermal resistance are key parameters to achieve high temperature. Profitability increases if a location with lower temperature demand, as well as risk of future shortage of supply, can be met. Feasibility also increases if existing pellet heating plant and district heating connection can be used and if lower rate of return on investment can be accepted. Access to HT-BTES in the district heating network enables greater flexibility and availability of production of District Heating, thereby facilitating readjustments to different strategies and policies. However, concerns for the durability of feasible borehole heat exchangers (BHE) exist in high temperature application.
Värmebehovet är starkt säsongsberoende, med låg last under perioder av högre omgivningstemperatur och hög last under perioder av lägre omgivningstemperaturer. I Göteborg finns en stor mängd spillvärme tillgängligt för fjärrvärmeproduktion sommartid när behovet av värme är lågt. Tillgång till säsongsvärmelager möjliggör att fjärrvärmeproduktion flyttas från vinterhalvår till sommarhalvår, vilket kan ge såväl lönsamhet som miljönytta. Borrhålsvärmelager är ett förhållandevis billigt sätt att lagra värme, och innebär att berggrunden värms upp under sommaren genom att varmt vatten flödar i borrhål, för att under vinterhalvåret användas genom att låta kallt vatten flöda i borrhålen och värmas upp. I traditionella borrhålsvärmelager används ofta värmepump för att höja värmelagrets urladdade temperatur, men på grund av höga temperaturkrav för fjärrvärme kan kostnaden för värmepump bli hög. I denna rapport föreslås ett system för att klara av att nå höga temperaturer till en lägre kostnad. Systemet består av ett borrhålsvärmelager anpassat för högre temperaturer (HT-BTES) samt pelletspannor för att spetsa lagrets utgående fluid för att nå hög temperatur. Syftet med rapporten är att undersöka potentialen för detta HT-BTES-system med avseende på dess tekniska begränsningar, förmåga till fjärrvärmeleverans, konsekvenser för fjärrvärmesystemet, samt lönsamhet och miljöpåverkan. För att garantera att inlagringen av värme inte är så stor att priset för inlagrad värme ökar väsentligt, utgår inlagringen från hur mycket värme som kyls bort i fjärrvärmenätet sommartid. I verkligheten finns betydligt mer värme tillgänglig till låg kostnad. När HT-BTES-systemet producerar fjärrvärme, ersätts fjärrvärmeproduktion från andra produktionsenheter, förutsatt att HT-BTES-systemets rörliga kostnader är lägre. I Göteborg ersätts främst naturgas från kraftvärme, men också en del flis. Kostnadsbesparingen beror på differensen för total fjärrvärmeproduktionskostnad med och utan HT-BTES-systemet. Undersökningen visar att besparingen är större om HT-BTES-systemet placeras i ett område där det är möjligt att mata ut fjärrvärme med lägre temperatur. Om urladdning från HT-BTES kan ske med hög temperatur ökar också besparingen. Detta sker om lagrets volym ökar, om avståndet mellan borrhål minskar eller om värmeöverföringen mellan det flödande vattnet i borrhålen och berggrunden ökar. Dessa egenskaper för lagret leder också till minskade koldioxidutsläpp. Storleken på besparingen beror dock i hög grad på hur bränslepriser utvecklas i framtiden. Strategiska fördelar med HT-BTES-systemet inkluderar; minskad miljöpåverkan, robust system med lång teknisk livslängd (för delar av HT-BTES-systemet), samt att inlagring av värme kan ske från många olika produktionsenheter. Dessutom kan positiva bieffekter identifieras. Undersökningen visar att HT-BTES-systemet har god potential att ge lönsamhet och minskad miljöpåverkan, och att anläggning och drift av lagret kan ske utan omfattande lokal miljöpåverkan. Det har också visats att de geologiska förutsättningarna för HT-BTES är goda på många platser i Göteborg, även om lokala förhållanden kan skilja sig åt. För att nå lönsamhet för HT-BTES-systemet krävs en avvägning på utformning av lagret för att nå hög urladdad temperatur utan att investeringskostnaden blir för stor. Undersökningen visar att om anslutning av HT-BTES-systemet kan ske mot befintlig anslutningspunkt eller till befintlig värmepanna kan investeringskostnaden minska och därmed lönsamheten öka. Placering av HT-BTES-systemet i områden med risk för överföringsbegränsningar kan också minska behovet av att förstärka fjärrvärmenätet, och således bidra till att minska de kostnader som förstärkning av nätet innebär. Betydelsefulla parametrar för att nå lönsamhet för HT-BTES-system inkluderar dessutom kostnaden för inlagrad värme liksom vilket vinstkrav som kan accepteras. Tillgång till HT-BTES möjliggör ökad nyttjandegrad och flexibilitet för fjärrvärmeproduktionsenheter, och därmed ökad anpassningsmöjlighet till förändrade förutsättningar på värmemarknaden. Dock återstår att visa att komponenter som klarar de höga temperaturkraven kan tillverkas till acceptabel kostnad.

Styles APA, Harvard, Vancouver, ISO, etc.

33

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Naser, Mohammad Yousef Mousa. « Computer Modeling of Solar Thermal System with Underground Storage Tank for Space Heating ». Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1620875130064807.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Lindberg, Fanny. « Performance Improvement from Single to Multi Latent Thermal Energy Storage System combined Water Heater ». Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170897.

Texte intégral

Résumé :

In numerous energy systems there are discrepancies between the energy supply and demand. One such system is domestic water heater. The hot water heater is a sensible heat storage where the thermal energy is stored through change in temperature. The sensible heat storage has the disadvantage of high losses and low energy density. An alternative to the sensible heat storage is the latent heat storage. The latent heat storage stores energy through phase change and exhibits high energy density. This method of storing energy is consequently more compact. Furthermore the latent heat storage can be charged during off peak hour and discharged when peaks arise at almost constant temperature level. A material that is commonly used in latent heat storages is phase change material (PCM). These have refined properties for the purpose of storing energy at phase changes. The aim of the study in this report was to present a theoretical solution for a PCM thermal energy storage (TES) combined water heater for domestic water use in single-family households. This was done through a model in COMSOL Multiphysics analysing a PCM TES heat exchanger. The study moreover aimed to compare and evaluate various authentic PCM TES whit respect to numbers of PCMs and their phase change temperature. The focus laid on comparing single PCM TES to multi PCM TES. A PCM TES was to be suggested for the system defined A numerical simulation was performed from a previously built model. A user profile of hot water in single-family households was derived from the Swedish Energy Agency. The profile was divided up into two main areas, off peak and on peak. During off peak the PCM TES was melted and thereby charged and during the peak the PCM was solidified, discharged. Four cases for charging and discharging was studied. Two of each case had the properties of multi PCM TES and two of single PCM TES. Furthermore, two of the cases had PCMs with phase change temperatures in the range of 42-60°C and the other two in the range of 35-55°C. The result of the study shows that a multi PCM TES with a high phase change temperature was preferable for the application studied. The capacity and power rate performance improvement from single to multi PCM TES during the discharging cycle reached up to 1,44% and 8,62% respectively.
I flera energisystem finns skillnader mellan utbud och efterfrågan på energi. Ett sådant system är varmvattenberedaren. Varmvattenberedaren är en sensibel värmelagring där värmeenergi lagras genom temperaturförändring i mediet. Två nackdelar med den sensibla värmelagringen är höga energiförluster och låg energitäthet i mediet. Ett alternativ till den sensibla värmelagringen är den latenta. Den latenta värmelagringen lagrar energi genom en fasändring i mediet och har hög energitäthet. Denna metod för att lagra energi är följaktligen mer kompakt. Dessutom har den latenta värmelagringen goda egenskaper för att laddas upp vid låg användning och laddas ur, dvs. konsumeras, när användningen är högre vid nästan konstant temperaturnivå. Ett material som vanligen används vid latent värmelagring är Phase Change Material (PCM). Dessa har förfinade egenskaper i syfte att lagra energi vid fasändringar. Syftet med studien i denna rapport var att presentera en teoretisk lösning för en PCM Thermal Energy Storage (TES) kombinerad varmvattenberedare för hushållsvattenanvändning i enskilda hushåll. Detta gjordes genom modellering COMSOL Multiphysics där en PCM TES värmeväxlare analyserades. Studien syftade dessutom till att jämföra och utvärdera olika autentiska PCM TES med fokus på antalet PCM och deras fasändringstemperatur. Fokus lades på att jämföra en-PCM TES med två-PCM TES. Syftet var vidare att rekommendera en PCM TES för det definierade systemet utifrån studien. En numerisk simulering utfördes från en tidigare byggd modell. En användarprofil för varmvattenanvändning i enskilda hushåll fastställd från Energimyndigheten användes som grund i arbetet. Profilen delades upp i två huvudområden, låganvändning och höganvändning. Under låganvändning smältes PCM och laddades därmed upp och under höganvändning stelnades PCM och laddades därmed ur. Fyra fall för laddning och urladdning studerades. Två av varje fall hade egenskaperna av två-PCM TES och de andra två av en-PCM TES. Vidare hade två av fallen PCMer med fasändringstemperatur i området av 42 till 60° C och de andra två i området av 35 till 55° C. Resultatet av studien visar att en multi PCM TES med hög fasomvandlingstemperatur var att föredra för den studerade applikationen. Kapacitetens och effektens prestandaförbättring från en- till två PCM TES under urladdningscykeln nådde upp till 1,44% respektive 8,62%.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Williams, Daniel David. « Cold side thermal energy storage system for improved operation of air cooled power plants ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78194.

Texte intégral

Résumé :

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 81-82).
Air cooled power plants experience significant performance fluctuations as plant cooling capacity reduces due to higher daytime temperature than nighttime temperature. The purpose of this thesis is to simulate the detailed operation of a cold side thermal energy storage system in order to evaluate its potential. An organic Rankine cycle geothermal power station is used as an example application. Detailed sizing and operation considerations are discussed. Several representative case studies compare the performance of candidate configurations. Operation of the selected configuration is then simulated for a full year and a proposed integration of the system with existing plant hardware is laid out. A correlation between weather trends and production is outlined. Finally an economic cost/benefit analysis performed to determine the payback period for implementing the proposed system. The cold side TES system is shown to shift substantial power generation capability from nighttime to daytime when electrical demand is highest, especially during hot summer months. For example, daily energy production is shown to increase by up to 18% under particularly favorable conditions. This redistribution of the power generation curve is accomplished with less than a 5% reduction in overall annual energy production in Mega-Watt hours. The system is shown to be more effective at shifting power generation capacity during warmer months than cooler months. The reduced day to night temperature fluctuation during cooler months results in a reduced thermal storage benefit under similar parasitic loads. The economic benefits of this system are dependent upon the on-peak vs off-peak electricity prices. Economic analysis using 2011 transient price data from the U.S. Midwest Region results in a small increase in annual income. The increased income from the proposed cold side TES system is found to be insufficient to outweigh the required capital investment at current electricity prices.
by Daniel David Williams.
S.M.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Fanny, Lindberg. « Performance Improvement from Single to Multi Latent Thermal Energy Storage System combined Water Heater ». Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175329.

Texte intégral

Résumé :

In numerous energy systems there are discrepancies between the energy supply and demand. One such system is domestic water heater. The hot water heater is a sensible heat storage where the thermal energy is stored through change in temperature. The sensible heat storage has the disadvantage of high losses and low energy density. An alternative to the sensible heat storage is the latent heat storage. The latent heat storage stores energy through phase change and exhibits high energy density. This method of storing energy is consequently more compact. Furthermore the latent heat storage can be charged during off peak hour and discharged when peaks arise at almost constant temperature level. A material that is commonly used in latent heat storages is phase change material (PCM). These have refined properties for the purpose of storing energy at phase changes. The aim of the study in this report was to present a theoretical solution for a PCM thermal energy storage (TES) combined water heater for domestic water use in single-family households. This was done through a model in COMSOL Multiphysics analysing a PCM TES heat exchanger. The study moreover aimed to compare and evaluate various authentic PCM TES whit respect to numbers of PCMs and their phase change temperature. The focus laid on comparing single PCM TES to multi PCM TES. A PCM TES was to be suggested for the system defined A numerical simulation was performed from a previously built model. A user profile of hot water in single-family households was derived from the Swedish Energy Agency. The profile was divided up into two main areas, off peak and on peak. During off peak the PCM TES was melted and thereby charged and during the peak the PCM was solidified, discharged. Four cases for charging and discharging was studied. Two of each case had the properties of multi PCM TES and two of single PCM TES. Furthermore, two of the cases had PCMs with phase change temperatures in the range of 42-60°C and the other two in the range of 35-55°C. The result of the study shows that a multi PCM TES with a high phase change temperature was preferable for the application studied. The capacity and power rate performance improvement from single to multi PCM TES during the discharging cycle reached up to 1,44% and 8,62% respectively.
I flera energisystem finns skillnader mellan utbud och efterfrågan på energi. Ett sådant system är varmvattenberedaren. Varmvattenberedaren är en sensibel värmelagring där värmeenergi lagras genom temperaturförändring i mediet. Två nackdelar med den sensibla värmelagringen är höga energiförluster och låg energitäthet i mediet. Ett alternativ till den sensibla värmelagringen är den latenta. Den latenta värmelagringen lagrar energi genom en fasändring i mediet och har hög energitäthet. Denna metod för att lagra energi är följaktligen mer kompakt. Dessutom har den latenta värmelagringen goda egenskaper för att laddas upp vid låg användning och laddas ur, dvs. konsumeras, när användningen är högre vid nästan konstant temperaturnivå. Ett material som vanligen används vid latent värmelagring är Phase Change Material (PCM). Dessa har förfinade egenskaper i syfte att lagra energi vid fasändringar. Syftet med studien i denna rapport var att presentera en teoretisk lösning för en PCM Thermal Energy Storage (TES) kombinerad varmvattenberedare för hushållsvattenanvändning i enskilda hushåll. Detta gjordes genom modellering COMSOL Multiphysics där en PCM TES värmeväxlare analyserades. Studien syftade dessutom till att jämföra och utvärdera olika autentiska PCM TES med fokus på antalet PCM och deras fasändringstemperatur. Fokus lades på att jämföra en-PCM TES med två-PCM TES. Syftet var vidare att rekommendera en PCM TES för det definierade systemet utifrån studien. En numerisk simulering utfördes från en tidigare byggd modell. En användarprofil för varmvattenanvändning i enskilda hushåll fastställd från Energimyndigheten användes som grund i arbetet. Profilen delades upp i två huvudområden, låganvändning och höganvändning. Under låganvändning smältes PCM och laddades därmed upp och under höganvändning stelnades PCM och laddades därmed ur. Fyra fall för laddning och urladdning studerades. Två av varje fall hade egenskaperna av två-PCM TES och de andra två av en-PCM TES. Vidare hade två av fallen PCMer med fasändringstemperatur i området av 42 till 60° C och de andra två i området av 35 till 55° C. Resultatet av studien visar att en multi PCM TES med hög fasomvandlingstemperatur var att föredra för den studerade applikationen. Kapacitetens och effektens prestandaförbättring från en- till två PCM TES under urladdningscykeln nådde upp till 1,44% respektive 8,62%.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Louw, Andre Du Randt. « Discrete and porous computational fluid dynamics modelling of an air-rock bed thermal energy storage system ». Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86233.

Texte intégral

Résumé :

Thesis (MScEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Concentrating solar power promises to be a potential solution for meeting the worlds energy needs in the future. One of the key features of this type of renewable energy technology is its ability to store energy effectively and relatively cheaply. An air-rock bed thermal energy storage system promises to be an effective and reasonably inexpensive storage system for concentrating solar power plants. Currently there is no such storage system commercially in operation in any concentrating solar power plant, and further research is required before such a system can be implemented. The main research areas to address are the thermal-mechanical behaviour of rocks, rock bed pressure drop correlations and effective and practical system designs. Recent studies have shown that the pressure drop over a packed bed of rocks is dependant on various aspects such as particle orientation relative to the flow direction, particle shape and surface roughness. The irregularity and unpredictability of the particle shapes make it difficult to formulate a general pressure drop correlation. Typical air-rock bed thermal design concepts consist of a large vertical square or cylindrical vessel in which the bed is contained. Such system designs are simple but susceptible to the ratcheting effect and large pressure drops. Several authors have proposed concepts to over-come these issues, but there remains a need for tools to prove the feasibility of the designs. The purpose of this paper is to investigate aDEM-CFD coupled approach that can aid the development of an air-rock bed thermal energy storage system. This study specifically focuses on the use of CFD. A complementary study focusses on DEM. The two areas of focus in this study are the pressure drop and system design. A discrete CFD simulation model is used to predict pressure drop over packed beds containing spherical and irregular particles. DEM is used to create randomly packed beds containing either spherical or irregularly shaped particles. This model is also used to determine the heat transfer between the fluid and particle surface. A porous CFD model is used to model system design concepts. Pressure drop and heat transfer data predicted by the discrete model, is used in the porous model to describe the pressure drop and thermal behaviour of a TES system. Results from the discrete CFD model shows that it can accurately predict the pressure drop over a packed bed of spheres with an average deviation of roughly 10%fromresults found in literature. The heat transfer between the fluid and particle surface also is accurately predicted, with an average deviation of between 13.36 % and 21.83 % from results found in literature. The discrete CFD model for packed beds containing irregular particles presented problems when generating a mesh for the CFD computational domain. The clump logic method was used to represent rock particles in this study. This method was proven by other studies to accurately model the rock particle and the rock packed bed structure using DEM. However, this technique presented problems when generating the surface mesh. As a result a simplified clump model was used to represent the rock particles. This simplified clump model showed characteristics of a packed bed of rocks in terms of pressure drop and heat transfer. However, the results suggest that the particles failed to represent formdrag. This was attributed to absence of blunt surfaces and sharp edges of the simplified clumpmodel normally found on rock particles. The irregular particles presented in this study proved to be inadequate for modelling universal characteristics of a packed bed of rocks in terms of pressure drop. The porous CFD model was validated against experimental measurement to predict the thermal behaviour of rock beds. The application of the porous model demonstrated that it is a useful design tool for system design concepts.
AFRIKAANSE OPSOMMING: Gekonsentreerde sonkrag beloof om ’n potensiële toekomstige oplossing te wees vir die wêreld se groeiende energie behoeftes. Een van die belangrikste eienskappe van hierdie tipe hernubare energie tegnologie is die vermoë om energie doeltreffend en relatief goedkoop te stoor. ’n Lug-klipbed termiese energie stoorstelsel beloof om ’n doeltreffende en redelik goedkoop stoorstelsel vir gekonsentreerde sonkragstasies te wees . Tans is daar geen sodanige stoorstelsel kommersieël in werking in enige gekonsentreerde sonkragstasie nie. Verdere navorsing is nodig voordat so ’n stelsel in werking gestel kan word. Die belangrikste navorsingsgebiede om aan te spreek is die termies-meganiese gedrag van klippe, klipbed drukverlies korrelasies en effektiewe en praktiese stelsel ontwerpe. Onlangse studies het getoon dat die drukverlies oor ’n gepakte bed van klippe afhanklik is van verskeie aspekte soos partikel oriëntasie tot die vloeirigting, partikel vormen oppervlak grofheid. Die onreëlmatigheid en onvoorspelbaarheid van die klip vorms maak dit moeilik om ’n algemene drukverlies korrelasie te formuleer. Tipiese lug-klipbed termiese ontwerp konsepte bestaan uit ’n groot vertikale vierkantige of silindriese houer waarin die gepakte bed is. Sodanige sisteem ontwerpe is eenvoudig, maar vatbaar vir die palrat effek en groot drukverliese. Verskeie studies het voorgestelde konsepte om hierdie kwessies te oorkom, maar daar is steeds ’n behoefte aanmetodes om die haalbaarheid van die ontwerpe te bewys. Die doel van hierdie studie is om ’n Diskreet Element Modelle (DEM) en numeriese vloeidinamika gekoppelde benadering te ontwikkel wat ’n lug-klipbed termiese energie stoorstelsel kan ondersoek. Hierdie studie fokus spesifiek op die gebruik van numeriese vloeidinamika. ’n Aanvullende studie fokus op DEM. Die twee areas van fokus in hierdie studie is die drukverlies en stelsel ontwerp. ’n Diskrete numeriese vloeidinamika simulasie model word gebruik om drukverlies te voorspel oor gepakte beddens met sferiese en onreëlmatige partikels. DEM word gebruik om lukraak gepakte beddens van óf sferiese óf onreëlmatige partikels te skep. Hierdie model is ook gebruik om die hitte-oordrag tussen die vloeistof en partikel oppervlak te bepaal. ’n Poreuse numeriese vloeidinamika model word gebruik omdie stelsel ontwerp konsepte voor te stel. Drukverlies en hitte-oordrag data, voorspel deur die diskrete model, word gebruik in die poreuse model om die drukverlies- en hittegedrag van ’n TES-stelsel te beskryf. Resultate van die diskrete numeriese vloeidinamikamodel toon dat dit akkuraat die drukverlies oor ’n gepakte bed van sfere kan voorspel met ’n gemiddelde afwyking van ongeveer 10%van die resultatewat in die literatuur aangetref word. Die hitte-oordrag tussen die vloeistof en partikel oppervlak is ook akkuraat voorspel, met ’n gemiddelde afwyking van tussen 13.36%en 21.83%van die resultate wat in die literatuur aangetref word. Die diskrete numeriese vloeidinamika model vir gepakte beddens met onreëlmatige partikels bied probleme wanneer ’n maas vir die numeriese vloeidinamika, numeriese domein gegenereer word. Die "clump"logika metode is gebruik om klip partikels te verteenwoordig in hierdie studie. Hierdiemetode is deur ander studies bewys om akkuraat die klip partikel en die klip gepakte bed-struktuur te modelleer deur die gebruik van DEM. Hierdie tegniek het egter probleme gebied toe die oppervlak maas gegenereer is. As gevolg hiervan is ’n vereenvoudigde "clump"model gebruik om die klip partikels te verteenwoordig. Die vereenvoudigde "clump"model vertoon karakteristieke eienskappe van ’n gepakte bed van klippe in terme van drukverlies en hitte oordrag. Die resultate het egter getoon dat die partikels nie vorm weerstand verteenwoordig nie. Hierdie resultate kan toegeskryf word aan die afwesigheid van gladde oppervlaktes en skerp kante, wat normaalweg op klip partikels gevind word, in die vereenvoudigde "clump"model. Die oneweredige partikels wat in hierdie studie voorgestel word, blykomnie geskik tewees vir die modellering van die universele karakteristieke eienskappe van ’n gepakte bed van klippe in terme van drukverlies nie. Die poreuse numeriese vloeidinamika model is met eksperimentele metings bevestig omdie termiese gedrag van klipbeddens te voorspel. Die toepassing van die poreuse model demonstreer dat dit ’n nuttige ontwerp metode is vir stelsel ontwerp konsepte.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Myska, Martin. « Possibilities with Stirling Engine and High Temperature Thermal Energy Storage in Multi-Energy Carrier System : An analysis of key factors influencing techno-economic perspective of Stirling engine and high-temperature thermal energy storage ». Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-53407.

Texte intégral

Résumé :

Small and medium-scale companies are trying to minimise their carbon footprint and improve their cash flow, renewable installations are increasing all over the Europe and are expected to do so in following years. However, their dependency on the weather cause pressure on matching the production with demand. An option how to challenge this problem is by using energy storage. The aim of this project is to determine techno-economic benefits of Stirling engine and high temperature thermal energy storage for installation in energy user system and identify key factors that affect the operation of such system. In order to determine these factors simulations in Matlab were conducted. The Matlab linear programming tool Optisolve using dual-simplex algorithm was used. The sensitivity analysis was conducted to test the energy system behaviour. Economic evaluation was done calculating discounted savings. From the results, it can be seen the significant benefit of SE-HT-TES installation is the increased self-consumption of the electricity from PV installation. While the self-consumption in cases when there was no energy storage implemented was around 67 % and in one case as low as 50 % with the SE-HT-TES the value has increased up to 100 %. Energy cost savings are 4.7 % of the cost for the original data set and go up to 6.2 % when simulation with load shift was executed. Simulations have also shown that energy customer with predictable energy demand pattern can achieve higher savings with the very same system. It was also confirmed that for users whose private renewable production does not match load potential savings are 30 % higher compared to the system where energy load peak is matching the PV production peak. Simulations also shown that the customers located in areas with higher electricity price volatility can benefit from such system greatly.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Olsen, Lindsay M. « Initial investigation of a novel thermal storage concept as part of a renewable energy system ». Monterey, California : Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34716.

Texte intégral

Résumé :

This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.
Approved for public release; distribution is unlimited
This thesis forms part of a larger study that aims to develop a renewable energy demonstration plant at the Naval Postgraduate School Turbopropulsion Laboratory. The architecture and design approach of the demonstration plant is outlined in this thesis. While all the components of the system are commercially available, the integration of the components is challenging. The results of the design approach presented the optimal way of integrating wind turbines, an electrical system, chiller units, and thermal storage tanks. Modular ice thermal tanks with polypropylene tubing were chosen for storage. The ice thermal storage units were selected over battery storage as they are more cost effective and potentially safer. A statistical analysis was performed using wind data from Monterey Airport, which was beneficial for choosing which wind turbines to implement in the system. The analysis determined that total energy captured by two, 4-kW vertical axis wind turbines was 2,554.8 kW-hours annually. Additionally, ANSYS Fluent was used to analyze the ice growth around the tubing at various ice and tube thicknesses. The ANSYS Fluent analysis showed that ice thickness affects the ice volume growth and change in enthalpy change more than wall thickness affects these conditions.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Hampus, Randén. « Performance improvement from single to multi phase change materials in a thermal energy storage system ». Thesis, KTH, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175153.

Texte intégral

Résumé :

Phase change materials are used in many applications to work as thermal energy storage systems. One way to transfer the heat is by letting water flow through a finned pipe submerged in i tank filled with PCMs. This model is analyzed with a finite element difference based numerical software. The power ratio between using single-PCM and multi-PCMs is compared. The hypothesis was that a multi-PCM configuration is more efficient than a single. The results show that a multi-PCM configuration is more efficient than a single-PCM configuration. It however also indicates that it is of great importance to chose the right temperature span of PCM temperatures to achieve as high power performance as possible. This is recommended for further studies.
Fasväxlingsmaterial (Phase Change Material, PCM) används i många sammanhang för att lagra energi vid konstant temperatur. Ett sätt att överföra värmen är att låta vatten flöda genom ett flänsat rör nedsänkt i en tank fylld med PCM. Denna modell analyseras med en FEM-baserad numerisk mjukvara. Studien jämför den utvunna effekten ur en modell med endast ett PCM, med effekten utvunnen ur en modell med tre olika PCM. Hypotesen var att ett system med flera material var bättre än ett system med endast ett för att erhålla maximal effekt. Resultatet visar att en modell med flera PCM är effektivare än en modell med endast ett. Det indikerar betydelsen av vilka temperaturer av PCM som väljs för att uppnå så hög effekt som möjligt. Detta område rekommenderas för fortsatta studier.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Hasib, A. M. M. Golam. « Effect of Dispersed Particles and Branching on the Performance of a Medium Temperature Thermal Energy Storage System ». Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc499995/.

Texte intégral

Résumé :

The main objective of my thesis is to develop a numerical model for small-scale thermal energy storage system and to see the effect of dispersing nano-particles and using fractal-like branching heat exchanger in phase change material for our proposed thermal energy storage system. The associated research problems investigated for phase change material (PCM) are the low thermal conductivity and low rate of heat transfer from heat transfer fluid to PCM in thermal energy storage system. In this study an intensive study is carried out to find the best material for thermal storage and later on as a high conductive nano-particle graphite is used to enhance the effective thermal conductivity of the mixed materials. As a thermal storage material molten solar Salt (60% NaNO3+40%KNO3) has been selected, after that detailed numerical modeling of the proposed design has been done using MATLAB algorithm and following the fixed grid enthalpy method. The model is based on the numerical computation of 1-D finite difference method using explicit scheme. The second part of the study is based on enhancing the heat transfer performance by introducing the concept of fractal network or branching heat exchanger. Results from the numerical computation have been utilized for the comparison between a conventional heating system (with a simple single tube as a heat exchanger) and a passive PCM thermal energy storage system with branching heat exchanger using NTU-effectiveness method and charging time calculation. The comparison results show a significant amount improvement using branching network and mixing nano-particle in terms of heat transfer (13.5% increase in effectiveness of branching level-02 heat exchangers from the conventional one ), thermal conductivity (increased 73.6% with 20% graphite nano-particle mix with solid PCM), charging time (57% decrease of charging time for the effect of both the dispersion of Graphite nano-particle and branching heat exchange) and pressure drop (36% decrease in level-02 branching). The results of this study prove that the proposed medium temperature TES system coupled with solar ORC can be the stepping-stone for energy efficient and sustainable future in small-scale/building level as the system proves to be better in terms of enhanced heat transfer, increased thermal conductivity and reduced pumping power and overall sustainability.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Boampong, James Kwadwo. « Solar thermal heating of a glasshouse using phase change material (PCM) thermal storage techniques ». Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/12863.

Texte intégral

Résumé :

The Royal Botanic Gardens (RGB) is used as an umbrella name for the institution that runs Kew and Wakehurst Place gardens in Sussex The RBG has a large number of glasshouses at Kew and Wakehurst sites that consume lots of heating energy which is a major concern and the group is looking for an alternative heating system that will be more efficient and sustainable to save energy, cost and reduce CO2 emissions. Glasshouse due to greenhouse effect trap solar energy in the space with the slightest solar gains but the energy trapped in the space most often is vented through the roof wasted to keep the space temperature to the required level. An environmental measurement was carried out in twenty one zones of the glasshouse to establish the temperature and humidity profiles in the zones for at least three weeks. The investigation established that large amount of heat energy is vented to the atmosphere wasted and therefore need a heating system that could absorb and store the waste thermal energy. Phase change material (PCM) thermal energy storage technique was selected to be the best options compared to the others. It has been established that active and passive solar systems could provide enough thermal energy to meet the glasshouse heating requirements. PCM filled heating pipes will be installed to absorb the heat energy trapped in the glasshouse and use it when needed. The research analysis established that 204 MWh of the trapped energy wasted could be saved. The space temperature of the glasshouse could be maintained through melting and freezing of the PCM filled in the heating pipes. The site CHP waste heat could be useful. The research results have shown that nearly zero CO2 emission heating system could be achieved and the project is technically, economically and environmentally viable.

Styles APA, Harvard, Vancouver, ISO, etc.

44

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Barrios, Rivero Matías. « EVALUATION OF AN AQUIFER THERMAL ENERGY STORAGE (ATES) SYSTEM FOR THE CITY HOSPITAL IN KARLSRUHE (GERMANY) ». Thesis, Karlsruhe Institute of Technology (KIT), Institute of Applied Geosciences (AGW), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-267554.

Texte intégral

Résumé :

The objective of the present study is to evaluate the economic, technical and environmental feasibility of an Aquifer Thermal Energy Storage (ATES) system combined with groundwater heat pumps (GWHP) for providing space cooling and heating for the future surgery building at the city hospital in Karlsruhe. The base case system used as reference for comparison is a system similar to the one currently supplying space cooling from a GWHP system and space heating by the local district-heating network. In addition, two alternative systems were included in the analysis, an Absorption Chiller (AbC) and a Desiccative Evaporative Cooling (DEC) system, both fed from the district-heating network. The study shows that the ATES system combined with a GWHP system is the most environmentally and economically attractive system for the planned facility. The results for the AbC system and the DEC systems show a negative net present value, meaning that this alternative is economically unfeasible. Furthermore, the AbC system and the DEC system do not provide any environmental advantage, showing an annual increase in CO2 emissions compared to the base case. A similar system like the one already providing cooling to some of the facilities would have several advantages over these two alternatives. However, it cannot compete with the ATES system together with GWHP, which apart from providing cooling at slightly higher efficiencies than the base case also delivers heating at high efficiencies. Therefore, it offers great potential savings and also provides an annual reduction in green house gas emissions. Concerning the technical feasibility of the four studied systems, no obstacle or significant barrier could be identified yet.

Styles APA, Harvard, Vancouver, ISO, etc.

46

MAHMOOD, MARIAM. « Study of Hybrid Solar Gas Turbine System : T100 Modeling and Dynamic Analysis of Thermal Energy Storage ». Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/930643.

Texte intégral

Résumé :

Concentrated Solar Power (CSP) hybrid gas turbine systems particularly based on the micro Gas Turbines (mGT) will be of great importance in future power infrastructure where energy security, economic feasibility and clean and efficient power generation are the key concerns. Integration of Thermal Energy Storage (TES) in CSP hybrid gas turbine systems could be a viable solution to overcome the intermittent nature of solar power, and increase the dispatchability. Based on this perception, a comprehensive analysis of both mGT cycle and TES technology should be undertaken, in order to achieve a better understanding of the behavior of TES and its interaction with other components in a hybrid gas turbine system. The present work intends to contribute to this analysis through mGT and TES system modeling and testing. This thesis is framed in two main parts: first part deals with T100 mGT modeling and second part focuses on the study of thermal storage systems. Regarding TES, detailed dynamic analysis of sensible heat storage is provided, while a preliminary study of thermochemical storage is conducted. The mGT performance diagnosis involves the development for steady-state simulation of T100, model validation, and application in real operating conditions at the Ansaldo Energia AE-T100 test rig. Furthermore, diagnostic application of the AE-T100 model for whole mGT cycle is discussed with the help of two case studies at AE-T100 test rig. AE-T100 model has also been applied in the real operating conditions of micro Humid Air Turbine (mHAT) system located at Vrije Universiteit Brussel (VUB), to highlight the modeling capability of AE-T100 tool as well as monitoring the recuperator performance in the VUB-mHAT cycle. The second part of this work concerns the dynamic modeling and experimental validation of a sensible TES system at laboratory scale, which is part of the Hybrid Solar Gas Turbine (HSGT) system developed at the University of Genova. TES is modeled with the help of a two-dimensional CFD model based on the ANSYS-FLUENT code, and a one-dimensional TRANSEO model employing software designed by the Thermochemical Power Group (TPG) at the University of Genova. The experimental validation, modeling capability to present the actual thermal stratification and State of Charge (SoC) of the TES, and scope of each model are also discussed. This study also highlighted the potential of TES system based on the monolithic structures for hybrid gas turbine systems i.e. low pressure drop across the TES which are acceptable for the whole gas turbine hybrid system, modular structure of the storage and very low thermal losses. In addition to the sensible heat storage system, ThermoChemical Storage (TCS) based on the redox cycle of cobalt oxides pair Co3O4\CoO was finally studied by the candidate during research period at Zhejiang University, China. The mathematical model which has been developed in MATLAB is based on the mass and energy conservation and reaction kinetics of the redox cycle, and has been validated against the experimental data available from literature. This work was aimed to study the process of thermochemical storage and understand the reaction kinetics of cobalt oxides with less computational effort. This analysis will help in design and optimization of the actual TCS system at the Zhejiang University, China. Overall, the knowledge and modelling capabilities developed for mGT cycle and TES systems in this study will be merged to develop a single simulation tool for mGT based CSP hybrid systems, in the future.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Muhammad, Mubarak Danladi. « Development of a cascaded latent heat storage system for parabolic trough solar thermal power generation ». Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9303.

Texte intégral

Résumé :

Concentrated solar power (CSP) has the potential of fulfilling the world’s electricity needs. Parabolic-trough system using synthetic oil as the HTF with operating temperature between 300 and 400o C, is the most matured CSP technology. A thermal storage system is required for the stable and cost effective operation of CSP plants. The current storage technology is the indirect two-tank system which is expensive and has high energy consumption due to the need to prevent the storage material from freezing. Latent heat storage (LHS) systems offer higher storage density translating into smaller storage size and higher performance but suitable phase change materials (PCMs) have low thermal conductivity, thus hindering the realization of their potential. The low thermal conductivity can be solved by heat transfer enhancement in the PCM. There is also lack of suitable commercially-available PCMs to cover the operating temperature range. In this study, a hybrid cascaded storage system (HCSS) consisting of a cascaded finned LHS and a high temperature sensible or concrete tube register (CTR) stages was proposed and analysed via modelling and simulation. Fluent CFD code and the Dymola simulation environment were employed. A validated CFD phase change model was used in determining the heat transfer characteristics during charging and discharging of a finned and unfinned LHS shell-and-tube storage element. The effects of various fin configurations were investigated and heat transfer coefficients that can be used for predicting the performance of the system were obtained. A model of the HCSS was then developed in the Dymola simulation environment. Simulations were conducted considering the required boundary conditions of the system to develop the best design of a system having a capacity of 875 MWhth, equivalent to 6 hours of full load operation of a 50 MWe power plant. The cascaded finned LHS section provided ~46% of the entire HCSS capacity. The HCSS and cascaded finned LHS section have volumetric specific capacities 9.3% and 54% greater than that of the two-tank system, respectively. It has been estimated that the capital cost of the system is ~12% greater than that of the two-tank system. Considering that the passive HCSS has lower operational and maintenance costs it will be more cost effective than the twotank system considering the life cycle of the system. There is no requirement of keeping the storage material above its melting temperature always. The HCSS has also the potential of even lower capital cost at higher capacities (>6 hours of full load operation).

Styles APA, Harvard, Vancouver, ISO, etc.

48

Souza, Luís Manoel de Paiva [UNESP]. « Levantamento de coeficientes de desempenho de armazenador térmico associado a refrigerador doméstico modificado ». Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/91720.

Texte intégral

Résumé :

Made available in DSpace on 2014-06-11T19:25:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-27Bitstream added on 2014-06-13T19:32:34Z : No. of bitstreams: 1 souza_lmp_me_bauru.pdf: 1572366 bytes, checksum: b4f3b5bc0ddb17fad3e39f5f59ec6a72 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
No estudo de reaproveitamento de energia térmica, os refrigeradores domésticos dissipam calor para o meio ambiente, através do seu condensador, e esse calor pode ser reciclado, ou seja, recuperado através de escoamento de água, como fluido refrigerante escoando pelo condensador e armazenada em um reservatório. Para isto, construi-se um aparato experimental contendo um refrigerador doméstico, duplex com capacidade de 263 litros para o gabinete de refrigeração e 74 litros para o gabinete de congelamento. O refrigerador tem seu condensador acrescido por um trocador de calor tipo tubos concêntricos em contra corrente, cuja fruição é condensar o fluido refrigente utilizando água em circulação. Dessa forma, caso ocorra o carregamento térmico total do tanque de armazenagem, o calor será originalmente dissipado para o meio ambiente, através do condensador aletado. A água aquecida é então armazenada em um reservatório térmico via estratificação térmica. Assim calculou-se as vazões de água aquecida e fluido refrigerante, como também o coeficiente de desempenho do sistema acumulado. Os resultados mostraram que a vazão de água bem como o coeficiente de desempenho do sistema aumenta de acordo com o aumento da pressão hidrostática. Desta maneira, dos resultados obtidos pode-se concluir que a otimização do experimento se dá de forma eficaz e que, o reaproveitamento da água quente proveniente do condensador é perfeitamente possível, reduzindoo consumo de energia elétrica com aquecedores de água e ainda, minimizando a dissipação de calor para o meio ambiente, sem alterar o funcionamento do refrigerador
In the study of recycling thermal energy it is know that domestic refrigerators dissipate heat to environment through the condenser. This heat can be recycled by a water flow, as a coolant in a modified condenser, and stored in a Domestic Hot Water Storage Tanks (DHWST). Thereby, an experimental apparatus was built containing one domestic refrigerator, each one with capacity of 263 liters in the cooling cabinet and 74 liters in the freezing cabinet. The refrigerators had the condenser increase by a type heat exchanger concentric tubes with a counter-current flow, which has the function of replace the original finned exchanger, condensing the coolant with water flow. Thus, in case the total thermal loading of the storage tank, the heat is dissipated to the original environment through the condenser finned. The heated water is then stored in a thermal reservoir via thermal stratification. In these conditions, the flow of heated water and refrigerant was calculated, as well as the coefficient of performance of the system. The results show that the water flow rate and the coefficient of performance of the system increases with the increase in hydrostatic pressure. According to these results, the experiment optimization is effective and it is totally possible to reuse the warm from modified condenser system, what could reduce the electric energy consumption in water beater and minimize the heat dissipation to environment, without modifying the refrigerator operation

Styles APA, Harvard, Vancouver, ISO, etc.

49

Maxamhud, Mahamed, et Arkam Shanshal. « SELF-SUFFICIENT OFF-GRID ENERGY SYSTEM FOR A ROWHOUSE USING PHOTOVOLTAIC PANELS COMBINED WITH HYDROGEN SYSTEM : Master thesis in energy system ». Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-49379.

Texte intégral

Résumé :

It is known that Sweden is categorised by being one of the regions that experience low solar radiation because it is located in the northern hemisphere that has a low potential of solar radiation during the colder seasons. The government of Sweden aim to promote a more sustainable future by applying more renewable initiative in the energy sector. One of the initiatives is by applying more renewable energy where PV panels will play a greater role in our society and in the energy sector. However, the produced energy from the PV panels is unpredictable due to changes in radiation throughout the day. One great way to tackle this issue is by combining PV panels with different energy storage system. This thesis evaluates an off-grid rowhouse in Eskilstuna Sweden where the PV panels are combined with a heat pump, thermal storage tank, including batteries and hydrogen system. The yearly electrical demand is met by utilizing PV panels, battery system for short term usage and hydrogen system for long-term usage during the colder seasons. The yearly thermal demand is met by the thermal storage tank. The thermal storage tank is charged by heat losses from the hydrogen system and thermal energy from heat pump.The calculations were simulated in Excel and MATLAB where OPTI-CE is composed with different components in the energy system. Furthermore, the off-grid household was evaluated from an economic outlook with respect to today’s market including the potential price decrease in 2030.The results indicated that the selected household is technically practicable to produce enough energy. The PV panels produces 13 560 kWh annually where the total electrical demand reaches 6 125 kWh yearly (including required electricity for the heat pump). The annual energy demand in terms of electricity and thermal heat reaches 12 500 kWh which is covered by the simulated energy system. The overproduction is stored in the batteries and hydrogen storage for later use. The back-up diesel generator does not need to operate, indicating that energy system supplies enough energy for the off-grid household. The thermal storage tank stores enough thermal energy regarding to the thermal load and stores most of the heat during the summer when there are high heat losses due to the charge of the hydrogen system. The simulated energy system has a life cycle cost reaching approximately k$318 with a total lifetime of 25 years. A similar off-grid system has the potential to reduce the life cycle cost to k$195 if the energy system is built in 2030 with a similar lifespan. The reduction occurs due to the potential price reduction for different components utilized in the energy system.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Leppin, Lorenz. « Development of Operational Strategies for a Heating Pump System with Photovoltaic, Electrical and Thermal Storage ». Thesis, Högskolan Dalarna, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:du-27304.

Texte intégral

Résumé :

This study describes the development of operational strategies for an exhaust air heat pump system that supplies space heating and domestic hot water. The system combines photovoltaic power production with two different storage types. These are electrical storage using batteries and thermal storage in using a domestic hot water tank and in form of the thermal capacity of the building. The investigation of the control strategies is carried out for a detailed single family house model in Sweden in the simulation software TRNSYS. The overall aim of the control strategies is to improve the performance of the energy system in terms of self-consumption, self-sufficiency, final energy and seasonal performance factor. Three algorithms are developed and compared to a base case without additional control. The first algorithm only uses the thermal storage in the hot water tank and the building. The second uses only the battery to store the photovoltaic electricity. The third control algorithm combines both storage types, electrical and thermal. The simulation results show that for the studied system the energetic improvement is higher with the use of electrical storage compared to using thermal storage. The biggest improvement however is reached with the third algorithm, using both storage types in combination. For the case of a photovoltaic-system with 9 kW and battery store with 10.8 kWh and a 180 l hot water store the self-consumption reaches up to 51% with a solar fraction of 41 %. The reduction in final energy consumption for this case is 3057 kWh (31 %) with the heat pump having a seasonal performance factor of 2.6. The highest self-consumption is reached with a photovoltaic-system of 3 kW and battery store with 3.6 kWh, which comes to 71 %.

Styles APA, Harvard, Vancouver, ISO, etc.

Thèses sur le sujet « THERMAL ENERGY STORAGE SYSTEM (TES) »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres