För ett genomsnittligt småhus i Sverige idag går ca 5000 kWh till hushållsel. Av dessa 5000 kWh går 7% till att driva diskmaskiner. Effektiviseringen av diskmaskiner har framförallt strävat efter en låg vatten- och energianvändning, en kort processtid samt en effektiv rening av disken. Det finns dock gränser för hur effektiva diskmaskinerna kan göras med traditionell teknik. Därför har producenter under de senaste åren börjat se sig om efter mindre traditionella metoder som till exempel bruket av en värmepump för att få ned energiförbrukningen. Syftet med det här examensarbetet har varit att ta fram systemlösningar för värmepump i diskmaskin samt att utvärdera energibesparingspotentialen i denna tillämpning. Målet har varit att ta fram och beskriva de möjliga systemlösningar som uppstår vid en idégenerering. Att välja ut två lösningar för närmare undersökning, att bestämma en lämplig kompressoreffekt samt att beräkna energibesparingen dessa lösningar ger. En litteraturstudie har gjorts av teknik och tillämpningar inom området, som till exempel värmeväxlaranvändning i diskmaskiner samt användandet av värmepumpar i andra vitvaror. Denna litteraturstudie följdes upp av en idégenerering, som tar hänsyn till möjliga värmekällor och –sänkor. Idégenereringen gav upphov till två systemlösningar som modellerades i MATLABs Simulink för att en lämplig kompressoreffekt och storleken på energibesparingen skulle bestämmas. De två utvalda lösningarna ifrån idégenereringen var utomhusluftlösningen, där värme hämtas från uteluften och energilagerlösningen, där värme hämtas ur ett energilager. I båda lösningarna överförs värmen till det kalla ingående vattnet. Energiåtgången för utomhusluftlösningen var beroende av köldmediets förångningstemperatur och modellering av lösningen visade att energiåtgången var 0,25 kWh vid en förångningstemperatur på -10°C, och 0,18 kWh vid 5°C. Vid modellering av energilagerlösningen påvisades en energiåtgång på 0,23 kWh. Slutsatsen som drogs var att kompressorn vid energilagerlösningen skall leverera en effekt på 240 W till köldmediet. / For an average detached house in Sweden today about 5000 kWh are used for household electricity. Of these 5000 kWh 7% are used to run dishwashers. The streamlining of dishwashers has above all strived for a lower water and energy use, a short process time along with a more efficient cleaning of the dishes. There are however limits for how efficient the dishwashers can be made with traditional technology and acceptable costs. Therefore producers have, during recent years, started looking for less traditional methods, for example the use of a heat pump to reduce the energy use. The purpose of this examination work has been to find system solutions for an application of a heat pump in a dishwasher and to evaluate the possible energy saving for each solution. The goal has been to find and describe possible system solutions, which came up during the idea generation. To choose some of these for a closer investigation, to decide a fitting mechanical power for the compressor and to calculate the energy saving these solutions give rise to. The method has consisted of a literature study, an idea generation, which takes the heat sources and sinks in consideration and a modelling in MATLAB’s Simulink of the selected solutions from the idea generation, which has been used to fit a mechanical power for the compressor. The result of the idea generation was two solutions, an outdoor air solution, which collects heat from the outdoor air and gives it to the cold water which enters the machine and a energy storage solution, which collect heat from a heat stock to give to the cold entering water. A modelling of these show an energy usage of 0,24 respectively 0,17 kWh for the outdoor air solution, with a heat source temperature at 10 °C respectively 5°C and a energy usage of 0,22 kWh for the energy storage solution for one round. The conclusion that was drawn was that the compressor of the energy storage solution should deliver a mechanical power of 240 W to the refrigerant.

Analizuojamos esamo gyvenamojo kvartalo, nutolusio nuo pagrindinės gyvenvietės aprūpinimo šilumine energija galimybės Širvintų mieste. Įvertinama esama gyvenamojo kvartalo geografinė padėtis bei specifika. Analizuojami kvartalo aprūpinimo šilumine energija būdai. Vertinama esamų trasų renovacija, bei dujomis arba malkomis kūrenamos katilinės šalia analizuojamo kvartalo įrengimas. Pateikiamas išlaidų, susijusių su trasų renovavimu bei katilinių įrengimu, vertinimas bei palyginimas. Pateikiamas katilinių poveikio aplinkai skaičiavimas. / In the final master work I have analyzed the supplying thermal energy to the existing residential quarter in Sirvintai city which is moved away from the main city. Also there is evaluated the existing geographical situacion and specific features of this residential quarter. The means of the suppling thermal energy to the residential quarter also is analyzing in this work. The revovation of existing tracks and the mounting the boiler-houses where the gas or wood is used and which are close to the residential quarter are evaluated in this paper work too. The expenses which is retaled to the renovation of heating tracks and boiler-houses mounting are estimated and compared. The calculation of the boiler-houses influence to the environment is also presented in this work.

Pagrindinis darbo tikslas- atlikti įstatymais nustatytų socialinių išmokų ir kompensacijų administravimo ir teikimo analizę Šilalės rajono savivaldybėje, įvertinti ir pateikti siūlymus dėl kompensacijų sistemos tobulinimo. Siekiant šio tikslo pirmiausiai aptarta Lietuvos socialinės paramos samprata, paramos poreikio atsiradimo priežastys, išanalizuoti ir susisteminti socialinės paramos ir pašalpų skyrimo principai, pateiktos piniginės socialinės paramos sistemos tobulinimo kryptys. Atlikta Lietuvos socialinės paramos šeimoms analizė. Patvirtinta suformuluota hipotezė, kad dabartinė pajamų kompensavimo sistema mažina darbo paskatas ir skatina žmones gyventi iš pašalpų. / The mani purpose-to carry out statutory social security benefits and compensation administration Šilalė analysis of the provision in the municipality to evaluate and provide suggestions for improving the system of compensation. To this end, in particular Lithuania discussed the concept of social support, the need to support causes, and to analyze the structure of social support and the award of grants provided financial support for improving the system of social trends. Analysis of the Lithuanian social analysis to support the family. Approved and formulated the hypothesis that the current system of income compensation reduces work incentives and encourage people to live on benefits.

Phase change materials (PCMs) are a viable option for compact thermal energy storage. Effective designs using PCMs require accurate knowledge of the thermal and physical properties, but for many PCMs these are not well known, and when known the knowledge is sometimes contradictory. Therefore, physical characteristics of several promising PCMs (K3PO4·7H2O, FeCl3·6H2O, Mn(NO3)2·4H2O) were determined. In addition, a life cycle assessment (LCA) of dodecanoic acid in a solar thermal energy storage system was carried out to determine the environmental impact for energy storage. This LCA showed that dodecanoic acid in a solar energy system would save energy and facilitate CO2 reductions. However, the economic cost is high and is unlikely to be implemented without incentives. Finally an experimental testbed for a solar thermal system utilizing dodecanoic acid was built. Preliminary measurements demonstrated the utility of this system.

The thermal efficiency of concentrated solar power (CSP) system depends on the maximum operating temperature of the system which is determined by the operating temperature of the TES device. Organic materials (such as synthetic oil, fatty acid, or paraffin wax) are typically used for TES. This limits the operating temperature of CSP units to below 400 degrees C. Increasing the operating temperature to 560 degrees C (i.e., the creeping temperature of stainless steel), can enhance the theoretical thermal efficiency from 54 percent to 63 percent. However, very few thermal storage materials are compatible for these high temperatures. Molten salts are thermally stable up to 600 degrees C and beyond. Using the molten salts as the TES materials confers several benefits, which include: (1) Higher operating temperature can significantly increase the overall cycle efficiency and resulting costs of power production. (2) Low cost of the molten salt materials can drastically reduce the cost. (3) The molten salts, which are environmentally safe, can also reduce the potential environmental impact. However, these materials suffer from poor thermo-physical properties. Impregnating these materials with nanoparticles can enhance these properties. Solvents doped with nanoparticles are termed as nanofluids. Nanofluids have been reported in the literature for the anomalous enhancement of their thermo-physical properties. In this study, the poor thermal properties of the molten salts were enhanced dramatically on mixing with nanoparticles. For example the specific heat capacity of these molten salt eutectics was found to be enhanced by as much as ~ 26 percent on mixing with nanoparticles at a mass fraction of ~ 1 percent. The resultant properties of these nanomaterials were found to be highly sensitive to small variations in the synthesis protocols. Computational models were also developed in this study to explore the fundamental transport mechanisms on the molecular scale for elucidating the anomalous enhancements in the thermo-physical properties that were measured in these experiments. This study is applicable for thermal energy storage systems utilized for other energy conversion technologies – such as geothermal energy, nuclear energy and a combination of energy generation technologies.

Le développement de systèmes de récupération d’énergie (ou energy harvesting systems en anglais) va de pair avec l’émergence de l’Internet des Objets et notamment la prolifération de réseaux de capteurs devant répondre aux besoins croissants en informations, que ce soit dans le domaine de l’industrie, de la sante, de la domotique ou de l’environnement qu’il soit urbain ou naturel. Les progrès réalisés ces dernières années dans le domaine des Technologies de l’Information et de la Communication ont permis de lever certains verrous technologiques au déploiement de ces réseaux de capteurs intelligents et autonomes, notamment grâce a l’amélioration des performances intrinsèques des composants microélectroniques (vitesse, consommation), la conception de circuits plus économes en énergie, ou bien la mise en place de standards de communications radio adaptes a ces contraintes énergies. Etant donné l’ubiquité des sources d’énergie, la fabrication de générateurs permettant d’alimenter directement ces capteurs à partir de ces sources représente une alternative viable à l’utilisation de batteries pour prolonger la durée de vie de ces capteurs communicants. Diverses technologies de générateurs ont ainsi été proposes pour s’adapter aux différentes formes que peut prendre l’énergie, qu’elle soit d’origine thermique, mécanique, solaire ou électromagnétique.Le présent travail est une contribution au développement de certains dispositifs de récupération thermiques basés sur l’exploitation des propriétés thermiques et mécaniques de bilames thermostatique. Ce type de générateurs, propose et développe au sein de STMicroelectronics à Crolles, se veut être une alternative fiable et bas cout a l’utilisation de matériaux thermoélectriques exploitant l’effet Seebeck pour générer de l’énergie électrique. Divers dispositifs ont déjà été fabriqués, démontrant la capacité des moteurs thermiques à base de bilames thermostatiques à alimenter des capteurs autonomes en fonctionnement synchrone et asynchrone. L’objectif de cette thèse est alors de démontrer la possibilité de miniaturiser de tels moteurs thermiques grâce aux techniques de fabrications utilisées en microélectronique. Afin de garantir le fonctionnement de ces systèmes a micro-échelle, un important travail de fond a d’abord été effectue sur la compréhension et la modélisation des phénomènes de couplages thermomécaniques a l’origine du comportement bistable des membranes bimétalliques. Ce travail a débouché sur la démonstration théorique du fonctionnement des moteurs thermiques a base de bilames et sur l’évaluation de leur performances énergétiques (énergie disponible, efficacité thermique, efficacité de Carnot relative). Dans la continuité de ce premier modèle, d’autres travaux ont été menés pour évaluer les performances de moteurs thermiques exploitant différents phénomènes de couplage électromécanique en vue de convertir l’énergie mécanique générée par les bilames thermostatiques en énergie électrique exploitable par les capteurs autonomes. La simulation du comportement des micro-générateurs à l’aide de ces divers modèles a debouché sur des lois d’échelles sur les performances des moteurs thermiques. Finalement, divers procédés de fabrications ont ete développé pour permettre la fabrication de microstructures thermiquement bistables. / The development of energy harvesting systems is linked to the emergence of the Internet of Things (IoT) and especially the proliferation of Wireless Sensors Networks that should respond to the growing needs for monitoring data in domains as diverse as the industry, the urban or natural environments, the home, or the human body etc. Recent progress in the field of information technologies have enabled to remove some of the technical obstables to the deployment of these smart and autonom devices, in particular thanks to the improvement of the performances of microelectronic components, the design of ultra-low-power circuits, or the creation of wireless communications standards adapted to the energy needs of wireless sensors. Given the great availability of energy sources, energy harvesters are reliable alternatives to batteries in order to extend the autonomy of these sensors. Various technologies of generators have been developped to adapt to the type of local energy sources (heat, vibration, light, radio-frequencies).The present work is a contribution to the development of thermal energy harvesters exploting the thermal and mechanical properties of bimetal thermostats. This type of technology developped at STMicroelectronics are intended to be a reliable and low-cost alternative to the use of thermoelectric materials exploing Seebeck effect to generate electricity from heat. Various devices were already fabricated at the macro-scale, demonstrating their ability to power wireless sensor nodes. In the continuity of these works, this PhD thesis aims to demonstrate the operation of these generators at the sub-millimetric scale. As a consequence, an important work on the modeling of the thermo-mechanical instability of bimetallic strips was made to understand the operation of bimetallic strip heat engines. This work enabled to theoretically demonstrate the capability of bimetallic to transform heat into mechanical energy and to evaluate the performances of such heat engines. Coupling between bimetallic strip heat engines and electro-mechanical transducers was also modeled to compare the performances of the current prototypes of generators. We then modeled the thermo-mechanical behavior of composite beams at the microscale and established scaling rules of the performances of the bimetallic strip heat engines, We finally developped microlectronic fabrication process to manufacture thermo-mechanically bistable beams at the microscale.

abstract: Recently, nanostructured metamaterials have attracted lots of attentions due to its tunable artificial properties. In particular, nanowire/nanohole based metamaterials which are known of the capability of large area fabrication were intensively studied. Most of the studies are only based on the electrical responses of the metamaterials; however, magnetic response, is usually neglected since magnetic material does not exist naturally within the visible or infrared range. For the past few years, artificial magnetic response from nanostructure based metamaterials has been proposed. This reveals the possibility of exciting resonance modes based on magnetic responses in nanowire/nanohole metamaterials which can potentially provide additional enhancement on radiative transport. On the other hand, beyond classical far-field radiative heat transfer, near-field radiation which is known of exceeding the Planck’s blackbody limit has also become a hot topic in the field. This PhD dissertation aims to obtain a deep fundamental understanding of nanowire/nanohole based metamaterials in both far-field and near-field in terms of both electrical and magnetic responses. The underlying mechanisms that can be excited by nanowire/nanohole metamaterials such as electrical surface plasmon polariton, magnetic hyperbolic mode, magnetic polariton, etc., will be theoretically studied in both far-field and near-field. Furthermore, other than conventional effective medium theory which only considers the electrical response of metamaterials, the artificial magnetic response of metamaterials will also be studied through parameter retrieval of far-field optical and radiative properties for studying near-field radiative transport. Moreover, a custom-made AFM tip based metrology will be employed to experimentally study near-field radiative transfer between a plate and a sphere separated by nanometer vacuum gaps in vacuum. This transformative research will break new ground in nanoscale radiative heat transfer for various applications in energy systems, thermal management, and thermal imaging and sensing. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2017

Este trabalho tem por objetivo analisar as perspectivas dos gases combustíveis como energia final para a obtenção de energia útil, em aquecimento direto (AD) e calor de processo (CP), identificando e quantificando potenciais como alternativa da eletrotermia. São comparados dois panoramas na avaliação das economias de energia primária pela substituição da eletrotermia: o primeiro considerando que a energia substituída oriunda de energéticos do parque gerador; e o segundo levando em conta que a redução se refletiu nas termelétricas. Para atingir este objetivo, o trabalho se inicia com uma revisão bibliográfica, onde são tratados os aspectos necessários para um melhor entendimento do texto, com os conceitos de eletrotermia, calor e termodinâmica, seguindo-se um capítulo destinado aos gases combustíveis, suas características e disponibilidade futura para a conversão. As informações básicas para a análise dos potenciais nos setores foram tomadas a partir do último Balanço de Energia Útil, além de trabalhos desenvolvidos no mercado industrial pelo autor. O trabalho discorre também sobre configurações tecnológicas usadas nas conversões, incluindo os custos envolvidos. Na conclusão, os cálculos mostraram que significativas economias de energia primária podem ser obtidas com a conversão da eletrotermia para gases combustíveis no setor industrial brasileiro, considerando a eletricidade produzida a partir de plantas termelétricas. / This paper aims to analyze the prospects of fuel gases as final energy in order to get useful energy in direct heating and process heat, identifying and qualifying potentials as the alternative of electrothermy. Two panoramas are compared in the evaluation of primary energy displacement: the first one considering the replaced energy coming from energy generating facilities and the second taking into account that the reduction was reflected in thermoelectric power plants. To achieve this goal, the work begins with a literature review which covers the aspects needed for a better understanding of the text, with the concepts of electrothermy, heat and thermodynamics, followed by a chapter intended for fuel gases, their characteristics and future readiness for conversion. The basic information for the analysis of potential sectors were taken for the last Useful Energy Balance, and work undertaken by the author in the industrial market. The paper also discourses about technological configurations used in conversions, including also the costs involved. In conclusion, the calculations showed that significant primary energy savings can be obtained through the conversion of electrothermy by fuel gases in the Brazilian industrial sector, taking into account the electricity produced from thermoelectric power plants.

abstract: Thermal Energy Storage (TES) is of great significance for many engineering applications as it allows surplus thermal energy to be stored and reused later, bridging the gap between requirement and energy use. Phase change materials (PCMs) are latent heat-based TES which have the ability to store and release heat through phase transition processes over a relatively narrow temperature range. PCMs have a wide range of operating temperatures and therefore can be used in various applications such as stand-alone heat storage in a renewable energy system, thermal storage in buildings, water heating systems, etc. In this dissertation, various PCMs are incorporated and investigated numerically and experimentally with different applications namely a thermochemical metal hydride (MH) storage system and thermal storage in buildings. In the second chapter, a new design consisting of an MH reactor encircled by a cylindrical sandwich bed packed with PCM is proposed. The role of the PCM is to store the heat released by the MH reactor during the hydrogenation process and reuse it later in the subsequent dehydrogenation process. In such a system, the exothermic and endothermic processes of the MH reactor can be utilized effectively by enhancing the thermal exchange between the MH reactor and the PCM bed. Similarly, in the third chapter, a novel design that integrates the MH reactor with cascaded PCM beds is proposed. In this design, two different types of PCMs with different melting temperatures and enthalpies are arranged in series to improve the heat transfer rate and consequently shorten the time duration of the hydrogenation and dehydrogenation processes. The performance of the new designs (in chapters 2 and 3) is investigated numerically and compared with the conventional designs in the literature. The results indicate that the new designs can significantly enhance the time duration of MH reaction (up to 87%). In the fourth chapter, organic coconut oil PCM (co-oil PCM) is explored experimentally and numerically for the first time as a thermal management tool in building applications. The results show that co-oil PCM can be a promising solution to improve the indoor thermal environment in semi-arid regions. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020

This thesis develops a calibrated model of the Cal Poly Central Chilled Water Plant with Thermal Energy Storage for use in determining an optimal operating control strategy. The model was developed using a transient systems simulation program (TRNSYS) that includes plant performance and manufacturer data for the primary system components, which are comprised of pumps, chillers, cooling towers, and a thermal energy storage tank. The model is calibrated to the actual measured performance of the plant using the current control strategy as a baseline. By observing and quantifying areas for potential improvement in plant performance under conditions of high campus cooling load demands, alternative control strategies for the plant are proposed. Operation of the plant under each of these control strategies is simulated in the model and evaluated for overall energy and demand-usage cost savings. These results are used to recommend improvements in the plant’s current control strategy, as well as to propose an optimal control strategy that may be applied to reduce plant operating costs. The results of the model identify that the plant can perform more economically by employing more chiller power to charge the Thermal Energy Storage tank to higher capacities during overnight periods when the utility rates are lower. Staging the operation of the different chillers to more precisely follow the tank charges during these off-peak periods can ensure faster tank charging when its capacity may not be sufficient to meet the peak and part-peak cooling load demands. A proposed control strategy to accomplish this breaks the overnight Off-Peak rate period into three periods with separate control setpoints, which are designed to maintain the tank charge capacity at the minimum levels to be able to accommodate the daily campus cooling demands during peak and part-peak hours.