Resumo: Considerando a importância da compreensão da dinâmica espaço temporal dos componentes do balanço de energia (BE) em escala regional para o gerenciamento de recursos hídrico e o manejo agrícola, o objetivo principal desta tese foi construir e analisar uma série temporal dos componentes do BE adequada às condições de clima subtropical úmido do Estado do Rio Grande do Sul. Para tanto, inicialmente foi avaliada a adequação de modelos de estimativa de BE para o Estado. Nesta etapa foram utilizados produtos MODIS e dados de referência medidos em uma torre micrometeorológica instalada em Cruz Alta – RS, usando valores instantâneos para um período de estudo de 2009 a 2011. Na sequência foi avaliada a adequação dos modelos em representar a variabilidade espacial dos componentes do BE. Nesta etapa foram usados produtos MODIS, dados de reanálise ERA Interim, dados de referência da torre micrometeorológica e dados de estações meteorológicas do INMET, para o mesmo período de estudo. Na última etapa do trabalho foi construída a série temporal dos componentes do BE usando o modelo METRIC, a qual abrangeu um período de 14 anos, de 2002 a 2016. Os resultados demonstraram que os três modelos analisados apresentam coerência com as medidas de referência, sendo as maiores limitações apresentadas pelo modelo SEBAL, as quais se atribui principalmente às condições ecoclimáticas do Estado e a baixa resolução espacial das imagens. Na análise da variabilidade espacial, o modelo METRIC apresentou maior consistência nos resultados e proporcionou maior número de dias com resultados válidos, sendo assim apontado como o mais apto para realização do restante do estudo. A série temporal construída possibilitou a compreensão dos padrões de distribuição espaço temporal dos componentes do BE no estado do Rio Grande do Sul. Há uma marcada sazonalidade nos componentes do BE, com maiores valores no verão e menores no inverno. G (fluxo de calor no solo) é o componente de menor magnitude e sua distribuição espacial e temporal é determinada pela distribuição de Rn (saldo de radiação). Já os componentes LE (fluxo de calor latente) e H (fluxo de calor sensível), são os que mostram magnitude maior e apresentam padrões de distribuição espacial e temporal coerentes com as condições climáticas e com os tipos de uso e cobertura na área de estudo. Observase um padrão inverso, com um gradiente de LE no sentido noroeste para sudeste e para o componente H, no sentido sudeste para noroeste. Sendo estas informações de grande importância para gerenciamento de recursos hídricos em escala regional, para estudos de zoneamento agrícola. / Abstract: Given the importance of understanding the temporal and spatial dynamics of of the energy balance (EB) components in a regional scale for the management of water resources and agricultural, the main objective of this thesis was to construct and analyze a time series of the components of BE appropriate to the subtropical humid climate conditions of the State of Rio Grande do Sul. In order to reach the objective initially, the adequacy of the models for the humid climate conditions was evaluated, in this step we used MODIS data and reference data measured in a micrometeorological tower installed in Cruz Alta - RS. The analyzes performed with instantaneous values and the study period was from 2009 to 2011. The next step evaluate the spatial variability of the BE components, the data used were the MODIS products, ERA Interim reanalysis data, reference data of the micrometeorological tower and INMET meteorological stations, for the same study period. In the last stage the time series of the BE components was constructed from the METRIC model. The period series was 14 years from 2002 to 2016.The results showed that the three models analyzed were consistent with the reference measurements, with the greatest limitations presented by the SEBAL model, which are mainly attributed to the state's eco-climatic conditions and the low spatial resolution of the images In the analysis of the spatial variability, the METRIC model presented greater consistency in the results and provided greater number of days with valid results, this model thus indicated as the most suitable for the rest of the study. The time series constructed allowed us to understand the temporal distribution patterns of BE components in the state of Rio Grande do Sul. There is a marked seasonality in the BE components, with higher values in summer and lower in winter. G is the smallest magnitude component and its spatial and temporal distribution is determined by the Rn distribution. On the other hand, the LE and H components are those that show higher magnitude and present spatial and temporal distribution patterns consistent with the climatic conditions and the types of use and coverage in the study area. An inverse pattern is observed, with a LE gradient from north-west to south-east and for H-component, from southeast to northwest.

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)

The accomplished case studies focus on the influence of land-use on the distributions of latent heat-fluxes and cloud-water. The numerical case studies were performed with the threedimensional non-hydrostatic Mesoscale-Model GESIMA for different land-use distributions applying always the same initial conditions of a cloudy day in spring with a geostrophic wind of 8 m/s from the west. The cloud-water distributions at different times and at different levels, their temporal development, the daily sums of the domain-averaged latent heat-fluxes and cloud-water mixing ratios were investigated. Even simple initial conditions (no orography, stable atmosphere) and simple pattern in the land-use distributions emphasize that the influence of surface heterogeneity on meteorological processes cannot be neglected. As shown in this case study, land-use distribution influences the distribution and the amount of cloud-water as weil as the latent heat-flux. On the whole, all these processes are very complex and non-linear. / Die durchgeführten Sensitivitätsstudien konzentrieren sich auf den Einfluß der Landnutzungsverteilung auf die Flüsse latenter Wärme und das Wolkenwasser. Die numerischen Untersuchungen wurden mit dem dreidimensionalen nicht-hydrostatischen Mesoskalen-Modell GESIMA für verschiedene Landnutzungsmuster unter immer den gleichen meteorologischen Anfangsbedingungen für einen bewölkten Frühlingstag mit einem geostrophischen Wind von 8 m/s durchgeführt. Die Wolkenwasserverteilung zu bestimmten Zeiten und in bestimmten Niveaus, die zeitliche Entwicklung der Wolkenwasserverteilung, die Tagessummen der Gebietsmittelwerte der Flüsse latenter Wärme und des Wolkenwassers werden untersucht. Auch einfache Randbedingungen (keine Orographie, stabile, atmosphärische Bedingungen) und einfache Landnutzungsverteilungsmuster machen deutlich, daß der Einfluß der Heterogenität der Unterlage auf meteorologische Prozesse nicht zu vernachlässigen ist. Sie kann entscheidend die Verteilungen der Flüsse latenter Wärme und des Wolkenwassers beeinflussen. Die damit verbundenen Prozesse sind äußerst komplex und nicht linear.

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.

Idag står världen inför en rad olika miljörelaterade problem. Ett av dessa och det kanske mest omtalade är hur utsläpp av växthusgaser sakta men säkert höjer planetens medeltemperatur. Hållbar utveckling är ett begrepp som driver diskussionen framåt om vad vi behöver göra och hur vi behöver förändras för att lösa problemen. Växthusgaserna och deras hot mot klimatet är starkt relaterat till energi. Förnyelsebara energikällor skulle kunna vara en dellösning på problemet men de kräver energilagring av olika former för att kunna ersätta sina fossila konkurrenter. Termisk energilagring är ett sätt att lagra energi på och kan delas upp i tre olika grupper. Dessa är sensibel, latent och termokemisk värmelagring. Syftet med denna litteraturstudie var att kartlägga olika applikationer av latent värmelagring som kan bidra till ett mer hållbart samhälle i framtiden. Resultatet visar att det finns många olika typer av så kallade fasomvandlingsmaterial (PCMs). Beroende på vid vilka temperaturer värme ska lagras vid används olika PCMs. PCMs kan användas för latent värmelagring inom många olika områden. Byggnader är ett av dessa områden där PCMs kan användas för att kyla och värma utrymmen antingen genom integration i ventilationssystem eller i själva byggnadsmaterialen. Latent värmelagring kan också användas i termiska solkraftverk. Latent värmelagring har på senare tid fått stor uppmärksamhet tack vare PCMs förmåga att lagra värme i små volymer och under konstant temperatur. Dock möter tekniken problem vid värmeöverföringen vilket t.ex. är fallet i lagring av termisk solenergi. Forskning pågår därför för att generellt höja PCMs termiska egenskaper. Ett exempel på detta är Nano-PCM. Resultatet visar även att latent värmelagring idag används av företag som affärsidé för olika tillämpningar. Från resultatet går det att dra slutsatsen att latent värmelagring används idag men att det krävs ytterligare forskning för att tekniken ska kunna konkurrera med andra värmelagringsmetoder. / Today, the world faces a number of environmental-related problems. One of these and perhaps most discussed is how emissions of greenhouse gases slowly but surely raise the planet’s average temperature. Sustainable development is a concept that drives the discussion forward and tells us what we need to do and how we need to change to solve the problems. Greenhouse gases and their threats to the climate are strongly related to energy. Renewable sources of energy could be a partial solution to the problem, but they require energy storage of different forms to replace their fossil competitors. Thermal energy storage is a way of storing energy and can be divided into three different groups. These are sensible, latent and thermochemical heat storage. The purpose of this literature study was to map different applications of latent heat storage that can contribute to a more sustainable society in the future. The result shows that there are many different types of phase changing materials (PCMs). Depending on the temperature at which heat is to be stored, different PCMs are used. PCMs can be used for latent heat storage in many different areas. Buildings are one of these areas where PCMs can be used to cool and heat spaces either through integration into ventilation systems or in the building materials itself. Latent heat storage can also be used in thermal solar power plants. Latent heat storage has recently received great attention thanks to PCMs ability to store heat in small volumes and under constant temperature. However, the technology is experiencing problems in the heat transfer, such is the case in the storage of thermal solar energy. Research is therefore ongoing to generally increase PCMs thermal properties. An example of this is Nano-PCM. The result also shows that latent heat storage today is used by companies as a business concept for various applications. From the result, it can be concluded that latent heat storage is used today, but that further research is required for the technology to compete with other heat storage methods.

The European commission has in the Energy Performance of Buildings Directive from 2010 decided that its member states were required to ensure that all new buildings by the end of 2020 were nearly zero-energy buildings. These buildings require small amounts of energy compared to its performance in example by keeping a pleasant indoor climate. To achieve these goals there is an option for integrating phase changing material into building material.   The purpose of this project was to determine which kind of PCM is suitable for use in building materials to increase its fire resitance, taking inspiration from the report Fasomvandlingsmaterial: Risker och möjligheter written by Michael Försth, Alexandra Byström and Jonathan Wolf. In particular, the aim was to observe if the application of PCM, in pure powder form, into pure concrete could increase the time until it reaches it critical temperature of 500 °C. The choice of PCM to be used was decided by a literature review and initial thermal tests, and in this case, Magnesium Carbonate Hydroxide Pentahydrate, MCHP, was used as a substitute for the cement, in this project.    The project has been carried out through a literature review and laboratory experiments. The laboratory experiments were performed in different stages. First, the thermal properties of the PCM were decided by using a DSC (differential scanning calorimeter) and a TGA (Thermogravimetric analysis). Three kinds of PCMs (Magnesium hydroxide, Aluminium hydroxide and MCHP) were tested from the results of the literature review. The DSC gave a variation in results between the three tested PCMs. MCHP showed two melting phases which produced different kind of fire-retardant products and theoretically would give two instances of stopping the heating of the concrete. With that MCHP was then chosen as the most appropriate one to be incorporated into concrete. From there, pure concrete samples and with PCM mixed in, with different weight percentage varying between 2-10 weight percent (wt.%) of the cements weight, with a thermocouple embedded in the bottom were manufactured. Thereafter, a cone calorimeter was used with the constant heat flux of 50 kW·m-2 as a source of heat radiation.   The results shows that the application of the PCM in the concrete by replacing the cement does not give any noticeable increase in its fire resistance by increasing the time until it reaches 500 °C. Neither did it show any signs of the heating curve to flatten out, which in theory would have occurred during melting of the PCM. This could depend on the way the heat transfers down through the concrete and melts the PCM along the way towards the bottom and the thermocouple measuring the temperature. Making the thermocouple only register the heating of the concrete in close proximity to it. Therefore only a small amount of PCM melts and the required energy is not enough to halt the heating. Theoretical calculations performed showed that the melting of the PCM in the case with 5 and 10 wt.% gave an improvement by increasing the time until critical temperature is reached with 4 % and 7.3 %, compared to a pure concrete sample. The melting of the PCM is responsible for 1 % respectively 2 % of that time increased compared to the pure concrete sample. The rest of the increase in time comes from the PCMs thermal properties which is higher than the cement. The literature study shows that there exist many suitable PCM for increasing a building material’s fire resistance, some of which are already used as fire retardants. It also shows that PCM can affect a material’s fire resistance in more ways than just the heat storage (latent heat) in the melting phase.    The conclusion of this report is that substituting concrete with MCHP in powder form is not suitable and does not affect the concretes fire resistance. But the usage of PCM in concrete should not be dismissed. There exist different ways to implement the PCM into the concrete which could give a desirable result.

Irreversible electroporation has recently emerged as an effective focal ablation technique. When performed clinically, the procedure involves placing electrodes into, or around, a target tissue and applying a series of short, but intense, pulsed electric fields. Oftentimes, patient specific treatment plans are employed to guide procedures by merging medical imaging with algorithms for determining the electric field distribution in the tissue. The electric field dictates treatment outcomes by increasing a cell's transmembrane potential to levels where it becomes energetically favorable for the membrane to shift to a state of enhanced permeability. If the membrane remains permeabilized long enough to disrupt homeostasis, cells eventually die. By utilizing this phenomenon, irreversible electroporation has had success in killing cancer cells and treating localized tumors. Additionally, if the pulse parameters are chosen to limit Joule heating, irreversible electroporation can be performed safely on surgically inoperable tumors located next to major blood vessels and nerves. As with all technologies, there is room for improvement. One drawback associated with therapeutic irreversible electroporation is that patients must be temporarily paralyzed and maintained under general anesthesia to prevent intense muscle contractions occurring in response to pulsing. The muscle contractions may be painful and can dislodge the electrodes. To overcome this limitation, we have developed a system capable of achieving non-thermal irreversible electroporation without causing muscle contractions. This progress is the main focus of this dissertation. We describe the theoretical basis for how this new system utilizes alterations in pulse polarity and duration to induce electroporation with little associated excitation of muscle and nerves. Additionally, the system is shown to have the theoretical potential to improve lesion predictability, especially in regions containing multiple tissue types. We perform experiments on three-dimensional in vitro tumor constructs and in vivo on healthy rat brain tissue and implanted tumors in mice. The tumor constructs offer a new way to rapidly characterize the cellular response and optimize pulse parameters, and the tests conducted on live tissue confirm the ability of this new ablation system to be used without general anesthesia and a neuromuscular blockade. Situations can arise in which it is challenging to design an electroporation protocol that simultaneously covers the targeted tissue with a sufficient electric field and avoids unwanted thermal effects. For instance, thermal damage can occur unintentionally if the applied voltage or number of pulses are raised to ablate a large volume in a single treatment. Additionally, the new system for inducing ablation without muscle contractions actually requires an elevated electric field. To ensure that these procedures can continue to be performed safely next to major blood vessels and nerves, we have developed new electrode devices that absorb heat out of the tissue during treatment. These devices incorporate phase change materials that, in the past, have been reserved for industrial applications. We describe an experimentally validated numerical model of tissue electroporation with phase change electrodes that illustrates their ability to reduce the probability for thermal damage. Additionally, a parametric study is conducted on various electrode properties to narrow in on the ideal design. / Ph. D.

Recently, buildings have been receiving more serious attention to help reduce global energy consumption. At the same time, thermal comfort has become an increasing concern for building occupants. Phase Change Materials (PCMs), which are capable of storing and releasing significant amounts of energy by melting and solidifying at a given temperature, are perceived as a promising opportunity for improving the thermal performance of buildings. This is because they use their thermophysical properties and latent heat while transforming state (or phase) as a feature for thermal energy storage systems to reduce overall energy demand, specifically during peaks hours, as well as to improve thermal comfort in buildings. This research aims to provide an overview of opportunities and challenges for the utilization of PCMs in the Architecture, Engineering, and Construction (AEC) sector, a broader understanding of specifically promising technologies, and a clarification of the effectiveness of different applications in building enclosures design especially in exterior walls. The research discusses how PCMs can be incorporated within building enclosures effectively to enhance building performance and improve thermal comfort while reducing heating and cooling energy consumption in buildings. The major objectives of the research include studying the properties of PCMs and their potential impact on building construction, clarifying PCMs selection criteria for building application, identifying the effectiveness of utilizing PCMs on saving energy, and evaluating the contribution of utilizing PCMs in building enclosures to thermal comfort. The research uses an exploratory quantitative approach that contains three main stages: 1) a systematic literature review, 2) laboratory experiments, and 3) validation to meet the goal of the research. Finally, by extrapolating results, the research ends with a practical assessment of application opportunities and how to effectively utilize PCMs in exterior walls of buildings. / PHD / With the growing concern of energy savings and selecting the most efficient way to provide thermal comfort for buildings’ users, buildings need to be constructed with an effective utilization method of materials and systems. Phase Change Materials (PCMs) have the ability to moderate temperatures within a specific range. They can be applied to reduce the energy used in buildings and improve thermal comfort. This is because they absorb heat when materials melt and release it when materials solidify. This research studies the properties of PCMs and their potential impact on building construction and clarifies PCM selection criteria for building applications. Also, the research illustrates the impacts of utilizing PCMs in different positions within an external wall on energy savings and thermal comfort. The research uses an exploratory quantitative approach that contains three main stages: 1) a systematic literature review, 2) laboratory experiments, and 3) validation to meet the goal of the research. Finally, the research ends with a practical assessment of application opportunities and how to effectively utilize PCMs in exterior walls of buildings.

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One of prospective procedures of absorbing thermal energy and releasing it during the required time is the application of phase change materials known as PCMs in building envelopes. High thermal energy storage (TES) materials has been a technology that effects the energy efficiency of a building by contributing in using onsite resources and reducing cooling or heating loads. Currently, many TES systems are emerging and contributing in building assemblies, however using an appropriate type of TES in a specific building and climate requires an in-depth knowledge of their properties. This research aims to provide a thorough review of a broad range of thermal energy storage technologies including their potential application in buildings. Subsequently, a comparative study and simulation between a basecase and an optimized model by PCM is thoroughly considered to understand the effect of high thermal storage building's shell on energy efficiency and indoor thermal comfort. Specifically this study proposes that the incorporation of PCM into glazing system as a high thermal capacity system will improve windows thermal performance and thermal capacity to varying climatic conditions. The generated results by eQUEST energy modeling software demonstrates approximately 25% reduction in cooling loads during the summer and 10% reduction in heating loads during the winter for optimized office building by PCM in hot arid climate of Arizona. Besides, using PCM in glazing system will reduce heat gain through the windows by conduction phenomenon. The hourly results indicates the effect of PCM as a thermal energy storage system in building envelopes for building's energy efficiency and thermal regulation. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.