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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.

The construction industry strives for climate neutrality by 2045-2050 with a focus oncollaboration, innovation, and efficient use of resources to reduce greenhouse gasemissions and promote sustainable construction methods. This degree project from theBuilding Engineering program at Halmstad University investigates energy efficiency andoptimization of the asphalt manufacturing process, especially heat storage in silos, incollaboration with Skanska Industrial Solutions.The study applies qualitative methods, including interviews with experts and visits to anasphalt plant in Sperlingsholm, Halmstad. The theoretical framework includes sustainabledevelopment, sustainable road networks, hot mix asphalt (HMA), and design andmaterials for heat storage silos.The research methodology included data collection, interviews, field visits andsimulations with COMSOL Multiphysics to analyse temperature changes and comparedifferent silo design options. Autodesk AutoCAD was used to create 2D drawings.The results emphasize energy efficiency and sustainability in asphalt manufacturing, withthe potential to reduce greenhouse gas emissions through optimized silo design andinsulation. Specifically, the implementation of heat storage silos shows a significantreduction in oil consumption and 𝐶𝑂2 emissions. The study further recommends researchfor validation and improvement in real production environments and contributes withinsights into sustainable construction methods, underscoring the need for technologicalinnovation to meet the environmental challenges in the construction industry.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: Solar energy is a time dependent, high-temperature radiant energy resource. The utility of a solar thermal energy system increases if the hot temperature source is available when it is needed most. This is realized by the thermal storage of the solar energy. Thermal storage gives greater versatility to a solar energy system by decoupling the heat source from the heat sink. A large quantity of energy may be stored during the melting process in a phase change material (PCM) within a small temperature range. This molten PCM can then deliver its absorbed heat at a constant temperature in a heating application. In this study a phase change storage system (PCS) is developed and proposed for a solar water heating application. This PCS system stores more heat per unit mass than would be possible with water across the same temperature range. The heat transfer rate in and out of many PCMs is slow because of the low thermal conductivity of the PCM. However, heat transfer enhancers (HTE), such as heat pipes and fins may be added to enhance heat absorption and heat removal rates. Heat pipes have the inherent capability to transfer heat at high rates across large distances, even where the temperature difference is small. In this thesis a description is given of a PCS system consisting of paraffin wax as the PCM and which uses rectangular heat pipes in conjunction with aluminium fins to enhance heat transfer. The storage design is modular and each module has the characteristic that enhanced heat transfer in and out of the PCM is possible when the module is heated or cooled. It also has the capability to quickly absorb or alternatively to supply heat at a nearly constant temperature during the phase change of the module. A rectangular module was designed and built. The module was then analysed under controlled heat absorption and heat removal cycles. The heat up experiment involved an electrical kettle as the hot temperature source. The heat sink was a mains water heat exchanger. The experimental results were compared to those of a transient numerical model, which calculates theoretically how the module will perform thermally under the given test conditions. The numerical model of the experimental set-up was validated when it was found that the numerical model results resemble the experimental results. The numerical model was then adapted to simulate a novel solar water heater (SWH) with an additional PCS container. The improvement over previous designs is that the additional storage container can be heated to a higher temperature than the allowable geyser temperature. The system also heats up and cools down at a faster rate than would be possible without the HTEs. From the numerical simulation the size and performance of such a system is determined. This numerical analysis indicated that a phase change storage system in a SWH application will increase the hot water delivered by a given solar collector and geyser by increasing the storage capacity and by heating up the geyser overnight for early morning hot water use. / AFRIKKANSE OPSOMMING: Son energie is ‘n tyd afhanklike, hoë temperatuur radiasie energiebron. Die bruikbaarheid van ‘n sontermiese energie sisteem verhoog indien die hoë temperatuur bron beskikbaar is wanneer dit die meeste benodig word. Dit kan verwesenlik word deur die sonenergie termies te stoor. Termiese storing bied groter veelsydigheid aan ‘n sontermiese stelsel deur effektief die hittebron te ontkoppel van die hitte sink. ‘n Groot hoeveelheid energie kan, gedurende die smeltingsproses in ‘n faseveranderingsmateriaal binne ‘n nou temperatuurband gestoor word. Hierdie gesmelte materiaal kan weer op sy beurt in die waterverhittingstoepassing, die geabsorbeerde hitte teen ‘n konstante temperatuur oordra. In hierdie studie word ‘n sonwaterverwarmer stelsel wat aangepas is deur ‘n addisionele latente hittestoor daaraan te heg, voorgestel. Hierdie faseverandering hittestoor kan meer hitte stoor as wat water in dieselfde temperatuur band sou kon. Die hitteoordrag tempo na en van baie van die faseveranderingsmateriale (FVM) is egter as gevolg van die lae termiese geleidingskoëfisient, stadig. Hierdie eienskap kan gelukkig verbeter word deur hittepype en hitteoordrag verhogings materiaal soos vinne by te voeg. Hittepype het die inherente eienskap om hitte teen ‘n hoë tempo oor groot afstande, oor te dra, selfs oor ‘n klein temperatuurverskil. In hierdie tesis word ‘n ondersoek rakende ‘n faseverandering storingsisteem wat bestaan uit paraffien was as die FVM en reghoekige hittepype wat te same met met aluminium finne gebruik word om die hitteoordragtempo te verhoog, beskryf. Die stoorontwerp is modulêr en elke module het die kenmerk van hoë hitteoordrag na en van die FVM. Die module het verder ook die eienskap om vining hitte te absorbeer of hitte af te gee. Dit gebeur teen ‘n konstante temperatuur gedurende die faseverandering van die FVM. Presies so ‘n reghoekige module is ontwerp en gebou en onder beheerde hitte absorbering- en hitte verwyderingsiklusse analiseer. Tydens die verhittings eksperiment is ‘n elektriese ketel van gebruik gemaak wat gedien het as die hoë temperatuur bron. Die hitte sink was ‘n hitteruiler wat kraanwater van ‘n konstante hoogte tenk ontvang het. Die resultate van die volledige toets is met die resultate van tydafhanklike numeriese model vergelyk. Hierdie numeriese model bereken teoreties wat die module se storing verrigting onder gegewe toets omstandighede sal wees. Die numeriese model se resultate het goed vergelyk met die resultate van die eksperimente. Die numeriese model van die module is toe aangepas om ‘n sonwaterverwarmer met addisionele stoortenk wat fase verandering materiaal gebruik, te simuleer. Hierdie ontwerp is anders as vorige ontwerpe in die sin dat hoër temperature as wat die warmwatertoestel kan hanteer, in die faseverandering storingstenk, bereik kan word. Die sisteem kan ook as gevolg van die hitteoordrag verhoging materiaal, vinniger verhit of afkoel en teen ‘n vinniger tempo. Die simulasie van die sonwaterverwarmer met FVM word gebruik om die grootte en verrigting van die sisteem te bepaal. Hierdie numeriese model toon aan dat wanneer ‘n addisionele faseverandering storingstelsel in ‘n sonwaterverwarmer toepassing gebruik word, die warm water wat die verbruiker uit die sisteem kan verkry, kan verhoog. Die rede hiervoor is dat meer hitte gestoor kan word, wat beskikbaar gemaak word aan die warm water tenk.

The dissertation investigates typical operation modes of the heat storage tank in the small-scale cogeneration (CHP) plant, analyses formation of thermal stratifi-cation in such storage tank and presents the simulation of the stratification. The main aim of the dissertation is to investigate peculiarities of operation modes of heat storage tank in small-scale CHP plant, develop an algorithm allowing to choose the storage tank volume and present a model allowing determination of thermal stratification in the storage tank at any time of its operation. / Disertacijoje nagrinėjami būdingi šilumos akumuliacinės talpos veikimo režimai, susiformuojantys nedidelės galios kogeneracinėje jėgainėje, tiriamas šiluminės stratifikacijos susidarymas tokioje talpoje ir atliekamas jos modeliavimas. Pagrindinis disertacijos tikslas – ištirti nedidelės galios kogeneracinės jėgainės šilumos akumuliacinės talpos veikimo režimų ypatumus, sudaryti algoritmą, padedantį parinkti tokios talpos tūrį ir pateikti modelį, leidžiantį nustatyti šiluminę stratifikaciją akumuliacinėje talpoje bet kuriuo jos veikimo metu.

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.

Made available in DSpace on 2014-06-11T19:33:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-10-24Bitstream added on 2014-06-13T20:05:37Z : No. of bitstreams: 1 oliveira_al_dr_jabo.pdf: 487509 bytes, checksum: 21986f8f6599c47af5da518d2f78570b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Foi estudada a eliminação de calor latente e estimado o fluxo térmico total ao sol e à sombra em cabras da raça Saanen mantidas em ambiente tropical, visando determinar importância da termólise evaporativa para esses animais e proporcionar subsídios para o estabelecimento de métodos de manejo em ambiente tropical. A evaporação total foi determinada por processo gravimétrico, usando-se um sistema de pesagem de precisão. A evaporação cutânea foi obtida por determinação direta através de uma cápsula ventilada; e a evaporação respiratória estimada a partir do fluxo térmico entre aparelho respiratório e o ambiente; determinaram-se ainda a estocagem térmica e as trocas convectivas e radiativas. Por ocasião de cada determinação, foram registradas a temperatura retal, a freqüência respiratória e a temperatura da superfície corporal, bem como variáveis ambientais: temperatura e umidade do ar, velocidade do vento e temperatura do globo negro. Foram avaliadas as características morfológicas do pelame (espessura da capa, comprimento médio, densidade numérica e ângulo dos pêlos) para cada animal. As análises estatísticas basearam-se no método dos quadrados mínimos para dados não-balanceados, tendo o modelo linear geral proposto incluído os efeitos: ambiente (fixo), animal (aleatório), interação animal x ambiente e regressão sobre a temperatura do ar, a umidade relativa, a temperatura radiante média, a temperatura da superfície corporal, a temperatura retal, a freqüência respiratória e a idade do animal, além das características morfológicas do pelame, no caso da evaporação cutânea. A termólise evaporativa compreendeu 61,5% da perda de calor para o ambiente, sendo a única via de perda térmica possível ao sol sob temperaturas radiante média acima de 35ºC... / The present work aimed at to study the elimination of latent heat and esteem the total thermal flow to the sun and the shade in Saanen goats in tropical environment, to determine importance of evaporative heat loss these animals and to provide subsidies for the establishment of methods of handling in tropical environment. The total evaporation was determined by means of gravimetrical process, for a weighing system of precision. The cutaneous evaporation was gotten by direct determination, by means of a ventilated capsule; the respiratory evaporation gotten by calculations of heat flow of respiratory device for environment. It was determined still the heat storage and the convective and radiative exchanges. For occasion of each determination, the rectal temperature, respiratory rate and surface temperature of the animal, as well as meteorological data: air temperature, relative humidity, wind speed and black globe temperature were register. The morphologic characteristics of the hair coat (coat thickness, hair length, numerical density and hair angle to skin) had been evaluated for each animal. The statistical analyses were carried through by the lest-squares method for not-balanced data. The considered model included the effect of environment and animal and the covariates: air temperature, relative humidity, mean radiating temperature, surface temperature, rectal temperature, respiratory rate and age of animal, beyond the morphologic characteristics of the hair coat for cutaneous evaporation. Heat loss evaporative understands 62.2% of the heat carried for environment exchange, being the way possible to the sun under radiant temperatures above of 35º...(Complete abstract, click electronic access below)

This thesis investigates the feasibility and benefits of integrating Thermochemical heat Storage (THS) into a CHP (Combined Heat and Power) plant. A case study is done for the CHP-plant in Sala, Sweden, with a maximum heat output of 20.9 MW and maximum electricity output of 9.6 MW. The THS type considered is calcium oxide in a hydroxide system. The fluctuations in electricity price for years 2020, 2030 and 2040 are considered and low-price electricity is used as a charging source for THS. During charging the superheated steam (endothermic reaction) is used to cover some of the district heating demand. The high temperature discharge from the THS is used as reheat in the Rankine cycle. The operations are modeled in Ebsilon and optimization is done in MATLAB using genetic algorithm with the objective to achieve maximum annual revenue. The results suggest that it is not feasible to introduce THS with electricity as a charging source in year 2020, but in 2030 and 2040 THS shows promising potential. The biggest increase in revenue comes from reduced fuel consumption, and, to a lesser extent, increased income from electricity. It is concluded that Calcium hydroxide is a promising candidate for integration into CHP during large electricity price fluctuation. The main drivers for the feasibility of this combination are high fuel price and large fluctuations of electricity price.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-11-08T18:16:29Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO (RAUL XAVIER).pdf: 7673146 bytes, checksum: 78c15f2215008f6151a91e0b52d56488 (MD5) / Made available in DSpace on 2016-11-08T18:16:29Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO (RAUL XAVIER).pdf: 7673146 bytes, checksum: 78c15f2215008f6151a91e0b52d56488 (MD5) Previous issue date: 2016-06-20 / CNPQ / O presente estudo teve como objetivo geral, avaliar a temperatura da superfície de alguns materiais utilizados na pavimentação do solo, de recintos urbanos na cidade do Recife-PE, visando determinar a contribuição desses materiais nas mudanças das variáveis climáticas, sobretudo para o aumento da temperatura e para a redução da umidade relativa do ar, objetivando mitigar os impactos das superfícies impermeabilizadas na qualidade ambiental dos recintos urbanos e melhorar o conforto térmico dos citadinos. Para isto, foram utilizadas duas imagens do sensor TM, a bordo do satélite Landsat 5, e elaborada uma classificação das temperaturas de superfície na cidade do Recife. Foi selecionado um recorte espacial, representativo de maior temperatura que corresponde ao 1ª Jardim de Boa Viagem, zona sul da cidade. A partir dos aspectos da morfologia urbana e características de uso e ocupação do solo, foram selecionados quatro pontos para a coleta de dados climáticos. Caracterizou-se o perfil microclimático do local e identificaram-se nove tipos de materiais de pavimentação. Em seguida mediram-se as temperaturas de superfície de cada material relacionando-os com as variáveis climáticas e os aspectos da forma urbana do local. Os materiais de pavimentação que apresentaram as maiores temperaturas de superfície tenderam a possuir cores escuras, como o asfalto, pedras portuguesas nas cores pretas, blocos de concreto intertravado nas cores vermelho e cinza-escuro e o concreto, apesar de possuir uma coloração cinza-claro. Estes materiais possuem baixos valores de albedo, visto que absorvem grandes quantidades de radiação solar, armazenados em seu interior, sob a forma de calor. Outro ponto a ser destacado, é a impermeabilidade dos materiais. As superfícies que apresentam as maiores temperaturas tendem a ser totalmente impermeáveis, ou seja, superfícies que não possuem poros, impedindo que a água da chuva escoe por entre os pavimentos e seja armazenada nas camadas e no solo abaixo dele. Em dias ensolarados, a água, quando evapora, resfria o pavimento. O presente estudo constatou que os materiais mais utilizados no revestimento do solo urbano são os que possuem as maiores temperaturas de superfície. Portanto, recomenda-se a preservação de áreas verdes e da arborização já existente; a elaboração de políticas públicas que incentivem a implantação da vegetação dentro de grandes empreendimentos imobiliários e industriais, ou seja, um maior percentual de utilização do terreno destinados a vegetação. / This study aimed to evaluate the surface temperature of some materials used in the ground paving, urban venues in the city of Recife-PE, in order to determine the contribution of each material changes in climate variables, especially the increase in temperature and reducing the relative humidity of form to mitigate the impacts of impervious surfaces in the environmental quality of urban precincts and improve the thermal comfort of city dwellers. For this, two TM images were used aboard the Landsat 5 satellite, and elaborated a classification of surface temperatures in the city of Recife. It selected a spatial area, representative of higher temperature that corresponds to the 1st Garden Boa Viagem, area south of the city. From the aspects of urban morphology and characteristics of use and occupation of land, four points were selected for the collection of weather data, the microclimate of the local profile was characterized and were identified nine types of paving materials. In a row were measured surface temperatures of each material relating them to the climatic variables and aspects of urban form of the site. The paving materials with the highest surface temperatures tended to have dark colors, such as asphalt, Portuguese stones in black colors, concrete blocks interlocked in red and dark gray, and the concrete itself, despite having a gray color -of course. These materials have low albedo values, since they absorb large amounts of solar radiation stored therein in the form of heat. Another point to note is the impermeability of the materials. The surfaces that exhibit higher temperatures tend to be totally impervious, ie, surfaces that do not have pores as they allow rain water to drain through the floor and be stored in the layers beneath it and ground. On sunny days, when the water evaporates, it cools the pavement. This study found that the most commonly used materials in the urban floor coverings, are those with the highest surface temperatures. Therefore recommends the preservation of green areas and the existing trees; the development of public policies that encourage the establishment of vegetation in large real estate and industrial projects, ie, a higher percentage of use of the land for the planting of seedlings.

Orientador: Kamal Abdel Radi Ismail / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T07:25:07Z (GMT). No. of bitstreams: 1 Paixao_LouryvalCoelho_M.pdf: 3782849 bytes, checksum: a8900089f4a65a6ee50cdc15b2dba208 (MD5) Previous issue date: 2009 / Resumo: O processo de solidificação de um material de mudança de fase em uma região anular ao redor de um cilindro resfriado pela passagem de um fluido em seu interior é estudado numérica e experimentalmente, objetivando aplicações em sistemas de armazenamento de calor latente. A solução do problema de mudança de fase é feita utilizando o método de imobilização de fronteiras, onde se aplica a transformada de coordenadas de forma que no novo sistema a fronteira móvel e irregular seja fixa e paralela às demais. O método de volumes finitos é usado para discretização das equações do modelo matemático que em seguidas são resolvidas computacionalmente. Os experimentos são realizados para 4 temperaturas e 3 números de Reynolds do fluido de trabalho: -5, -10, -15, -20ºC e 741, 1484, 2280 respectivamente. Posteriormente, foi introduzido um promotor de turbulência helicoidal para aumentar o coeficiente de transferência de calor onde foram realizados 6 experimentos para temperaturas de -10, -15ºC e, com os mesmos números de Reynolds anteriores. Os resultados experimentais foram comparados com os resultados numéricos. / Abstract: The process of solidification of a material of change of phase in a region annular around of a cylinder cooled by fluid passing in its interior is studied numerical and experimentally, objectifying applications in systems of storage of latent heat. The boundary immobilization technique is used for solving for phase-change problem. The coordinate transformation is performed so that in the new system the moving and irregular boundary become fixes and parallel to the others. The finite-volume methodology is used discretization of the equation from the mathematical model witch are than solved by a computer program. The experiments are made for 4 temperatures and 3 Reynolds numbers of the fluid: 741, 1484, and 2280 respectively. A turbulence promoter was insert inner tube to enhancement the coefficient of heat transference, where 6 experiments were made to -10 and -15ºC temperature with the previous Reynolds numbers. The experimental results had been compared with the numerical results. / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica