Дисертації: "Electric and gas heating"

1

Míková, Šárka. "Vytápění bytového komplexu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227537.

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This diploma thesis focuses on the design of heating and hot water reservoir in an apartment complex. For three variants of heat sources (gas condensing boiler, heat pump and electric boiler) is evaluated their economic profitability for heating and hot water heating. For the best selected heat sources is drawn up the technical solution of heating in the apartment complex.

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2

Ladomérská, Jana. "Vytápění objektu zdroji na různé druhy paliv." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227584.

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In my final thesis I am processing a proposal for heating and preparing hot water for a restaurant with accommodation. This is a three-storey brick house. It is situated on the territory of the Ústí region. The aim of my work is to propose and to assess the appropriate heat source for this object. In the object I chose heating radiators. The proposal is processed in two variants. In the first variant, I suggest a cascade of condensing boilers using as a source of heat. In the second variant, I suggest a cascade of electrical boilers. Hot water will be prepared in reservoir of warm water. The source of hot water will be the same as the source for heating.

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3

Barufi, Clara Bonomi. "Identificação de barreiras para a ampliação do uso de gases combustíveis para aquecimento de água no setor residencial." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-29102008-124300/.

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Este trabalho é motivado pela constatação de que a instalação de sistemas de aquecimento de água a gases combustíveis nos apartamentos novos pode ter custos inferiores à instalação de sistemas elétricos e pelas perspectivas de aumento da oferta de gás natural no país. Considerando isso e a perspectiva de aumento no consumo de eletricidade, a pesquisa procura identificar barreiras para expansão do uso dos sistemas a gás, sugerindo formas para que sejam superadas. Considerando que as decisões tomadas durante a construção definem em grande medida os usos da energia nos imóveis, o trabalho se baseia numa pesquisa de campo desenvolvida por meio de entrevistas com agentes da construção civil. Inclui ainda uma contextualização sobre o uso da energia no setor residencial. Essa contextualização mostra a evolução do mercado brasileiro de gases combustíveis, a baixa participação histórica desses energéticos no aquecimento de água e as perspectivas de crescimento da oferta de gás natural no país. Também descreve o uso de água quente para banho, abordando os principais sistemas de aquecimento disponíveis no mercado paulistano. Perspectivas relativas ao aumento do consumo de eletricidade e de desenvolvimento do mercado imobiliário completam essa contextualização. A pesquisa mostra que já há ampla disseminação do uso de sistemas de aquecimento de água a gás na cidade de São Paulo. Esse desenvolvimento deveu-se a fatores como a obrigatoriedade da introdução de tais sistemas em alguns tipos de construção a partir de meados dos anos 1980, as exigências de conforto dos consumidores de classe média e classe alta e ao racionamento de eletricidade de 2001. Por outro lado, verifica-se que o chuveiro elétrico continua sendo usado nas construções voltadas para a classe baixa. Como esse é o segmento com maior demanda por novas residências, identifica-se um espaço importante para substituição de eletrotermia e aumento do uso dos gases combustíveis para aquecimento de água.
This research is motivated by the verification that the installation of gas based water-heating systems in new apartments may be cheaper than the use of electric systems. It is also motivated by the perspectives of a growing supply of natural gas in the country. Considering these points and the perspective of general growing use of electricity, this research identifies barriers to expand the use of gas based systems, suggesting ways to overcome those barriers. Considering that the energy uses in an apartment are largely affected by decisions taken during the construction of the building, the study is based on a field research developed through interviews with construction agents. It also includes a definition on the residential energy use, which details the gas (natural gas and LPG) market evolution, the historically reduced use of these fuels in water-heating systems, and the perspectives of rising supply of natural gas in Brazil. It also describes the use of hot water to hygiene, considering the main systems available in São Paulo. This context is completed by the perspectives related to the increase of electricity demand and the current real estate market development. The research concludes that gas based water-heating systems are already extensively used in São Paulo. This development is related to the mandatory use of those systems in some apartment configurations, the users demand for comfort, and the 2001 electric power shortage. On the other hand, it shows that electric showers are still largely used in building of poorer families. Since this segment has the largest demand for new houses in the country, there is space to substitute energy consumed for thermal purposes with the direct use of gas.

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4

Jurka, Vít. "Návrh vytápění z pohledu primární energie." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226837.

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This master´s thesis proposal addresses the heating from the perspective of primary energy in the object. The building is located in Brno and is used as a villa with a pool hall. The object of this work is the selection of appropriate variants of three heat sources (gas boiler, pellet and electric) in terms of primary energy. The project is design of the heating system chosen mode of heat, which is a pellet boiler. The theoretical part is focused on the pellets and their history, classification, properties, production, storage and transport.

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5

Novik, Frode Karstein. "Power system for electric heating of pipelines." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8936.

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Direct electrical heating (DEH) of pipelines is a flow assurance method that has proven to be a good and reliable solution for preventing the formation of hydrates and wax in multiphase flow lines. The technology is installed on several pipelines in the North Sea and has become StatoilHydros preferred method for flow assurance. Tyrihans is the newest installation with 10 MW DEH for a 43 km pipline. However, the pipeline represents a considerable single-phase load which makes the power system dependent on a balancing unit for providing symmetrical conditions. This limits the step out distance and is not suitable for subsea installation. Aker Solutions has proposed several specially connected transformers for subsea power supply of DEH systems, Scott-T being one of them. The Scott-T transformer is a three-to-two-phase transformer which provides balanced electrical power between the two systems when the two secondary one-phase loads are equal. By implementing this transformer, it can be possible to install the power supply subsea as there is no need for a balancing unit. In addition, the system may be applicable for long step out distances. This is because the pipeline is inductive and can use the reactive power produced by the long cable which also can increase the critical cable length. There are however some limitations on this system using the Scott-T transformer. There is a large variation in the magnetic permeability between individual joints of the pipeline. This can result in different load impedance of the two pipe sections connected to the Scott-T transformer. The result is unbalance in the power system. The method of symmetrical components is applied to investigate the behavior during unbalanced loading of the Scott-transformer. The relationship between the negative- and the positive sequence component of the current is used to express the degree of unsymmetry. For the simulations in SIMPOW, the Scott-T transformer is modelled by the use of Dynamic Simulation Language. The simulations on the DSL model give correct and reliable results for analysing the the degree of unsymmetry in the Scott-T transformer. When the load impedance of one pipe section is varied, simulation proves that it can change between 0.75 and 1.34 per unit of the other pipe impedance. The Scott-T transformer does still provide electrical power between the two systems which is below the limit for the degree of unsymmetry (15%). Case 1 and Case 2 introduce two possible configurations for a subsea DEH system with the Scott-T transformer implemented. The configurations include an onshore power supply which is connected to a subsea power system for direct electrical heating and a subsea load at the far end of the subsea cable. The pipeline in Case 1 is 100 km long and is divided into two pipe sections of 50 km which are connected to a Scott-T transformer. The pipeline in Case 2 is 200 km long and is divided into four pipe sections of 50 km each. There are two Scott-T transformers in Case 2. For normal operation of the subsea load (50 MW, cosfi=0.9) and heating the pipe content from the ambient sea emperature, the results indicate that tap changers are necessary to keep the Scott-T transformers secondary terminal voltage at 25 kV. This meets the requirement in both cases for heating the pipe content from 4 to 25 degrees celsius within 48 hours after a shutdown of the process. The degree of unsymmetry is zero for both cases when the system is operated as normal. However, all system simulations indicate that reactive power compensation has to be included for Case 1 as well as for Case 2 in order to have a power factor of unity at the onshore grid connection. The fault scenarios indicate that the degree of unsymmetry is dependent on both the type of fault and the power supply in the system. For Case 1, the relationship (I-/I+) is only of 3.3% in the subsea cable when there is a short-circuit at DEHBUS3, but as much as 87% at the grid connection. The degree of unsymmetry in the Scott-T transformer is then 67%. This is far beyond the limit for maximum negative sequence component of 15%. The significant unsymmetry in the line between the grid and BUS1 is most likely due to the large power delivered to the fault. During the fault, the reactive power delivered to the system increases from 10.6 Mvar to 131.9 Mvar after the fault, but the active power increases only from 75.2 MW to 87.1 MW. This means that it is most likely the reactive power that contributes to the consequent unsymmetry and negative sequence component of the current. There are two Scott-T transformers installed in Case 2. If the DEH system is only heating the pipe section closest to shore (at DEHBUS33), simulations show that the three-phase power system becomes unsymmetric which results in different phase currents. The degree of unsymmetry at the grid connection is 32% when only the pipe section at DEHBUS33 is heated. In addition, the unbalance in the three-phase system caused by SCOTT1 involves unbalance in the SCOTT2 transformer as well. The load voltages are not equal in magnitude and dephased of 90 degrees for this mode, but are 32 kV and 35 kV respectively and dephased of 88 degrees. This concludes a very important behavior of the Scott-T transformer. The simulations conclude that the Scott-T transformer provides symmetrical conditions for both configurations when the two load impedances are equal. However, Case 2 shows an important result when installing two Scott-T transformers in the same system. Unbalanced loading of one of the specially connected transformers gives unsymmetrical conditions in the three-phase system which results in unbalanced load voltages for the other Scott-T transformer. The analysis is limited to the configurations given for Case 1 and Case 2, but shows typical results when an alternative transformer connection is implemented in a DEH system.

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6

Madhavi, S. "Carrier Mobility And High Field Transport in Modulation Doped p-Type Ge/Si1-xGex And n-Type Si/Si1-xGex Heterostructures." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/294.

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Modulation doped heterostructures have revolutionized the operation of field effect devices by increasing the speed of operation. One of the factors that affects the speed of operation of these devices is the mobility of the carriers, which is intrinsic to the material used. Mobility of electrons in silicon based devices has improved drastically over the years, reaching as high as 50.000cm2/Vs at 4.2K and 2600cm2/Vs at room temperature. However, the mobility of holes in p-type silicon devices still remains comparatively lesser than the electron mobility because of large effective masses and complicated valence band structure involved. Germanium is known to have the largest hole mobility of all the known semiconductors and is considered most suitable to fabricate high speed p-type devices. Moreover, it is also possible to integrate germanium and its alloy (Si1_zGex ) into the existing silicon technology. With the use of sophisticated growth techniques it has been possible to grow epitaxial layers of silicon and germanium on Si1_zGex alloy layers grown on silicon substrates. In tills thesis we investigate in detail the electrical properties of p-type germanium and n-type silicon thin films grown by these techniques. It is important to do a comparative study of transport in these two systems not only to understand the physics involved but also to study their compatibility in complementary field effect devices (cMODFET). The studies reported in this thesis lay emphasis both on the low and high field transport properties of these systems. We report experimental data for the maximum room temperature mobility of holes achieved m germanium thin films grown on Si1_zGex layers that is comparable to the mobility of electrons in silicon films. We also report experiments performed to study the high field degradation of carrier mobility due to "carrier heating" in these systems. We also report studies on the effect of lattice heating on mobility of carriers as a function of applied electric field. To understand the physics behind the observed phenomenon, we model our data based on the existing theories for low and high field transport. We report complete numerical calculations based on these theories to explain the observed qualitative difference in the transport properties of p-type germanium and ii-type silicon systems. The consistency between the experimental data and theoretical modeling reported in this work is very satisfactory.

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7

Saraiva, José Carlos. "Custo das opções para o aquecimento de água na habitação de interesse social em São Paulo - CDHU." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-19072012-110713/.

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A dissertação utiliza a pesquisa como método experimental e investigativo para identificar os fatores condicionantes para a definição da infraestrutura de aquecimento de água para banho (gás, elétrico e solar térmico) nas edificações residenciais de interesse popular, construídas no município de São Paulo. A partir das informações de três projetos e do dimensionamento da infraestrutura de cada opção, determinam-se seus custos para um projeto típico, exclusivamente para o aquecimento de água para banho. Também são determinados os custos de aquisição, instalação, infraestrutura e operação de cada configuração. O método Life Cycle Cost Analysis (LCCA) é utilizado para comparar financeiramente diversas alternativas. Os resultados permitem avaliar o interesse na realização de infraestruturas combinadas de forma a possibilitar a qualquer momento a utilização de aparelhos instantâneos, elétrico ou a gás, com ou sem o apoio solar térmico. Essa infraestrutura combinada permite a liberdade de escolha ao usuário, de forma individual e a qualquer momento, do aquecimento de água para banho, tendo em vista o seu custo benefício, eventualmente associadas às oportunidades oferecidas pelas distribuidoras de energias e/ou pelos fabricantes de aparelhos e/ou políticas públicas. Os resultados alcançados apresentam importantes dados para subsidiar discussões e análises comparativas, estabelecendo os caminhos para orientar a escolha da infraestrutura.
The paper uses research as investigative and experimental method to identify the factors responsible for the definition of infrastructure for bathing water heating (gas, electric and solar thermal) in residential buildings of popular interest, built in São Paulo. Based on the information from three projects and the sizing of the infrastructure of each of them, the costs for a typical project exclusively for bathing water heating, are determined. Besides that, are also determined, the costs of acquisition, installation, infrastructure and operation of each configuration. The method - Life Cycle Cost Analysis (LCCA) is used to compare the various financial alternatives. The results allow to evaluate the interest in carrying out infrastructures combined to enable anytime instant use of appliance, electric or gas, with or without the solar thermal support. This combined infrastructure allows the user free choice, individually and at any time, for heating water for bathing, in view of its cost benefit, possibly combined with the opportunities offered by energy distributors and / or the device manufacturers and / or public policy. The results present relevant data to support comparative discussion and analysis, setting ways to guide the choice of infrastructure.

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8

Holth, Erik. "Model Predictive Control of mixed solar and electric heating." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9106.

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In this report we will model a heat system consisting of a heat storage tank and an application. The heat storage tank is supplied by a heating element and heated water from a solar collector. The main objective of the heat system is to mainatian a reference temperature in the application (a house). Weather forecasts will be used as weather data affecting the heat system. We will assume that the weather forecasts and the actual weather will be the same. The heat sytem will consist of simplified nonlinear differential equations and be controlled by a model predictive controller (mpc). The mpc controller will use a linearized model of the nonlinear process. The average predicted outside temperature from the weather forecasts will be used as nominal value for the same temperature in the linearized model in the mpc controller. The mpc controller will measure some disturbances to make more efficient control. The most imortant disturbance will be the temperature of the water coming out of the solar collector, that will flow into the heat storage. By measuring this temperature, the mpc controller can apply it to its predictor and make sure that the power of the heating element in the heat storage is reduced when solar collector heated water is available. This is to make sure that the heat storage has enough capacity to receive the heated water from the solar collector, while still maintaining a reasonable temperature in the heat storage. Simulation with different weighting of the inputs in the mpc controller will show that heating element power consumption is influenced by these weights.

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9

Hinchliffe, Stephen. "Solid-state high-frequency electric process heating power supplies." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/32518.

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A detailed critical review has been made of both solid state power devices and circuit topologies with emphasis on their application to high frequency electric process heating power supplies operating between 3and 30 MHz. A number of prototype units have been designed and constructed and their suitability for high frequency induction heating and dielectric heating applications investigated. Desirable qualities being robustness, tolerance to load mismatch, ease of design, simplicity and cost of constituent components as compared with present day valve equipment The experience gained in these investigations has resulted in the choice of the power MOSFET as the most appropriate device and Class E amplifier as being the most applicable circuit topology for the generation of RF power for high frequency electric process heating applications. A practical and theoretical study has been made of the limitations of the power MOSFET as a high frequency switching device. The effect of source feedback on the switching speed of T03 packaged devices has been investigated by the addition of a second source terminal in a specially modified T03 package. Novel drive circuits have been developed enabling high frequency switching of both power and RF MOSFETs. These have been employed in inverters operating at 3.3 MHz at power levels up to 600 W and at frequencies between 7 and 27 MHz at power levels over 100 W, with conversion efficiencies of up to 95%.

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10

Soderlund, Matthew Roger. "Congeneration dedicated to heating and cooling." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/17672.

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11

Wongsa-Ngasri, Pisit. "Ohmic heating of biomaterials: peeling and effects of rotating electric field." The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1078447669.

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12

Leung, Tommy (Tommy Chun Ting). "Coupled natural gas and electric power systems." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98547.

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Thesis: Ph. D., Massachusetts Institute of Technology, Engineering Systems Division, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 235-240).
Scarce pipeline capacity in regions that rely on natural gas technologies for electricity generation has created volatile prices and reliability concerns. Gas-fired generation firms uniquely operate as large consumers in the gas market and large producers in the electricity market. To explore the effects of this coupling, this dissertation investigates decisions for firms that own gas-fired power plants by proposing a mixed-integer linear programming model that explicitly represents multi-year pipeline capacity commit- ments and service agreements, annual forward capacity offers, annual maintenance schedules, and daily fuel purchases and electricity generation. This dissertation's primary contributions consist of a detailed representation of a gas-fired power-plant owner's planning problem; a hierarchical application of a state-based dimensionality reduction technique to solve the hourly unit commitment problem over different tem- poral scales; a technique to evaluate a firm's forward capacity market offer, including a probabilistic approach to evaluate the risk of forced outages; a case study of New England's gas-electricity system; and an exploration of the applicability of forward capacity markets to reliability problems for other basic goods.
by Tommy Leung.
Ph. D.

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13

Ojha, Abhi. "Coupled Natural Gas and Electric Power Systems." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78666.

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Decreasing gas prices and the pressing need for fast-responding electric power generators are currently transforming natural gas networks. The intermittent operation of gas-fired plants to balance wind generation introduces spatiotemporal fluctuations of increasing gas demand. At the heart of modeling, monitoring, and control of gas networks is a set of nonlinear equations relating nodal gas injections and pressures to flows over pipelines. Given gas demands at all points of the network, the gas flow task aims at finding the rest of the physical quantities. For a tree network, the problem enjoys a closed-form solution; yet solving the equations for practical meshed networks is non-trivial. This problem is posed here as a feasibility problem involving quadratic equalities and inequalities, and is further relaxed to a convex semidefinite program (SDP) minimization. Drawing parallels to the power flow problem, the relaxation is shown to be exact if the cost function is judiciously designed using a representative set of network states. Numerical tests on a Belgian gas network corroborate the superiority of the novel method in recovering the actual gas network state over a Newton-Raphson solver. This thesis also considers the coupled infrastructures of natural gas and electric power systems. The gas and electric networks are coupled through gas-fired generators, which serve as shoulder and peaking plants for the electric power system. The optimal dispatch of coupled natural gas and electric power systems is posed as a relaxed convex minimization problem, which is solved using the feasible point pursuit (FPP) algorithm. For a decentralized solution, the alternating direction method of multipliers (ADMM) is used in collaboration with the FPP. Numerical experiments conducted on a Belgian gas network connected to the IEEE 14 bus benchmark system corroborate significant enhancements on computational efficiency compared with the centralized FPP-based approach.
Master of Science

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14

Marcotte, Michèle. "Ohmic heating of viscous liquid foods." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ55357.pdf.

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15

Silva, Edson Batista da. "Performance analysis of gas turbine opeerating with low heating value fuels." Instituto Tecnológico de Aeronáutica, 2012. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2215.

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Gas turbines are generally designed to operate with a specific fuel type. Power plants usually use gas turbine models which operate with natural gas, but there is the possibility of using other kinds of gaseous fuels. In some instances, a fuel of a different calorific value may be available near the power plant site, making the use of the fuel of interest to the plant owner. These fuels can be gases obtained from steel (from blast furnaces and coking plants), from gasification processes of coal or biomass, among others. In this work, a performance analysis on a gas turbine, which was originally designed to run on natural gas, was carried out after changing to lower calorific value fuels. For the purpose of this study, a well known gas turbine performance calculation program was used named GasTurb11. A gas turbine model was created and calculated at design point. This model was defined as the reference gas turbine. Off-design performance studies were done to adjust the reference gas turbine with data from the chosen gas turbine. A good agreement was obtained between the results of the model operating with natural gas at off-design point and the data available from literature for the reference gas turbine. After the validation process, further performance tests were conducted while changing the fuel calculation value. A reduction in the compressor';s surge margin was identified when using the fuels studied. Two strategies are adopted in order to study the effects of the surge margin: the first by extracting a portion of the air at the compressor exit in order to recover the surge margin, and the second strategy was to establish a fixed value for the surge margin. These control strategies proved to be technically feasible and ensured that the gas turbine operated safely at off-design point.

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16

Wang, Kaiyang. "Ring opening polymerisation of ɛ-caprolactone using microwave electric and magnetic heating". Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49540/.

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The work presented in this thesis aims to highlight the differences in heating methods, which are conventional, microwave electric, and microwave magnetic heating, for the ring opening polymerisation of ɛ-caprolactone, as well as the development of an alternative catalyst that is specifically used in microwave magnetic heating to replace the current benchmark catalyst. Chapter 1 introduces the background of this thesis. There is also an overview of various types of biodegradable polymers, polymerisation techniques, and catalysts used in the polymerisation. An introduction into the basics of microwave and microwave electric and magnetic heating is also provided in this chapter. Chapter 2 goes on to explain the analytical techniques that are used to characterise the polymer and the dielectric properties. Procedures in locating the reaction vessel at the microwave electric and magnetic dominant positions in the microwave reactor are described. Experimental procedures that are used throughout this thesis are also explained. Chapter 3 investigates the dielectric properties of various types of metal complexes in both solid powder form and when dissolved in a solvent, to study the factors that affect the interaction between these complexes and the microwave electromagnetic field. Then further investigation into a series of heating experiments of solutions containing these complexes is carried out, to see if the empirical observations follow the same trend as predicted from the dielectric property results. Chapter 4 explores the first application of microwave magnetic heating to the ring opening polymerisation of ɛ-caprolactone catalysed by metal halides, and compares this to the conventional and microwave electric heating, and investigates the effects of different heating methods have on the overall polymerisation. This chapter also investigates various metal halides that experienced different response to the microwave electric and magnetic heating to see how this affects the polymerisation process. Chapter 5 describes the development of novel organometllic catalysts that can be used in the ring opening polymerisation of ɛ-caprolactone with the application of microwave magnetic heating, and possibly replace the existing benchmark catalyst Sn(Oct)2. The use of various heating methods is also investigated to see what effects they have on the overall process.

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Боянівський, Владислав Петрович. "Підвищення ефективності печей для переплавки алюмінієвого брухту". Master's thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/24376.

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Магістерська дисертація на тему «Підвищення ефективності печей для переплавки алюмінієвого брухту»: 104 с., 35 рис., 12 табл., 4 додатки, 15 джерел. Об’єкт дослідження – піч для переплавки алюмінієвого брухту. Мета роботи – підвищення енергетичної ефективності та удосконалення конструкції печей для переплавки алюмінієвого брухту. Проаналізовані основні способи підвищення енергетичної ефективності. Наведені результати розрахунків енергетичної ефективності печі місткістю 6 т, потужністю 600 кВт, для переплвки алюмінієвого брухту. Показано, що за рахунок зменшення терміну відкриття форкамер знизилися витрати підведеної теплоти в печі на 45 %, а за рахунок зміни теплоізоляційних шарів - на 21 %. Підібрані газоспалюючі пристрої – пальники типу ГПП-5 та наведена схема їх розміщення в боковій передній стінці печі. Виконані розрахунки енергетичної та економічної ефективності переводу печі з електричного нагріву на газовий, при цьому для газового нагріву витрати підведеної теплоти зменшуються на 9 – 10 % порівняно з електричним. Розрахунками визначено, що використання газового нагріву порівняно з електричним економічно більш ефективно, оскільки витрати на природний газ в циклі плавки для модернізованої печі потужністю 600 кВт зменшуються приблизно на 10 %. Розроблена конструкція печі з нахиленим склепінням, для якої порівняно з традиційним зменшується термін плавки у середньому на 11 %, а ККД підвищується на 7 %. Для утилізації теплоти димових газів обрано односторонньо-голчастий металевий рекуператор для підігріву дуттьового повітря з площею поверхні нагріву 12 м2. В результаті встановлення рекуператора температура димових газів знижується від 800 °С до 390 °С, при цьому температура дуттьового повітря підвищується від 20 °С до 350 °С. Величина економії палива складає 16,9 %. На базі програмного забезпечення Solid Works побудовані геометричні моделі багатошарових стінок печі та отримані результати розподілу температурних полів по товщині огороджувальних конструкцій. Наведені результати співставні з експериментальними даними отриманими на реальних печах. Передбачені заходи з безпечної і комфортної роботи в приміщенні науково-дослідної лабораторії та заходи з пожежної безпеки та безпеки в надзвичайних ситуаціях. Розроблено стартап-проект за шаблоном Business Model Canvas.
Master's dissertation on "Improving the efficiency of furnaces for aluminum scrap remelting": 104 p., 35 f., 12 tables, 4 applications, 15 sources. The object of the study is an oven for aluminum scrap remelting. The purpose of the work is to increase energy efficiency and improve the design of furnaces for aluminum scrap remelting. Analyzed the main ways of improving energy efficiency. Presented the results of calculations of the energy efficiency of a 6-ton capacity kiln with a capacity of 600 kW for the remelting of aluminum scrap. It is shown that due to reduction of the opening time of the firebox, the cost of the supplied heat in the furnace decreased by 45% and due to the change of the thermal insulation layers - by 21%. Selected gas-fired devices - burners type GPP-5 and the scheme of their placement in the side of the front wall of the furnace. The calculations of the energy and economic efficiency of the furnace conversion from the electric heating to the gas have been performed, while for the gas heating the costs of the supplied heat are reduced by 9 - 10% in comparison with the electric one. Calculations have shown that the use of gas heating compared to electric is economically more efficient, since the cost of natural gas in the melt cycle for a 600 kV upgraded furnace decreases by about 10%. Developed the furnace design with an inclined vault for which the average melting time decreases by 11% compared to the traditional one, and the efficiency increases by 7%. For utilization of flue gases heat was chosen one-sided-needle metal recuperator for heating of blown air with the area of the heating surface 12 m2. As a result of the installation of the recuperator, the temperature of the flue gases is reduced from 800 °C to 390 °C, while the ambient air temperature rises from 20 ° C to 350 C. The amount of fuel savings is 16.9 %. Based on the Solid Works software, constructed geometric models of the multilayer walls of the furnace and obtained the results of the distribution of temperature fields along the thickness of the enclosing structures. The presented results are comparable to the experimental data obtained on real furnaces. Made provision for safe and comfortable work in the premises of a research laboratory and fire and safety measures in emergencies. A startup project based on the Business Model Canvas template has been developed.
Магистерская диссертация на тему «Повышение эффективности печей для переплавки алюминиевого лома» 104 с., 35 рис., 12 табл., 4 приложения, 15 источников. Объект исследования - печь для переплавки алюминиевого лома. Цель работы - повышение энергетической эффективности и совершенствование конструкции печей для переплавки алюминиевого лома. Проанализированы основные способы повышения энергетической эффективности. Приведены результаты расчетов энергетической эффективности печи вместимостью 6 т, мощностью 600 кВт, для переплавки алюминиевого лома. Показано, что за счет уменьшения срока открытия форкамер снизились расходы подведенной теплоты в печи на 45%, а за счет изменения теплоизоляционных слоев - на 21%. Выбраны газосжигающие устройства - горелки типа ГПП-5 и приведена схема их размещения в боковой передней стенке печи. Выполнены расчеты энергетической и экономической эффективности перевода печи с электрического нагрева на газовый, при этом для газового нагрева расходы подведенной теплоты уменьшаются на 9 - 10% по сравнению с электрическим. Расчетами установлено, что использование газового нагрева по сравнению с электрическим экономически более эффективно, поскольку затраты на природный газ в цикле плавки для модернизированной печи мощностью 600 кВт уменьшаются примерно на 10%. Разработана конструкция печи с наклонным сводом, для которой по сравнению с традиционным уменьшается срок плавки в среднем на 11%, а КПД повышается на 7%. Для утилизации теплоты дымовых газов выбран односторонне-игольчатый металлический рекуператор для подогрева дутьевого воздуха с площадью поверхности нагрева 12 м2. В результате установки рекуператора температура дымовых газов снижается от 800 °С до 390 °С, при этом температура дутьевого воздуха повышается от 20 °С до 350 °С. Величина экономии топлива составляет 16,9%. На базе программного обеспечения Solid Works построены геометрические модели многослойных стенок печи и получены результаты распределения температурных полей по толщине ограждающих конструкций. Приведены результаты сопоставимы с экспериментальными данными полученными на реальных печах. Предусмотрены меры по безопасной и комфортной работе в помещении научно-исследовательской лаборатории. Разработан стартап-проект по шаблону Business Model Canvas.

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Boswell, Michael John. "Gas engines for domestic engine-driven heat pumps." Thesis, Oxford Brookes University, 1992. http://radar.brookes.ac.uk/radar/items/37f7ed18-4b86-6ab3-8ba6-1c27947fb1ce/1.

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An experimental and theoretical investigation has been undertaken into the performance of a small prototype, water-cooled, gas-fuelled engine designed for use as a domestic heat pump prime mover. In light of the application, fuel type and capacity, both experimental and theoretical study of similar engines is at best poorly documented in the literature. A comprehensive engine test facility has been set up, incorporating extensive calorimetry, a separate lubrication system, emissions monitoring and high speed data acquisition for in-cylinder pressure measurement and analysis. Two new experimental cylinder heads have been designed together with new induction and exhaust systems, both to improve performance and to enable further investigation of the combustion process. A preliminary parametric study of the combustion process established that the thermal efficiency and emission levels are strongly dependent on operational and design variables and that a lean, fast-burning combustion process in a slow speed engine coupled with careful control of other operating variables had the potential for improving efficiency, reducing emissions, and lowering frictional losses and noise levels with enhanced durability. Accordingly, new information has been obtained relating to rates of heat release, energy flows and emission levels over a wide range of design and operating conditions with utility for and consistent with an envelope of conditions appropriate to such a lean burn strategy. Modelling techniques have been developed and used as diagnostic tools in conjunction with the experimental data to investigate the influence of operating and design variables on rates of heat release and energy flows. The models have been validated using the experimental data over a wide range of operating conditions and incorporated into a thermodynamic engine model for use as a sub-model in an overall heat pump model. The experimental and theoretical programme has provided a valuable insight into the lean burn strategy and realised a considerable improvement in the performance of the prototype engine. The theoretical study benefits from a new approach to small gas engine design and development.

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Paterson, Lindsay Jane. "An investigation of soil heating by natural gas pipelines in southern Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0020/MQ55700.pdf.

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Chung, Tse-Ming. "Prediction of zone temperatures, cooling loads and illuminances from numerical simulation of the interaction between fluorescent lighting and HVAC systems." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/33238.

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A numerical model has been developed for the dynamic simulation of heat and radiation transfer from lamps and ballasts in an enclosure. The model, named LITEAC1, calculates temperatures, cooling loads and illuminances at each simulation time step. LITEAC1 is an improvement upon existing models in the literature in the following aspects: it performs dynamic simulation for all nodes without assuming that some nodes are massless; it calculates illuminances on room surfaces; and it runs faster on a desktop computer. In order to refine the simulation of the two-way interaction between lighting and HVAC systems, a fluorescent lamp positive column discharge model, named LAMPPC, has been incorporated into LITEAC1 to improve calculation of the conversion of input electrical energy into light, thermal radiation and heat. LAMPPC employs established principles in plasma physics to quantify the energy conversion processes.

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Lilly, Dana Elizabeth. "Analysis and performance of gas-electric hybrid chiller systems." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/15996.

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Farnsworth, Kimberly Dawn Richards. "Variable frequency microwave curing of polymer dielectrics." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/10928.

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Lindquist, Charlie. "Flue gas heat recovery for district heating : Analysis of flue gas condensation on a crematorium facility at Hovdestalund, Västerås." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54759.

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This degree project investigates the technical and economic possibility of a heat recovery system on Hovdestalund crematorium. The crematorium will have a solution that allows the facility to become both a producer and consumer to the district heating network. This work became relevant because the Swedish church is going to expand Hovdestalund with additional ovens and therefore energy efficiency is in their sight. With the help of Mälarenergi, a business model to be connected to the district heating network is created for Hovdestalund. The project will go through how to handle the flue gases, either by connecting the crematorium to the district heating network, or to cool down the gases with a cooling tower. When using the flue gases for district heating, two cases of different heat recovery potential are investigated. The first case is taken from an already made investigation by Kadesjös on Hovdestalund where they assume a potential of 400kWh/cremation. The second case is taken from literature study where the potential is 242,5kWh/cremation. A technical solution that can separate when heat is supplied to the network versus withdrawn is chosen to help with billing and general surveillance across the system. Connecting Hovdestalund to the network will not affect Mälarenergi’s operation negatively, the temperature can reach around 95 degrees Celsius and thus considered as high-grade heat. Having a lower temperature supplied to the network at a higher amount could lead to some problems in lowering the networks overall temperature. Using a cooling tower would not be as optimal as it would only cool down the flue gases, there would be no self-consumption nor heat sold to the network. Most of the investment cost will come from laying down a new pipeline for the district heating. The pipeline will have a length of roughly 140m which results in a cost of ~1MSEK. Along with the district heating unit, the total investment cost becomes 1 138 000 SEK. To investigate the economic possibility, the net present value is used. The systems profit comes from selling excess heat or the value of self-consuming heat rather than buying it from Mälarenergi. Between the two recovery potential cases, bought heat, self-consumed heat, and heat demand will be the same as the only difference will be the amount of sold heat. These will be the same because during operation time of the ovens, the recovered heat will cover the hourly demand entirely. In case 1, the amount of sold heat will result in ~90tSEK annually which will lead to a payback time of 6-7 years. Case 2 will sell heat for ~45tSEK annually, this will lead to a payback time of 8-9 years. Compared to Kadesjös result which received a final cost of 10MSEK after 20 years, this report shows a final cost of 7,4MSEK and 6,49MSEK based on recovery potential.

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Sai-man, Leung Alfred. "Measured and simulated light losses in furnished interiors lit by electric lighting." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243242.

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Simon, M. J. "The thermal performance of water cooled panels in electric arc steelmaking furnaces." Thesis, Sheffield Hallam University, 1989. http://shura.shu.ac.uk/20363/.

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The initial stage of the work was a study of an 80 tonne industrial furnace, taking observations, panel water temperature data and samples of slag layers from the sidewalls. This resulted in a simple model of layer formation which explained the observed structures, and also the effect of slag layer thickness on heat losses was examined. However, the complexity and variety of structures found were such that a full series of direct thermal conductivity measurements was deemed impractical, and so a theoretical model to calculate the thermal conductivity of complex structures from the thermal conductivities of it s components was developed. Other aspects of heat transfer both within the furnace and from the furnace interior to the water cooling were also explored. In order to obtain a reliable value of thermal conductivity for the slag component of layer structures, a technique was developed to measure the thermal conductivity of the slag. This consisted of firstly determining a viable route for the production of homogenous samples, followed by the design, construction and refinement of an experimental measuring rig. After a large number of preliminary measurements, a series of thermal conductivity values at temperatures between 300 and 800 °C were measured using operating conditions calibrated against a heat storage brick sample of known thermal conductivity. These results were used to provide the data for the theoretical thermal conductivity model, which was then applied to real structures for which thermal data was available. Comparison of the results showed good correlation. Finally, in the appended case study, the heat loss calculation was applied for various furnace situations to identify the potential heat loss savings that could be achieved by controlling the slag layer thickness and structure, and the financial implications.

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Polyzakis, Apostolos. "Technoeconomic evaluation of trigeneraton plant: Gas turbine performance, absorption cooling and district heating." Thesis, Cranfield University, 2006. http://hdl.handle.net/1826/1832.

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This PhD thesis is a demand led study taking into account changes in ambient conditions and power settings of a tri-generation power plant. Includes an evaluation tool for combined heat, cooling and power generation plant. The thesis is based on an overall technical-economic analysis of the tri-generation system, including: 1. Energy demand analysis and evaluation of actual tri-generation case studies. 2. Modelling of the prime mover (Gas Turbine, GT) 3. Modelling of the absorption cooling system, (LiBr/Water). 4. Economic analysis and evaluation of the entire tri-generation plant. Initially, the main effort is to carry out research concerning the energy demands of different actual cases. The research includes sourcing, collecting, classification and evaluation of the available information. The cases cover a wide range of economic life and the resulting data specifies the energy needs which the purposed tri-generation power plant needs to cover. The second part deals with the prime mover (namely the Gas Turbine, GT) modelling and simulation. The technical part of the assessment includes the Design Point (DP) and Off Design (OD) analysis of the GT. In other words, the performance analysis simulates different thermodynamic cycles (Simple, or with Heat Exchanger), and different configurations (one or two shafts). Also, the computer programming code is capable of simulating the effects of the use of different types of fuel, ambient conditions, part load conditions, degradation, or the extraction of power for district heating or for absorption cooling. The third part includes the simulation of the absorption cooling system alone and/or in co-operation with the prime mover. The simulation is based upon the premise that the original prime mover is replaceable. Finally, an evaluation methodology of tri-generation plants, is introduced taking into account, both technical facts and economic data -based on certain cases from Greek reality- helping the potential users to decide whether it is profitable to use such technology or not. The economic scene will include the basic economic facts such as initial cost, handling and operational cost (fuel prices, maintenance etc), using methodology based on Net Present Value (NPV). This thesis suggests several tri-generation technology modes. The more economic favourable than the conventional technology is the 2-shaft simple cycle mode for the cases of international airport (12MW total power demand) and the isolated island (120MW), while the 1-shaft simple cycle mode is the more economic favourable for the case of hotel (1MW). The main contribution of the thesis is that it provides an intergraded realistic tool, which simulates the future operation (technical and economic) of a trigeneration plant, capable of helping the potential investor decide if it is profitable to proceed with the investment.

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27

Tanikella, Ravindra V. "Variable frequency microwave processing of materials for microelectronic applications." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/10271.

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Wendelstorf, Jens. "Ab initio modelling of thermal plasma gas discharges (electric arcs)." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961148527.

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Davies, Mark H. "Numerical modelling of weld pool convection in gas metal arc welding /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phd2563.pdf.

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30

Smailes, Allan J. "Thermal modelling of gas metal arc welding using finite element analysis /." Title page, contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ENS/09enss635.pdf.

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31

Durham, Emily Kilpatrick. "Moderate Electric Field Treatment for Saccharification of Cellulosic Materials." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1431082825.

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32

Dalla, Silvia Carla. "Modelling of minority ion kinetics in tokamak plasmas during ion cyclotron resonant heating." Thesis, London South Bank University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245069.

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Cherukupalli, Sudhakar Ellapragada. "Surface charge accumulation on spacers under switching impulses in sulphur hexafluoride gas." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26973.

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Metal encapsulation with compressed sulphur hexafluoride gas insulation has reduced the size of power substations and improved their reliability. Due to the superior insulating properties of this gas, its application in Gas Insulated Transmission lines (GITL) and Gas Insulated Substations (GIS) is increasing. Such systems invariably require solid support spacers for supporting high voltage conductors and for compartmentalizing sections of the systems. It has been found that, although the dielectric strength of sulphur hexafluoride is high compared to other gases, in the presence of a solid spacer, the dielectric integrity of the system is impaired. For DC GIS and GITL, free of any particulate contamination, anomalous flashover during a polarity reversal of the applied voltage has been attributed to charge accumulation on the spacer surface. The present work examines the effect of switching impulse voltages on the charge accumulation on support spacers in sulphur hexafluoride gas and the effect of AC precharging on impulse flashover. The charge accumulation on the spacer has been measured using a capacitive probe. A three-dimensional surface charge simulation technique has been developed to convert the probe potential measurements to an equivalent charge distribution. Electric field variation on the spacer surface due to this computed charge can be then obtained with this program. The results indicate that spacers acquire charges even under impulse voltage application in non-uniform field gaps. These charges affect the prebreakdown phenomenon and the breakdown behavior of spacer gaps. Under AC voltages, spacers in uniform fields do not acquire charges as has been reported by previous investigators. Under non-uniform field conditions however, AC precharging of spacers does affect the impulse flashover. The variation however, seems to fall within the statistical scatter of pure impulse flashover.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate

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34

Reniers, Jorn. "Analysis of a real-time signal for greenhouse gas emissions of district heating consumption." Thesis, KTH, Industriell ekologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169508.

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The district heating system (DHS) of Stockholm is one of the largest systems in the world with a total yearly production of 10TWh of heat and 2TWh of electricity (through combined heat and power plants). Large amounts of greenhouse gasses (GHG) are emitted to produce this heat and electricity. Given the goal of the City of Stockholm to reduce the amount of GHG emissions to 3 ton per capita in 2015 and to keep reducing emissions at a similar rate after 2015, it is important to identify the potentials for further reductions. Numerous studies have been done on how the DHS can become more sustainable by installing new generation units. However, also the consumers have an influence on the DHS. After all, it are the consumers who decide when and how much heat or electricity they use. Most former studies and environmental guidelines for the DHS in Stockholm focussed on the producer side. This thesis looks at the consumer perspective of the (heat of the) district heating system. A real-time signal giving the greenhouse gas emissions of individual households is developed and its potential and challenges are discussed. With this signal, households that want to minimise their environmental impact have a tool to decrease their environmental impact by changing their consumption. This can be a first step to transform the DHS to a smart district heating system. First, generic models to calculate the dynamic greenhouse gas intensity of the heat production of district heating and to calculate the greenhouse gas emissions related to the heat consumption of households are suggested. Then the feedback signal with those real-time household emissions is calculated for representative households in Stockholm based on data of Stockholm’s DHS and data about hot tap water consumption in Sweden. Results indicate that variations in household level greenhouse gas emissions mostly reflect changes in consumption but can also result from changes by the producer. Intraday variations are mostly caused by changes in hot tap water consumption, while variations on a timescale of a few days are caused by changes in heating consumption (changing weather) and changes made by the producer (to use different fuels). Then several scenarios are calculated, each scenario looking at the actions a consumer can take to shift or reduce his/her consumption (decrease hot tap water usage, lower indoor temperature etc.). The real-time household emissions are calculated again to see if the signal gives the needed incentives (is the household rewarded for its effort? Does it get further incentives?). It was found that a strong time-incentive (to decrease consumption when it saves most emissions) is missing if the average perspective is used to calculate the emission intensity of the heat production. Also, the results confirmed the finding that the feedback signal might not reflect changes in consumption. Finally, challenges for the signal are discussed. One of the major hurdles is the fact that household consumption of heat (heating and hot tap water) can often not be measured on a household level. Thus, it has to be estimated but it seems very difficult to get this estimation accurate enough to give correct feedback to households, especially about the emissions saved by their efforts to reduce/shift their consumption. Secondly, the time resolution should be chosen well to still get accurate results but not make the signal to data-intensive. Finally, the result is heavily dependent on the chosen methodology (average or marginal perspective? Do you account for the electrical side of the DHS? How about the distribution losses? Etc.).

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Cross, Richard Barrie Michael. "Low temperature (<150°C) hydrogenated amorphous silicongrown by PECVD with source gas heating." Thesis, De Montfort University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.502097.

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Low temperature « 150°C) hydrogenated amorphous silicon grown by PECVD with source gas heating Richard Barrie Michael Cross Hydrogenated amorphous silicon (a-Si:H) is a semiconductor that is widely used in a variety of applications. A particularly important development has been the incorporation of this material into thin film transistor (TFT) arrays for the active matrix addressing of liquid crystal displays. Plasma Enhanced Chemical Vapour Deposition (PECVD) is one of the most successful techniques currently in use for the deposition of device quality a-Si:H. However, there is an increasing desire to improve process compatibility with low cost, plastic substrates. This entails trying to reduce the deposition temperature from approximately 250 - 300°C to below 150 °C, whilst maintaining material quality. This thesis describes the design of a novel, low temperature PECVD system incorporating the facility to pre-heat the deposition source gases. The physical and electronic properties of a-Si:H deposited at <150°C are investigated, and the performance of TFT structures incorporating optimised material as the active layer is described. It is shown that the physical properties of a-Si:H produced at a substrate temperature of 125°C with the source gas line heated to 400 °C are commensurate with films deposited at 250-300 °C. The hydrogen content of the optimised film was found to be 10.5 %, with a Tauc bandgap of 1.66 eV. Pre-heating of the source gases also leads to an increase in the proportion ofhydrogen bonded in the monohydride configuration. It is suggested that the diffusion of the film-forming gaseous species is enhanced by this technique, resulting in a reduction in the degree of disorder within the film and hydrogen elimination. Consequently, the concentration of hydrogen and the Tauc bandgap also decrease, leading to an increase in photoconductivity of one order of magnitude. TFTs exhibit a switching ratio of 105 , which is approximately an order of magnitude smaller than high temperature a-Si:H TFTs, but a comparable OFF current of approximately 10.12A. However, the field effect mobility of these devices is very poor (10.3 cm2V·1s·I). This is thought to be due to a high interface state density at the boundary between the low temperature, gas-heated a-Si:H layer and the high temperature silicon nitride gate insulator.

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36

Polyzakis, Apostolos L. "Technoeconomic evaluation of tri-generation plant : gas turbine performance, absorption cooling and district heating." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/1832.

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This PhD thesis is a demand led study taking into account changes in ambient conditions and power settings of a tri-generation power plant. Includes an evaluation tool for combined heat, cooling and power generation plant. The thesis is based on an overall technical-economic analysis of the tri-generation system, including: 1. Energy demand analysis and evaluation of actual tri-generation case studies. 2. Modelling of the prime mover (Gas Turbine, GT) 3. Modelling of the absorption cooling system, (LiBr/Water). 4. Economic analysis and evaluation of the entire tri-generation plant. Initially, the main effort is to carry out research concerning the energy demands of different actual cases. The research includes sourcing, collecting, classification and evaluation of the available information. The cases cover a wide range of economic life and the resulting data specifies the energy needs which the purposed tri-generation power plant needs to cover. The second part deals with the prime mover (namely the Gas Turbine, GT) modelling and simulation. The technical part of the assessment includes the Design Point (DP) and Off Design (OD) analysis of the GT. In other words, the performance analysis simulates different thermodynamic cycles (Simple, or with Heat Exchanger), and different configurations (one or two shafts). Also, the computer programming code is capable of simulating the effects of the use of different types of fuel, ambient conditions, part load conditions, degradation, or the extraction of power for district heating or for absorption cooling. The third part includes the simulation of the absorption cooling system alone and/or in co-operation with the prime mover. The simulation is based upon the premise that the original prime mover is replaceable. Finally, an evaluation methodology of tri-generation plants, is introduced taking into account, both technical facts and economic data -based on certain cases from Greek reality- helping the potential users to decide whether it is profitable to use such technology or not. The economic scene will include the basic economic facts such as initial cost, handling and operational cost (fuel prices, maintenance etc), using methodology based on Net Present Value (NPV). This thesis suggests several tri-generation technology modes. The more economic favourable than the conventional technology is the 2-shaft simple cycle mode for the cases of international airport (12MW total power demand) and the isolated island (120MW), while the 1-shaft simple cycle mode is the more economic favourable for the case of hotel (1MW). The main contribution of the thesis is that it provides an intergraded realistic tool, which simulates the future operation (technical and economic) of a trigeneration plant, capable of helping the potential investor decide if it is profitable to proceed with the investment.

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37

Contreras, Jesse Alberto. "Axial Temperature Gradients in Gas Chromatography." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2645.

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The easiest and most effective way to influence the separation process in gas chromatography (GC) is achieved by controlling the temperature of the chromatographic column. In conventional GC, the temperature along the length of the column is constant at any given time, T(t). In my research, I investigated the effects of temperature gradients on GC separations as a function of time and position, T(t,x), along the column. This separation mode is called thermal gradient GC (TGGC). The research reported in this dissertation highlights the fundamental principles of axial temperature gradients and the separation potential of the TGGC technique. These goals were achieved through the development of mathematical models and instrumentation that allowed study of the effects of axial temperature gradients. The use of mathematical models and computer simulation facilitated evaluation of different gradient profiles and separation strategies prior to development of the instrumentation, providing theoretical proof of concept. Three instruments capable of generating axial temperature gradients, based on convective cooling and resistive heating, were developed and evaluated. Unique axial temperature gradients, such as nonlinear and moving sawtooth temperature gradients with custom profiles were generated and evaluated. The results showed that moving sawtooth temperature gradients allowed continuous analysis and were well-suited for comprehensive GCxGC separations. The use of custom temperature profiles allowed unique control over the separation power of the system, improving separations, as well as selectively increasing the peak capacity and signal-to-noise. A direct comparison of TGGC with conventional GC methods showed that TGGC produces equivalent separations to temperature programmed GC. This technology holds great promise for performing smart separations in which the column volume is most efficiently utilized and optimum separations can be quickly achieved. Moreover, precise control of the elution of compounds can be used to greatly reduce method development time in GC. This feature can be automated using feedback to develop efficient separations with minimum user intervention. This technology is of special interest in micro-GC systems, which allows relatively easy incorporation of resistive heating elements in the micro-column design.

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38

Kamanzi, Janvier. "Thermal electric solar power conversion panel development." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2527.

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Thesis (DTech (Engineering))--Cape Peninsula University of Technology, 2017.
The world has been experiencing energy-related problems following pressuring energy demands which go along with the global economy growth. These problems can be phrased in three paradoxical statements: Firstly, in spite of a massive and costless solar energy, global unprecedented energy crisis has prevailed, resulting in skyrocketing costs. Secondly, though the sun releases a clean energy, yet conventional plants are mainly being run on unclean energy sources despite their part in the climate changes and global warming. Thirdly, while a negligible percentage of the solar energy is used for power generation purposes, it is not optimally exploited since more than its half is wasted in the form of heat which contributes to lowering efficiency of solar cells and causes their premature degradation and anticipated ageing. The research is geared at addressing the issue related to unsatisfactory efficiencies and anticipated ageing of solar modules. The methodology adopted to achieve the research aim consisted of a literature survey which in turn inspired the devising of a high-efficiency novel thermal electric solar power panel. Through an in-depth overview, the literature survey outlined the rationale of the research interest, factors affecting the performance of PVs as well as existing strategies towards addressing spotted shortcomings. While photovoltaic (PV) panels could be identified as the most reliable platform for sunlight-to-electricity conversion, they exhibit a shortcoming in terms of following the sun so as to maximize exposure to sunlight which negatively affects PVs’ efficiencies in one hand. On the other hand, the inability of solar cells to reflect the unusable heat energy present in the sunlight poses as a lifespan threat. Strategies and techniques in place to track the sun and keep PVs in nominal operational temperatures were therefore reviewed.

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39

Prior, J. J. "A new multi-tracer gas technique for measuring interzonal air flows in buildings." Thesis, University of Westminster, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372387.

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40

Šťastný, Radek. "Technická zařízení budov v budovách s téměř nulovou spotřebou." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265411.

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Master´s thesis is focusing on zero energy building with technical equipment. The building was built in 70. decade of last century. It has been using for sport and cultular events until these days. Restaurant was connected to sport hall. First part is focusing on zero energy building and technical equipment, their using, combination and optimal connecting in systém. Second part solving how many fotovoltaic panels must be in the system to reching economic advantage. In third part is solving how to connecting fotovoltaic panels to the system.

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41

Nikopoulos, Achilles. "Design and energy analysis of a hybrid electric natural gas vehicle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40218.pdf.

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42

Agelii, Harald. "Dipole Orientation of Gas Phase Ubiquitin Using Time Dependent Electric Fields." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415340.

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The method of dipole orientation of protein complexes using electric fields plays a key role in the development of single particle imaging, since it enables orientation of the protein in vacuum. In the orientation process the protein is exposed to an external electric field along which the dipole axis of the protein will eventually align. Earlier studies using molecular dynamics simulations have implemented a constant electric field to examine the dipole orientation process. However, when injected into the electric field the protein experiences a gradually increasing field strength converging to some terminal field strength rather than a constant electric field. In order to examine the effects of the time-dependant nature of the electric field, in comparison to a constant one, fields with different time dependances were implemented in molecular dynamics simulations in vacuum performed with GROMACS. Ubiquitin was chosen as a model protein. The results of the study show time-increasing fields tend to result in slower orientation, but preserve the structure of the protein better than for a constant field. It was also shown that after 10 ns electric field exposure, with terminal field strengths greater or equal to 0.6Vnm^-1, there was no apparent difference of the average degree of orientation of proteins within the time-increasing fields and the constant one. However, for fields of greater or equal to 1.5Vnm^-1 the constant field tended to result in a larger change of the protein structure.

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43

Kaptain, Tyler J. "Hardware Scaled Co-Simulation of Optimal Controlled Hybrid Gas-Electric Propulsion." Cleveland State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu1631634390032462.

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44

Kamal, Rajeev. "Optimization and Performance Study of Select Heating Ventilation and Air Conditioning Technologies for Commercial Buildings." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6656.

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Buildings contribute a significant part to the electricity demand profile and peak demand for the electrical utilities. The addition of renewable energy generation adds additional variability and uncertainty to the power system. Demand side management in the buildings can help improve the demand profile for the utilities by shifting some of the demand from peak to off-peak times. Heating, ventilation and air-conditioning contribute around 45% to the overall demand of a building. This research studies two strategies for reducing the peak as well as shifting some demand from peak to off-peak periods in commercial buildings: 1. Use of gas heat pumps in place of electric heat pumps, and 2. Shifting demand for air conditioning from peak to off-peak by thermal energy storage in chilled water and ice. The first part of this study evaluates the field performance of gas engine-driven heat pumps (GEHP) tested in a commercial building in Florida. Four GEHP units of 8 Tons of Refrigeration (TR) capacity each providing air-conditioning to seven thermal zones in a commercial building, were instrumented for measuring their performance. The operation of these GEHPs was recorded for ten months, analyzed and compared with prior results reported in the literature. The instantaneous COPunit of these systems varied from 0.1 to 1.4 during typical summer week operation. The COP was low because the gas engines for the heat pumps were being used for loads that were much lower than design capacity which resulted in much lower efficiencies than expected. The performance of equivalent electric heat pump was simulated from a building energy model developed to mimic the measured building loads. An economic comparison of GEHPs and conventional electrical heat pumps was done based on the measured and simulated results. The average performance of the GEHP units was estimated to lie between those of EER-9.2 and EER-11.8 systems. The performance of GEHP systems suffers due to lower efficiency at part load operation. The study highlighted the need for optimum system sizing for GEHP/HVAC systems to meet the building load to obtain better performance in buildings. The second part of this study focusses on using chilled water or ice as thermal energy storage for shifting the air conditioning load from peak to off-peak in a commercial building. Thermal energy storage can play a very important role in providing demand-side management for diversifying the utility demand from buildings. Model of a large commercial office building is developed with thermal storage for cooling for peak power shifting. Three variations of the model were developed and analyzed for their performance with 1) ice storage, 2) chilled water storage with mixed storage tank and 3) chilled water storage with stratified tank, using EnergyPlus 8.5 software developed by the US Department of Energy. Operation strategy with tactical control to incorporate peak power schedule was developed using energy management system (EMS). The modeled HVAC system was optimized for minimum cost with the optimal storage capacity and chiller size using JEPlus. Based on the simulation, an optimal storage capacity of 40-45 GJ was estimated for the large office building model along with 40% smaller chiller capacity resulting in higher chiller part-load performance. Additionally, the auxiliary system like pump and condenser were also optimized to smaller capacities and thus resulting in less power demand during operation. The overall annual saving potential was found in the range of 7-10% for cooling electricity use resulting in 10-17% reduction in costs to the consumer. A possible annual peak shifting of 25-78% was found from the simulation results after comparing with the reference models. Adopting TES in commercial buildings and achieving 25% peak shifting could result in a reduction in peak summer demand of 1398 MW in Tampa.

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45

Yuan, Qiulin. "Studies of electric discharges and their interactions with gases." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/22086.

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Measurements of the effect of increasing the discharge column voltage gradient were investigated using argon based mixtures with nitrogen, oxygen and sulphur hexafluoride in a plasma torch. The theoretical calculation of the voltage gradient and the electron number density was based on the Saha equation which was modified for application to the gas mixtures. The investigations showed that a mixture of Ar and SF6 was most effective and increased the voltage gradient to 0.5 V/mm from 0.3 V/mm. The best mixture was 89% Ar, 10% N2 , 1% SF6 based on the highest increase of the voltage gradient and the least added gas. A model has been developed to illustrate the effects of dissociation, excitation, ionisation of gases and their effects on the discharge column voltage gradient: The mode of an electric discharge in Ar was investigated using spectroscopy. The study showed that for a glow discharge the 520.0 nm line and for an arc discharge the 427.1 nm line were unique. These lines were used to investigate a Glydarc electric discharge which was shown to be a mixture of the glow and the arc discharges. Measurements of the transition of the glow to arc in Ar with discharge current ranging from 0.1 A to 1.0 A at atmospheric pressure showed that at the lower value of discharge current (O. 25 A) the spectral lines were dominated by the near infra-red lines whereas at the higher value of discharge current (1.0 A) the spectral lines were included from the near infra-red to the near UV. The Glydarc electric discharge has been studied in still and fast air flows at atmospheric pressure over a range of discharge currents from 100 mA to 3 A. The results showed that the increase of the discharge voltage with increasing discharge current was due to increase of the discharge column length which varied with time and the air flow rate and was not due to a positive dynamic characteristic.

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46

Zavattoni, Laëtitia. "Conduction phenomena through gas and insulating solids in HVDC gas insulated substations, and consequences on electric field distribution." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT063/document.

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L'émergence des énergies renouvelables a entraîné le développement de nouvelles technologies pour la distribution de l'énergie sur de longues distances. Ces dernières sont basées sur le transport via de hautes tensions continues (HVDC) pour éviter les pertes capacitives. Ce réseau de distribution est interconnecté via des Postes Sous Enveloppes Métalliques (PSEM), dont l'isolation est composée de gaz sous pression (SF6) et d'isolants solides (résine époxy), qui doivent résister sous HVDC. Dans ces dispositifs, le champ électrique n'est plus déterminé par la permittivité relative des matériaux, mais par leurs résistivités et les phénomènes d'accumulation de charges. Dans le cas d'un isolant solide présentant une interface avec un gaz, des électrons ou des ions vont être susceptibles de se déplacer suivant les lignes de champ électrique et charger la surface de l'isolant solide. Le comportement des propriétés des isolants (solides et gazeux) constitue un enjeu majeur dans le développement de PSEM HVDC, notamment dans la compréhension des mécanismes d'accumulation et relaxation des charges.Dans ce travail de thèse, la caractérisation de l'isolant solide a d'abord été étudiée, basée sur des mesures de courants faibles bruits. Il est ainsi possible de mesurer le courant de fuite dans le volume et sur la surface des échantillons, dans une enceinte sous pression, à haut champ électrique et pour différentes températures. Ces mesures ont mis en évidence que les résistivités de volume et de surface sont fortement impactées par l'augmentation de la température et la teneur en eau des échantillons. Il a également été montré que la résistivité de surface a un comportement non-linéaire en fonction du champ électrique. Un modèle numérique a été développé pour simuler les résultats obtenus, et implémenter les propriétés de surface de l'isolant solide.Les propriétés isolantes du gaz ont également été étudiées pour différentes géométries de champ électrique, dans le but d'estimer la contribution du courant passant à travers le gaz, sur l'accumulation de charge en surface de l'isolant solide. Des courants non négligeables sont mesurés dans le gaz (~pA-nA). Pour déterminer les mécanismes responsables de la présence de tels courants, il a été caractérisé selon plusieurs paramètres (la rugosité de la surface de l'électrode, la nature du matériau, le champ électrique, la température et l'humidité relative). Cela a mis en évidence que les variations de courants dépendent du conditionnement du dispositif, et sont donc fortement influencés par l'humidité relative adsorbée sur les surfaces du dispositif (électrodes et cuves). En présence d'un système sec, de faibles courants sont mesurés (~pA), et augmentent en fonction de la température. A l'inverse, dans le cas d'un système humide, le courant diminue avec l'augmentation de la température. Ces résultats, combinés à l'influence de la rugosité de l'électrode, suggèrent fortement un mécanisme d'injection de charge à la surface de l'électrode, favorisé en présence d'eau adsorbée.Enfin, les résultats obtenus pour les deux isolants solides et gazeux sont utilisés pour élaborer un modèle numérique ayant une forme proche de celle de l'application industrielle, et permettent d'observer la modification de la distribution du champ électrique en présence de la concentration en eau et du gradient de température. Une estimation du courant circulant au travers des isolants est donc possible.En conclusion, ce travail donne les variations des résistivités de volume et de surface dans une résine époxy en fonction de la température et du champ électrique. Il met également en évidence la forte influence de l'humidité relative et de la température sur les mécanismes d'injection de charges qui contribuent au courant mesuré à travers le gaz. Cette caractérisation approfondie permet de développer une simulation qui prédit les variations de la distribution du champ électrique au sein d'un PSEM sous tension continue
The emergence of renewable energy leads to a development of new technologies for energy distribution across long distances. The latter will be based on High Voltage Direct Current (HVDC) to avoid capacitance losses. This network is interconnected using Gas Insulated Substation (GIS), which insulation is composed of pressurized gas (SF6) and solid insulators (epoxy resin), which have to withstand HVDC. The electric field is not anymore determined by permittivity of materials, but by resistivities and charge accumulation. In the case of an insulator with an interface with gas, electrons or ions will move across electric field lines and will charge the surface of the solid insulator. The behavior of insulator's properties (gas and solid) constitutes a major challenge for the development of HVDC GIS, to understand the charge relaxation/accumulation mechanisms.In this work, the characterization of solid insulator has first been investigated, based on a low-noise current measurement method. It is thus possible to measure the leakage current through samples and onto their surface, in a pressurized gas, at high electric field and for different temperatures. Those measurements permit to evidence that both volume and surface resistivities are strongly impacted by the increase of temperature and water concentration. It has also been shown that surface resistivity has a non-linear behavior with electric field. A numerical model was developed, to simulate experimental results, showing that the surface properties of the insulator can be implemented.Furthermore, the insulating properties of the gas were also investigated through different electric field geometry (coaxial and uniform), in order to estimate the contribution of current through gas on the charge accumulated on solid insulators. It has been found that a non-negligible current passes through the gas (~pA to nA). To determine the mechanisms responsible for such currents, the latter has been characterized depending on several parameters (electrode surface roughness, material nature, electric field, temperature and relative humidity). It revealed that the variations of currents are strongly impacted by the conditioning of the device and thus by the relative humidity adsorbed on electrodes and enclosure surfaces. In presence of a dry system (dry gas and device) low current were measured (~pA), which increases with temperature. On the contrary, in case of a “wet” system (humid gas and device) the current decreases with increasing temperature. Those results combined with the influence of the electrode roughness, strongly suggest a mechanism of charge injection at the electrode surface, enhanced by water adsorption.Finally, the results obtained for both solid and gaseous insulations are used to develop a numerical model with a shape close to the industrial application, and observe the modification of electric field distribution in presence of water concentration and temperature gradient. An estimation of current flowing through the insulator and gas is thus possible in case of uniform and gradient temperature.In conclusion, this work gives the variations of both volume and surface resistivities in an epoxy resin with temperature and electric field. It also evidences the major influence of relative humidity and temperature on charge injection mechanisms which contribute to the current measured through gas. The extensive characterization performed, enables to develop a simulation which predicts the variations of electric field distribution within an HVDC GIS

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47

Byerley, Aaron R. "Heat transfer near the entrance to a film cooling hole in a gas turbine blade." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329915.

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48

Vigueras, Zuniga Marco Osvaldo. "Analysis of gas turbine compressor fouling and washing on line." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2448.

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This work presents a model of the fouling mechanism and the evaluation of compressor washing on line. The results of this research were obtained from experimental and computational models. The experimental model analyzed the localization of the particle deposition on the blade surface and the change of the surface roughness condition. The design of the test rig was based on the cascade blade arrangement and blade aerodynamics. The results of the experiment demonstrated that fouling occurred on both surfaces of the blade. This mechanism mainly affected the leading edge region of the blade. The increment of the surface roughness on this region was 1.0 μm. This result was used to create the CFD model (FLUENT). According to the results of the CFD, fouling reduced the thickness of the boundary layer region and increased the drag force of the blade. The model of fouling was created based on the experiment and CFD results and was used to calculate the engine performance in the simulation code (TURBOMATCH). The engine performance results demonstrated that in five days fouling can affect the overall efficiency by 3.5%. The evaluation of the compressor washing on line was based on the experimental tests and simulation of the engine performance. This system demonstrated that it could recover 99% of the original blade surface. In addition, this system was evaluated in a study case of a Power Plant, where it proved itself to be a techno-economic way to recover the power of the engine due to fouling. The model of the fouling mechanism presented in this work was validated by experimental tests, CFD models and information from real engines. However, for further applications of the model, it would be necessary to consider the specific conditions of fouling in each new environment.

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49

Fsadni, Andrew M. "The fundamentals of two-phase flow in wet domestic central heating systems." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6953.

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An emerging trend in the building services industry is the installation of passive deaerators on the flow line of domestic wet central heating systems. To date, no data and theoretical models predicting the two-phase flow characteristics in domestic wet central heating systems are available in the open literature. This gap in literature has prevented essential design improvements to passive deaerators thus impeding the efficiency enhancement of such devices. Hence, the current study is aimed at assisting designers of deaeration devices by providing fundamental data and model correlations with respect to the two-phase flow characteristics typical in a wet domestic central heating system. For this purpose an experimental research project was adopted and several studies were carried out, including; (1) a comprehensive review to understand the background of the phenomena, (2) the design and construction of an experimental test rig to conduct the necessary investigations into the phenomenon of two-phase flow in domestic wet central heating systems, (3) the development of a reliable image capture and analysis technique, (4) the completion of a number of experiments to investigate typical bubble sizes, volumetric void fractions, bubble distributions and nucleation and dissolution rates and (5) the correlation of the data gathered as part of the present study with existing bubble size, nucleation and dissolution prediction models. This research has, for the first time, provided an in depth analysis into two-phase flow characteristics in wet domestic central heating systems through the use of a high speed camera and image analysis techniques. The two-phase phenomenon finds its origins in high dissolved gas concentrations present in the water flowing through the closed loop system, thus resulting in super saturation conditions at the primary heat exchange wall conditions. Bubble sizes at the boiler flow line were found to be dependent on the bulk fluid velocity, heat flux and pressure, with a measured mean diameter in the range of 0.13 mm to 0.39 mm. The Winterton (1972a) force balance model for bubble size prediction was in reasonable agreement with the experimental results. This model was further improved through the correlation of our data with the inclusion of dimensionless groups. Bubble nucleation rates have been calculated in the range of 0.3 to 4 bubbles / cm2 s with total system bubble production rates measured in the range of 784 to 6920 bubbles per second. Bubble nucleation rates have been calculated through the consideration of the heat exchanger surface under super saturation conditions. A correlation for the model by Hepworth et al. (2003) for nonclassical heterogeneous nucleation is proposed based on the experimental data gathered during the present study. Experimental results have shown dissolution rates for the bubble size ratio in the range of 0.4 to 12 % per second with system conditions. A modification of the model developed by Epstein and Plesset (1950) for stationary bubble dissolution is proposed with the inclusion of the Sherwood number to capture the effects of turbulent diffusion. The volumetric void fraction distribution in vertical pipes was found to be quasi-homogenous across the pipe section while being strongly dependent on gravitational and turbulence effects in horizontal pipe bubbly flow. A CFD simulation predicted the volumetric void fraction distribution with reasonable accuracy.

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50

Burton, Michael S. M. (Michael J. ). Massachusetts Institute of Technology. "Solar-electric and gas powered, long-endurance UAV sizing via geometric programming." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112414.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-85).
Fueled by telecommunication needs and opportunities, there has been a recent push to develop aircraft that can provide long-endurance (days to weeks) persistent aerial coverage. These aircraft present a complicated systems engineering problem because of the multifaceted interaction between aerodynamics, structures, environmental effects, and engine, battery, and other component performance. Using geometric programming, models capturing the interaction between disciplines are used to analyze the feasible limits of solar-electric and gas powered, long-endurance aircraft in seconds to a level of detail and speed not previously achieved in initial aircraft sizing and design. The results show that long-endurance, gas powered aircraft are generally more robust to higher wind speeds than solar-powered aircraft, but are limited in their endurance by the amount of fuel that they can carry. While solar-electric powered aircraft can theoretically fly for months, they are operationally limited by reduced solar flux during the winter and wind speeds at higher latitudes. A detailed trade study between gas-powered and solar-powered aircraft is performed to discover which architecture is best suited to meet a given set of requirements, and what is the optimum size and endurance of that platform.
by Michael Burton.
S.M.

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