The goal of this thesis is to explain the current dynamical development of the energy policy of the EU with the focus on the gas sector. Furthermore, this work examines what role in that process plays the European Commission. Lastly, it seeks to ascertain whether the EU's energy policy has a real impact on the development of the gas markets of Bulgaria, Czech Republic and Lithuania. The first two questions are answered with the aid of John W. Kingdon's Multiple stream theory. The conclusion has it that the key role in the creation of the EU's energy policy was taken up by the European Commission, which can be described as the Kingdon's policy entrepreneur. As a true entrepreneur the Commission attempted to build the way for the creation of the single EU gas market, which would be based on sufficient cross-border infrastructure and diversified gas imports. Such a conclusion is supported by the Commission's activities leading to the adoption of important energy legislation, as the third energy package, and essential funds as were European Energy Programme for Recovery and the Connecting Europe Facility. Latter, this work looks into the third research question. On the case studies of Bulgaria, the Czech Republic and Lithuania it proves, that the outputs of the entrepreneur activities of the Commission...

This master’s thesis elaborates a design of water heating and heating system for a building of a rehabilitation center in Horný Hričov. The theoretical section describes operational efficiency of gas boilers and associated calculation methods. The experimental section covers measurements of condensing gas boiler at various temperatures of heating water conducted in university laboratory. Operational efficiency was then calculated using indirect method based on the measurement results. Subsequently, calculated values and values measured by an operational efficiency analyzer were compared. The comparison revealed minor deviations in operational efficiency values and different values of condensing heat utilization between the calculations and the analyzer results. The analytical section of the thesis consists of complex designs of two versions of the heating system and the water heating. The first design version uses condensing gas boilers as a heat source while the second version uses a water-air heat pump instead. The project section of the thesis is executed in the scope for a building permit and consists of a technical report and a design documentation.

No description available.

[pt] Diante da crise ambiental dos dias atuais, desenvolver tecnologias de menor impacto negativo e promover ações de eficiência energética tornam-se imprescindíveis para conciliar produtividade e redução de emissões. Neste contexto, aprofundar-se no estudo de motores de combustão interna modelando seu funcionamento se apresenta como uma ferramenta bastante interessante, seja por ensaios em bancada ou modelagens. O presente trabalho buscou desenvolver modelos usando diferentes arquiteturas de Redes Neurais Artificiais (RNAs) para obter parâmetros de performance de Motores de Combustão Interna movidos a gás natural e a misturas de diesel – biodiesel – etanol. Para o primeiro caso, foram coletados dados de 5 motores visando a avaliação da eficiência térmica, consumo específico, temperatura de exaustão, e para o segundo a base de dados contempla um motor, sobre o qual foram avaliados, em acréscimo aos parâmetros mencionados, os coeficientes de compressão e expansão da politrópica, o consumo específico de etanol, a taxa máxima de liberação de calor e a pressão máxima. Para as redes que apresentaram melhores resultados, foram construídas superfícies de resposta a fim de analisar os modelos sobre a perspectiva do fenômeno que representam. Foi possível obter modelos com boa representatividade dos parâmetros mencionados (obtendo valores de R2 acima de 70 por cento para dados de treino e teste), exceto para os dois coeficientes da politrópica. Neste caso, embora os erros fossem relativamente satisfatórios, as superfícies de resposta atingiram extremos que não condizem com a teoria relacionada. Por outro lado, foi possível construir um modelo para a eficiência térmica a partir do consumo e abertura da válvula, com R2 de 99 por cento para treino e teste. Isto se explica pelo fato de que a primeira variável de entrada é parte da equação que calcula o parâmetro em questão, e a segunda está ligada à relação ar-combustível da mistura. / [en] Faced with the current environmental crisis, developing technologies with less negative impact and promoting energy efficiency actions are essential to reconcile productivity and emissions reduction. In this context, the study of internal combustion engines by modeling their operation presents itself as a very interesting tool, whether by bench tests or modeling. The present work aimed to develop models using different architectures of Artificial Neural Networks (ANNs) to obtain performance parameters of Internal Combustion Engines powered by natural gas and blends of diesel – biodiesel – ethanol. For the first case, 5 engines were considered to evaluate the thermal efficiency, specific consumption, exhaust temperature, and for the second case, the database includes an engine, on which, in addition to the mentioned parameters, the compression and expansion polytropic coefficients were evaluated, the specific consumption of ethanol, the maximum rate of heat release and the maximum pressure. For the networks that presented better results, response surfaces were made in order to analyze the models from the perspective of the phenomenon they represent. It was possible to obtain models with good representation of the mentioned parameters (obtaining R2 values above 70 percent for training and test data), except for the two polytropic coefficients. In this case, although the errors were relatively satisfactory, the response surfaces reached extremes that do not agree with the related theory. On the other hand, it was possible to build a model for thermal efficiency from consumption and throttle, with R2 of 99 percent for training and testing. This is explained by the fact that the first input variable is part of the equation that calculates this parameter, and the second is linked to the air-fuel ratio of the mixture.

[pt] Nos últimos anos, a indústria automotiva se reinventou para atender às demandas do mercado, que tem se mostrado competitivo em um contexto com legislações ambientais severas. Uma alternativa para reduzir as emissões de gases de efeito estufa prejudiciais ao longo da vida do veículo são os carros elétricos. No entanto, a produção e o descarte de baterias elétricas ainda é um problema a ser resolvido. Por isso, as empresas também buscam alternativas para aumentar a eficiência do motor de combustão interna e desenvolver tecnologias verdes, como a Ignição por Compressão de Carga Homogênea ou a Ignição por Compressão Assistida por Centelha (SACI). Uma rotina MATLAB foi criada para prever o desempenho da combustão SACI de gás natural usando um modelo termodinâmico de duas zonas. Este trabalho realiza análise de sensibilidade para cinco parâmetros de desempenho: eficiência térmica (Nth), pressão efetiva média indicada (IMEP), emissões de NOx, temperatura média no cilindro (Tavg) e tempo de autoignição (AIT), com várias variáveis como a velocidade do motor (RPM), a razão de equivalência combustível-ar (0s), o tempo da centelha (0s), a razão de compressão (rc) e a pressão de admissão (Pint), usando planejamento de experimentos para avaliar o impacto dos fatores. O Planejamento de Composto Central indica que o RPM e o 0 foram os fatores mais importantes no SACI, uma vez que influenciam todos os parâmetros de desempenho. A Pint foi significativa em três parâmetros de desempenho (Nth, IMEP e Tavg), assim como o 0s (NOx, Tavg e AIT). A rc foi relevante em apenas um deles (AIT). Além disso, uma Análise Univariada foi feita para comparar as técnicas de ignição por centelha (SI) e SACI. Os resultados indicam que os motores SACI tendem a ser cerca de 9% mais eficientes e as emissões de NOx caem mais de 90%. / [en] In the last few years, the automotive industry has reinvented itself to meet the demands of the international market, which has been increasingly competitive in a context with environmental laws each year more severe. One alternative to lower harmful greenhouse gases emissions over the life of the vehicle is electric cars. However, the production and disposal of electric batteries is still a major problem to be solved. Therefore, companies are also searching for other potentialities to increase the internal combustion engine s efficiency and develop green technology, such as Homogeneous Charge Compression Ignition (HCCI) or Spark-Assisted Compression Ignition (SACI). A MATLAB routine was created to predict the performance of SACI multimode combustion of natural gas using a two-zone thermodynamic model. This work performs sensitivity analysis for five performance parameters: thermal efficiency (Nth), indicated mean effective pressure (IMEP), NOx emissions, mean in-cylinder temperature (Tavg), and auto-ignition timing (AIT), with several variables such as engine speed (RPM), fuel-air equivalence ratio (0s), spark timing (0s), compression ratio (rc), and intake pressure (Pint), using the design of experiments tools to assess the factors impact. The Central Composite Design indicates that RPM and 0 were the most important SACI factors since they influence all engine performance parameters. The Pint was significant in three performance parameters (Nth, IMEP and Tavg), as was 0s (NOx, Tavg and AIT). The rc, however, was relevant in only one of them (AIT). Furthermore, a Univariate Analysis (UA) was done to compare Spark-Ignition (SI) and SACI engines. The results show that SACI engines tend to be around 9% more efficient, NOx emissions drop notably, more than 90%, IMEP presents an increase of 76%, and Tavg decreases 200-300 K.

High-Pressure Partial Oxidation (HP-POX) of natural gas is one of the techniques in the synthesis gas production by non-catalytic reforming. On the path to emissions reduction, all operating facilities must be optimized to satisfy environmental regulations. In a rapidly changing economic and political environment, technological development from lab-scale to demo-scale, and industrial-scale is no longer feasible. Therefore, new research and design methods must be applied. One of such methods commonly used in science and industry is numerical modeling, which utilizes Computational Fluid Dynamics (CFD), Reduce Order Models (ROMs), kinetic, and equilibrium models. The CFD models provide details about flow field, temperature distribution, and species conversion. However, the computational effort required to conduct such calculations is significant. The computationally expensive CFD models cannot be effectively used in the reactor optimization. Herewith, other modeling techniques utilizing kinetic and equilibrium models do not provide necessary details for process optimization and can only be used for adjustments of boundary conditions, investigation of specific processes occurring in the reactor, or development of sub-models for CFD. A numerical investigation was conducted to validate existing CFD models against benchmark experiments. The results reveled that the CFD model is sensitive to modeling parameters, when simulating complex flows where turbulence-chemistry interaction occurs. Moreover, it was shown that the results sensitivity increases along with the oxidizer/fuel inlet velocities ratio. Based on the conducted experiments, the CFD model validation resulted in definition of the modeling parameters suitable for modeling of HP-POX of natural gas. Based on the validated CFD model, a ROM for HP-POX of natural gas was developed. The model assumes that the reactor consists of several zones characterized by specific conversion processes. Moreover, the model considers inlet streams dissipation upon the injection, and includes several optimization stages that allows model adjustments for any reactor geometry and boundary conditions. It was shown that the developed ROM can reproduce global reactor characteristics at non-equilibrium conditions unlike other ROMs, kinetic, or equilibrium models. Moreover, the validation against CFD results showed that the ROM can correctly account for the \gls{rtd} in the reactors of different geometries and volumes without extensive additional optimization. Finally, new experiments were designed and conduced at semi-industrial HP-POX facility at TU Bergakademie Freiberg. The experiments aimed to study the influence of different oxidizer/fuel velocities ratios on the reactants mixing and process characteristics at high operating pressures. The high velocity difference between oxidizer and fuel was achieved by injection of High-Velocity Oxidizer (HVO). The experiments showed no significant influence of the HVO on the global reactor characteristics and overall species conversion process. However, the numerical analysis of the experimental results demonstrated that the oxidation zone is affected by the oxidizer inlet velocity, and becomes less efficient in the fuel conversion when the oxidizer/fuel inlet velocities ratio is increased. In summary, a sophisticated numerical model validation was conducted and sensitivity of the numerical results to the modeling parameters was carefully studied. The novel natural gas conversion technique was experimentally studied. Based on the conducted experiments and numerical evaluation a ROM was developed. The ROM is capable of producing high accuracy results and greatly decreases the computational effort and time needed for reactor development and optimization.

[pt] Devido a sua ampla gama de aplicações, o gás natural ocupa papel importante na matriz energética global. No Brasil, a descoberta do pré-sal transformou a história do país em relação a exploração de óleo e gás. Porém, o gás lá encontrado possui grandes quantidades de CO2 associado, que requerem remoção por existirem normas da ANP que limitam o gás natural comercializado a 3 por cento mol. Diversas tecnologias se mostraram capazes de realizar essa remoção, porém para altas quantidades de CO2, a tecnologia de membranas vem sendo destaque nas plataformas offshore de extração de petróleo. Seu reduzido footprint é um grande atrativo, devido ao espaço limitado das plataformas. O presente trabalho compara a área e volume ocupados e os pesos totais dos arranjos 3D de módulos de membranas fibra oca e espiral para a separação de CO2 do gás natural no pré-sal brasileiro. Para isso, foram construídas maquetes 3D no software Solidworks (marca registrada), baseando-se em dados de plantas reais offshore em operação e dados disponibilizados pelos principais fornecedores dos módulos de membrana, para tentar alcançar valores mais próximos da realidade. Foi constatado que os módulos fibra oca apresentam grande vantagem sobre os espirais em relação a área do módulo individual (8.340,91 m2 vs 26,24 m2 ) e ao número de módulos necessários (48 vs 15.120), e também em relação às plantas completas, tanto em área e volume, quanto em peso. Uma planta completa de módulos fibra oca ocuparia apenas 7,75 por cento do volume da planta de módulos espirais. O peso da primeira totalizaria 38,42 t em oposição a 765,62 t da segunda planta. / [en] Due to its wide range of applications, natural gas plays an important role in the global energy matrix. In Brazil, the discovery of the pre-salt transformed the country s history in relation to oil and gas exploration. However, the gas found there has large amounts of associated CO2, which require removal because there are ANP standards that limit commercialized natural gas to 3 percent mol. Several technologies have proven capable of achieving this removal, but for high amounts of CO2, membrane technology has been on the spotlight on offshore oil extraction platforms. Its reduced footprint is a major attraction, due to the limited space on the platforms. The present work compares the occupied area and volume and the total weights of 3D arrangements of hollow fiber and spiral wound membrane modules for the separation of CO2 from natural gas in the Brazilian pre-salt. To achieve this, 3D models were built in Solidworks (trademark) software, based on real offshore plants in operation and data provided by leading membrane module suppliers, in an attempt to achieve results closer to reality. It was found that hollow fiber modules offer significant advantages over spiral wound modules in relation to the membrane area of the individual module (8,340.91 m2 vs 26.24 m2 ) and the number of modules required (48 vs 15,120), and also in relation to complete plants, both in area and volume, as well as in weight. A complete hollow fiber module plant would occupy only 7.75 percent of the volume of the spiral wound module plant. The weight of the first would total 38.42 t as opposed to 765.62 t of the second plant.

[ES] El aumento global de las emisiones de gases de efecto invernadero desde el inicio de la Revolución Industrial se ha convertido en un grave peligro para la vida humana. Además de la generación de energía y la industria, el transporte, con el aumento del número total de vehículos en las últimas décadas, es uno de los principales responsables de este incremento exponencial de los gases causantes del calentamiento global. De hecho, ciudades como Barcelona o Madrid, entre muchas otras, están imponiendo restricciones al tráfico para mitigar esta situación. Sin embargo, la humanidad aún está a tiempo de invertir esta tendencia negativa y solucionar el problema medioambiental para las generaciones futuras. El objetivo principal de la presente Tesis se centra en el estudio, implementación y análisis del concepto de encendido por precámara pasiva para su aplicación en la próxima generación de vehículos automóviles. Más específicamente, esta investigación aborda los fenómenos físicos que intervienen en el proceso de combustión cuando se utiliza el sistema de encendido por precámara en un motor de encendido provocado. A continuación, se aplican algunas estrategias para mejorar el rendimiento térmico que se obtiene operando con este concepto. Finalmente, a partir del conocimiento generado, se presentan unas directrices básicas para el prediseño de este tipo de precámaras. La primera aproximación al concepto consiste en su implementación directa en el motor, obteniendo resultados experimentales en tres condiciones de funcionamiento diferentes en términos de carga y régimen de giro del motor. Además, también se evalúan diferentes geometrías de precámara. Aunque su implementación directa es relativamente sencilla mediante la sustitución de la bujía, la comprensión de ciertos fenómenos relevantes relacionados con la combustión, como el intercambio de gases o la penetración de los chorros, es extremadamente difícil sin el apoyo de herramientas computacionales. Esta es la principal razón que justifica el uso de herramientas numéricas 1D en la presente Tesis, ya que con un modelado adecuado basado en datos experimentales, se puede obtener información relevante en aquellas situaciones en las que no es factible generarla experimentalmente. Estas herramientas 1D tienen las ventajas de su bajo coste computacional y su capacidad de proporcionar resultados en poco tiempo. En cuanto al rendimiento térmico, se adoptan dos estrategias diferentes, como el aumento de lambda o el aumento de la tasa de recirculación de los gases de escape, para incrementar aún más las ventajas del sistema de encendido por precámara pasiva. Sin embargo, se alcanzan los límites físicos de aplicación de ambas estrategias y se proponen una serie de posibilidades para ampliar estos límites y aumentar el rendimiento térmico. Finalmente, a partir de los resultados experimentales y numéricos, se sugieren algunas pautas para diseñar una precámara que aproveche las ventajas observadas, aumentando el rendimiento térmico en comparación con los conceptos de encendido por bujía convencional y por precámara pasiva actuales. / [CA] L'augment global de les emissions de gasos d'efecte d'hivernacle des de l'inici de la Revolució Industrial s'ha convertit en un greu perill per a la vida humana. A més de la generació d'energia i la indústria, el transport, amb l'augment del nombre total de vehicles en les últimes dècades, és un dels principals responsables d'aquest increment exponencial dels gasos causants de l'escalfament global. De fet, ciutats com Barcelona o Madrid, entre moltes altres, estan imposant restriccions al trànsit per a mitigar aquesta situació. No obstant això, la humanitat encara és a temps d'invertir aquesta tendència negativa i solucionar el problema mediambiental per a les generacions futures. L'objectiu principal de la present Tesi se centra en l'estudi, implementació i anàlisi del concepte d'encesa per precàmera passiva per a la seua aplicació en la pròxima generació de vehicles automòbils. Més específicament, aquesta investigació aborda els fenòmens físics que intervenen en el procés de combustió quan s'utilitza el sistema d'encesa per precàmera en un motor d'encesa provocada. A continuació, s'apliquen algunes estratègies per a millorar el rendiment tèrmic que s'obté operant amb aquest concepte. Finalment, a partir del coneixement generat, es presenten unes directrius bàsiques per al predisseny d'aquesta mena de precàmeres. La primera aproximació al concepte consisteix en la seua implementació directa en el motor, obtenint resultats experimentals en tres condicions de funcionament diferents en termes de càrrega i règim de gir del motor. A més, també s'avaluen diferents geometries de precàmera. Encara que la seua implementació directa és relativament senzilla mitjançant la substitució de la bugia, la comprensió d'uns certs fenòmens rellevants relacionats amb la combustió, com l'intercanvi de gasos o la penetració dels dolls, és extremadament difícil sense el suport d'eines computacionals. Aquesta és la principal raó que justifica l'ús d'eines numèriques 1D en la present Tesi, ja que amb un modelatge adequat basat en dades experimentals es pot obtindre informació rellevant en aquelles situacions en les quals no és factible generar-la experimentalment. Aquestes eines 1D tenen com a principal avantatge el seu baix cost computacional i la seua capacitat de proporcionar resultats en poc temps. Quant al rendiment tèrmic, s'adopten dues estratègies diferents, com l'augment de lambda o l'augment de la taxa de recirculació dels gasos d'escapament, per a incrementar encara més els avantatges del sistema d'encesa per precàmera passiva. No obstant això, s'aconsegueixen els límits físics d'aplicació de totes dues estratègies i es proposen una sèrie de possibilitats per a ampliar aquests límits i augmentar el rendiment tèrmic. Finalment, a partir dels resultats experimentals i numèrics, se suggereixen algunes pautes per a dissenyar una precàmera que aprofite els avantatges observats, augmentant el rendiment tèrmic en comparació amb els conceptes d'encesa per bugia convencional i per precàmera passiva actuals. / [EN] The global greenhouse gas emissions increase since the start of the Industrial Revolution has become a serious hazard to human life. In addition to power generation and industry, transportation, with the rise in the total vehicle number in the last decades, is one of the main contributors to this exponential increase of global warming-causing gases. In fact, cities such as Barcelona or Madrid, among many others, are imposing traffic restrictions to mitigate this situation. However, mankind is still on time to reverse this negative tendency and fix the environmental issue for the upcoming generations. The main goal of the present Thesis focuses on the study, implementation and analysis of the passive pre-chamber ignition concept in a near-future light-duty passenger car application. To be more specific, the investigation addresses the physical phenomena involving the combustion process when pre-chamber ignition system is used in a spark-ignition engine. Then, some strategies to improve thermal efficiency while employing this concept are applied. Finally, with all the knowledge gathered, basic guidelines for a pre-chamber pre-design are presented. The first approach to the concept consists of its direct implementation in the engine, obtaining experimental results in three different operating conditions in terms of engine load and speed. Furthermore, different prechamber geometries are also evaluated. Although its direct implementation is relatively straightforward by exchanging the spark plug, understanding some of the relevant phenomena related to the combustion process, such as gas exchange or jet-tip penetration, is extremely difficult without the support of computational tools. This is the main reason supporting the use of 1D numerical tools in the present Thesis, since with proper modeling based on experimental data, further knowledge can be obtained in those situations where experimental evaluations are not feasible. These 1D tools have the benefits of their low computational cost and their ability to provide reasonably good results in a short period of time. In terms of thermal efficiency, two different strategies, such as the increase of lambda or the increase of the exhaust gas re-circulation rate, are adopted to extend further the benefits of the passive pre-chamber ignition system. However, the physical application limits of both strategies are reached, and a series of possibilities are proposed to expand these limits and increase thermal efficiency. Finally, with all the experimental and numerical results, some guidelines are suggested to design a pre-chamber that takes advantage of the benefits, increasing thermal efficiency compared with the conventional spark ignition and the current passive pre-chamber concepts. / The respondent wishes to acknowledge the financial support received through contract FPI-S2-19-21993 of the Programa de Apoyo para la Investigación y Desarrollo (PAID) of Universitat Politècnica de València. Parts of the work presented in this thesis have been supported by different collaborations with the research partner Sandia National Laboratories LLC, 7011 East Ave, Livermore, California, US. / Martínez Hernándiz, PJ. (2023). Implementation and Analysis of the Pre-Chamber Ignition Concept in a SI Engine for Passenger Car Applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202063

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<p> One primary focus on internal combustion engines is that these engines create multiple harmful exhaust gases that can cause damage to the environment. There are a number of advanced strategies that are currently being investigated to help reduce the amount of these harmful emissions that are emitted from IC engines. One such method of reducing harmful emission gases focuses on the three-way-catalyst. A three-way-catalyst (TWC) is an exhaust emission control device that is designed in such a way to take harmful exhaust gases and convert them into less harmful gases through various chemical reactions within the TWC. To help further the reduction of these harmful gases in the TWC, a novel two-loop control and estimation strategy is used. This control and estimation strategy involves the use of two loops with an inner-loop controller, outer-loop robust controller, and an estimator in the outer-loop. The estimator consists of a TWC model and an extended Kalman filter which is used to estimate the fractional oxidation state (FOS) of the TWC. This estimated FOS is then used by the robust controller, along with other parameters, to produce a desired engine lambda reference signal, λup. This desired lambda signal is then used by the inner-loop controller to control the engine lambda. Accurate control of lambda is important because the air-fuel-ratio range for a TWC to effectively achieve oxidation and reduction simultaneously is extremely narrow. Another primary focus in the field of internal combustion engines is designing and tuning advanced models within GT-Power that can accurately predict what will happen when running an actual engine. Designing, troubleshooting, and testing a GT-Power model is an extensive but rewarding process. Creating an accurate engine model can not only provide one with primary engine data that is also measurable in a test cell, but can also provide insight into some of the intricate processes and nature of the engine that are difficult or impossible to physically measure. Cummins has an extensive process of tuning GT-Power engine models. This process include items such as initial model calibrations, model discretizations, turbocharger tunings, and other items. Some of these processes are used to calibrate both Cummins Power Systems Business Unit engines as well as a Purdue B6.7N natural gas engine. </p>