This thesis describes the development of a micromachine model and associated data acquisition system, which is used to study the improvement of the transient response of a ship's diesel generator set following a severe disturbance. The improvement in response is obtained by the use of transient rotor acceleration as a single extra feedback signal into the excitation and governor systems of the micromachine model. The response of the ship system is predicted by theoretical studies, which use a multiprocessor system to implement a Park's two axes, five winding model of the ship's generator together with the associated automatic voltage regulator and diesel governor models. The optimal feedback gains obtained from the theoretical studies are then used to obtain results from the micromachine system, a comparison between the theoretical and experimental results confirms the conclusion that a significant improvement in the system's transient response is obtained. This improvement is maintained when changes are made to the alternator load and the fault duration, without any alterations to the system feedback gains.

The mobile preschools of Uppsala are buses that are provided as a complement for stationary preschools. The buses are connected to one stationary preschool that provides the necessities such as food and a place for the children to be before and after the daily trips. In Uppsala, there are five mobile preschool buses and they have been operated since 2009. For the bus to provide heat, warm food and energy for activities on the bus, there is a generator installed that runs on biodiesel. The emissions from the generator, in combination with the loud noises that it emits, are of concern for both the children and educators on the bus as well as the people around it. This has caused for alternative ways to deliver electricity to the bus. This study examines three scenarios for delivering electricity and tries to evaluate what the best option could be from different Points of view. The three scenarios are replacing the generator with either a battery, replacing the generator with electricity poles and to replace the generator with a more efficient and quieter one. When evaluating the different scenarios from an economical point of view, the study found that the electricity poles would be the best option. When evaluating the best option with respect to the children and educators, the study found that the battery would be the best option. The negative consequences for continuing to use a generator to supply electricity would be a health hazard for the children and a limitation for the educators in the freedom of choosing location for the bus to visit.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-28T15:11:55Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese - Kamylla Alexandre - Engenharia Química.pdf: 4003208 bytes, checksum: 7181a381a784e64a2607a30d6852175a (MD5) / Made available in DSpace on 2016-07-28T15:11:55Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Tese - Kamylla Alexandre - Engenharia Química.pdf: 4003208 bytes, checksum: 7181a381a784e64a2607a30d6852175a (MD5) Previous issue date: 2016-02-24 / A redução da disponibilidade de combustíveis e o aumento das restrições ambientais à emissão de poluentes, inerente à geração de energia, têm justificado o investimento em projetos industriais que minimizem seu consumo energético. A Petrobras é um dos maiores consumidores de energia do país e, dados os custos decorrentes das tarifas de energia, a geração própria sempre foi uma preocupação da Companhia. Nesse contexto os fluidos refrigerantes secundários, que possuem propriedades de transmitir calor a longas distâncias, são de especial interesse para unidades nessa área de desenvolvimento tecnológico. Os sistemas de refrigeração são empregados em diversos setores industriais, como nas petroquímicas, e em termelétricas utilizadas como unidades de cogeração em refinarias. Esses sistemas são constituídos, comumente, por compressores, trocadores de calor, torres de resfriamento, tubulações, bombas, ventiladores e instrumentação para controle. Uma “Unidade de Refrigeração” utiliza refrigerantes primários para armazenamento e transporte de calor ou frio a curtas distâncias em sistemas à compressão de vapor ou por absorção. Para o transporte de energia calorífica a longas distâncias são geralmente utilizados os refrigerantes secundários compostos de água e glicóis (anti-congelantes) ou salmouras e aditivos. Contudo, essas substâncias anticongelantes reduzem a capacidade calorífica e a condutividade térmica da água. Por outro lado, nanopartículas metálicas têm a propriedade de aumentar a condutividade térmica do meio onde são adicionadas. O presente trabalho investigou, através de experimentos em um arranjo experimental de bancada de testes de um grupo gerador diesel, a influência da adição de nanopartículas em uma solução de etilenoglicol utilizada como refrigerante secundário. Para isso utilizou-se injeções de água gelada, produzida por um chiller de compressão de vapor (R22), na linha de alta temperatura (HT) do motor do grupo gerador. Para armazenamento e registros dos dados foi utilizado um equipamento do tipo datalogger. Foram testadas diferentes set-points de temperatura de entrada da água da linha de HT no motor (64oC, 67 oC, 70 oC, 73 oC e 76 oC). Essas temperaturas foram testadas com água pura e com solução aquosa de etilenoglicol a 30%, sem e com a adição de nanopartículas (2%, 4% e 6%). Em todas as condições foram realizadas medidas do consumo específico de combustível e avaliadas as velocidades de resposta no sistema. Um percentual de 2,0% de nanopartículas, em volume, apresentou-se como ideal para o desempenho do nanofluido. Em função da ausência, no mercado brasileiro, de unidades de refrigeração por absorção com potência menor que 64 TR, foi elaborado um modelo dinâmico e simulado um chiller de absorção (H2O-LiBr), visando uma construção futura e utilização desse tipo de equipamento em escala piloto. / The reduced availability of fuel and increasing environmental restrictions on emissions, inherent in the power generation, have justified the investment in industrial projects that minimize their energy consumption. Petrobras is one of the country's largest energy consumers and, given the costs of the tariffs, the very generation has always been a concern of the Company. In this context the secondary refrigerants, which have properties of transmitting the heat over long distances, are of particular interest for technological development units in this area. Cooling systems are employed in various industrial sectors such as the petrochemical, and power plants used as cogeneration units in refineries. These systems are made, usually for compressors, heat exchangers, cooling towers, pipes, pumps, fans and instrumentation control. A "cooling unit" uses primary refrigerant for storage and transport of heat or cold at close range systems in the vapor compression or absorption. For the heat energy transport over long distances are usually used secondary refrigerants composed of water and alcohols (anti-freeze) or pickles and additives. However, such antifreeze substances reduce the heat capacity and thermal conductivity of water. Moreover, metal nanoparticles have the property of increasing the thermal conductivity of the medium in which they are added. This study investigated through experiments in an experimental test bench arrangement of a diesel generator set, the influence of the addition of nanoparticles in a solution of ethylene glycol used as secondary coolant. For this used ice water injections, produced by a vapor compression chiller (R22), in the high temperature line (HT) of the engine generator set. For storage and records of the data was used an equipment type datalogger. They tested different set-points for the HT line of the engine inlet water temperature (64 °C, 67 °C, 70 °C, 73 °C and 76 °C). These temperatures were tested with pure water and ethylene glycol 30% aqueous solution, with and without the addition of nanoparticles (2%, 4% and 6%). In all conditions were performed measurements of specific fuel consumption and evaluated the response speeds in the system. A percentage of 2.0% nanoparticles by volume was presented as ideal for the performance of nanofluid. Due to the absence, in the Brazilian market of refrigeration units by absorbing less power than 64 TR, it designed a dynamic model and a simulated absorption chiller (H2O-LiBr), aimed at future construction and use of such equipment in pilot scale.

This thesis presents and describes new global trends among build and operation of datacenters. Further it contains practical application of particular examples, and the theory is supplemented by new findings from given field.

This thesis is a study on integration of photovoltaic generators into an existing diesel-unreliable grid connected system at the Lebanese village of Khiam. The main goal of implementing PV-diesel hybrid system is to reduce diesel consumption and the import of fossil fuel used in electricity power supply. Before designing the system, it is necessary to create a load profile for 120 households and pre-design the size of the PV generator, the capacity of storage system and inverter type/size selection. The load profile data is based on the average of monthly energy consumption gathered from Khiam village households. Detailed simulations and financial analysis are performed with HOMER to compare different systems and their viability. The simulations include four different designs starting from the existing system, diesel generator with unreliable grid, followed by PV generator and unreliable grid, PV and diesel generator and ended with the complete hybrid system. Once the Hybrid system is determined a detailed design is done to optimize the lowest cost PV-diesel hybrid system. The final simulated PV-diesel hybrid system is suggested with a PV capacity of 270 kWp, existing diesel capacity with 200 kVA, an inverter output of 115 kW and battery bank nominal capacity is 1872 kWh. The system renewable fraction is 53% and the project life cycle is 25 years. The PV-diesel hybrid system is projected to produce electricity at a cost of 0.12 USD/kWh. This cost is significantly lower than the 0.26 USD/kWh paid to the diesel operator, as well as lower than 0.13 USD/kWh paid to the utility grid. In addition, and according to the given information from the owner, an estimated diesel consumption of 104000 ltr/year, the simulation result shows diesel consumption at 40000 ltr/year. The reduced carbon dioxide production by 65%, from 776 to 272 tons per year, provides further justification for the PV installation in a commercial PV-diesel hybrid system.

Master`s thesis deals with the economic situation of the company STEL-INVEST, Ltd., which will be basis for the decision to extend the entrepreneurial activity by the new service. The company STEL-IVEST, Ltd. is currently engaged in services and maintenance in the field of telecommunication.

The performance of a combined vapor-compression cycle/ORC is evaluated using waste-heat from a diesel generator. A flat plate microchannel heat exchanger is employed to provide energy exchange between the diesel exhaust stream and an oil loop, which provides energy to a boiler. This study finds an increased diesel duty corresponds with an increased cooling capacity, for a maximum of 5 kW of cooling (with 13.5 kWe diesel load). System COP is reduced with a higher input power due to limitations in the cooling cycle. A number of solutions are identified to increase the COP and cooling capacity. A new microchannel heat exchanger to recovery heat is designed to increase performance compared to the previous version. / Graduation date: 2012

La nature intermittente et aléatoire des sources renouvelables, telles que le photovoltaïque et l’éolien, nécessite un complément de stockage, tel une batterie et un système de secours énergétique, tel un générateur diesel, en particulier dans un système autonome. En ce qui concerne le générateur diesel, il a besoin d'un certain temps pour démarrer et il ne peut pas donner immédiatement la puissance nécessaire, en raison de son comportement dynamique. Alors, la qualité de l'énergie est abaissée pendant cette période en raison du manque de puissance. Par conséquent, pendant la période de démarrage du générateur diesel, un supercondensateur est suggéré pour équilibrer la puissance en raison de sa réponse rapide et de sa densité de puissance élevée. Une stratégie de contrôle de puissance est proposée pour réaliser la coordination entre le générateur diesel et le supercondensateur. La simulation et les résultats expérimentaux montrent que la stratégie de contrôle proposée est capable de réguler la tension du bus continu dans des limites acceptables et d’alimenter la charge pendant la sous production d'énergie renouvelable ou lors d'augmentation de la demande de la charge. De plus, le supercondensateur peut également être utilisé pour surmonter les limites de stockage électrochimique telles que son état de charge et son courant maximal. Ainsi, cette thèse propose le contrôle de puissance en temps réel pour un micro réseau continu avec un système hybride photovoltaïque-batterie-supercondensateur-diesel, visant à répondre à la demande de puissance de charge avec fiabilité et à stabiliser de la tension du bus continu. La simulation et les résultats expérimentaux montrent également que la stratégie de contrôle améliore les performances dynamiques et statiques du micro réseau continu pour différentes conditions de fonctionnement. De plus, afin de minimiser le coût énergétique du groupe diesel, le coût du carburant et la consommation de carburant sont analysés à travers plusieurs tests expérimentaux. Par conséquent, la valeur optimale de sa production d'énergie est déduite et appliquée dans une nouvelle stratégie de gestion de la puissance est proposée. Cette stratégie peut atteindre l'objectif de maximiser l'utilisation de l'énergie photovoltaïque et de prendre en compte la caractéristique de démarrage lent et le coût énergétique du générateur diesel. Les simulations et expérimentations sont réalisées en utilisant des données photovoltaïques réelles pour illustrer les performances et le comportement du système hybride. Les résultats obtenus vérifient l'efficacité de cette stratégie. De plus la comparaison avec la stratégie de gestion de la puissance précédente, dans laquelle le coût d’énergie du générateur diesel n'est pas pris en compte, démontre que la nouvelle stratégie de gestion peut réduire le coût total du système de puissance à courant continu hybride. / The intermittent and random nature of renewable sources, such as photovoltaic and wind turbine, asks for the complement of storage, such as battery and back-up energy, such as diesel generator, especially in a standalone power system. Concerning the diesel generator, it needs some time to start up and cannot immediately offer the needed power, due to its dynamic behavior. Hence, the power quality is lowered down during this period because of the shortage of power. Therefore, during the period of the diesel generator starting up, a supercapacitor is suggested to compensate the power balance because of its fast response and high power density. A power control strategy is proposed to achieve the coordination between diesel generator and supercapacitor. Both simulation and experimental results show that the proposed control strategy is able to regulate the DC bus voltage within the acceptable limits and supplying the load during the renewable power under generation or load step-increase situations. In addition, the supercapacitor can be also used to overcome the electrochemical storage limits like its state of charge and maximum current. So, this thesis proposes the real time power control for a hybrid photovoltaic-battery-supercapacitor-diesel generator DC microgrid system, aiming to meet the load power demand with reliability and stabilizing the DC bus voltage. Both simulation and experimental results show that the designed control strategy improves the DC microgrid dynamic and static performances under different operating conditions. Furthermore, in order to minimize the diesel generator energy cost, the fuel cost and fuel consumption are analysed through several experimental tests. Therefore, the optimal value of its power generation is deduced and applied in a newly proposed energy management strategy. This strategy can achieve the goal of maximizing the utilization of photovoltaic energy and taking into account the slow start-up characteristic and energy cost of diesel generator. Both simulation and experimental studies are carried out by using the real photovoltaic data to illustrate the performance and the behavior of the hybrid system. The obtained results verify the effectiveness of this strategy. Furthermore, the comparison with the previous energy management strategy, in which the diesel generator energy cost is not considered, demonstrates that the newly proposed energy management strategy can reduce the total cost of the hybrid DC power system.

[pt] O inevitável crescimento da demanda por recursos energéticos, imposta por tempos de acelerada transformação econômica e social, e as imposições da pauta climática, fomentam o interesse pelo estudo de processos mais eficientes e menos poluentes. Neste contexto, por meio de simulações no MATLAB/Simulink, este trabalho realiza o dimensionamento, simulação e otimização de um sistema híbrido de geração de energia elétrica, desconectado da rede (off-grid), composto por grupos geradores e banco de baterias, visando aplicações comerciais com diferentes níveis de demanda, em cenários sazonais distintos. Também é objeto de estudo, avaliar os ganhos em eficiência e emissões de poluentes atmosféricos, comparandose os cenários simulados a partir de estimativas de linha de base. Os sistemas são compostos por geradores a Diesel (linha de base) com potências entre 600 e 5200kW, geradores a Gás Natural com potências entre 400 e 5088kW, e bancos de baterias com capacidades entre 900 e 9000kWh para os cenários alternativos. Foi realizada uma análise energética dos sistemas, considerando variação da energia, estado de carga, consumo específico de combustível, eficiência e outros, além da análise das emissões de poluentes advindos dos geradores. Por fim, com as variáveis de saída do modelo, comparou-se os resultados entre os diversos casos e os cenários de linha de base, além de analisar a influência dos fatores utilizados para criação dos cenários simulados (tipos de geração, variabilidade da carga e multiplicadores). Em comparação entre a linha de base, e o cenário mais promissor (Gás Natural + bancos de baterias), observou-se, na média, aumento de eficiência de até 19,8 por cento para o verão, e 26,7 por cento para o inverno. Além de detectar aumento das emissões de hidrocarbonetos não queimados e monóxido de carbono, e redução das emissões de óxido de nitrogênio, material particulado e dióxido de carbono. / [en] The inevitable growth in demand for energy resources, imposed by times of accelerated economic and social transformation, and the impositions of the climate agenda, encourage interest in the study of more efficient and less polluting processes. In this context, performing simulations in MATLAB/Simulink, this work carries out the sizing, simulation and optimization of a hybrid power generation system, disconnected from the grid (off-grid), and composed by generator sets and battery banks, aiming commercial applications with different levels of demand, in different seasonal scenarios. It is also object of study to evaluate the gains in efficiency and the emissions of atmospheric pollutants, comparing the simulated scenarios from baseline estimates. The systems are composed by diesel generators (baseline) with output power between 600 and 5200kW, Natural Gas generators with output power between 400 and 5088kW, and battery banks with capacities between 900 and 9000kWh for alternative scenarios. An energy analysis of the systems was performed, considering energy variation, state of charge, C rate, engine load levels, specific fuel consumption and efficiency. In addition, the analysis of pollutant emissions from generators. Finally, with the model s output variables, the results were compared between the different cases and the baseline scenarios, in addition to analyzing the influence of the factors used to create the simulated scenarios (types of generation, load variability and multipliers). In comparison between the baseline and the most promising scenario (Natural Gas + battery banks), it was possible to observe average gains with efficiency increases of up to 19.8 percent for the summer, and 26.7 percent for the winter. In addition to detecting increased emissions of unburned hydrocarbons and carbon monoxide, and reduction in emissions of nitrous oxide, particulate matter and carbon dioxide.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-11-12T14:43:57Z No. of bitstreams: 1 kamilaperesrocha.pdf: 4837972 bytes, checksum: 8ccb175cc20788fe527b134046b240f4 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-11-23T13:11:27Z (GMT) No. of bitstreams: 1 kamilaperesrocha.pdf: 4837972 bytes, checksum: 8ccb175cc20788fe527b134046b240f4 (MD5) / Made available in DSpace on 2018-11-23T13:11:27Z (GMT). No. of bitstreams: 1 kamilaperesrocha.pdf: 4837972 bytes, checksum: 8ccb175cc20788fe527b134046b240f4 (MD5) Previous issue date: 2018-08-29 / O presente trabalho apresenta uma metodologia para o planejamento ótimo de microrredes em redes de distribuição de energia elétrica. Para tanto, é apresentada a formulação dos elementos propostos incluindo sua modelagem técnico-econômica. O objetivo principal é a abordagem das vantagens do sistema de compensação de energia elétrica estipulado pela resolução normativa n◦ 482/2012 da ANEEL, na busca por redução dos custos de energia em um horizonte de planejamento de longo prazo. Para isso, faz-se a utilização da meta-heurística denominada SIA com propósito de obter o dimensionamento otimizado dos elementos da microrrede. A determinação dessa técnica se deve a quantidade de combinações possíveis devido a complexidade do problema apresentado. É traçado, ainda, um comparativo com o método de busca exaustiva para análise das soluções geradas e do tempo computacional requerido para as duas metodologias propostas. O projeto aborda a implantação de fontes de energia renovável eólica e solar e gerador a diesel para análise de estudos de caso para consumidores comercial e residencial. Por último, é realizado um comparativo com resultados provenientes de um software de dimensionamento de microrredes, denominado HOMER Pro R . / The present work presents a methodology for the optimal planning of microgrids in electricitydistributionnetworks. Forthatreason, theformulationoftheproposedelements includingtheirtechnical-economicmodelingispresented. Themainobjectiveistoapproach the advantages of the net metering stipulated by ANEEL normative resolution 482/2012, in the search for reduction of energy costs in a long-term planning horizon. Therefore, the meta-heuristic called SIA is implemented with the purpose of obtaining the optimized sizing of the elements of the microgrid. The determination of this technique come from the amount of possible combinations due to the complexity of the presented problem. A comparison with the exhaustive search method for the analysis of the generated solutions and the computational time required for the two proposed methodologies is also drawn. The project addresses the deployment of wind and solar renewable energy sources and diesel generator for analysis of case studies for commercial and residential consumers. Finally, a comparison is made with results from HOMER Pro R, a microgrid software.