O objetivo deste trabalho é modelar a arquitetura de uma usina solar fotovoltaica arrefecida intitulada UFVa, utilizando um protótipo de verificação. A metodologia se baseia na medição, verificação e análise dos dados de temperatura e produção de energia elétrica dos strings de teste (arrefecido) e comparação (não arrefecido), estudo do comportamento da alimentação de água do sistema de arrefecimento e o impacto das condições climáticas na operação do protótipo de UFVa. Por meio das análises dos dados constatou-se que, para o período entre as 09h00min e as 17h30min, os módulos PV do string de teste sempre operam com temperaturas inferiores aos módulos PV do string de comparação. Durante o período de testes, no qual a temperatura dos módulos PV do string de comparação operou acima de 55,0°C, as temperaturas médias e máximas registradas nos módulos PV do string de teste foram inferiores a 37,0 °C, operando sempre abaixo da temperatura nominal de operação da célula (NOCT). A produção de energia elétrica no string de teste superou a do string de comparação em 3,0kWh/dia. Portanto, o sistema de arrefecimento reduz a temperatura de operação dos módulos PV, principalmente no período de máxima geração elétrica, que corresponde ao período das 11h00min às 15h00min, proporcionando ganhos médios de rendimento de 5,9% na produção de energia, 10,3% na potência e 5,4% no FC. / In this work we use a verification prototype to model the architecture of a solar photovoltaic power plant equipped with a cooling system. The power plant we model is called UFVa. The methodology is based on the measurement, verification, and data analysis of temperature, electricity generation, test strings (cooled) and comparison strings (not cooled), along with a study of the water feeding behavior of the cooling system, and the impact of climatic conditions in the UFVa prototype operation. By analyzing the data we observed that, for the period between 09:00am and 5:30pm, the PV modules of the test string operate at temperatures below those of the PV modules of the comparison string. During the tests, in which the temperature of the PV modules of the comparison string operated above 55.0°C, the average and the maximum temperatures recorded in the PV modules of the testing string lied below 37.0°C, operating below the NOCT. Regarding the generation of electricity, the test string generated 3.0 kWh/day more than the comparison string. Hence, the cooling system decreases the operating temperature of the PV modules, particularly during the maximum power generation period which is from 11am to 3pm. This leads to efficiency average gains of up to 5.9% in the generation of electricity, 10.3% in the power, and 5.3% in the PR and PF.

Com o constante desenvolvimento das áreas urbanas e aumento do consumo energético destinado a conforto térmico, um estudo foi realizado para formulação de uma metodologia de análise termoeconômica de sistemas distritais de resfriamento. O objetivo principal é descrever uma metodologia referente à implantação de sistemas distritais no Brasil, por sua vez, o objetivo secundário é aplicar a metodologia no estado de São Paulo, analisando as premissas utilizadas na metodologia. Primeiramente, apresentou-se uma visão geral e revisão de literatura dos sistemas de aquecimento e resfriamento distrital, indicando suas vantagens e desvantagens, bem como as diversas aplicações e desafios para sua implantação. Aplicações no cenário mundial foram expostas e analisadas, demonstrando que sua utilização em diversos países se estende por décadas. As principais vantagens observadas nas aplicações existentes estão relacionadas a maior eficiência energética e exergética global, redução das emissões de gases poluentes e confiabilidade do sistema. Por fim, a metodologia aplicada está apresentada em cinco etapas, de forma ordenada, baseando-se nas etapas de um projeto de sistemas distritais. Seu resultado é baseado em rotinas, simulações de processos e procedimentos de otimização, bem como aplicação de indicadores energéticos. Ao final das etapas e seu desenvolvimento matemático obtém-se um estudo preliminar de viabilidade da implantação de um sistema distrital. O estudo de caso apresentado aplica a metodologia para a cidade de São Paulo buscando descrever com detalhamento as premissas e etapas descritas. / The constant development of urban areas and increased energy consumption for thermal comfort encourage studies that formulate a methodology for thermoeconomic analysis of district cooling systems. The main objective is to describe a thermoeconomic methodology related to the implementation of district systems in Brazil. The secondary objective is to apply the methodology in the state of São Paulo, analyzing the premises used in the methodology. At first, an overview and literature review of district heating and cooling systems was presented, indicating their advantages and disadvantages, just as the various applications and challenges for their implementation. Applications on the world stage have been introduced and analyzed, demonstrating that their use in several countries extends for decades. The main advantages observed in the existing applications are related to global energy and exergy efficiency, reduction in greenhouse gases and reliability of the systems. Finally, the applied methodology is presented in five steps in an orderly manner based on the steps of a district system project. Its result is based on routines, process simulations and optimization procedures, as well as application of energy indicators. At the end of the steps and their mathematical development a preliminary study of the feasibility of the implantation of a district system is obtained. The present case study applies the methodology for the city of São Paulo and describe in detail the premises and steps.

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

A measurement system is to be presented, which is used to obtain the I-V characteristics of a solar cell and to track its temperature during irra-diation before mounting it into a complete array/module. This project presents both the design and implementation of an Electronic load for testing the solar cell under field conditions of 10000 W/m^2, which is able to provide current versus voltage and power versus voltage charac-teristics of a solar cell using a software based model developed in Lab-VIEW. An efficient water cooling method which includes a heat pipe array system is also suggested. This thesis presents the maximum power tracking of a solar cell and the corresponding voltage and current values. In addition, the design of the clamp system provides an easy means of replacing the solar cell during testing.Keywords: Solar cell, Metal Oxide Semiconductor Field Effect Transistor (MOSFET), I-V characteristics, cooling system, solar cell clamp system, LabVIEW, Graphical User Interface (GUI).

Data centers are computing infrastructure facilities that house arrays of electronic racks containing high power dissipation data processing and storage equipment whose temperature must be maintained within allowable limits. In this research, the sustainable and reliable operations of the electronic equipment in data centers are shown to be possible through the Open Engineering Systems paradigm. A design approach is developed to bring adaptability and robustness, two main features of open systems, in multi-scale convective systems such as data centers. The presented approach is centered on the integration of three constructs: a) Proper Orthogonal Decomposition (POD) based multi-scale modeling, b) compromise Decision Support Problem (cDSP), and c) robust design to overcome the challenges in thermal-fluid modeling, having multiple objectives, and inherent variability management, respectively. Two new POD based reduced order thermal modeling methods are presented to simulate multi-parameter dependent temperature field in multi-scale thermal/fluid systems such as data centers. The methods are verified to achieve an adaptable, robust, and energy efficient thermal design of an air-cooled data center cell with an annual increase in the power consumption for the next ten years. Also, a simpler reduced order modeling approach centered on POD technique with modal coefficient interpolation is validated against experimental measurements in an operational data center facility.

Die Veranstaltung widmete sich mit der Borverdünnung in Druckwasserreaktoren bzw. mit der Verstopfung der Sumpfansaugsiebe durch freigesetztes Isolationsmaterial schwerpunktmäßig zwei Themen der Reaktorsicherheit, die auch in aktuellen Aufsichtsverfahren eine Rolle spielen. Eingebettet in den internationalen Kontext wollten die Veranstalter die sicherheitstechnische Bedeutung dieser Themen für die deutschen Anlagen beleuchten und die Auswirkungen auf die zu erbringenden Sicherheitsnachweise und den Anlagenbetrieb darstellen. Dabei kamen Gutachter, Vertreter der Forschung, Hersteller und Betreiber gleichermaßen zu Wort. Der Fachtag sollte den Teilnehmern aber insbesondere vermitteln, welche Beiträge die privat und öffentlich finanzierte Reaktorsicherheitsforschung zur Aufklärung der jeweiligen Ereignisabläufe und ihrer sicherheitstechnischen Bedeutung geleistet hat. In diesem Forschungskontext spielen, auch international, die Methoden der so genannten Computational Fluid Dynamics (CFD) eine zunehmende Rolle. Deshalb widmete sich eine Sitzung den Grundlagen, Möglichkeiten und Grenzen von CFD-Methoden. Dabei wurden u.a. Anwendungen zur Borvermischung und zum Verhalten von Mineralwolle im Sumpf präsentiert.

This thesis is based on eight articles all related to the characteristics of the cooling system and plate evaporator of a household refrigerator. Through these articles, knowledge is provided that can be used to increase the operational efficiency in household refrigeration. Papers A, B and C focus on heat transfer and pressure drop in a commonly used free convection evaporator – the plate evaporator. Applicable correlations are suggested on how to estimate the air side heat transfer, the refrigerant side pressure drop and the refrigerant side heat transfer. Papers D, E and F hold a unique experimental study of the refrigerant charge distribution in the cooling system at transient and steady state conditions. From this cyclic losses are identified and estimated and ways to overcome them are suggested. In paper G the topic “charging and throttling” is investigated in an unparalleled experimental study based on more than 600 data points at different quantities of charge and expansions device capacities. It results in recommendations on how to optimize the capillary tube length and the quantity of refrigerant charge. Finally, Paper H holds a thermographic study of the overall cooling system operating at transient conditions. Overall, a potential to lower the energy use by as much as 25 % was identified in the refrigerator studied. About 10 % was found on the evaporator’s air side. 1-2 % was identified as losses related to the edge effect of the evaporator plate. About 8 % was estimated to be cyclic losses. About 5 % was found in cycle length optimization.  It is believed that most of these findings are of general interest for the whole field of household refrigeration even though the results come from one type of refrigerator. Suggestions of simple means to reduce the losses without increasing the unit price are provided within the thesis / <p>QC 20120411</p>

Pour faire face à la forte augmentation de la consommation en climatisation et la consommation électrique associée, il est nécessaire de développer des systèmes de rafraîchissement basse consommation de bâtiment. Ce travail propose un nouveau système de rafraîchissement qui se veut économe en énergie, peu coûteux et simple à installer. Il associe les techniques de dissipation de chaleur par évaporation, rayonnement vers le ciel et géothermie. Ce système est constitué d'un réservoir poreux installé en extérieur et d'un réservoir de stockage placé dans le vide sanitaire. Lorsque le bâtiment a besoin de rafraîchissement, une pompe puise de l'eau fraîche dans le stockage, la fait passer dans le plancher rafraîchissant pour absorber la chaleur excédentaire du bâtiment puis stocke l'eau dans le réservoir poreux placé à l'extérieur. Le réservoir poreux refroidit l'eau qu'il contient par évaporation, rayonnement vers le ciel puis se vide dans le stockage. Le réservoir de stockage installé dans le vide sanitaire se refroidit aussi en continu grâce au contact direct avec le sol. Les propriétés poreuses et la géométrie du réservoir poreux influent fortement sur ses performances de refroidissement. Une étude paramétrique menée avec un modèle numérique simulant les transferts hydriques et thermique permet de choisir un réservoir adéquat pour cette application. Un réservoir poreux donnant de bonnes performances (70 W/m2 de puissance évaporative) a été identifié. Le système de rafraîchissement a été installé et testé expérimentalement sur une maison à échelle réelle à Bordeaux. Mis en service durant l'été 2015, le système a fonctionné de façon autonome durant 44 jours. L'utilisation de ce système a permis de maintenir durant la période de test un très bon confort thermique à l'intérieur d'un bâtiment expérimental bien isolé, non ventilé, avec des apports solaires, tout en ayant une consommation électrique faible (le COP moyen du système est de 20.8). Un modèle numérique du système complet a été développé sous Modelica, calibré sur les mesures expérimentales puis couplé à un modèle de bâtiment. Les résultats de simulation montrent que l'installation de ce système améliore nettement le confort intérieur du bâtiment sur l'ensemble de l'été pour toutes les configurations testées (climat, gestion des voletsdots). Un système aux dimensions optimisées (avec un stockage de 2.2 m3 et un réservoir poreux de 0.215 m3), installé sur une maison individuelle type RT2012 de 100 m2 à Bordeaux, fonctionne avec un COP moyen de 24 et permet de maintenir un bon niveau de confort à l'intérieur du bâtiment tout l'été. / To face the dramatic increase of energy consumption due to air conditioning use in buildings, new low energy consumption systems need to be developed. This work proposes a new cooling system which aims to be energy efficient, cheap and easy to install. This system takes advantage of evaporation cooling, ground earth cooling and sky radiative cooling techniques. The two main components of this new system are a porous tank set outside and a storage tank set in the basement of the building. When the inside house temperature exceeds the comfort temperature, cool water passes from the storage tank through the cooling floor, removes heat from the building and is then send to the porous tank. The water contained in the porous tank is cooled down due to evaporation and radiative effects and then flows back to the storage. The storage tank installed in the basement enables further cooling of the water thanks to direct contact with the ground. Porous properties and geometry of the tank have a great influence on the cooling performances of the tank. A heat and mass transfer model has been developed to simulate the thermal and hydric behavior of the tank. This model has been used to choose an appropriate tank. A tank giving good performances (70 W/m2 of evaporative power) is identified. The complete cooling system has been installed on a house in Bordeaux and tested at real scale during an experimental campaign. The system worked for 44 days during summer 2015 and allowed to maintain a very good thermal comfort level in the experimental building (insulated, with solar load and without ventilation). Its very low electricity needs brings the average coefficient of performance of the system to 20.8. A numerical model of the system has been developed, calibrated with experimental data and coupled with a building model. Simulation results show that for all tested configurations (climate, shading…), the system clearly improves the thermal comfort in the building. Optimized sizing, keepinp reasonnable tank sizes (storage and evaporator volumes of 2.2 m3 and 0.215 m3 respectively), shows that this system works with an average COP of 24 and maintains a good comfort level in an individual house of 100 m2 located in Bordeaux.

La réduction de la masse des véhicules, notamment des Groupes Motopropulseurs contribue à la réduction des émissions polluantes. Aujourd’hui afin d’aboutir à cet objectif, la conception de pièces automobiles (Carter Mécanisme, Carter Cylindre) en matériau allégé tel que l’aluminium et ses alliages est en plein essor. Pour la production de grande série, ces alliages sont mis en œuvre par le procédé de fonderie ‘’Aluminium sous pression’’.Ce procédé utilise des moules métalliques. La maîtrise du comportement thermique du moule : chauffage, refroidissement interne (par circuit) et externe, est un point clef pour la qualité et la cadence de production.Dans ce mémoire, le processus industriel est détaillé depuis la fermeture du moule et l’injection du métal liquide jusqu’à l’ouverture du moule et l’extraction de la pièce (carter mécanisme RENAULT). Ensuite, le design détaillé du moule, les différentes générations de circuit de refroidissement et les paramètres de chaque étape de la fabrication utilisés compte tenu du système de refroidissement actuel sont présentés. Le circuit de refroidissement du moule est aujourd’hui positionné dans le moule de façon empirique. Le but ultime de cette thèse est de donner les éléments clés de la conception du circuit de refroidissement d’un point vue thermique. Pour cela, une modélisation complète du phénomène a été réalisée et validée par 8 thermocouples et la position du system de refroidissement a été définie a partir des équations thermiques. Le cycle thermique du moule a été donc optimisé et nous a permis d’abaisser et d’homogénéiser les champs de température à la surface du moule pendant la production en vue d’une augmentation de la productivité, la santé des pièces et la durée de vie du moule. / Reducing the weight of vehicles, specially the powertrain Group, contributes to the reduction of the emissions. Today, in order to achieve this objective, the automobile parts conception (Housing gear box, Cylinder block) in lightweight materials such as aluminum and its alloys is increasing. For the mass production, aluminum alloys are formed by a foundry process called ‘’High Pressure Die Casting’’.This process uses the metal molds. Control the thermal behavior of the mold : Heating, intern cooling (by circuit) and extern cooling, is a key point to ensure castings quality and rate of production.In this thesis, the industrial process has been detailed since the mold closing and aluminum melting injection in the die, to the mold opening time and the part (Gearbox RENAULT) ejection. Then, the mold design details, different generation of the cooling systems and the parameters of each step of the manufacturing process taking into account the actual cooling system are presented. The actual cooling systems in the dies are positioned today in empirical way. The ultimate goal of this thesis is to provide the key elements for the cooling system conception from the thermal behavior point of view. For this one, a complete modeling of the phenomena has been realized and validated by 8 thermocouples and the cooling system position has been defined from the thermal equations. The thermal cycle of the die has been optimized and allowed us to reduce and homogenize the temperature fields on the die surface during the production. The rate of production, the castings quality and the lifetime of the die have been consequently increased.

No atual período de incertezas na geração e transmissão de energia elétrica no Brasil, a utilização dos sistemas de cogeração com uso de gás natural, tornou-se uma grande oportunidade econômica, estratégica e tecnológica, para as pequenas e médias empresas, considerando a extensão e perspectivas de expansão da rede de distribuição de gás natural. Uma empresa farmacêutica para se manter competitiva e reduzir o impacto dos custos indiretos em seus produtos, necessitava aumentar sua linha de injetáveis, produzindo no Brasil alguns medicamentos que até então eram importados de filiais em outros países e para que isto fosse possível, teria de investir na construção de novos laboratórios, compra de equipamentos, aumento de utilidades para sua fabricação como vapor de água para injetáveis, sistema de HVAC para salas limpas, o que levaria a um aumento de consumo de energia, vapor, água de refrigeração. Este investimento inviabilizaria a produção desta nova linha de produtos, pois tanto o custo do investimento em novas centrais de utilidades, quanto mais o custo desta geração e sua manutenção, decretariam um fim para a esta empreita. Neste trabalho, apresentou-se uma alternativa como solução para viabilizar esta instalação, trocando-se os chillers convencionais por um chiller de absorção, que alem de consumir pouca energia elétrica utilizando a troca térmica entre brometo de lítio e vapor para gerar água de resfriamento para o sistema de ar condicionado, o sistema proposto proporcionou um aumento de fornecimento de vapor não só para alimentar o sistema de HVAC como para a produção da fabrica, anexo a esta caldeira de recuperação é proposto a instalação de uma turbina á gás com condições suficientes de gerar energia elétrica para todo o site e ainda ter condições de negociar o excedente de energia para ser vendido para a concessionária. O resultado deste sistema proposto demonstrou uma excelente eficiência, frente ao sistema convencional, o que tecnicamente se apresentou como muito viável. / In the current period of uncertainty in the generation and transmission of electric energy in Brazil, the use of cogeneration systems using natural gas, has become a great economic opportunity, strategic and technology for small and medium enterprises, considering the extent and prospects for expansion of the distribution of natural gas. A pharmaceutical company to remain competitive and reduce the impact of indirect costs in their products, needed to increase its line of injectables, producing here in Brazil some drugs that were previously imported from subsidiaries in other countries and to make this possible, would invest in building new laboratories, purchase equipment, increase of utilities for its manufacture steam as water for injection, the HVAC system for clean rooms, leading to an increased consumption of energy, steam, cooling water. This investment would make impracticable the production of this new line of products, therefore not only the cost of the investment in new central offices of utilities, the more the cost of this generation of utilities and its maintenance, would decree an end for the this take over on a contract basis. In this work, presented as an alternative solution to enable this facility, exchanging conventional chillers for an absorption chiller, which besides consume little electricity using the heat exchange between lithium bromide to generate steam and cooling water for the air conditioning system, the proposed system provided an increased supply of steam to feed not only the HVAC system for the production of manufactures, attached to this recovery boiler is proposed to install a gas turbine with sufficient conditions generate electricity for the entire site and still be able to trade the surplus energy to be sold to the utility. The result of this proposed system showed an excellent efficiency, compared to the conventional system, which technically is presented as very viable.