L'objectif de cette thèse est d'étudier un système énergétique intégré dans l'enveloppe des bâtiments permettant de préchauffer l'air neuf.L'originalité du travail repose sur le fait que ce mur est équipé de matériau à changement de phase (MCP).Celui-ci a pour rôle de stocker l'énergie solaire captée en façade puis de la déstocker en préchauffant l'air neuf de ventilation. Notre étude est constituée de deux grandes phases, une phase expérimentale et une phase numérique.La phase expérimentale consiste à effectuer des essais en laboratoire, afin de connaître le comportement du système étudié sous sollicitations thermiques. Ces essais ont été réalisés grâce à un prototype du mur, instrumenté et installé entre deux cellules avec des conditions climatiques contrôlées.Le but de la phase numérique est de mettre en place un modèle ID permettant de simuler le comportement thermique du mur et en particulier celui du MCP. Ce modèle a été validé en comparant les résultats numériques avec ceux obtenus expérimentalement.Pour modéliser le changement de phase nous avons utilisé les paramètres thermophysiques du matériau obtenu par caractérisation expérimentale réalisée dans notre laboratoire. Nous avons ensuite utilisé la méthode de la capacité variable pour simuler le comportement de la paroi stockeuse du mur. Dans la dernière partie du travail numérique le modèle a été utilisé afin de montrer l'influence de quelques paramètres permettant d'optimiser les gains énergétiques.La simulation dynamique du système a été effectuée grâce au logiciel TRNsys, qui nous a permis d'effectuer des bilans énergétiques et d'estimer l'efficacité du système pour des climats variés. / The objective of this thesis is to study an integrated energy system in the building envelope for fresh air preheating. The originality of the work is that the wall is equipped with phase-change material (MCP) packed into briquettes. The main role ofthe wall is to preheat the fresh air (coming from outside) by destocking the solar energy captured in sunny periods.Our study consists of two phases, an experimental phase and a numerical one. The experimental phase involves a series of tests that allow studying the thermal behaviour of the system under thermal stress. These tests were done in laboratory through a prototype of the wall which is instrumented and installed between two airconditioned cells.The purpose of the numerical phase is to develop a one-dimensional model to simulate the thermal behaviour of the wall and especially that of MCP. This model has been validated by comparing numerical results with those obtained experimentally. To model the phase changing we used the thermophysical parameters of the same material obtained by experimental characterization conducted in our laboratory.We used a variable capacity method whose principle is to vary the heat capacity as a function of temperature in order to simulate the phase changing of the wall. The last part of the numerical work is the exploitation of the model, the aim is to determine the optimal configuration of the wall that provides maximum energy savings. Dynamic simulation of the system was performed using the TRNSYS. This one is equipped with weather files which allow carrying out heat balances and the estimation of the system efficiency for various climates.

In this study, the goal is to optimize the process and to reduce the clogging tendency during the continuous casting process. The focus is on clogging when the refractory base material (RBM) in the SEN is in contact with the liquid steel. It is difficult or impossible to avoid non-metallic inclusions in the liquid steel, but by a selection of a good RBM in the SEN clogging can be reduced.   Different process steps were evaluated during the casting process in order to reduce the clogging tendency. First, the preheating of the SEN was studied. The results showed that the SEN can be decarburized during the preheating process. In addition, decarburization of SEN causes a larger risk for clogging. Two types of plasma coatings were implemented to protect the RBM, to prevent reactions with the RBM, and to reduce the clogging tendency. Calcium titanate (CaTiO3) mixed with yttria stabilized zirconia (YSZ) plasma coatings were tested in laboratory and pilot plant trials, for casting of aluminium-killed low-carbon steels. For casting of cerium alloyed stainless steels, YSZ plasma coatings were tested in laboratory, pilot plant and industrial trials. The results showed that the clogging tendency was reduced when implementing both coating materials.   It is also of importance to produce clean steel in order to reduce clogging. Therefore, the steel cleanliness in the tundish was studied experimentally. The result showed that inclusions originated from the slag, deoxidation products and tundish refractory and that they were present in the tundish as well as in the final steel product. / <p>QC 20170227</p> / VINNOVA

Atualmente, há a necessidade de se desenvolver aços com alta resistência à propagação de trincas, especialmente em condições de carregamentos cíclicos, ou seja, resistentes à fadiga, na qual sua aplicabilidade se da em função de suas propriedades mecânicas. No presente trabalho estudou-se o efeito do preaquecimento na zona afetada pelo calor do aço AISI/SAE 4130 com composição química modificada, com altos teores de Mo, comparando as propriedades mecânicas e microestruturais nas condições como soldada, tratada termicamente e aplicando a técnica de Metodologia do Preaquecimento Combinado (MPC) com otimização de ciclos térmicos através da combinação do preaquecimento entre o 1º e 3º passe da 1º e 2º camada, respectivamente. A fim de avaliar as propriedades mecânicas, foram realizados ensaios de microdureza, mapeamento de dureza e ensaio de tenacidade ao impacto charpy. Para análise microestrutural, foi realizado microscopia ótica e microscópio eletrônico de varredura (MEV) para analisar as regiões de grãos grosseiros, fino e as intersecções entre as regiões da Zona Afetada pelo Calor (ZAC), quando aplicado o MPC. Como resultado, observa-se que preaquecimento é uma forma efetiva de redução de dureza, chegando a uma redução máxima de 71 HV0,1, quando comparado às temperaturas de preaquecimento entre 150 e 400 ºC. No entanto há um severo efeito deletério na tenacidade, podendo chegar a uma queda de 71% da energia absorvida. O tratamento térmico pós soldagem (TTPS) se mostrou eficiente apenas para amostra soldada com temperaturas de preaquecimento de 150 ºC, para as demais temperaturas não houve benefício, tanto em redução de dureza, quanto na restauração da tenacidade. No entanto, para temperatura de preaquecimento de 230 ºC também foi observado o acréscimo de dureza após o TTPS devido ao efeito de endurecimento secundário por precipitação de carbonetos metálicos (MC). A técnica MPC se mostrou muito eficiente em redução da dureza e restauração da tenacidade, e este fenômeno está associado à capacidade de solubilizar os carbonetos que precipitam durante a soldagem, fenômeno que não ocorre com a aplicação do TTPS. / Currently, it is necessary to develop materials with high resistance to crack propagation, especially under conditions of cyclic loading condition such as fatigue resistant, in which its applicability is due to its mechanical properties. In the present work the effect of preheating in the heat-affected zone of the AISI / SAE 4130 steel with modified chemical composition (High Mo) was compared, regarding its mechanical and microstructural properties of each welding condition, As weld, post weld heat treated and applying the Methodology of combined preheating (MCP) with optimization of thermal cycles by combining the preheating between the 1st pass of 1st layer and the 3rd pass of 2nd layer. In order to evaluate the mechanical properties, microhardness tests, hardness mapping and charpy V notch tests were performed. For microstructural analysis, optical and scanning electron microscopy (SEM) were used to analyze the coarse grained regions and the intersections between the Heat Affected Zones (HAZ) regions, when applied to the MPC. As a result, it is observed that preheating is an effective form of reduction of hardness, reaching a maximum reduction of 71 HV0,1, when compared to the preheating temperatures between 150 and 400ºC, however there is a severe deleterious effect in the toughness, dropping up to 71% of the absorbed energy. The post weld heat treatment (PWHT) is efficient only for welded sample with preheating temperatures of 150 ºC, for the other temperatures there was no benefit, either in reduction of hardness or restoration of toughness. However, for the preheating temperature of 230 °C it was observed the increase of hardness after the PWHT due to the effect of secondary hardening by precipitation of metal carbides (MC). The MPC technique proved to be very efficient in decreasing hardness and restoring toughness, and this phenomenon is associated with the ability to solubilize the carbides that precipitate during welding, which is not observed while PWHT is applied.

Im Rahmen der vorliegenden Arbeit wird gezeigt, wie ein Gebäude- und Anlagensimulationsprogramm mit bekannten Optimierungsalgorithmen gekoppelt und zur theoretischen Lösung optimaler Steuer- und Regelprobleme in der Gebäudetechnik eingesetzt werden kann. Theoretische Optimallösungen erlauben im Sinne eines optimalen Vergleichsprozesses die Bewertung praktisch anderweitig umsetzbarer Steuerungs- und Regelungsmechanismen. Die im Hinblick auf ein gewähltes Gütekriterium erforderliche Notwendigkeit zur Verbesserung von vorhandenen Steuerungs- und Regelungsszenarien sowie die theoretisch maximal erreichbaren Extremwerte lassen sich leicht abschätzen.

The renewed interest in energy for biomass is supported by the need for different energy sources and the need to protect the environment. Recently, because of increases in crude oil prices, limited resources of fossil oil and environmental concerns there has been renewed focus on vegetable oils and animal fats to make a biodiesel fuel. What is known as biodiesel (methyl or ethyl esters) is a vegetable oil or animal fat chemically treated to replace traditional diesel fuel. Performance parameters and exhaust emissions of a diesel engine fuelled with sunflower and beef tallow ethyl esters and a blend of ethyl and methyl esters, subjected to pre-heating at two temperatures ranges, namely T55 (50 to 60ºC) and T75 (70 to 80ºC), in order to lower its viscosities, have been investigated. Tests were carried out at full load conditions in a four cylinders, four-stroke indirect injection diesel engine. Engine tests, short-term, were conducted at a range speed from 1900 to 4400 rpm. The injection timing was retarded from the manufacturer s recommended setting. The tests were carried out using the same engine and test procedures so that comparative assessments may be made. The tests data were used for evaluating the brake power, exhaust gas temperatures, specific fuel consumption and gaseous emissions. The analysis of the results determined that the level of pre-heating have influence on the performance for used esters. The tests performed at T55 showed the best values of torque (N.m), power (kW) and specific fuel consumption (g.kW-1.h-1) that the tests performed at T75. The bests experiments results were obtained with sunflower ethyl ester and the blend containing 50,0% sunflower ethyl ester and 50,0% beef tallow methyl ester, at -2º BTDC and T55 temperature range. The findings showed that, by using biodiesel, harmful emissions (CO, HC and NOx) can be reduced to some extent of B2 by adjusting the injection pump timing properly and pre-heating of fuel. / O renovado interesse por energia da biomassa é apoiado na necessidade de fontes alternativas de energia e de proteção ambiental. Recentemente, devido ao aumento dos preços do óleo cru, a limitação de seus recursos e as questões relacionadas ao ambiente, um renovado foco passou a existir sobre os óleos vegetais e gorduras animais para produção de um biodiesel combustível. O que é conhecido como biodiesel (éster metílico ou etílico) é um óleo vegetal ou gordura animal tratado quimicamente para substituir o combustível diesel tradicional. Parâmetros de desempenho e emissões de exaustão foram investigados para um motor diesel alimentado com ésteres etílicos de óleo de girassol e de sebo bovino e por uma mistura composta pelo éster etílico de óleo de girassol e pelo metílico de sebo bovino numa proporção volumétrica igual (50,0%+50,0%). Os ésteres estavam sujeitos ao pré-aquecimento segundo duas faixas de temperaturas, chamadas de T55 (50 a 60ºC) e T75 (70 a 80ºC), como forma de redução da viscosidade. Os testes foram conduzidos sob condição de carga máxima em um motor diesel de quatro cilindros, quatro tempos e de injeção indireta de combustível. Os ensaios de curta duração foram efetuados em uma faixa de rotações compreendida entre 1900 e 4400 rpm. O ponto de avanço de injeção foi atrasado em relação ao ponto original recomendado pelo fabricante. Os testes foram conduzidos utilizando o mesmo motor e os mesmos procedimentos de testes para permitir a comparação dos valores obtidos. Nos ensaios foram obtidos os valores de potência, torque, consumo específico de combustível e gases de exaustão. A análise dos resultados indica que o nível de pré-aquecimento tem influência sobre o desempenho dos ésteres utilizados. Os ensaios conduzidos à T55 mostraram melhores valores para torque (N.m), potência (kW) e consumo específico de combustível (g.kW-1.h-1) que os testes executados à T75. Os melhores resultados do experimento foram obtidos pelo éster etílico de girassol e pela mistura contendo 50,0% de éster etílico de girassol e 50% de éster metílico de sebo bovino, sob 2º (P2) de atraso no ponto de injeção e aquecidos na faixa de temperaturas de T55. Os resultados indicam que, pelo uso do biodiesel, as emissões prejudiciais (CO, HC e NOx) podem ser reduzidas aos mesmos níveis do B2 através do ajuste apropriado do ponto de avanço da injeção e o pré-aquecimento do combustível.

Tato diplomová práce se zabývá předehřevem spalovacího vzduchu a jeho vlivem na parametry spalovacího procesu. V teoretické části je zpracován přehled nejčastějších znečišťujících látek z průmyslového spalování. Je popsána aktuálně platná relevantní legislativa v Evropské unii a jsou porovnány její implementace do národní legislativy v České republice a v Německu. Dále je provedena klasifikace hořáků z hlediska různých kritérií a rešerše předchozí práce v oblasti předehřevu spalovacího vzduchu. Na zkušebně hořáků byla provedena experimentální studie dvou různých hořáků na zemní plyn při konstantním tepelném příkonu 750 kW se spalovacím vzduchem předehřátým až na 250 °C. Výsledky odhalily pozitivní vliv předehřevu na účinnost spalování. Množství emisí NOx a CO naopak rostlo s teplotou spalovacího vzduchu.

The master’s thesis deals with the bypass system of steam turbine, especially about its heating during normal operation and cold start up. At the beginning of work, a preliminary thermodynamic calculation of condensing steam turbine with two uncontrolled extractions is made. This is followed by theoretical description and design of bypass system and design of heating during normal operation and cold start-up. The main goal of thesis is optimalization of heating, when the heating branch is connected back to turbine supply line. In the end, all options of heating are compared in terms of power output.

This work deals with issues of the wetting forces during soldering and evaluates material and procedural effects on the soldering process. The aim is to set the technology operations to get best quality of soldered joints.

The target of the study is theoretical explaining the condition of creation of the soldered point with regard to basic and additional mat. Below, the detailed analysis of the existing technical problem and consecutive design of the solution method.Content of the study is also technological process of production of the barking knife and choice of the efficient producer.

Yes / In order to improve the performance of the reverse osmosis (RO) desalination plant powered by photovoltaic (PV), two cooling systems were proposed in this study to cool the PV and preheating the RO feed water as well. In the cooling design (1), the cooling fluid flows in direct contact with the back surface of the PV through channels of half circular cross-sections. While in the design (2), it flows through channels of squar cross-sections fixed on the PV back surface. Two nano-fluids were also tested as cooling fluid: H2O/CuO and H2O/Al2O3, in addition to distilled water for the purpose of comparison. The effect of changing the weight concentration of the nano-fluid (0.05, 0.1, and 0.15%) on the PV performance was also investigated. The results showed that the PV integrated with the cooling design (1) achieves better performance compared to design (2) at all studied cooling fluids. The improvements in the electric efficiency of the PV integrated with design (1) reached 39.5, 34.8 and 27.3 % when CuO and Al2O3 nano-fluids and distilled water were used as cooling fluid, respectively, compared to the uncooled PV. Based on the obtained experimental results, the PV integrated with design (1) was selected to power the RO with H2O/CuO nano-fluid of weight concentration 0.15% and flow rate 0.15 kg/s being used as the coolant. The RO powered by the improved PV was tested at different salinities of brackish water when the preheating technique was implemented. The results showed that the proposed PV-RO desalination system produces 366 l/day when brackish water of salinity 3000 ppm was used.