La variété des pratiques de compostage et les différences de nature des substrats modifient la vitesse de dégradation de la matière organique (MO), la qualité finale du compost produit et la part d'émissions sous forme de polluants gazeux. L'optimisation du procédé nécessite la prédiction de ces transformations ou la réalisation d'essais empiriques. Cette thèse analyse les interactions entre les processus biologiques, biochimiques, physico-chimiques et thermodynamiques majeurs à l'origine de la stabilisation de la MO et des émissions gazeuses de CO2, H2O, NH3, N2O. Elle se focalise sur le compostage par aération passive en andain d'effluents d'élevage. La méthode s'appuie sur la modélisation dynamique et des expérimentations. L'impact des interactions entre la biodégradabilité du carbone, la disponibilité de l'azote, l'humidité et la porosité, sur la cinétique et la stœchiométrie des émissions gazeuses est analysé à partir d’observations en conditions contrôlées et sur une plateforme de compostage. Les écarts de répétabilité faibles en conditions contrôlées deviennent élevés en conditions de reproductibilité sur le terrain. Un modèle dynamique de compostage a été développé simulant la stabilisation de la MO et les émissions de CO2, H2O, NH3, N2O. Il est composé de quatre modules simulant les cinétiques d'oxydation de la MO par une population microbienne, les échanges thermiques et l'aération passive, le transfert d'oxygène, les transformations de l'azote. Lors de la phase thermophile, le facteur limitant le plus rapidement l'organisation de la MO est la disponibilité de l'azote. L'abaissement de la porosité entraîne une diminution des pertes gazeuses par l'augmentation de l'organisation de la MO. Le fractionnement initial de la MO ainsi que la teneur initiale en biomasse microbienne sont les facteurs clés pour prédire les cinétiques d'organisation de la MO. La calibration des paramètres d’initialisation du modèle reste à améliorer / The variety of the practices and the differences in nature of the substrates modify the kinetics of degradation of organic matter (OM), the final quality of the produced compost and the fraction emitted as gaseous pollutants. To optimize the composting process, it is required to predict these transformations or to do some empirical test. This thesis analyzes the interactions between the main biological, biochemical, physicochemical and thermodynamic processes which explain the OM stabilization and the gaseous emissions of CO2, H2O, NH3, N2O. Focus is done on windrow composting with passive aeration. The method is based on dynamic semi-empirical modeling of the process and experimentations. The impact of the interactions between bioavailability of carbon and nitrogen, moisture and porosity, on the kinetics and the stoechiometry of the gaseous emissions is analyzed with data gathered in controlled conditions and on a commercial composting plant. The repeatability differences are small in controlled conditions but higher in field conditions. A dynamic model of composting was developed simulating the stabilization of OM as well as the emissions of CO2, H2O, NH3, N2O. This model is composed of four coupled modules which simulate the kinetics of oxidation of OM by a heterotrophic microbial population, the heat transfers leading to the passive aeration, the transfer of oxygen, the transformations of nitrogen. During the thermopilic phase, the first factor limiting the organization of OM is the availability of nitrogen. The decrease in porosity induces a reduction in the gas losses through the increase in the organization of OM. The initial OM fractionation and the initial microbial biomass are the key factors to predict the kinetics of organization of OM. The calibration of the specific parameters used for model initialization needs a further implementation

Le joint à rainures hélicoïdales (JRH) est l'une des solutions techniques d'étanchéité sans contact utilisées dans les machines tournantes. Ce dispositif est conçu pour des applications bien particulières qui nécessitent une durée de vie et une non-tolérance aux fuites au-delà des limites que peuvent satisfaire les joints à contact. Le JRH est caractérisé par l'absence d'usure due au jeu radiale nettement supérieure aux amplitudes des aspérités et les défauts de fabrication. L'étanchéité est obtenue grâce aux rainures hélicoïdales présentes sur l'une des ses surfaces internes. Ces rainures sont à l'origine de phénomènes hydrodynamiques synthétisant un débit de pompage de même ordre que le débit de fuite.Dans ce travail, un modèle numérique pour le calcul d'étanchéité dans les JRH est proposé. Basé sur la théorie des films minces, le comportement de ce dernier est déterminé par le calcul du champ de pression et du remplissage qui satisfont l'Equation de Reynolds Modifiée (ERM). Cette dernière permet de bien gérer les frontières de rupture et de reformation du film. La résolution est faite par la méthode des éléments finis.La caractérisation du pouvoir d'étanchéité du JRH est faite par « la longueur utile » qui spécifie largeur, dans la direction axiale, de la zone occupée par le fluide lorsque l'étanchéité s'établisse. Cette étendue du domaine étant une inconnue du problème, on itère sur la longueur du joint jusqu'à l'obtention d'un débit axial nul sur le bord. Néanmoins, l'étanchéité dans le JRH dépend d'un certain nombre de paramètres géométriques et de fonctionnement. Il s'agit de la forme des rainures, leurs inclinaisons ainsi que la vitesse de rotation. Tout d'abord, une géométrie optimale de fonctionnement a été déterminée. Les aspects turbulents de l'écoulement et le comportement thermique, selon un bilan thermique global, sont également étudiés. Enfin, l'introduction des effets d'excentricité a permis de statuer sur les phénomènes dynamiques dans le JRH. / The viscoseal is one of the contacts less sealing technical solutions used in machinery. This device is designed for very specific applications requiring durability and non-tolerance leakage past the limits that can satisfy joints contact. The viscoseal is characterized by the friction absence due to radial clearance well above the asperities amplitudes and the manufacturing defects. The sealing is obtained by the helical grooves formed in one of its internal surfaces. These grooves induce a hydrodynamic phenomenon that synthesizes same pumping rate of the same order as the leakage rate.In this work, a numerical model is proposed to calculate the seal in the viscoseal. Based on the thin film theory, the behavior of the latter is determined by the calculation of the pressure field and the filling that satisfy the Modified Reynolds Equation (MRE). The latter allows managing the borders of the film breaking and reformation. Resolution is made by the finite element method.The sealing power characterization in the viscoseal is made by the "sealing length" that specifies width of the fluid full area, in the axial direction, when the sealing is established. This domain extension is unknown, it iterates over the length of the seal until a zero axial flow over the edge. However, in the sealing depends on several geometrical and operating parameters. It is about the shape of the grooves, their angle orientation of and the journal speed.First, an optimal operating geometry was determined. Turbulent aspects of flow and thermal behavior, according to a global heat balance, are also studied. Finally, the introduction of eccentricity effects allowed approving dynamic phenomena in the viscoseal.

The aim of the master’s thesis is to design a condensing steam turbine based on given inputs. Firstly, a design and computation of heat balance is made, followed by thermodynamic calculation of steam turbine channel and a design of compensatory piston of axial forces. Last part of the thesis consists of a review of a change of cooling water temperature in condensator on last turbine stages. The structural drawing of longitudinal section of turbine is included as well.

The diploma thesis deals with design of gas steam boiler with given parameters of steam. Blast furnace and coke oven gas are used as fuel. At the beginning of this work, both co-fired fuels are presented to us, their chemical analysis and stoichiometry are performed. The main part of the diploma thesis deals with the dimensioning of individual heat exchange surfaces such as steam superheaters, evaporators, economizers and air heaters. All heat exchange surfaces meet recommended parameters such as recommended steam rates, flue gas, etc. At the end, the total heat balance of the boiler is performed. Part of the work is also drawing documentation showing the main dimensions of the boiler. It is also indicated the connection of individual heat exchange surfaces.

Thesis is focused on calculation of the condenser of flue gas, which is created by burning of natural gas. In the first part is theoretical overview of equations describing film condensation and physical properties of the flue gas. The second part deals with practical thermal calculation of the specified condenser. In third part parametric study is done in which a tempature of cooling water at inlet and the coefficient of excess air are changed. The last part of the thesis is dedicated to geometric design of the flue gas condenser whose required power is 8 MW.

Master thesis is dealing with the issue of condensate creation and removal from the Nesher Ramle steam turbine during start-up and steady state. At the beginning a preliminary calculation of heat balance and the turbine itself is done. It is followed by description and design of drainage system supplemented by calculation of the steam flow through the orifices. Steam flow calculation was done via S. D. Morris, Pavelek with Kalčík and Ambrož, all three methods were compared. The main goal is the theoretical calculation of the amount of condensate created during start-up which is influenced by its initial state from which it is started. Three default states are considered, cold, warm and hot. In the last chapter the comparison of theoretical calculation with the measured data on real turbine is done and it is supported by the evaluation of the data from the measurement of the steam turbine at steady state on maximum power and half power. From the steady state analysis, percentage of water flow to expander from the total amount of condensate formed in the turbine were obtained.

The master thesis deals with the design, tracing and dimensioning of condensate pipeline. In the beginning, a preliminary calculation of heat balance is done. It is followed by a description of the main condensate system supplemented by the computational design of pipeline and the calculation of pressure losses in this pipeline. The crucial part of the thesis is the calculation of pressure losses, which is done in two ways. The first approach to calculation of pressure losses in the pipeline is calculated using values of representative resistance coefficient for pipe ele-ments using Idelchik literature and for individual types of valves using values from datasheets of Siemens Energy suppliers. In the second approach to calculation representative resistance coefficients for pipe elements and individual types of valves CRANE literature are used. Then both approaches of choosing representative resistance coefficients are compared and evaluated. Based on the calculated values, a suitable pump is selected at the end of the master thesis.

This master thesis designes the calculation of fluid boiler with specific part - the circular fluid bed. The heat is given by combustion of wood biomass. The thesis is devided into several parts. All necessary elementary results are going to be reached within these parts: an analysis of solid fuel, stechiometry calculation, discussion on output limits and the environmental point of view, definition of elemental heat losses and general heat efficiency, calculation and design of a combustion part and its heat loads and calculation of enthalpies with different ash concentrations. All these phases get to a successful design of the fluid boiler heat balance and sizes of heat-flow surfaces. The composition of the boiler shows the added drawing.

Turbogenerator unit 100B TGU, produced in the First Brno Engineering Velká Bíteš a.s., works in Brayton indirect circulation. The aim of this work is the proposal to increase performance levels of technological unit in which the micro-turbine is applied. The work presents various ways to increase performance and efficiency of circulation. The possible options are compared with each of the technological and economic terms. Based on these criteria was selected variant feeding additional water into the circulation. For this design was the work of a mathematical model based on, which was established as the economic balance of the selected variants. The thesis also proposes a technological scheme, which is already incorporated the selected variant and an outline of the verification tests.

The aim of this Master’s thesis is to design a steam condensing turbine with three bleeds. First, a heat balance of the steam cycle is calculated, followed by thermodynamic and stress calculation of the turbine blading and design of a gland steam system and drain system. A price proposal is suggested for the given steam turbine. In the end, a design drawing of the steam turbine is constructed.