The threat of depletion of fossil fuels is the driving force to diversify energy sources in the Czech Republic respectively in the European Union but also worldwide. One of these potential sources are being biomass boilers. The construction of these boilers has expanded in recent years because of government support for the construction of clean energy sources. Whether it is a burning of clean biomass or just incorporation of biomass to fossil fuels, teh substitution of fossil fuels and biomass boilers are the ideal solution. Their major advantages include significant reductions in emissions, mainly sulfur compounds, organic closure of the cycle of CO2 and disposal costs of spent residue.

This master’s thesis is dealing with design of steam boiler for wood chips. Wood chips are considered as biomass and so the steam boiler is considerate to enviroment. Main purpose of this work is calculation of size and number of water/steam heating surfaces so the boiler can produce steam with required parametres of temperature, pressure and amount.

The present thesis is focused on calculation prediction of characteristic parameters of combustion process in combustion chamber which is installed at burners testing laboratory. In the thesis basic theoretical knowledge needed for description of heat transfer in process combustion equipment are given. The Plug Flow Furnace Model is based on this knowledge. This model is used to evaluation of specific heat flux in tube furnaces. In the next step the Plug – Flow model is modified and adapted on the combustion chamber. Obtained results are compared with a measured data. By this comparison quality of this model is assessed.

The purpose of this Diploma Thesis is the construction design of the steam boiler with natural circulation for the combustion of wood biomass according to the specified parameters. It is the boiler with the power of 12 tons per hour of superheated vapor output parameters of 3,3 Mpa at a temperature of 400 °C and a temperature of feed water 105 °C. For the specified parameters I first calculated the stoichiometric calculations, boiler efficiency, and followed by using geometrical parameters of the blocks and thermal calculations set design and the number of heat transfer surfaces, depending on the input parameters of the air and water and output parameters of vapor. The work also includes drawings of the boiler.

The thesis is focused on the experimental investigation of the oxygen enhanced combustion technology (OEC), which uses the combustion air with higher concentration of oxygen, i.e. more than 21 %. The OEC technology is used in those industrial applications, which requires higher thermal efficiency, increased productivity, improved character of the flame, reduced equipment cost, lower volume of exhaust gases and improved product quality. Although this technology involves a number of advantages, it is appropriate to mention some of its disadvantages such as refractory damage, inconsistent heating, increased pollutant emission or flame disturbance and/or flashback. The combustion tests of OEC were carried out at the burners testing facility that enables to test many types of burners (gaseous, liquid, or combined). The two-staged low-NOx burner fired by natural gas was used during the tests. The observed parameters include the effect of oxygen concentration in the combustion air on the NOx emissions, heat flux into the wall of the combustion chamber, in-flame temperature distribution in the horizontal symmetry plane of the combustion chamber and also the shape and dimensions of the flame. The combustion tests of the air-enrichment, air-oxy/fuel and O 2 lancing OEC methods were carried out at the burner thermal input of 750 kW and air excess of 1,1 for two combustion regimes, namely one-staged and two-staged fuel supply.

The aim of this thesis is the proposal of a coal mill system and a combustion chamber for the boiler PK 4S situated in Košice CHP station with regard to transition to the new fuel. This proposal is focused on the elimination of NOx emissions. The calculation is based on required parameters of the boiler and declared characteristic of the new fuel. The proposal of the coal mill system includes three roller mills working in closed circuit with direct blowing. One of the mills serves as a reserve in case of failure. Dimensions of the dry bottom combustion chamber are proposed considering the applied primary measures to reduce NOx emissions so that the temperature at the end of the furnace would not be higher than maximal allowed temperature 1200 °C.

<p dir="ltr">This study contributes to research involving wave rotor combustors by studying the</p><p dir="ltr">development of a hot jet issuing from a cylindrical pre-combustion chamber. The pre-chamber was</p><p dir="ltr">developed to provide a hot fuel-air mixture as an ignition source to a rectangular combustion</p><p dir="ltr">chamber, which models the properties of a wave rotor channel. The pre-combustion chamber in</p><p dir="ltr">this study was rebuilt for study and placed in a new housing so that buoyancy effects could be</p><p dir="ltr">studied in tandem with other characteristics. The effectiveness of this hot jet is estimated by using</p><p dir="ltr">devices and instrumentation to measure properties inside the pre-chamber under many different</p><p dir="ltr">conditions. The properties tracked in this study include maximum pressure, the pressure and time</p><p dir="ltr">at which an aluminum diaphragm ruptures, and the moment a developed flame reaches a precise</p><p dir="ltr">location within the chamber. The pressure is tracked through use of a high-frequency pressure</p><p dir="ltr">transducer, the diaphragm rupture moment is captured with a high-speed video camera, and the</p><p dir="ltr">flame within the pre-chamber is detected by a custom-built ionization probe. The experimental</p><p dir="ltr">apparatus was used in three configurations to study any potential buoyancy effects and utilized</p><p dir="ltr">three different gaseous fuels, including a 50%-50% methane-hydrogen blend, pure methane, and</p><p dir="ltr">pure hydrogen. Additionally, the equivalence ratio within the pre-chamber was varied from values</p><p dir="ltr">of 0.9 to 1.2, and the initial pressure was set to either 1.0, 1.5, or 1.75 atm. In all cases, combustion</p><p dir="ltr">was initiated from a spark plug, causing a flame to develop until the diaphragm breaks, releasing</p><p dir="ltr">a hot jet of fuel and air from the nozzle inserted into the pre-chamber. In the pressure transducer</p><p dir="ltr">tests, it was found that hydrogen produced the highest pressures and fastest rupture times, and</p><p dir="ltr">methane produced the lowest pressures and slowest rupture times. The methane-hydrogen blend</p><p dir="ltr">provided a middle ground between the two pure fuels. An equivalence ratio of 1.1 consistently</p><p dir="ltr">provided the highest pressure values and fastest rupture out of all tested values. It was also found</p><p dir="ltr">that the orientation has a noticeable impact on both the pressure development and rupture moment</p><p dir="ltr">as higher maximum pressures were achieved when the chamber was laid flat in the “vertical jet”</p><p dir="ltr">orientation as compared to when it was stood upright in the “horizontal jet” orientation.</p><p dir="ltr">Additionally, increasing the initial pressure strongly increased the maximum developed pressure</p><p dir="ltr">but had minimal impact on the rupture moment. The tests done with the ion probe demonstrated</p><p dir="ltr">that an equivalence ratio of 1.1 produces a flame that reaches the ion probe faster than an</p><p dir="ltr">equivalence ratio of 1.0 for the methane-hydrogen blend. In its current form, the ion probe setup</p><p>18</p><p dir="ltr">has significant limitations and should continue to be developed for future studies. The properties</p><p dir="ltr">analyzed in this study deepen the understanding of the processes that occur within the pre-chamber</p><p dir="ltr">and aid in understanding the conditions that may exist in the hot jet produced by it as the nozzle</p><p dir="ltr">ruptures. The knowledge gained in the study can also be applied to develop models that can predict</p><p dir="ltr">other parameters that are difficult to physically measure.</p>

The primary requirements for a modern industrial gas turbine consist of a continuous trend of an increasing efficiency combined with very low emissions in a robust, cost-effective manner. To fulfil these tasks a high turbine inlet temperature together with advanced dry low NOX combustion chambers are employed. These dry low NOX combustion chambers generate a rather flat temperature profile compared to previous generation gas turbines, which have a rather parabolic temperature profile before the nozzle guide vane. This means that the nozzle guide vane endwall heat load for modern gas turbines is much higher compared to previous generation gas turbines. Therefore the prediction of the nozzle guide vane flow field and endwall heat transfer is crucial for the engineering task of the design layout of the vane endwall cooling system. The present study is directed towards establishing new in-depth aerodynamic and endwall heat transfer knowledge for an advanced nozzle guide vane of a modern industrial gas turbine. To reach this objective the physical processes and effects which cause the different flow fields and the endwall heat transfer pattern in a baseline configuration, a combustion chamber variant, a heat shield variant without and with additional cooling air and a cavity variant without and with additional cooling air have been investigated. The variants, which differ from the simplified baseline configuration, apply design elements which are commonly used in real modern gas turbines. This research area is crucial for the nozzle guide vane endwall heat transfer, especially for the advanced design of the nozzle guide vane of a modern industrial gas turbine and has so far hardly been investigated in the open literature. For the experimental aerodynamic and endwall heat transfer research of the baseline configuration of the advanced nozzle guide vane geometry a new low pressure, low temperature test facility has been developed, designed and constructed, since no experimental heat transfer data exist in the open literature for this type of vane configuration. The new test rig consists of a linear cascade with the baseline configuration of the advanced nozzle guide vane geometry with four upscaled airfoils and three flow passages. For the aerodynamic tests the two middle airfoils and the hub and the tip endwall are instrumented with pressure taps to monitor the Mach number distribution. For the heat transfer tests the temperature distribution on the hub endwall is measured via thermography. The analysis of these measurements, including comparisons to research in the open literature shows that the new test rig generates accurate and reproducible results which give confidence that it is a reliable tool for the experimental aerodynamic and heat transfer research on the advanced nozzle guide vane of a modern industrial gas turbine. Previous own research work together with the numerical analysis performed in another part of the project as well as conclusions from a detailed literature study lead to the conclusion that advanced Navier-Stokes CFD tools with the v2-f turbulence model are most suitable for the calculation of the flow field and the endwall heat transfer of turbine vanes and blades. Therefore this numerical tool, validated against different vane and blade geometries and for different flow conditions, has been chosen for the numerical aerodynamic and endwall heat transfer research of the advanced nozzle guide vane of a modern industrial gas turbine. The evaluation of the numerical and experimental investigations of the baseline configuration of the advanced design of a nozzle guide vane shows the flow field of an advanced mid-loaded airfoil design with the features to reduce total airfoil losses. For the hub endwall of the baseline configuration of the advanced design of a nozzle guide vane the flow characteristics and heat transfer features of the classical vane endwall secondary flow model can be detected with a very weak intensity and geometric extension compared to the studies of less advanced vane geometries in the open literature. A detailed analysis of the numerical simulations and the experimental data showed very good qualitative and quantitative agreement for the three-dimensional flow field and the endwall heat transfer. These findings, together with the evaluations obtained from the open literature, lead to the conclusions that selected CFD software Fluent together with the applied v2-f turbulence model exhibits a high level of general applicability and is not tuned to a special vane or blade geometry. Therefore the CFD code Fluent with the v2-f turbulence model has been selected for the research of the influence of the several geometric variants of the baseline configuration on the flow field and the hub endwall heat transfer of the advanced nozzle guide vane of a modern industrial gas turbine. Most of the vane endwall heat transfer research in the open literature has been carried out only for baseline configurations of the flow path between combustion chamber and nozzle guide vane. Such a simplified geometry consists of a long, planar undisturbed approach length upstream of the nozzle guide vane. The design of real modern industrial gas turbines however requires often significant variations from this baseline configuration consisting of air-cooled heat shields and purged cavities between the combustion chamber and the nozzle guide vane. A detailed evaluation of the flow field and the endwall heat transfer shows major differences between the baseline and the heat shield configuration. The heat shield in front of the airfoil of the nozzle guide vane influences the secondary flow field and the endwall heat transfer pattern strongly. Additional cooling air, released under the heat shield has a distinctive influence as well. Also the cavity between the combustion chamber and the nozzle guide vane affects the secondary flow field and the endwall heat transfer pattern. Here the influence of additional cavity cooling air is more decisive. The results of the detailed studies of the geometric variants are applied to formulate guidelines for an optimized design of the flow path between the combustion chamber and the nozzle guide vane and the nozzle guide vane endwall cooling configuration of next-generation industrial gas turbines. / QC 20100917

This master’s thesis deals with design of intake port for turbocharged Mazda 13B-T engine with Wankel-type rotating piston motion aiming for possible modifications leading to increase of performance parameters. The main objective of this thesis is to propose appropriate modifications in order to achieve increased torque in widest possible engine speed range.

Diploma thesis deals with use of combustion chamber to drive the electric bus charging unit. Based on the research and analysis of operation economy, a turboexpander with an air pressure tank is selected to drive the charging unit. A thermodynamic design is created for this variant. Based on this design a unit layout is proposed. Layout drawings are created for the proposed layout.