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Master thesis is concerned with gas turbines from Siemens company. The thesis consists of two main parts. In the first part describes the different types of turbines, their characteristics and use in practice. The following is a detailed description of components and systems the biggest industrial gas turbine SGT-800. The second part discusses about the necessary steps for commissioning turbine. These particulars are managing software, testing, commissioning and phasing of the turbine generator to the distribution network. The conclusion is devoted to the example of calculating return investment on the overall gas turbine project.

Master thesis deals with analysis of characteristic points of two-shaft combustion turbine cycle for two different concepts of turbine’s arrangement. Computational model is compiled within the thesis for serial and parallel arrangement. Thermodynamic magnitudes of characteristic points of cycle are calculated with the computational model for designed operating point. Initial values of the computational model are chosen in consideration of reaching compromise between maximal thermal efficiency and maximal specific power.

The power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power (CSP) and waste heat recovery (WHR) applications. With this regard, this dissertation is intended to perform thorough thermodynamic analyses and optimization of S-CO2 Brayton cycles for both of these applications. A modeling tool has been developed, which enables one to predict and analyze the thermodynamic performance of the S-CO2 Brayton cycles in various configurations employing recuperation, recompression, intercooling and reheating. The modeling tool is fully flexible in terms of encompassing the entire feasible design domain and rectifying possible infeasible solutions. Moreover, it is computationally efficient in order to handle time consuming optimization problems. A robust optimization tool has also been developed by employing the principles of genetic algorithm. The developed genetic algorithm code is capable of optimizing non-linear systems with several decision variables simultaneously, and without being trapped in local optimum points. Two optimization schemes, i.e. single-objective and multi-objective, are considered in optimizing the S-CO2 cycles for high temperature solar tower applications. In order to reduce the size and cost of solar block, the global maximum efficiency of the power block should be realized. Therefore, the single-objective optimization scheme is considered to find the optimum design points that correspond to the global maximum efficiency of S-CO2 cycles. Four configurations of S-CO2 Brayton cycles are investigated, and the optimum design point for each configuration is determined. Ultimately, the effects of recompression, reheating, and intercooling on the thermodynamic performance of the recuperated S-CO2 Brayton cycle are analyzed. The results reveal that the main limiting factors in the optimization process are maximum cycle temperature, minimum heat rejection temperature, and pinch point temperature difference. The maximum cycle pressure is also a limiting factor in all studied cases except the simple recuperated cycle. The optimized cycle efficiency varies from 55.77% to 62.02% with consideration of reasonable component performances as we add recompression, reheat and intercooling to the simple recuperated cycle (RC). Although addition of reheating and intercooling to the recuperated recompression cycle (RRC) increases the cycle efficiency by about 3.45 percent points, the simplicity of RC and RRC configurations makes them more promising options at this early development stage of S-CO2 cycles, and are used for further studies in this dissertation. The results of efficiency maximization show that achieving the highest efficiency does not necessarily coincide with the highest cycle specific power. In addition to the efficiency, the specific power is also an important parameter when it comes to investment and decision making since it directly affects the power generation capacity, the size of components and the cost of power blocks. Consequently, the multi-objective optimization scheme is devised to simultaneously maximize both the cycle efficiency and specific power in the simple recuperated and recuperated recompression configurations. The optimization results are presented in the form of two optimum trade-off curves, also known as Pareto fronts, which enable decision makers to choose their desired compromise between the objectives, and to avoid naive solution points obtained from a single-objective optimization approach. Moreover, the comparison of the Pareto optimal fronts associated with the studied configurations reveals the optimum operational region of the recompression configuration where it presents superior performance over the simple recuperated cycle. Considering the extensive potential of waste heat recovery from energy intensive industries and stand-alone gas turbines, this dissertation also investigates the optimum design point of S-CO2 Brayton cycles for a wide range of waste heat source temperatures (500 K to 1100 K). Once again, the simple recuperated and recuperated recompression configurations are selected for this application. The utilization of heat in WHR applications is fundamentally different from that in closed loop heat source applications. The temperature pinching issues are recognized in the waste recovery heat exchangers, which brings about a trade-off between the cycle efficiency and amount of recovered heat. Therefore, maximization of net power output for a given waste heat source is of paramount practical interest rather than the maximization of cycle efficiency. The results demonstrate that by changing the heat source temperature from one application to another, the variation of optimum pressure ratio is insignificant. However, the optimum CO2 to waste gas mass flow ratio and turbine inlet temperature should properly be adjusted. The RRC configuration provides minor increase in power output as compared to RC configuration. Although cycle efficiencies as high as 34.8% and 39.7% can be achieved in RC and RRC configurations respectively, the overall conversion efficiency is less than 26% in RRC and 24.5% in RC.

An air‐cycle air conditioning system, using a typical automotive turbocharger as the core of the system, was designed and tested. Effects on engine performance were kept to a minimum while providing the maximum amount of cooling possible and minimizing weight and space requirements. A test stand utilizing shop compressed air was developed to measure component performance. An unmodified automotive turbocharger was tested initially as a baseline in a Reversed‐Brayton Cycle air cooling system. Once the baseline was established, another aircycle machine, assembled from commercial turbocharger components chosen individually to optimize their performance for cooling purposes, was tested to improve the overall cycle efficiency. Finally, once the air‐cycle air conditioning system was optimized, it was tested on an engine to simulate more realistic operating conditions and performance. The shop‐air test stand experiments showed a peak dry‐air‐rated (DAR) coefficient of performance (COP) of 0.38 and a DAR cooling capacity of 0.45 tons for the baseline turbocharger, and a peak DAR COP of 0.73 and DAR cooling capacity of 1.5 tons for the optimized system with a modified turbocharger. The on‐engine testing was limited due to a thrust bearing failure in the ACM. However, the data collected at lower engine load and speed indicates a DAR COP of 0.56 and a DAR cooling capacity of 0.72 tons. On‐engine testing was planned to include operating points where the stock turbocharger was utilizing turbine‐bypass to limit boost pressure. While it wasn't possible to continue testing, it is expected that DAR COP and cooling capacity would have increased at higher engine load and speed, where turbine‐bypass operation typically occurs.

No description available.

PRESENTATION DES MODELES RELATIFS AUX DIFFERENTS ELEMENTS CONSTITUTIFS DE LA BOUCLE THERMIQUE ET DU MODELE GLOBAL DE CELLE-CI. APPLICATION DE LA METHODE CLASSIQUE DE COMMANDE CLASSIQUE AVEC CRITERE QUADRATIQUE SANS PRENDRE EN COMPTE DE FACON EXPLICITE LES CONTRAINTES. ELABORATION D'UNE COMMANDE UTILISANT "L'ETAT ADJOINT" METTANT A PROFIT CERTAINES PARTICULARITES DU SYSTEME. SIMULATION DES COMMANDES POUR DIFFERENTS ENSOLEILLEMENTS ET DIFFERENTS CHANGEMENTS DE CONSIGNE<br />PRESENTATION OF THE MODELS RELATIVE TO THE VARIOUS ELEMENTS CONSTITUTING THE THERMAL LOOP AND OF THE GLOBAL MODEL OF THE LOOP. APPLICATION OF THE CLASSICAL METHOD OF CONVENTIONAL DRIVE WITH QUADRATIC CRITERION WITHOUT EXPLICITELY TAKING INTO ACCOUNT THE CONSTRAINTS. ELABORATION OF A DRIVE USING THE "ADJOINT STATE" AND TAKING ADVANTAGE OF SOME PECULIARITIES OF THE SYSTEM. SIMULATION OF THE DRIVES FOR VARIOUS DEGREES OF SUNSHINE AND FOR VARIOUS CHANGES IN THE INSTRUCTIONS

Recently, the supercritical carbon dioxide (s-CO2) Brayton cycle has been identified as a promising candidate for solar-thermal energy conversion due to its potentially high thermal efficiency (50%, for turbine inlet temperatures of ~ 1000 K). Realization of such a system requires development of solar receivers which can raise the temperature of s-CO2 by over 200 K, to a receiver outlet temperature of 1000 K. Volumetric receivers are an attractive alternative to tubular receivers due to their geometry, functionality and reduced thermal losses. A concept of a ceramic pressurized volumetric receiver for s-CO2 has been developed in this work. Computational Fluid Dynamics (CFD) analysis along with a Discrete Ordinate method (DOM) radiation heat transfer model has been carried out, and the results for temperature distribution in the receiver and the resulting thermal efficiency are presented. Issues regarding material selection for the absorber structure, window, coating, receiver body and insulation are also addressed. A modular small scale prototype with 0.5 kWth solar heat input has been designed. The design of a small scale s-CO2 loop for testing this receiver module is also presented in this work. There is a lot of ongoing investigation for design and simulation of different configurations of heat exchangers and solar receivers using s-CO2 as the working fluid, in which wall temperatures up to 1000 K are encountered. While CO2 is considered to be transparent as far as solar radiation spectrum is concerned, there may be considerable absorption of radiation in the longer wavelength range associated with radiation emission from the heated cavity walls and tubes inside the receivers. An attempt has been made, in this study, to include radiation modelling to capture the effect of absorption bands of s-CO2 and the radiative heat transfer among the equipment surfaces. As a case study, a numerical study has been performed to evaluate the contribution of radiative heat transfer as compared to convection and conduction, for s-CO2 flow through a circular pipe. The intent is to provide a guideline for future research to determine the conditions for which radiation heat transfer modelling inside the pipe can be significant, and what errors can be expected otherwise. The effect of parameters such as Reynolds number, pipe diameter, length to diameter ratio, wall emissivity and total wall heat flux has been studied. The effect of radiation modelling on wall temperatures attained for certain amount of heat flux to be transferred to s-CO2 is also studied. The resulting temperature distribution, in turn, affects the estimation of heat loss to the environment

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.