Rural electrification has long been the most important topic on the development agenda of many countries. The needs for power supplies to rural areas increased significantly in the past decades. Extending electricity grids to rural areas is of a very high initial cost and is not viable economically. Micro hydroelectric power plants provide a good economical solution, which is also environmentally very friendly. The current study concentrates on selecting and optimizing a suitable cross-flow micro-turbine to be used in micro hydroelectric power plants. Cross-flow turbines are in general of simple structure, low cost, easy to fabricate and of modest efficiency. The main purpose of the present work is to optimize the performance of a selected turbine by establishing the optimal turbine’s design parameters. A complete analysis of the internal flow, which is of turbulent, two-phase and three dimensional in nature, was undertaken by simulating it using various CFD simulation codes. This study reports on the flow simulation using ANSYS CFX with a two-phase flow model, water-air free surface model and shear stress transport (SST) turbulence model. Prediction velocity and pressure fields of inside the turbine are, subsequently, used to characterize the turbine performance for different geometric parameters including the number of runner blades, the angle of attack, the ratio of inner to outer diameter, the nozzle profile, the blade profile, the nozzle throat width, the nozzle to runner blades width and the runner blades width to outer runner diameter. The results revealed the highly complex nature of the flow and provided a very good insight to the flow structure and performance optimization parameters.

Orientador: Paulo de Barros Correia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T15:04:34Z (GMT). No. of bitstreams: 1 Colnago_GlauberRenato_D.pdf: 3941653 bytes, checksum: 2d5aa45eb54c758162bd82a78a5739f3 (MD5) Previous issue date: 2011 / Resumo: Segundo cenários de previsões, a demanda de energia elétrica no Brasil tende a continuar crescendo, implicando na necessidade de se aumentar a oferta de energia através da instalação de novas usinas. Além disto, mostra-se importante a repotenciação de usinas existentes, pois se trata de uma alternativa de custos reduzidos para expandir a oferta de energia e a adequada operação das usinas. Baseado nisto, propõe-se duas metodologias para a otimização do potencial hidrelétrico. A primeira é a especificação de turbinas hidráulicas para usinas em construção, ou em repotenciação. A segunda metodologia diz respeito à operação de usinas em uma base diária, podendo tratar unidades geradoras (turbina-gerador) com diferentes curvas de eficiência, coordenando a maximização da eficiência na geração da energia com a minimização do número de partidas e paradas dessas unidades. Para esta última metodologia, como os objetivos são conflitantes, pode-se obter diversas soluções de despacho com características de manobras de unidades e eficiência diferentes, que podem ser quantificadas para se chegar à solução mais adequada de acordo com o preço da energia e estimativas de custos de manobras. Com relação à primeira metodologia, sabe-se que, geralmente, instala-se o mesmo tipo de turbina em todas as unidades geradoras, porém cada usina possui um regime de operação, o que motiva as seguintes questões: utilizar diferentes tipos de curvas de efi- ciência em uma usina pode trazer melhorias técnicas e econômicas? Quais formatos de curvas de eficiência seriam adequados para quais regimes de operação? A primeira metodologia, portanto, faz a escolha de perfis de curvas de eficiência de forma a maximizar a geração. Comparou-se curvas de eficiência características de turbinas Kaplan e Hélice. Os resultados mostram que, com operação adequada, pode-se chegar a patamares de eficiência com turbinas Hélice superiores às Kaplan, e o primeiro tipo possui a vantagem de ter menor custo. Ambos os problemas foram formulados como modelos matemáticos não lineares inteiros mistos e resolvidos com técnicas de algoritmos genéticos / Abstract: According to forecasts, the electric energy demand in Brazil will be increased, showing the necessity to increase the electric capacity by building new power plants. Moreover, the repowering of the existent power plants and an appropriate power plants operation are important. In this context, we propose two methodologies to optimize hydroelectric power plants potential. The first methodology is the specification of hydroelectric turbines to new hydro power plants, or to plants to be repowered. The second methodology is related to the power plants diarly operation and it considers generation units with different efficiency curves. It is a model with the objectives of maximizing the plant efficiency and minimizing the generation units start up and shut down. For this last methodology, there were obtained some different solutions, with different characteristics of efficiency and different number of generation units start up and shut down. Those solutions can be qualified according to the electric energy price and costs of the status changes, with the objective to choose the most advantageous solution. In respect to the first methodology, it is known that, generally, the same configuration of turbines is installed into all generation units. However, every hydroelectric power plant has a different operation system. Therefore, the present thesis proposes to address the following question: Is it an advantageous option to choose different configuration of turbines in a same power plant? Which design of turbine efficiency curves would be ideal for each operation system? The first methodology chose turbine efficiency curves designs to optimize the electric energy efficiency. Kaplan and Propeller turbine efficiency curves were compared. The results show that, with an appropriate operation, it is possible to obtain higher efficiency level with Propeller when compared to Kaplan, and the first turbine has the advantage of lower costs. Both methodology were formulated as mixed integer non-linear mathematical models and are solved with genetic algorithms techniques / Doutorado / Doutor em Planejamento de Sistemas Energéticos

This project is in collaboration with the Hydro-Quebec Research Institute (IREQ) and the Canadian Centre for Electron Microscopy (CCEM) on the mechanical test performance of miniature-scale micro-tensile specimens. The objective of the thesis project is to create an efficient and reliable fabrication route for producing micro-tensile specimens and to validate the accuracy of a newly custom-built micro-tensile bench at IREQ. The fabrication techniques developed and outlined in this thesis use the underlying fundamental physical mechanisms of secondary electron microscopy (SEM), focused-ion beam (FIB), and the femtosecond (fs)-laser machining for producing optimal quality micro-tensile specimens. The mechanical testing of the specimens is geared towards studying the localized deformation occurring in the microstructure when the size of the specimen only limits a number of grains and grain boundaries in order to target the specific detailed measurement of the mechanical behaviour of individual grains and interfaces. The goal for creating an optimal fabrication route for micro-tensile specimens is to carry out micro-mechanical testing of the primary turbine steels of 415 martensitic stainless steel used in the manufacture of Francis turbine components at Hydro-Quebec. The mechanical testing of single phase and interphase interface 415 steel micro-tensile specimens are considered building blocks to developing digital twin models of the steel microstructure. The experimental data from the mechanical tests would be fed into the crystal plasticity finite element models (CPFEM) that are currently being developed by researchers at IREQ. With the development of digital twin models, engineers at IREQ would be able to predict crack initiation at the microstructure level (prior to crack propagation into macro-scale cracks) by observing the evolution of the grain’s crystallographic orientation and morphology, as well as deformation mechanisms such as martensite formation and twinning produced from localized induced strains in the microstructure. In addition, self-organized dislocation processes such as dislocation nucleation and dislocation escape through the free surface can also be studied using the CPFEM models for size-limited mechanical deformation behaviour of miniature-scale mechanical test specimens. The fabrication routes studied in this thesis project use the combination of the fs-laser and plasma focused ion beam (PFIB) to machine the micro-tensile specimens. (100) single crystal copper was the ideal material chosen to validate the accuracy of the micro-tensile bench and quality of the fs-laser-machined tensile specimens, due to its ductile nature and well-characterized properties studied in literature. A mechanical size effect was studied for single crystal copper specimens with different gauge thicknesses. It was observed from the micro-tension testing that the strength of the specimens increased with decreasing gauge thickness occurring in the size-limited tensile gauges. In addition, it was determined there was negligible differences in the size effect seen between the PFIB-machined copper micro-tensile specimens and the fs-laser-machined micro-tensile specimens, demonstrating that the fs-laser is a reliable machining route for the micro-tensile specimens. X-ray computed tomography was used to validate the correct geometry of the machined gauge section produced from an innovative gauge thinning method adopted from IREQ’s research collaborator, Dr. Robert Wheeler. As well, finite-element analysis (FEA) was performed to determine the deformation behaviour under both linear-elastic and non-linear elastoplastic conditions of (100) copper and 415 steel models simulated in pure tension, prior to the fabrication of the micro-tensile specimens, respectively. Furthermore, significant progress has been made towards targeting martensite grains in the 415-steel microstructure using electron backscattered diffraction (EBSD) analysis to produce single crystal and interphase interface micro-tensile specimens. A workflow towards grain targeting using EBSD analysis has been developed, as well as for the relocation of grains using reference fiducial marks for future fabrication of the single crystal and interphase interface 415 micro-tensile specimens. / Thesis / Master of Applied Science (MASc) / Hydro-Quebec is an energy utilities company that operates the design of Francis hydro-turbines to supply hydroelectric power across the province of Quebec. The hydro-turbines have an expected service life of 70 years. Unfortunately, the turbines can get replaced by new ones prior to reaching half of its service life, due to the development of severe fatigue crack growth in the primary components of the turbines. A solution proposed by the researchers at the Hydro-Quebec Research Institute (IREQ) is to determine a linkage between the turbine’s steel’s microstructure and the mechanical behaviour of the turbine steels. Deformation of the material starts at the microstructure level, where dislocations glide through the material lattice, causing both reversible (elastic) and irreversible (plastic) deformation. Therefore, a solution was proposed by the researchers at IREQ to create computational models of the steel microstructure to predict the deformation of the steel’s microstructure. Being able to predict the deformation mechanisms through the simulation models of the microstructures allows for engineers at Hydro-Quebec to schedule regular maintenance of the turbines more efficiently and provide metallurgists the knowledge on what is occurring at the microstructure level and what can be done to improve the chemical and physical composition of the steel. To develop the digital twin models, experimental data must be collected through mechanical testing of miniature mechanical test specimens of the turbine steels. The mechanical properties of the single phases and interphase interface specimens are fed into the models as building blocks to building a microstructure map of the turbine steels. Micro-tension testing of micro-tensile specimen provides direct information about the material’s mechanical properties. In this work, a reliable and efficient fabrication route for micro-tensile specimens was developed for the purpose of extracting mechanical properties of single phase and interphase interface turbine steel specimens using focused ion beam (FIB) and femtosecond laser machining.

Two of the most important environmental challenges in the 21st century are to protect the quality of fresh water resources and to utilize renewable energy sources to lower greenhouse gas emissions. This study contributes to the solution of the first challenge by providing methodologies for optimal design of real-time water quality monitoring systems and interpretation of data supplied by the monitoring system to identify potential pollution sources in river networks. In this study, the optimal river water quality monitoring network design aspect of the overall monitoring program is addressed by a novel methodology for the analysis of this problem. In this analysis, the locations of sampling sites are determined such that the contaminant detection time is minimized for the river network while achieving maximum reliability for the monitoring system performance. The data collected from these monitoring stations can be used to identify contamination source locations. This study suggests a methodology that utilizes a classification routine which associates the observations on a contaminant spill with one or more of the candidate spill locations in the river network. This approach consists of a training step followed by a sequential elimination of the candidate spill locations which lead to the identification of potential spill locations. In order to contribute the solution of the second environmental challenge, this study suggests utilizing available excess energy in water distribution systems by providing a methodology for optimal design of energy recovery systems. The energy recovery in water distribution systems is possible by using micro hydroelectric turbines to harvest available excess energy inevitably produced to satisfy consumer demands and to maintain adequate pressures. In this study, an optimization approach for the design of energy recovery systems in water distribution networks is proposed. This methodology is based on finding the best locations for micro hydroelectric plants in the network to recover the excess energy. Due to the unsteady nature of flow in water distribution networks, the proposed methodology also determines optimum operation schedules for the micro turbines.