An existing solar-powered water pumping system located in Mutomo, Kenya has beenevaluated in this paper. The requirement for this system is to produce a minimum of25m³ water per day throughout the year.The aim of this thesis is to investigate theperformance of the currently installed system and find a suitable replacement in termsof efficiency and economic viability. In order to acquire the necessary knowledge forthis project, a literature study was carried out to analyse the research within the area.Three simulation models were created which all include an electric motor driven by aphotovoltaic array and are connected to a submersible groundwater pump. Allmodels utilise space vector pulse width modulation. One model of an inductionmotor that represents the currently installed system, one induction motor thatdelivers a minimum of 25 m³ water per day, and one model of a permanent magnetsynchronous motor for comparison. Simulations using weather data, representing anaverage day for each month of the year were carried out. It was shown that thecurrently installed system does not fulfil the requirement of producing 25 m³ waterper day, and in addition produces a significant amount of energy that can not beutilised. It was also shown that the efficiency of the permanent magnet synchronousmotor was superior to the induction motors. In order to compare the systems interms of economic viability, price quotations from world leading manufacturers wereacquired. The results of the economic comparison show that the superior efficiencyof the permanent magnet synchronous motor was not enough to compensate for thehigher investment cost.

Este trabalho trata da aplicação de técnicas de identificação de sistemas dinâmicos a ensaios com veículos submarinos não tripulados ou com modelos em escala auto-propelidos de veículos submarinos. Complementa-se, desta forma as investigações que vêm sendo realizadas no Laboratório de Veículos Não Tripulados, LVNT, voltadas à estimativa de parâmetros hidrodinâmicos de veículos autônomos submarinos, AUVs. Estas têm utilizado os métodos pertencentes a outras classes de abordagens para a estimativa de modelos de manobras para veículos submarinos como os métodos CFD e ASE (de BARROS, et. al., 2004, 2006, 2008a, 2008b; de BARROS e DANTAS, 2012). Outras atribuições deste trabalho dizem respeito à compreensão e desenvolvimento na modelagem linear da dinâmica de manobra de veículos submarinos, teoria e implementação de métodos de identificação de sistemas aplicados a resultados de ensaios com modelos auto-propelidos. As atividades de estudo foram divididas de acordo com os temas relativos à dinâmica de veículos submarinos, conceitos físicos envolvidos nas derivadas hidrodinâmicas de estabilidade, técnicas de identificação de sistemas e aspectos tecnológicos e experimentais da utilização de ensaios com modelos auto-propelidos. As atividades voltadas ao atendimento de tais metas envolveram, durante o programa de pesquisa, estudos de modelos analíticos, simulação numérica do movimento, realização de experimentos em piscina e campo com um AUV, e a implementação de ferramentas numéricas de análise de dados e estimação de parâmetros de manobra. / This paper is related to the application of techniques for identifying dynamic systems testing scale models of underwater vehicles or even unmanned underwater vehicles in real scale. Complementing in this way the investigations that have been conducted in the Laboratory of Unmanned Vehicles, LVNT, aimed to estimate the hydrodynamic parameters of autonomous underwater vehicles, AUVs. They have used the methods belonging to the three other classes mentioned (of Barros, et. Al., 2004, 2006, 2008a, 2008b; Barros and the DANTAS, 2012). Other tasks of this work relates to the understanding and development in modeling linear dynamic manoeuvring underwater vehicles, theory and implementation of identification methods applied to systems test results with self-propelled models. The study activities were divided according to themes related to the dynamics of underwater vehicles, physical concepts derived in the hydrodynamic stability, system identification techniques and technological aspects and experimental trials with use of self-propelled models. The activities aimed at meeting those goals involved during the research program, studies of analytical models, numerical simulation of the movement, performing experiments with a swimming pool and AUV, and implementation of numerical tools for data analysis and parameter estimation maneuver.

A new centrifugal pump has been devised to handle two-phase flow. However, it requires full scale testing to allow further development. Testing is required to verify performance and to gain information needed to apply this design in the field. Further, testing will allow mathematical models to be validated which will allow increased understanding of the pump's behavior. To perform this testing, a new facility was designed and constructed. This facility consists of a closed flow loop. The pump is supplied by separate air and water inlet flows that mix just before entering the pump. These flows can be controlled to give a desired gas volume fraction and overall flow rate. The pump outlet flows into a tank which separates the fluids allowing them to re-circulate. Operating inlet pressures of up to three hundred PSIG will be used with a flow rate of twelve hundred gallons per minute. A two-hundred fifty horsepower electric motor is used to power the pump. The loop is equipped with instrumentation to measure temperature, pressure, flow rate, pump speed, pump shaft horsepower, shaft torque, and shaft axial load. The pump itself has a clear inlet section and a clear section allowing visualization of the second stage volute interior as well as numerous pressure taps along the second stage volute. This instrumentation is sufficient to completely characterize the pump. Design and construction details are provided as well as a history of the initial operating experiences and data collected. A discussion of lessons learned is given in the conclusions. Future projects intended to use this facility are also given. Finally, detailed design drawings are supplied as well as operating instructions and checklists.

There are some alternatives of artificial lift methods to increase the production of oil well or to keep it producing. Sucker rod pumping (SRP) and electrical submersible pumping (ESP) systems are selected for the design and economical evaluation of thirteen oil wells of R field. Although selected wells are already producing artificially, they are redesigned for SRP and ESP. LoadCalC software developed by Lufkin and SubPUMP developed by DSSC are used for SRP and ESP designs respectively. For economic evaluation, the rate of return (ROR) of each design is calculated for ten year period. In technical comparison, advantage of higher production ability with lower power consumption was observed in ESP applications. In wells which have lower production than 100 bpd, SRP takes the advantage as it has the ability of low volume lifting. In economical comparison it was observed that using both methods together was given better result. By increasing the number of wells that were applied ESP, 3.61% of increment in ROR was obtained relative to the present status.

Plataformas semi-submersíveis, utilizadas como estruturas flutuantes na prospecção e exploração de petróleo em águas profundas, têm sua geometria composta basicamente por elementos horizontais totalmente submersos (pontoons), pelo convés, e por elementos verticais que cruzam a superfície livre (colunas), estes últimos ligando os pontoons ao convés. Tal geometria é eficaz para manter reduzidas as oscilações sob a ação de ondas, mormente o heave, bem como para prover flutuação, área de convés e estabilidade estática compatíveis com a missão. Neste trabalho aplicam-se modelos bastante simplificados para representação de características geométricas e dos atributos acima mencionados. De fato, pontoons e colunas são representados por trechos de cilindros, enquanto que as oscilações sob ondas são determinadas a partir de formulação semelhante à Equação de Morison. Tais modelos compõem um processo de otimização para determinar dimensões principais e proporções que satisfaçam certos requisitos quanto ao peso, à área de convés, à estabilidade estática e ao heave. Resultados numéricos para as oscilações sob ondas são confrontados com dados experimentais obtidos para plataformas em escala reduzida ensaiadas no canal de ondas do Laboratório de Engenharia Naval e Oceânica da EPUSP, observando-se boa aproximação. O processo de otimização é aplicado a situações descritas na literatura, chegando-se a resultados compatíveis com aqueles publicados, com a vantagem da simplicidade dos modelos analítico-numéricos aqui adotados. / Semi-submersible platforms, which are used as floating structures for oil production and exploration in deep waters, have their geometry composed basically of totally submerged horizontal elements (pontoons), the deck, and vertical elements that cross the free surface, these latter linking the pontoons to the deck. This geometry is efficient for keeping the oscillations due to wave excitation at small levels, specially the heave, as well to provide floatation, deck area and static stability compatible to the platform?s mission. In the present work, rather simplified models are applied for the representation of the geometric characteristics and of the other above mentioned attributes. In fact, pontoons and columns are represented by cylinders, and oscillations due to waves are determined by a formulation similar to Morison?s equation. These models take part in an optimization process for the determination of the main dimensions and proportions that satisfy certain requirements concerning weight, deck area, static stability and the heave. Numerical results for the oscillations due to waves are compared to experimental data obtained for scaled platforms tested in the wave channel of the Naval and Oceanic Engineering Laboratory of EPUSP, leading to reasonable approximations. The optimization process is applied to some cases described in the Literature, leading to results compatible with the published ones, but with the advantage of the simplicity of the analytic-numerical models here adopted.

Orientadores: Antonio Carlos Bannwart, Marcelo Moreira Ganzarolli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-22T03:35:14Z (GMT). No. of bitstreams: 1 Betonico_GustavodeCarvalho_M.pdf: 2382106 bytes, checksum: a84e8f76b2a2dcf28078dd9283ecef59 (MD5) Previous issue date: 2013 / Resumo: Neste trabalho foi desenvolvido um modelo para determinação da temperatura do motor de uma bomba centrífuga submersa (BCS) sob condições variáveis de vazão e carga. Este leva em consideração o comportamento acoplado entre o motor, a bomba e o sistema de produção. Assim, dada uma frequência ajustada no variador de frequência, a temperatura do motor é determinada como resultado do equilíbrio entre a produção de calor, calculada a partir da potência que a bomba demanda do motor, e a extração do calor, calculada a partir da vazão. Neste modelo, considera-se a BCS instalada num módulo de bombeamento submarino localizado perto do poço produtor. Foi estudada a transferência de calor por convecção no módulo de bombeio, onde um escoamento descendente ocorre no anular externo entre o revestimento e a camisa de refrigeração e um fluxo ascendente ocorre no anular interno entre a camisa de refrigeração e o motor. Um estudo de transferência de calor por convecção foi elaborado comparando modelos baseados no perfil de temperatura plenamente desenvolvido com modelos que consideram o desenvolvimento da camada limite térmica. Uma vez que o único ponto de medição da temperatura se localiza na extremidade inferior do enrolamento de estator, o modelo desenvolvido neste trabalho também determina a distribuição de temperatura do motor. Um estudo de caso foi realizado com diversas viscosidades de óleo e frações de água. Os resultados mostram a elevação da temperatura do motor, quando sua velocidade é continuamente aumentada. Também se mostrou que, negligenciar os efeitos do desenvolvimento da camada limite térmica, quando ocorre escoamento laminar, pode resultar num motor superaquecido, onde na verdade, a temperatura máxima do motor é muito menor do que o seu limite superior. Modelos baseados no perfil temperatura plenamente desenvolvidos sofrem de imprecisão, quando utilizados em aplicações de fluidos viscosos, devido ao grande comprimento entrada térmica / Abstract: A model to predict the motor temperature of an electrical submersible pump, under variable conditions of flow rate and loading, has been developed. This model takes into account the coupled behavior between motor, pump and production system. Thus, given a frequency set in the variable speed drive, the motor temperature is determined as a result of the equilibrium between the heat generation, calculated from the power that the pump demands from the motor, and the heat extraction, calculated from the flow rate. In this model, the electrical submersible pump is supposed to be installed in a subsea pumping module located near the producer well. It has been studied the convective heat transfer in the pumping module, where a downward flow occurs in the external annulus between the casing and the shroud, and an upward flow happens in the internal annulus between the shroud and the motor. A convective heat transfer study has been run comparing models based on fully developed temperature profile and models that consider the development of the thermal boundary layer. Since the only point of temperature measurement is located at the lower end of the stator winding, the model developed in this work also determines the temperature distribution of the motor. A case study has been run with several oil viscosities and water cut. The results show a motor temperature rise when motor speed is continuously increased. It is also showed that, when laminar flow occurs, neglecting the effect of the thermal boundary layer development may result in an overheated motor prediction where actually, motor maximum temperature is much smaller than its upper limit. Fully developed temperature profile models suffer of inaccuracy when used in viscous fluid applications, due to its big thermal entry length / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

The main aim of this thesis is the application of ideas to achieve innovation and modernization in the field of design of submersible personal watercraft. Another aim is to show the own creative activity and the ability to move an object from the field of functionality to the field of aesthetics, ergonomics and practicality at an affordable verified techniques, current manufacturing technologies and materials.

The design of an underwater observation vessel is the main objective during the thesis. An innovative approach will be applied in terms of modernization and design of the chosen topic. This work shows the author‘s creativity and ability to execute the required task in a specific time frame based on the appropriate level for a thesis. It reveals the steps that lead to an aesthetically balanced object from a functional product. Ergonomic standards and contemporary materials have been one of the basic knowledge.

A superhydrophobic coating can be produced using a hydrophobic material textured with surface roughness on the micro-/nano-scale. Such a coating on the outside of a submersible body may result in reduced skin-friction drag due to a trapped layer of air in the coating. However, this layer may become unstable when subjected to elevated hydrostatic pressures, and a coating’s performance is compromised beyond a certain threshold (critical pressure). This thesis presents a numerical model for predicting the pressure tolerances of superhydrophobic coatings comprised of randomly deposited hydrophobic particles or fibers. We have also derived a set of force-balance-based analytical equations for predicting critical pressure in surfaces with ordered roughness, and compared our numerical model against it, observing reasonable agreement. The numerical model was then applied in a large parameter study, predicting critical pressure for coatings with a given set of microstructure properties.

The paper compares electricity production between the semi-submersible and the spar-buoy floating wind turbine systems under normal, stochastic and extreme wind conditions at Utsira Nord site located on the Norwegian continental shelf in the North Sea. The analysis of complex behavior of the floating wind turbine system and the fluid-structure interaction is performed in aero-servo-hydro-elastic code ASHES. The results indicate a slightly better energy performance of the semi-submersible than the spar in all load cases but one. The pitch and heave degrees of freedom are evaluated as the most relevant for the power output. It is shown that pitch and heave platform motions have smaller displacement in the semi-submersible floater than in the spar under average environmental conditions and at the rated wind speed operating range. The simulation also confirmed that the energy yield is very sensitive to the magnitude of the loads: the spar performed best under mild environmental conditions, while the semi-submersible was better under medium environmental conditions. Small difference in energy yield is attributed to the same baseline blade and external controller properties used for both floaters where generator torque was kept constant to limit the power excursions above the rated power. The method proposed under this paper has demonstrated that a good approximation of the energy performance of the floating wind turbine system can be performed in a fast and effective manner.