Dissertations / Theses on the topic 'Pumping Systems'

Grassland and farmland degradation is considered as one of the worst environmental and economic threats for China. The degradation process negatively affects food and water security, economy, society and climate changes. Photovoltaic water pumping (PVWP) technology for irrigation is an innovative and sustainable solution to curb the grassland degradation. At the same time it can promote the conservation of farmland, especially in remote areas of China. The combination of PVWP technology with water saving irrigation techniques and sustainable management of the groundwater resources can lead to several benefits. These include enhancing grassland productivity, halting wind and rainfall erosion, providing higher incomes and better living conditions for farmers.    This doctoral thesis aims to bridge the current knowledge gaps, optimize system implementation and prevent system failures. This work represents thus a step forward to solve the current and future nexus between energy, water and food security in China, using PVWP technology for irrigation. Models for the dynamic simulations of PVWP systems, irrigation water requirements (IWR) and crop response to water have been presented and integrated. Field measurements at a pilot PVWP system in Inner Mongolia have been conducted to analyse the reliability of the models adopted. A revision of the traditional design approaches and a new optimization procedure based on a genetic algorithm (GA) have been proposed to guarantee the match between IWR and water supply, to minimize the system failures and to maximize crop productivity and thus the PVWP system profitability and effectiveness. Several economic analyses have been conducted to establish the most cost effective solution for irrigation and to evaluate the project profitability. The possible benefits generated by the PVWP system implementation have been highlighted, as well as the effects of the most sensitive parameters, such as forage price and incentives. The results show that PVWP system represents the best technical and economic solution to provide water for irrigation in the remote areas compared to other traditional water pumping technologies. The environmental benefits have been also addressed, evaluating the CO2 emissions saving achievable from the PVWP system operation. The assessment of the feasible and optimal areas for implementing PVWP systems in China has been conducted using spatial analysis and an optimization tool for the entire supply chain of forage production. The results show that the potentials of PVWP systems in China are large. Nevertheless, the feasible and optimal locations are extremely sensitive to several environmental and economic para­meters such as forage IWR, groundwater depth, and CO2 credits that need to be carefully taken into account in the planning process.    Although this doctoral thesis has used China as case study, PVWP technology can be applied for irrigation purposes all over the world both for off- and on-grid applications leading to several economic and environmental benefits.

Photovoltaic pumping systems have become a favourable solution for water supply particularly for sunny regions that have no access to an electric grid. The maximization of energy utilization of these systems via maximum power point tracking (MPPT) has not been sufficiently exploited in the literature. As a result, most commercial photovoltaic pumping systems either utilize inefficient MPPT control or do not utilize MPPT control at all thus wasting up to 50% of the available solar power depending on component matching and weather conditions. It is therefore important that the operating behaviour of these systems under MPPT control must be better understood and their reliability proven under practical operating conditions. This thesis details an investigation of the performance characteristics of directly connected photovoltaic pumping systems, systems operated at a constant array voltage, and those utilizing MPPT control. Two hill-climbing MPPT algorithms namely perturb and observe algorithm and incremental conductance algorithm were chosen because of their simplicity and ease of implementation with a low cost microcontroller/DSP. Particular focus is given to the evaluation of the practical implementation of these two MPPT algorithms and the choice of their parameters. A simple and accurate empirical model is derived for each individual component of the system and the system is simulated numerically using the MATLAB/Simulink environment. A comprehensive analysis of the stability and the performance characteristics of the system in different operation modes is presented. The various advantages and drawbacks of each MPPT control technique are identified and energy utilization efficiency is calculated for different weather conditions. Experimental operation of the system was tested using a 1080Wp photovoltaic array connected to a lkW permanent magnet de motor-centrifugal pump set. A power converter was constructed and used as a pump controller to match the motor-pump set with the PV array. A Texas Instruments TMS320F2812 DSP based eZdsp kit was used for real-time control and data acquisition. Data acquisition is accomplished utilizing the real-time data exchange feature of the DSP kit. Practical results show very good agreement with the numerical simulation of the systems.

Electron transport in single lateral quantum dot (QD) and parallel lateral double quantum dot (DQD) systems is modeled using semiclassical rate equations. The Zeeman effect, in conjunction with resonant tunneling, is used to select the spin of electrons involved in transport. We show adiabatic spin pumping by periodic variation of the systems' confining parameters, namely the quantum point contacts (QPCs) dictating the boundaries of the dots, and the gate voltage applied to each dot. The limitations of adiabatic spin pumping are subsequently examined by counting the average spin pumped per cycle when frequency and interdot capacitance are adjusted.
ID: 031001288; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Eduardo Mucciolo.; Title from PDF title page (viewed February 26, 2013).; Thesis (M.S.)--University of Central Florida, 2012.; Includes bibliographical references (p. 109-118).
M.S.
Masters
Physics
Sciences
Physics

Master of Science
Department of Architectural Engineering
Fred Hasler
Ground-coupled heat pump (GCHP) systems use the ground as a heat source or sink that absorbs heat from or rejects heat to the soil, respectively; this is referred to as the geothermal heat exchanger. Apart from the geothermal heat exchanger, there are two other main system components that make up a GCHP system: heat pumps and circulation pumps. This report studies four GCHP pumping systems and makes comparisons between the four using life-cycle cost analyses for six building models. The goal for this analysis was to discover commonalities between the models in order to provide designers insight into which pumping system is the most cost effective. The analysis was performed by first creating energy models to obtain system and zone load information, as well as system part-load data and geothermal heat exchanger performance. From the zone load information, heat pump selections were then performed to indicate the worst case piping path that is required for pump head calculations. Piping layouts were created to establish pipe lengths for the pump head calculations as well. Other piping components such as valves and fittings and the air separator pressure drops were also calculated. Once the pump head calculations were complete for each system, pump schedules were created. From there initial unit and installation costs were determined for each pump, as well as their replacement costs. The part-load data from the energy models were then used to obtain annual pump energy consumption and pump utility cost. Finally, assumptions were made to establish regular and preventative maintenance requirements for each pumping system. Initial and replacement unit costs, annual utility cost and regular and preventative maintenance costs were the components used in the life-cycle cost analysis. Each of these components was converted to 30-year projected costs and added to create a total life-cycle cost for each pumping system. Comparisons were then made and the results showed that a primary pumping system with VFD control and 100% redundancy was the most cost effective system. However, there are other considerations such as controllability, flexibility and availability that might persuade designers to choose one of the other alternate solutions.

Grassland degradation is considered as one of the worst environmental and economic problems in China because of the negative impacts on water and food security. The application of the photovoltaic water pumping (PVWP) technology for irrigation is an innovative and sustainable solution to curb the progress of grassland desertification and to promote the conservation of farmland in remote areas. The combination of PVWP with water saving irrigation techniques and the sustainable management of the water resources enhances the grass productivity enabling to halt wind and rainfall erosion and to provide higher incomes and better living conditions for farmers. PVWP systems have been used for more than 40 years especially for drinking purposes, livestock watering and irrigation in small-medium size applications. Nevertheless, several knowledge gaps still exist and system failures still occur, which are mainly bounded to the system design procedure and optimization. The technical and economic feasibilities related to the system implementation, especially effectiveness and profitability, need to be addressed. Moreover, irrigation in remote areas constrained by availability of water resources has to be investigated for a better understanding of PVWP system integration with the environment and for optimization purposes. This thesis is to bridge the current knowledge gaps, optimize system implementation and prevent system failures    Validation of the models adopted and optimization of the system on the basis of solar energy resources and exploitable groundwater has been performed for a pilot PVWP system in Inner Mongolia. The match between the water supplied through the pumping system and the grass water demand has been studied, and the effects of pumping on the available resources and the crop productivity have been evaluated. The economic analyses have also been conducted in order to establish the most cost effective solution to provide water for irrigation and to evaluate the project profitability. In addition, the CO2 emission reductions by using PV technology have been assessed as well.   It was found that the proper designed PVWP system represents the best technical and economic solution to provide water for irrigation in the remote areas compared to other water pumping technologies, such as diesel water pumping and wind power water pumping due to the high positive net present values and short payback periods.

This thesis was aimed to develop, investigate and optimize high power Nd:YAG laser system for OPCPA (Optical Parametric Chirped Pulse Amplifiers) pump. The particular attention is paid for the temporal characteristics of the Nd:YAG amplifies output pulse. Employment of Fabry-Perоt etalons in the cavities of two-stage Nd:YAG regenerative amplifier enables for amplified pulse stretching from 60 fs to ~ 100 ps pulse widths. The modulation of amplified pulse envelope is minimal when ration of thickness of the etalons is around 2. Envelope modulation can be controlled by changing the reflectivity of etalons. In order to improve amplified pulse contrast, we for the first time to our knowledge implemented second order intensity dependent filter, based on the effect of fundamental pulse polarization rotation in unbalanced second harmonic generators. By using this method, the contrast of the output pulses was improved by >102 times. We also demonstrated that Gaussian pulses from the output of Nd: YAG amplifiers can be transformed into flat–top pulses by using cascade second harmonic generation processes. The developed high output energy Nd:YAG amplifiers system for OPCPA pumping is optically synchronized with pulses of Yb:KGW oscillator and features two 532 nm outputs with pulse parameters: a) Gaussian pulse profile, ~ 300 mJ energy, 75 ps pulsewidth; b) hiper- Gaussian pulse profile, ~100 mJ energy, pulse width 100-150 ps.
Disertacija yra skirta sukurti, ištirti ir optimizuoti didelės galios Nd: YAG lazerių sistemą efektyviam moduliuotos fazės signalų optinių parametrinių stiprintuvų kaupinimui. Ypatingas dėmesys yra skiriamas Nd:YAG stiprintuvų išvadinių impulsų laikinių parametrų formavimui. Pademonstravome, kad Fabry-Pero interferometrų panaudojimas Nd:YAG dvipakopio regeneracinio stiprintuvo rezonatoriuose leidžia stiprinamų impulsų trukmę padidinti nuo ~ 60 fs iki 100 ps. Tuo tarpu išvadinių impulsų laikinės plėtros mastas bei gaubtinės moduliacijos gylis gali būti valdomas keičiant etalonų atspindžio koeficientą, o jų gaubtinės moduliacijos vertė mažiausia, kai etalonų storio santykis artimas 2. Sustiprintų impulsų kontrasto gerinimui pirmą kartą pritaikėme netiesinį antros eilės filtrą, veikiantį fundamentinės spinduliuotės poliarizacijos sukimo, išderintame antros harmonikos generatoriuje, efekto pagrindu. Tokiu būdu Nd:YAG stiprintuvuose sustiprintų impulsų kontrasto vertė pagerinta apie 102 kartų. Taip pat pademonstruota, kad Nd: YAG stiprinimo sistemos išėjime naudojant pakopinius antros harmonikos generacijos procesus, Gauso formos impulsus galima transformuoti į hipergauso impulsus. Sukurta didelės išvadinės energijos pikosekundinė Nd:YAG stiprintuvų sistema yra optiškai sinchronizuota su užduodančio femtosekundinio Yb:KGW osciliatoriaus impulsais ir turi ~ 300 mJ , 75 ps trukmės Gauso impulsų bei 100 mJ, > 100 ps trukmės hipergauso laikinės formos impulsų išvadus.

The continual increase in electrical energy demand in South Africa has resulted in a precariously low reserve margin in supply from the primary utility, Eskom. This resulted in extensive load shedding throughout the country. Far-reaching measures had to be introduced in order to ensure a reliable supply of electricity. DSM interventions were shown to be very successful short term solutions for the mining industry, reducing the strain on the national grid. This resulted in an increasing number of investigations to broaden the base of DSM projects to other industries. One such intervention was the Usutu-Vaal water distribution scheme, situated near Standerton, South Africa. This scheme includes the Grootdraai, Tutuka, Grootfontein, Rietfontein and Naauwpoort pumping stations. With a combined installed capacity of 36.5MW and the extremely large water storage capacities, these pump stations have been identified as prime candidates for DSM interventions. This dissertation discusses the method followed for a DSM project intervention and the results of the implementation. The national grid was relieved by an average of 12.3 MW during the Eskom weekday peak period, by shifting the pumping load into the off-peak periods. Simulations have shown that an annual financial saving of approximately R4.7million may be expected.
Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.
Includes bibliographical references (leaves 105-109).
The mission of the ISN is to explore the long-range vision of the role of nanotechnology in the future of soldier protection. Unprecedented survivability will arise from the cohesive and comprehensive coordination of the functions and interactions of each technology. The present work approaches these objectives with basic research to support the development of two multifunctional soldier survivability systems, pumping microfibers and mechanochromic pixels. Progress was made along the two major paths of investigation towards the realization of a pumping microfiber. Polypyrrole was chemically deposited onto copolyetherester. Tubular polypyrrole actuators at the millimeter scale were electrochemically fabricated and actuated. Mechanochromic polymers can be combined with actuating polymers to create a color changing pixel. Reflectance spectrum changes with strain in mechanochromic materials were characterized. Several pixel designs were analyzed and tested in which the polymer actuator polypyrrole induces deformation of the mechanochromic block copolymer. Integrative studies inform the overall systems architecture of the far future battlesuit. Scoping calculations to investigate battlesuit functionality requirements were performed.
(cont.) The multiscale, multifunctional design solutions employed in the human body and the US Army and were studied, and the Dynamic Systems Integration Map was developed to apply the lessons learned to coordinate and leverage the many emerging survivability technologies.
by Melinda Joy Cromie.
S.M.

In the last few decades, droplet microfluidics has been developed as a new area of microfluidics, where samples are compartmentalised in another immiscible phase. With these micro-droplets, Taylor dispersion can be minimised between samples and thorough mixing is easy and fast within the droplets themselves. Moreover, the sample consumptions are comparatively low as the samples are limited within nano-litre, pico-litre or even smaller droplets. Due to these attractive features, droplet microfluidics has been widely used as a platform to study various phenomena in chemistry, biology and physics. Droplets are normally generated in a T-junction or flow-focusing with syringe pumps or other pressure sources. An alternative way to generate droplets is to sequentially aspirate aqueous samples and carrier oil under negative pressures. Both of the typical T-junction methods and the current aspiration methods, have limitations in freely introducing/collecting samples into designed droplets, such as continuous sampling where introduction of samples does not affect the droplet generation, and in-situ sampling where samples from environment can be directly introduced into droplets. This ‘sample in’ problem is still a challenge in droplet microfluidics. This thesis addresses the two droplets sampling issues in droplet microfluidics: continuous droplet sampling, and in-situ droplet sampling. To solve the first issue, a novel microfluidic platform was engineered which includes aspiration droplet generators, a peristaltic pumping system and a feedback system which is used to synchronise droplet generation with pulsations of flowrates from the peristaltic pump. The demonstration of this platform successfully shows the capability of continuously generating and pumping droplets. To solve the second issue, a micro peristaltic pump was engineered to realise a robust droplet generation method and a direct sample introduction from ‘out-world’ to chip. The results show that this device is capable of generating droplets in-situ.

Bibliography: p. 221-223.
Two prototype three phase AC photovoltaic pump systems (Solvo, ML T) and a DC PV pump (Miltek) were tested on a farm borehole in Namibia (latitude 21°6', longitude 17°6'). The PV array consisted of twelve modules (636Wpeak) mounted on a single-axis passive tracker. The depth of the water was 75m and a progressive cavity pump with a self-compensating stator was used in all the tests. Customised data acquisition was designed to measure performance characteristics through a range of operating conditions (mainly steady state); a secondary data acquisition system was used to capture samples of high frequency signals. The data allowed detailed analysis of system, subsystem and component performance, as well as performance evaluation over Standard Solar Days. The focus of the investigation was evaluation of the AC prototypes, in terms of performance, other technical factors, reliability and economic criteria. The analog-based DC system served as a basis for comparison. Both AC systems employed microprocessor control and PWM variable-frequency variable-voltage inversion. Efficiencies, optimality, stability, start-up behaviour, non-productive operating modes and protection were examined. A number of recommendations were proposed for improvements in the basic control algorithms, monitoring and managing non-productive modes, improved protection, layout and user diagnostic features.

This thesis addresses three distinct topics within oilfield production technology: 1) Inline oil-water separation for subsea applications, 2) Model based constrained optimization for production networks of high water cut wells boosted by ESPs (Downhole Electric Submersible Pumps), and 3) Hydraulic analysis of a novel configured hexagonal positive displacement pump. While each of the three topics in the thesis is investigated and discussed in a stand-alone manner, they all share a common industry objective; increasing the yield and prolonging the viable production period of hydrocarbon producing fields. More specifically, they reside within two important classes of production technology challenges; (a) boosting the deliverability and the flow of wells with high water content, and (b) separating and removing of water from hydrocarbon streams as close as possible to the source in a production gathering system. Numerical modeling is the main methodology employed in the three topics, where modeling results are substantiated by field scale or laboratory generated data. The inline oil-water separation technology addressed in this thesis is based on a controlled and distributed tapping from the lower side of a water rich stream flowing in an inclined pipe spool. The long term objective is to develop a capability for seabed separation near the subsea wells in mature offshore fields with high water production and declining reservoir pressure. The intention is to reduce the backpressure on the wells and increase or maintain their production level. The production gain is achieved by harnessing and hydraulically manipulating the energy of the inlet mixture stream to reduce the backpressure exerted by the outlet streams. Important and unique features of the concept are; the separation and phase splitting do not consume external energy, there are no major moving parts, and there is inherent performance tolerance to deviations from the design set-points. The thesis expands an earlier IPT/NTNU concept verification research project (Sponsored by the Research Council program DEMO 2000) which involved experimenting with a low pressure full scale separator test facility. This thesis progresses the relevant previous knowledge and information from a concept validation level to establishing and validating a more detailed design strategy and a more focused performance design for the separator. The thesis brings the investigated separation approach to a mature level where the fluid mechanics design aspects are largely clear and understood and are ready as an input for the mechanical design of a separator prototype. The separation was analyzed from the multiphase hydraulic design point of view using numerical experimentation as the primary tool. The research methodology comprised of conducting the following tasks: (a) developing a procedure to assess the potential production gain of installing the inline separator in a subsea production system and to identify the design requirements for obtaining a specified separator performance, (b) introducing and demonstrating concepts to quantify the drainage performance of a single and multiple taping points, (c) Validating the usefulness of 3D CFD (Computational Fluid Dynamics) methods to represent  the fluid dynamics details of an oil-in-water dispersion and separation, (d) Employing the same 3D CFD model to reproduce the laboratory experimental results. The other two topics in the thesis constitute a response to emerging field scale problems where the industry have called for an immediate and sound modeling based diagnostic and modeling based investigative design. The second topic addresses an optimization strategy for large oil production systems consisting of clusters of high water cut, low GOR oil wells producing by ESP. The production streams of the wells converge through a multi branched surface gathering system into a system of main flow conduits leading to a single processing plant. The objective is to perform a model based numerical optimization to maximize oil production and reduce lift costs by modifying ESP rotor rotation frequency while complying with multiple operational constraints. While industry is currently in possession of tools to perform such tasks the outcome is inconsistent and yields poor optimization result when modeling large system with many wells, complex network and large number of constraints. An investigative task to clarify the source of the difficulties was deemed necessary. The optimization technique is described in the thesis and employed to quantifying the achievable production gains. It also identifies the computational hurdles encountered in computing the global production optimum. The thesis reports and discusses modeling and optimization using three cases: two are scaled-down synthetic cases to establish the fundamentals of the computational process, and one case on a field-scale production system is used to capture the impact of system complexity. The observed outcome and the conclusions of the investigation provide bases for a robust and consistent production optimization program of a large field. The details of this industrial scale project are beyond the scope of this thesis The third topic deals with modeling and critical analysis of a novel design of a positive displacement pump for drilling mud circulation. The concept has been commercialized and launched to the offshore market in recent years (commercially called “Hex pump”). The obvious attractiveness of the pump is its compactness and its small footprint when mounted on congested offshore platforms. However, the pumping performance of the pilot installation was very poor exhibiting excessive pulsation, vibration, mechanical failures and noise. These have driven expensive and critical drilling operations offshore to a halt. It has been recognized at this stage that the unique and innovative design features of the pump together with the criticality of it good and safe performance warned a thorough model based concept analysis and verification. The thesis describes the hydraulic performance modeling and its use to identify the concept inherent pulsation generating source. The conducted modeling and its interpretation are of novel nature and the results revealed a fundamental conceptual flaw. The research outcome had a prompt and an immediate impact on the industry decision of deploying this novel pump type.

The control of fluid dynamics is essential to ensure efficient, reliable and safe operation of pumping systems. A pump puts fluid in motion by adding energy to it. This kinetic energy, observed as pressure, is carried in the fluid and slowly lost to friction in the piping system. Uncontrolled fluid in motion can physically destroy the pump, piping, valves, meters and other system components.

Les préoccupations actuelles concernant l'exploitation sécuritaire des centrales nucléaires existantes et la conception d’architectures spéciales envisagées pour la quatrième génération de réacteurs nucléaires se combinent avec l’intérêt plus prononcé pour l'efficacité et la fiabilité de l'équipement d'un système énergétique. Cela fait que dans un souci de meilleure compréhension et optimisation basée sur des moyens modernes de conception assistée par l’ordinateur, l'étude de différentes parties de ces systèmes fait de plus en plus l’objet de recherches approfondies. . Parmi les types proposés pour la quatrième génération de réacteurs nucléaires font partie ceux ayant comme agent de refroidissement les sels fondus, respectivement le sodium fondu. En raison de leurs propriétés physiques, les sels fondus et le sodium liquide ont le potentiel d'être déplacés par les pompes électromagnétiques. Cet ouvrage est à la fois une étude approfondie des phénomènes qui se produisent en raison de l'écoulement du fluide dans le champ électromagnétique d’une pompe électromagnétique - interaction magnétohydrodynamique - et un rapport sur les capacités et les avantages des outils informatiques modernes pour faciliter la conception et l'optimisation des pompes électromagnétiques. Afin d’atteindre l'objectif principal de la thèse, notamment une meilleure compréhension des phénomènes interdépendants spécifique à l’opération des pompes électromagnétiques, deux objectifs secondaires ont été considérés. Le premier objectif concerne la pleine exploitation des modèles électromagnétiques numériques en éléments finis afin d'obtenir autant d'informations que possible sur le comportement des pompes électromagnétiques, dans l’hypothèse où on ne tient pas compte de l'écoulement des fluides. Le deuxième objectif était la construction des modèles numériques qui réunissent l’électromagnétisme et la dynamique des fluides, respectivement des modèles numériques qui regroupent les deux phénomènes caractérisant l’écoulement magnétohydrodynamique dans les canaux des pompes électromagnétiques. Dans l'étude dédiée au pompage électromagnétique de sels fondus, la thèse met en évidence des problèmes spécifiques liés à la génération de forces électromagnétiques dans les fluides faibles conducteurs d'électricité et fournit des résultats sur les applications où le pompage électromagnétique de sels fondus peut être efficace. À l’aide des modèles électromagnétiques nous avons obtenu des informations importantes sur l'influence du nombre de pôles électromagnétiques et de la fréquence d’alimentation sur la caractéristique Pression - Vitesse des pompes annulaires à induction. Ils ont été analysés le phénomène de blindage créé par les parois métalliques - avec des répercussions négatives sur les performances de la pompe, les effets de freinage exercés à l'entrée et à la sortie du canal de la pompe et la relation entre la capacité de surcharge hydrodynamique et la caractéristique Pression - Vitesse des pompes à induction. Une section spéciale a été consacrée à l'analyse de la dépendance de la force électromagnétique du temps et de l’espace et à l’étude de non-uniformitées des quantités de nature électromagnétique en direction azimutale dans les pompes annulaires à induction.Dans le chapitre qui traite de l'interaction magnétohydrodynamique à base de modèles couplés, ils sont proposés deux modèles qui couplent l'électromagnétisme et l’écoulement. Ils sont présentés les avantages des modèles couplés, en matière de la précision des résultats, par rapport aux modèles électromagnétiques. Il est également présenté l'évolution des profils de vitesse, de densité de force et de courant sous l'influence du champ électromagnétique et de l’écoulement de sodium à vitesses différentes. Les contributions de la thèse sont complétées par des observations importantes sur les méthodes de travail et les logiciels utilisés tout au long de l'étude
The actual concerns with respect to safe operation of existing nuclear plants and to designing special architectures envisaged for the fourth generation of nuclear reactors, corroborated with the increasing interest for efficiency and reliability of any equipment belonging to an energetic system, make that more and more research endeavors to be devoted to the study of various parts of these systems for a better understanding and optimization based on modern techniques of computer aided design. Among the types proposed for the fourth generation of nuclear reactors belong those that have as cooling agent molten salts, respectively liquid sodium. Many reactors of previous generations use mechanical pumps of special design for driving the coolants. Molten salts and liquid sodium, thanks to their physical properties, have the potential to be driven using electromagnetic pumps. Although the technology of electromagnetic pumping of electroconductive fluids was developed since the first half of the last century, currently it undergoes a revival due to the reconsideration of its multiple technological and security advantages. This work is both an intimate study of the phenomena that occur as a result of the electroconductive fluids flow in the electromagnetic field of an electromagnetic pump – magnetohydrodynamic interaction - and a report on the capabilities and advantages of modern computational tools to facilitate design and optimization of electromagnetic pumps.To achieve the principal goal of deeper understanding of the interdependent phenomena specific to electromagnetic pumps operation, two auxiliary objectives were considered. The first is related to the full exploitation of electromagnetic finite element models in order to retrieve as much information as possible about electromagnetic pumps behavior in a simplifying hypothesis that does not take into account the fluid dynamics. The second auxiliary objective is to build numerical models that couple the electromagnetism and the fluid dynamics, namely the two interdependent physics that govern the magnetohydrodynamic flow through channels of electromagnetic pumps.In the section dealing with the study of electromagnetic pumping of molten salts, the thesis highlights specific problems related the generation of electromagnetic forces in fluids with low electrical conductivity and provides results with respect to applications where electromagnetic pumping of molten salts can be effective. With the electromagnetic numerical models were obtained important data about the influence of the number of electromagnetic poles and supply frequency on the Pressure – Velocity characteristic of annular linear induction pumps. Were analyzed the shielding effect generated by the metallic walls - with negative repercussions on pumps performances, braking effects exerted at pump inlet and pump outlet and the connection between the overload capacity and Pressure – Velocity characteristic of induction pumps. A special portion was devoted to the analysis of the time and space dependence of the electromagnetic force and to the study of the non-uniformities of electromagnetic quantities in azimuth direction of annular linear induction pumps.In the chapter devoted to the magnetohydrodynamic interaction through coupled models, the thesis proposes two models that couple the electromagnetism and the fluid flow, one realized using multiphysic software and the second by coupling two different softwares. There are presented the advantages of the coupled models with respect to the results accuracy in comparison with electromagnetic models. It is presented the evolution of velocity, force and current densities profiles under the influence of the electromagnetic field and of different sodium mean velocities.The contributions of the thesis are completed with significant observations related to the study methods and software tools used along the study process
Preocupările actuale în legătură cu exploatarea în siguranță a centralelor nucleare existente și în legătură cu proiectarea arhitecturilor speciale de reactoare nucleare pentru generația a patra,coroborate cu interesul tot mai pronunțat pentru eficiența și fiabilitatea oricărui echipament dintr-un sistem energetic, fac ca tot mai multe demersuri de cercetare să se îndrepte spre studiul diverselor subansamble ale acestor sisteme pentru o mai buna înțelegere și optimizare pe baza mijloacelor moderne de proiectare asistată de calculator. Din rândul tipurilor propuse pentru generația a patra de reactoare nucleare fac parte și cele care au ca agent de răcire săruri topite, respectiv sodiu topit. Multe reactoare nucleare de generație anterioară folosesc ca mijloc de antrenare a fluidelor de răcire pompe mecanice de construcție specială. Sărurile topite ăi sodiul lichid, datorită proprietăților fizice,au potențialul de a fi recirculate cu ajutorul pompelor electromagnetice. Deși tehnologia pompării electromagnetice a fluidelor electroconductoare a fost dezvoltată încă din prima parte a secolului trecut, în prezent cunoaște o renaștere datorită reconsiderării multiplelor avantaje tehnologice și de securitate în exploatare. Lucrarea de față este atât un studiu al fenomenelor intime ce au loc ca urmare a curgerii fluidelor electroconductoare în câmpul electromagnetic al pompelor electromagnetice – interacțiune magnetohidrodinamică - cât și un raport despre capabilitățile și avantajele uneltelor moderne de calcul de a înlesni proiectarea și optimizarea pompelor electromagnetice. Pentru a atinge scopul principal al tezei, și anume o înțelegere mai adâncă a fenomenelor interdependente specifice funcționării pompelor electromagnetice, au fost considerate două obiective secundare. Primul obiectiv se referă la exploatarea la maximum a modelelor electromagnetice numerice în element finit cu scopul de a obține cât mai multe informații cu putință despre comportamentul pompelor electromagnetice în ipoteza care nu ia în considerare curgerea fluidelor. Al doilea obiectiv a fost construirea unor modele numerice care cuplează electromagnetismul și curgerea, respectiv, cuplează modelele numerice ale celor două fenomene ce caracterizează curgerea magnetohidrodinamică din canalele pompelor electromagnetice. În partea dedicată studiului pompării electromagnetice a sărurilor topite, teza evidențiază problemele specifice legate de generarea forțelor electromagnetice în fluide slab conductoare electric și oferă rezultate cu privire la aplicațiile unde pomparea electromagnetică a sărurilor topite poate fi eficientă. Cu ajutorul modelelor electromagnetice s-au obținut date importante despre influența numărului de poli electromagnetici și frecvența de alimentare asupra caracteristicii Presiune – Viteză a pompelor electromagnetice inelare de inducție. Au fost analizate fenomenul de ecranare creat de peretii metalici – cu repercursiuni negative asupra performanțelor pompelor, efectele de frânare exercitate la intrarea și la ieșirea din canalul de pompare și legătura dintre capacitatea de suprasarcină hidrodinamică și caracteristica Presiune – Viteză a pompelor de inducție. O secțiune specială a fost consacrată analizei dependenței de timp și a variației de la punct la punct a forței electromagnetice, precum și studiului neuniformităților mărimilor de natură electromagnetic în direcție azimutală în pompele inelare de inducție. În capitolul despre interacțiunea magnetohidrodinamică pe baza modelelor cuplate, se propun două modele ce cuplează electromagnetismul și curgerea fluidelor, unul realizat cu ajutorul unui singur software și al doilea realizat prin cuplarea a două software-uri diferite. Sunt prezentate avantajele modelelor cuplate din punctul de vedere al acurateței rezultatelor în comparație cu modelele electromagnetice …

The optimal design of a bulk water supply system is centered on two major objectives: cost efficiency and the formation of a design solution that is appropriate for the conditions in which the system is to be implemented. The currently employed CSIR (2000) design guidelines utilise deterministic measures to size system components. The efficiency of following a deterministic approach to bulk water system design, involving pumping systems, was investigated. This was seen as necessary owing to the vast spectrum of influences and the interrelation of parameters that constitute a bulk water supply system. A model developed by Chang & van Zyl (2012) sought to address this inefficiency by optimizing a bulk water supply system, with the core objectives of cost and reliability. The determination of these objectives was achieved by using a capital cost model for cost determination and a stochastic model developed by Van Zyl et al. (2008) for reliability. While this produced workable results, the application was relatively limited, and applied only to non-pumped, gravity-fed flow. As such, the failure mechanisms of the supply system did not include the effects of pump failure, an important influence on overall system reliability. In addition, the costing system was based solely on capital cost and did not take into account the life-cycle cost involved with the implementation of a bulk water supply system. The investigation sought to expand the applicability of the model through the incorporation of pumping systems and life-cycle costing. It was further intended to compare the expanded model to both the model developed by Chang & van Zyl (2012) and the CSIR (2000) guidelines. A sensitivity analysis would also be performed.

The purpose of this dissertation is to identify the best alternative method of load shifting on clear water pumping systems in the mining industry. This can be done through a comparison analysis between manual and automated Demand Side Management (DSM) projects. The study holds benefits for Eskom and any client wishing to participate in the program. Eskom, by choosing the best method, will ensure sustainable load shifting while the client benefits financially through lower electricity costs. In order to perform this study, research was conducted on the requirements for additional electricity supply in South Africa. Research showed that there is an urgent requirement for additional electricity supply to ensure continued economical growth. DSM was identified as one of the most favourable methods that could be implemented to address the problem. A reason for this is DSM projects are economically viable and can be implemented in a relatively short time. The initiative would also decrease the need for increasing electrical generation capacity. During the research study important information regarding the computation process for load shifting and cost saving performance was gathered. Research was also conducted on the effect of DSM on labour and maintenance cost reduction, as well as economical engineering methods that can be used for alternative selection. The difference in performance between automated and manual systems was compared. The results showed that a 40% improvement of automated systems over manual systems were attainable and sustainable. This will realise a total saving of approximately 45% in electricity costs for the client. Savings in labour and maintenance costs are shown to be achievable through the automation of pumping systems. These saving results were used in the Engineering Economic alternative selection methods where applicable. Economic calculations confirmed that automated projects are the most viable control method. From the comparison study, it is shown that automated controlled systems are more advantageous than manually controlled systems. It will therefore be in the best interest of the client to automate a manually controlled pumping system, as it will result in additional load shifting and cost saving.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2009.

Recent developments have indicated high oxygen consumption rates of about 35 g-mole/m³-min during oxidative pressure leaching. At such high oxygen consumption rates the mass transfer of dissolved oxygen at the gas-liquid interface may become rate-limiting. The objective of this study was to obtain an understanding of the gas-liquid mass transfer processes that take place in mechanically agitated pressure leaching systems. The classical reaction between sodium sulphite and dissolved oxygen to form sulphate at atmospheric pressure was used to determine the oxygen mass transfer rates in a 200-liter asymmetrical plastic tank, modelled after the shape of the first compartment of the zinc pressure leach. The effect of this asymmetry was compared with the work of Swiniarski who used a cylindrical symmetrical tank of similar volume. A number of process variables such as the impeller type and size, the impeller speed, the impeller immersion depth and the effect of full baffles that affect mixing were investigated. Also, the volumetric power consumption associated with the mass transfer rates were measured. The results indicate that the asymmetrical tank is at least 3.6 times more efficient in mass transfer than the symmetrical tank. There is a critical speed below which the mass transfer parameter, K[formula omitted], is almost zero and above which K[formula omitted] increases almost linearly with impeller tip speed. A simple energy balance model for bubble creation can predict the critical tip speed. It is shown that K[formula omitted] is enhanced at shallow depths, with a corresponding high mass transfer to energy ratio. The relative effectiveness of impeller types and sizes with regard to the use of power for gas-liquid mass transfer was established. Full baffles degrade the mass transfer rate at increased depth of impeller immersion. The results also add substantial support to the findings provided by DeGraaf [5] that: (i) The dimensionless correlations used in liquid mixing systems do not accurately predict dispersion rates by agitators. (ii) The optimum conditions for gas dispersion and the consequent generation of gas-liquid interfacial area are different from fluid mixing. (iii) The classical mixing power equations for impellers markedly overestimate power requirements during impeller gas dispersion.
Applied Science, Faculty of
Materials Engineering, Department of
Graduate

Global growing demand for agricultural production has put increased pressure on freshwater resources in various global locations. Many areas have saline groundwater resources which have not been utilized for agriculture due to the economics associated with water pumping and desalination. Limited availability to electricity and high operational costs of diesel generators are major obstacles to utilization of these resources. Reduced costs associated with large-scale renewable energy have renewed interest in understanding the potential impacts of developing distributed photovoltaic (PV) powered water pumping and desalination systems for agriculture. In order to determine the economic feasibility of solar-powered water pumping and desalination for agriculture, an engineering system model that performs hourly simulations of direct-coupled PV pumping and desalination systems by integrating environmental resource data and industrial component performance data was developed. Optimization algorithms were created to identify the best membrane type, control method and reverse osmosis system configuration for a given set of locational parameters. Economic analysis shows that PV-powered systems are more economical than diesel-powered systems for water pumping, with water desalination costs for PV- and diesel-powered systems being comparable. Grid-powered systems are able to pump and desalinate water for a lower cost than PV or diesel for all cases evaluated. A sensitivity analysis is performed to generalize results for different input parameters and illustrate the impact of input variables on water unit costs. Several case studies in the Jordan Valley were evaluated to illustrate the economic viability of solar-based systems with simulation results including a direct comparison to diesel- and grid-connected alternatives. Results indicate that under fair environmental conditions and irrigating greenhouse vegetables, the PV-, diesel-, and grid-powered systems produce favorable internal rates of return of 40%, 84%, and 248%, respectively. Under poor environmental conditions and less profitable crops the PV-, diesel-, and grid-powered systems all result in negative internal rates of return, illustrating the need for optimal location and crop selection for system implementation.

Les systèmes photovoltaïques de pompage d'eau (PVWPS) sont une solution intéressante pour améliorer l’accès à l’eau dans les communautés rurales des pays en voie de développement. Cette thèse développe une méthodologie de conception optimale des PVWPS pour l’accès à l’eau domestique basée sur une approche interdisciplinaire. L’objectif est de déterminer les dimensionnements du PVWPS et ses positions géographiques dans le village qui maximisent l’impact positif du système sur le développement socio-économique et minimisent son coût sur cycle de vie. Cette méthodologie est appliquée au cas d’un village rural du Burkina Faso, où nous avons collecté des données techniques et sociaux-économiques depuis 2 ans. La première originalité principale de ce travail est la modélisation du lien entre la conception du PVWPS et son impact socio-économique, ce qui permet d’inclure l’impact socio-économique comme fonction objectif de l’optimisation. La seconde originalité principale est l’intégration de la position géographique du PVWPS dans le village comme variable d’optimisation, en plus du dimensionnement du système. Cette méthodologie pourrait également être appliquée à la mise en place d'autres types de systèmes, tels que les moulins communaux alimentés par énergie photovoltaïque dans les zones isolées ou les bornes de recharges publiques pour les véhicules électriques dans les villes
Photovoltaic water pumping systems (PVWPS) are an interesting solution to improve access to water in rural communities of developing countries. This thesis develops a methodology for the optimal design of PVWPS for domestic consumption based on an interdisciplinary approach. The objective is to determine the sizings of the PVWPS and its geographical positions in the village that maximize the positive impact of the system on socio-economic development and minimize its life-cycle cost. This methodology is applied to the case of a rural village in Burkina Faso, where we have been collecting technical and socio-economic data for 2 years. The first main originality of this work is the modelling of the link between the design of a PVWPS and its socio-economic impact, which allows to include the socio-economic impact to be included as an objective function of the optimisation. The second main originality is the inclusion of the geographical position of the PVWPS in the village as an optimisation variable, in addition to the sizing of the system. There is potential for applying the proposed methodology for the set-up of other types of systems such as community mills powered by photovoltaic energy in isolated areas and public charging points for electrical vehicles in cities

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.

In the villages along the Amazon river, the access to clean drinking water is lacking. In Progreso, the Swedish foundation Ankarstiftelsen and the non-governmental organization Entropika have installed a water purification system to solve this problem. The water used in the purification system is today pumped from a tributary to the Amazon river with a gasoline pump. This comes with social, ecologic and economic problems. To solve these problems, a solar water pumping system has been developed. After a preparing literature study on the topic, a field study was done to find relevant data. From this, an Excel program was made to optimize a suitable solution. Together with suggestions from three companies, two with a surface pump and one with a submersible pump, the system including a submersible pump was considered the most preferable. This mainly due to lower cost, weight and maintenance. Further, the suggestions were used to control the accuracy of the developed Excel program. This program can be used for future optimizations of systems with similar character.
I byarna längs Amazonfloden är tillgången till rent dricksvatten bristfällig. Organisationerna Ankarstiftelsen och Entropika är verksamma i området och arbetar för en ökad levnadsstandard åt lokalbefolkningen. I byn Progreso har organisationerna installerat ett vattenreningssystem för att lösa problemet. Systemet använder flodvatten som renas med sandfilter och sedimentering. Vattnet pumpas idag från en biflod till Amazonfloden med en bensindriven pump. Pumpen är mycket stöldbegärlig och måste därför bäras ner till floden vid varje användning. Den väger 70 kg och utgör en arbetsbörda för vattenmästaren i byn. Utöver det är regelbundna kostanden för drivmedlet ett problem då invånarna saknar en stabil inkomst. Dessutom orsakar den bensindrivna pumpen miljöfarliga utsläpp. För att lösa de sociala, ekonomiska och ekologiska bristerna har ett solvattenpumpssystem dimensionerats. Efter en förberedande litteraturstudie inom ämnet utfördes en fältstudie i Progreso för att hitta relevanta data. Fältstudien bestod av distansmätningar och intervjuer med invånarna. Intervjuerna gav svar på huruvida dagens system fungerar samt det önskade vattenbehovet från det nya systemet. Med funna data kunde beräkningar utföras och ett Excelprogram utvecklas för att optimera ett för platsen passande system. Från tre systemförslag framtagna av företag, två förslag med ytpump och ett med en dränkbar pump, togs beslutet att den dränkbara pumpen var att föredra. Detta främst på grund av lägre kostnad, vikt och underhåll. Vidare användes förslagen för att undersöka pålitligheten hos Excelprogrammet som ämnar till att används för framtida system av liknande karaktär.

Sub-Saharan Africa is the region in the world that suffers the most from poverty and its worst effects: hunger, lack of water and diseases. And the problem is not even decreasing: in the past years there has been a peak in undernourishment in the continent. Furthermore, according to ongoing research, the area is expected to be one of the most affected by climate change. A solution that tackles at the same time water scarcity, diseases, hunger and greenhouse gas emissions is urgent. Luckily, with the development in the past years of the solar photovoltaic and battery technologies, these solutions can now compete head-to-head with fossil-fuelled pumps. Indeed, the photovoltaic water pump (PVWP) is becoming the preferred solution for locals and NGOs, enabling a cheaper, less pollutant and more self-sustainable growth vector. In this thesis, a PVWP system is pre-designed. This means that the effect of the different variables over the system are studied, without aiming to design any specific system. However, the calculations are done with the climatic conditions of Fada N’gourma (Burkina Faso) as an example. To start, the importance of water for basic supply, sanitation and agriculture is researched through reviewing existing literature. The specific advantages of an advanced method of irrigation such as drip irrigation are also investigated. To continue, the analysis of the influence of each parameter intervening in the system is undertaken. First, a method to calculate the watering needs of the plants (through the concept of evapotranspiration), and simultaneously the passive self-regulation of PVWP systems for irrigation purposes is analysed. Second, the possibility to calculate faithfully the optimal angle with only climatic values and the size of the orchard is demonstrated. Third, a model to obtain the optimal diameter of the pipes through the optimisation of the cost is elaborated. The specific influence of the pump efficiency in this process is also explored. Fourth, an analysis on the effect in the system resilience to weather changes depending on the different starting dates for planting the crops is done. To finish, some considerations and a preliminary design are made. The option of implementing a storage system is discussed, with advantages of the batteries and the water tank. A quick economical evaluation done, leading to the conclusion that a PVWP system of the characteristics studied is viable under most of the circumstances.

In 2011 the mining industry purchased 14.5% of the electrical energy generated by Eskom. During 2011 in South Africa, dewatering pump systems on gold mines were the fourth largest electrical energy consumer on South African mines therefor making dewatering pumps ideal candidates to generate significant financial savings. These savings can be realised by controlling time-of-use (TOU) schedules. Previous studies concentrated on the impact of improving a pumping scheme of a single mineshaft. This dissertation will focus on the operations of a complete dewatering system consisting of multiple mineshafts. The case study will consist of a gold mine complex comprising of five different shafts - each with its own reticulation system – as well as the larger interconnected water reticulation system. Various pumping options were investigated, simulated and verified. The interaction between shafts was determined when load-shifting was scheduled for all the shafts taking each shaft’s particular infrastructure into account. The underground dewatering system was automated and optimised based on the simulation results. Mine safety protocols were adhered to while optimal pump operational schedules were introduced.
Thesis (MIng (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 26).
The D-lab Honduras team designed and constructed a wind-powered water pump in rural Honduras during IAP 2007. Currently, the system does not work under its own power and water must be pumped by hand. This thesis seeks to explore a variety of mechanism and aerodynamic changes to allow the system to function as designed. The novel modifications to the Savonius rotor that were made do not seem to improve its performance. Within the constraints of the installed components, the current rotor should perform well pending other changes. The most promising improvements to the system are weight reducing and friction reducing measures, and in combination with understanding the wind conditions in the immediate vicinity of the rotor, changes will be made this summer so that unassisted wind pumping will be possible.
by Aron Zingman.
S.B.

Cette étude s’intéresse à la conception systémique intégrant simultanément les questions de dimensionnement et de gestion optimale de l'énergie. Le système étudié concerne un procédé de pompage intégrant un processus de dessalement d’eaux saumâtres alimenté par des sources de puissance hybrides renouvelable incluant un minimum de stockage électrochimique. Ce cas d’étude appartient à une classe typique de systèmes autonomes alimentés par des sources intermittentes dont profil de puissance a une forme "donnée" : « selon les conditions climatiques (ensoleillement, vent), avec un minimum de stockage d’électricité, la puissance offerte doit être convertie ou stockée hydrauliquement sous peine d’être gaspillée ». L'influence des conditions d'environnement et la robustesse du processus d’optimisation est enfin aussi discutée dans cette thèse. Deux types de modèles mathématiques, dynamiques et quasi-statiques, sont mis en œuvre pour décrire l'ensemble du dispositif. Le système est tout d’abord modélisé dynamiquement par Bond Graphs. Pour une simulation plus rapide, plus adaptée à l’optimisation globale du système, un modèle quasi-statique est créé pour être simulé dans l'environnement Matlab. Pour de tels dispositifs, étant donné une certaine puissance offerte au fil du vent et du soleil, trouver le point optimal de fonctionnement à chaque période consiste en un partage de puissance entre les sous systèmes de pompage et de traitement de l’eau : ce processus est plutôt complexe compte tenu des non linéarités (courbes rendement – puissance) et de la présence de nombreuses contraintes relatives aux limitations de puissance des pompes, aux conditions de niveau des réservoirs, ainsi qu’aux limitations de pression et de débit dans les processus hydrauliques (pompes osmoseur). Nous montrerons qu’il n’est pas si trivial de choisir une fonction objectif qui assure simultanément la performance et la robuste du système vis-à-vis des conditions d’environnement : une fonction objectif robuste quel que soit le profil de puissance des sources est ainsi proposée pour mettre en œuvre une gestion optimale de l’énergie. Le problème d’optimisation étant posé sous forme standard, consistant en la maximisation d’une fonction objectif sous contraintes, des approches d’optimisation efficaces par programmation non linéaire sont employées. La question du dimensionnement et son couplage à la gestion énergétique est finalement étudiée. En particulier, l’intérêt de la modularité des systèmes, considérant plusieurs pompes connectées en parallèle pour la même fonction, est investigué
This study focuses on systemic design, integrating simultaneously issues of sizing and optimal energy management. The system under study consists of a pumping process including a brackish water desalination system fed by hybrid renewable power sources with minimum electrochemical storage. Such a device belongs to the class of “autonomous systems” supplied by intermittent sources whose power profile has a “given” waveform: “with minimum electrical storage, power has to be converted, stored in water tanks, or wasted following climatic (sun, wind) conditions”. Influence of environment conditions and robustness of the optimization process is then also discussed in this thesis. Both dynamic and quasi static models are implemented for representing the whole system. The device is firstly modeled dynamically by Bond Graph methodology. For faster simulations, which are more suitable for system optimization, a quasi static model is created to be simulated in the Matlab environment. For such systems, given a certain source power, finding optimal operation point at each period consists of a power sharing between all pumping devices: it is a complex process with huge nonlinearities (efficiency vs power curves) and with many constraints as for the limitation of pump powers, tank level conditions, or pressure and flow limitations in hydraulic network and pumping devices. It is not so trivial to define an objective function which ensures system performance and robustness versus environment conditions: a convenient objective function, whatever the input power profile, is then proposed to implement the optimal management. The optimization problem being mathematically expressed, consisting of objective function maximization under constraints, efficient optimization methods by non linear programming are implemented. The issue of sizing and its coupling with system management efficiency is finally studied. In particular, the interest of modular operation with several pumps connected in parallel is also concerned in this research

Esta dissertaÃÃo de mestrado apresenta um sistema para bombeamento de Ãgua utilizando um gerador eÃlico autÃnomo de pequeno porte, instalado em frente ao aÃude do Campus da UFC. A potÃncia do gerador à de 1 kW e o mesmo utiliza a tecnologia de Ãmà permanente garantindo vantagens como: menores perdas no rotor, menor aquecimento e o alcance de maiores rendimentos. AlÃm do gerador eÃlico, o sistema à composto por um conjunto motor-bomba centrÃfuga de 0,5 cv de potÃncia, um medidor de vazÃo, um medidor de pressÃo, um analisador de energia que registra valores de grandezas elÃtricas (corrente, tensÃo, potÃncia), um datalogger para coleta de dados e um anemÃmetro de conchas para mediÃÃo de vento. O projeto consiste em determinar o rendimento deste sistema para as condiÃÃes de vento do local da instalaÃÃo, a partir de dados coletados durante os meses de maio e julho de 2008. Os resultados demonstram que em apenas cerca de 10,97% do total de dias referentes ao mÃs de maio e cerca de 54,57% do total de dias do mÃs de julho, o conjunto motor-bomba foi acionado pelo gerador eÃlico e que os rendimentos globais variam entre 0,41 e 0,74%. Observando os valores de vazÃo encontrados, quando comparados com a curva caracterÃstica da bomba utilizada, percebe-se uma sub-utilizaÃÃo da mesma, principalmente no mÃs de maio.
This work presents a system for water pumping using an independent small wind generator, installed in the UFCÂs Campus. The generatorâs power is 1 kW and uses a permanent magnet technology providing advantages such as: lower losses in the rotor, lower heating and achieving higher yields. Besides the wind generator, the system consists of centrifugal pump-motor assembly 0,5 cv of power, a flow meter, a pressure meter, an energy analyzer that records the electrical data (current, voltage, power), a datalogger for data collection and a shell anemometer for measuring of wind speed. The project consists in determining the performance of this system for the local wind conditions, from data collected during the months of May and July 2008. The results show that in only about 10,97% of total days for the month of May and about 54,57% of the total days of July, the pump-motor was triggered by the wind generator and the global yields ranging between 0,41 to 0,74%. Observing the flow values found when compared with the characteristic curve of the pump used, there is a perceived under-utilization of the same, especially in May.

Le domaine de recherche de la spintronique vise a concevoir des dispositifs électroniques misant sur le degré de libre de spin pour transporter de l'information. An d'intégrer ces courants de spin dans des dispositifs électroniques, il est particulièrement intéressant d'étudier l'inter-conversion d'un pur courant de spin en un courant de charge par l'effet Hall de spin, ainsi que le transfert de moment angulaire entre les électrons de conduction d'un métal normal (NM) et l'aimantation d'un ferromagnétique (FM) (couple de transfert de spin / pompage de spin). An de mieux comprendre ces différentes interaction, cette thèse se concentre sur l'étude du système hybride constitué de la juxtaposition d'un ferrimagnétique isolant, le grenat d'yttrium fer (YIG), et d'un métal normal _a fort couplage spin-orbite (Pt ou Ta), nécessaire pour bénéficier de la polarisation en spin de l'interface par un courant électrique dans le plan. Nous avons étudié le pompage de spin et la magnétorésistance produite par l'effet Hall de spin a l'interface entre des bicouches de YIG j Pt et YIG j Ta, et ceci sur des lms étendus de YIG de 200 nm d'épaisseur, produits par épitaxie en phase liquide. Nous observons que la tension électrique, produite par l'effet Hall de spin inverse, change de signe entre du Pt et du Ta confirmant ainsi l'inversion des signes de l'angle de Hall entre ces deux matériaux. En outre, en mesurant la variation de la tension de Hall inverse en fonction de l'épaisseur de la couche de Ta, nous avons réussi à borner la longueur de diffusion de spin dans le Ta. Tant le YIG j Pt et le YIG j Ta affiche une variation semblable de la magnétorésistance a effet Hall de spin en fonction de l'orientation du champ magnétique. Pour étudier l'inuence interfaciale du pompage de spin…
Spintronics aims at designing electronic devices which capitalize on the spin degree of freedom to transport information using spin currents. In order to incorporate spin currents intoelectronic devices, it is particularly interesting to study the interconversion from a spin current, the motion of spin angular momentum, to a charge current (Spin Hall Effect) as well as the transfer of spin angular momentum between the conduction electrons of a normal metal (NM) and the magnetization of a ferromagnet (FM) (Spin Transfer Torque/Spin Pumping). To investigate the interplay of those effects this thesis studies hybrid systems of the ferromagnetic insulator Yttrium Iron Garnet and normal metals with large spin-orbit coupling, a prerequisite for spin Hall e_ect. We study spin pumping and spin hall magnetoresistance in YIGjPt and YIGjTa bi-layers using extended _lms of 200 nm thick YIG, grown by liquid phase epitaxy. The inverse spin Hall voltages in Pt and Ta confirm the opposite signs of spin Hall angles in these two materials. Moreover, from the dependence of the inverse spin Hall voltage on the Ta thickness, we constrain the spin di_usion length in Ta. Both the YIGjPt and YIGjTa systems display a similar variation of resistance upon magnetic eld orientation, the spin Hall magnetoresistance. To study the inuence of interfacial spin pumping and a possible reverse e_ect, it is desirable to work with thin _lm thicknesses. A high quality 20 nm thick YIG _lm was grown by pulsed laser deposition, showing a damping similar to that of bulk YIG. We use nano-lithography to pattern series of YIG(20nm) and YIG(20nm)jPt(13nm) discs with diameters between 300 and 700 nm. The ferromagnetic resonance (FMR) spectra of the individual sub-micron sized samples are recorded through magnetic resonance force microscopy. . Passing dc-current through micron sized YIGjPt disks reveal a variation of the FMR linewidth consistent with the geometry and amplitude of the expected SHE transfer torque. In the absence of exciting microwave _elds, a variation in the magnetization is detected when the dc-current reaches the expected threshold for auto oscillations

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
The purpose of this thesis is to compare two ways of water delivering in an irrigation scheme, considering the investment and maintenance costs: high and low pressure. The irrigation scheme considered is the “Circuito Hidráulico de Baleizão-Quintos”, included in the Multi-purpose Project of Alqueva. The scheme is divided in 5 blocks, with a gross scheme area of 7992 ha. The secondary aim is to determine for the blocks that in the original project require pumping stations (blocks 4 and 5), which is the combination between hydraulic head in the beginning of the secondary network and pipe size along that network, which allows the best ratio between investment costs and maintenance costs, and determine the lowest total present costs, or a close value, for the assumed life span of the project, assuring a pre-determined pressure on the hydrants. It was concluded that the distribution in low pressure has lower investment and annual maintenance costs and also presents lower annual energy consumption. A sensitivity analysis to what farmers pay for energy annually showed that if they pay 2.2 times what the managing entity pays, the total present costs for the assumed life span of the project are lower for high pressure distribution.

Rural electrification has been a priority for many governmental and international donor organisations. Grid extension and various renewable energy technology (RET) options are recognised as viable means of providing enhanced energy and water services to isolated rural communities, and these have been successfully deployed in many regions across the world. In Nigeria, decentralized energy generation systems based on solar PV systems are often used to meet the low energy demands of rural areas and they have also been widely adopted for water pumping purposes in these places. However, the failure or underperformance of many of these installations is in stark contrast to their theoretical viabilities as asserted in many academic papers; this suggests deep underlying problems. Such failures have discouraged government and policy makers from supporting solar PV and, as an extension, other forms of RE projects as viable options for isolated rural locations, even when grid extensions to these places often remain economically and practically challenging. Hence, whereas a number solar PV projects have been implemented in rural communities in the country, appraisal of their success and failures has moved at a much slower pace. Evidence is needed, not only about the factors that contribute to the deployment of these RE installations, but also on issues that took place after such installations have been completed: if the technology fulfils people’s needs and priorities, if the equipment remained in working order and for how long, and the particular and general decisions and actions that may have contributed to the success or failure of the installations. The aim of this study is therefore two-fold. Firstly, to reveal and understand the fundamental issues and factors that mitigate against the proper deployment, diffusion and performance of solar PV installations in isolated rural locations in Nigeria and, secondly, to develop a framework and set of recommendations that could lead to improved deployment processes and better performance of such installations. In order to understand and address these fundamental issues, a systematic analysis of relevant literatures on renewable energy technologies and technology diffusion is initially undertaken. In addition, multiple methods including site visits, observation and physical evaluation of installations, interviews and discussions with stakeholders and key players, and seven exploratory studies of rural communities are utilised to collect primary data on the performance and effectiveness of solar PV installations. Thirty-Eight indicators across five core sustainability dimensions of Technical, Economical/Financial, Environmental Impact, Social-Ethical Development, and Institutional Development and Government Policies are used to assess and evaluate the study cases, revealing diverse and interconnected pre- and post-installation factors that contribute to both successful and failed installations. A main finding of the study is that involvement of private energy providers in the deployment and running of solar PV installations in rural communities in the country is more effective than the sole use of government agencies or contractors. It was also revealed that a number of factors including weak or absence of post-installation maintenance arrangements, non-existence of local representative authorities, failure to enlighten local residents on limitations of the installation and to train them on basic maintenance practices, weak implementation and low success of government policies, weak institutions and overlapping functions of government agencies impacted negatively on the performance of the installations. In addition, the study provides insights into the interrelationships between the factors; how the presence or absence of some can strengthen or weaken others. Finally, a framework and set of recommendations are generated that could support improved deployment procedures and enhanced performance of solar PV installations in rural communities. Although the study deals with the Nigerian situation, some of the findings can be readily extended to other developing countries with similar challenges in the provision of energy and water services to isolated rural communities.

Abstract This thesis reports simulations of direct observables in electron and nuclear spin relaxation experiments in an example paramagnetic system, as well as polarization transfer occurring in a spin-exchange optical pumping (SEOP) experiment. Studies of paramagnetic relaxation are important, e.g., in the development of agents used for enhanced contrast in magnetic resonance imaging. SEOP is used to produce hyperpolarized noble gases, which are then used to, e.g., enhance sensitivity in structural studies of matter with nuclear magnetic resonance. Presently the theory, available software and hardware for such computational modeling have reached a state in which quantitative reproduction of the experimentally observed magnetization decay is possible from first principles. The present multiscale computations are carried out from first principles combining molecular dynamics simulations of atomistic motion and quantum-chemical electronic structure calculations of the spin interaction parameters that enter the effective spin Hamiltonian. A time series of the spin Hamiltonian is then explicitly used to propagate spin dynamics in the system, and dynamical time constants of the magnetization are obtained through ensemble averaging. The complete decay of electron spin magnetization could be followed directly within the duration of the simulation, whereas the nuclear spin relaxation rates were extracted using Kubo’s theory regarding generalized cumulant expansion and stochastic processes. The extracted electron and nuclear spin relaxation rates for the chosen prototypic system, the aqueous solution of Ni²⁺, are in quantitative and semi-quantitative agreement, respectively, with the available experimental results. The simulations of polarization transfer corroborate the empirical observations on the importance of van der Waals complexes and binary collisions in the spin-exchange process. Long van der Waals complexes represent the overwhelmingly most significant kind of individual events, but the short binary collisions can also give a relatively important contribution due to their vast abundance. This thesis represents a first study in which first principles-calculated trajectories of individual events could be followed. The simulations reported in this thesis were run without any empirical parametrization and thus represent a significant step in first-principles computational modeling of magnetization dynamics.

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Despite the emergence of other forms of artificial lift, sucker rod pumping systems remains hegemonic because of its flexibility of operation and lower investment cost compared to other lifting techniques developed. A successful rod pumping sizing necessarily passes through the supply of estimated flow and the controlled wear of pumping equipment used in the mounted configuration. However, the mediation of these elements is particularly challenging, especially for most designers dealing with this work, which still lack the experience needed to get good projects pumping in time. Even with the existence of various computer applications on the market in order to facilitate this task, they must face a grueling process of trial and error until you get the most appropriate combination of equipment for installation in the well. This thesis proposes the creation of an expert system in the design of sucker rod pumping systems. Its mission is to guide a petroleum engineer in the task of selecting a range of equipment appropriate to the context provided by the characteristics of the oil that will be raised to the surface. Features such as the level of gas separation, presence of corrosive elements, possibility of production of sand and waxing are taken into account in selecting the pumping unit, sucker-rod strings and subsurface pump and their operation mode. It is able to approximate the inferente process in the way of human reasoning, which leads to results closer to those obtained by a specialist. For this, their production rules were based on the theory of fuzzy sets, able to model vague concepts typically present in human reasoning. The calculations of operating parameters of the pumping system are made by the API RP 11L method. Based on information input, the system is able to return to the user a set of pumping configurations that meet a given design flow, but without subjecting the selected equipment to an effort beyond that which can bear
Apesar do surgimento de outras t?cnicas de eleva??o artificial de petr?leo, sistemas de bombeio mec?nico mant?m-se hegem?nicos devido ? sua flexibilidade de atua??o e custo menor de investimento se comparada com outras t?cnicas de eleva??o desenvolvidas. Um dimensionamento de bombeio mec?nico bem sucedido necessariamente passa pelo atendimento da vaz?o prevista e pelo desgaste controlado dos equipamentos de bombeio utilizados na configura??o montada. Entretanto, a concilia??o destes elementos mostrase particularmente desafiadora, sobretudo para a maioria dos projetistas que lidam com este trabalho, que n?o possuem ainda a experi?ncia necess?ria para chegar a bons projetos de bombeio em tempo h?bil. Mesmo com a exist?ncia de diversos aplicativos computacionais no mercado com o objetivo de facilitar esta tarefa, eles precisam enfrentar um exaustivo processo de tentativa e erro at? chegar a combina??o mais adequada de equipamentos para instala??o no po?o. A proposta do presente trabalho consiste em desenvolver um sistema especialista no dimensionamento de sistemas de bombeio mec?nico. Ele tem a miss?o de guiar um engenheiro de petr?leo na tarefa de selecionar um conjunto de equipamentos apropriados ao contexto provido pelas caracter?sticas do ?leo que ser? produzido. Caracter?sticas como o n?vel de separa??o do g?s, presen?a de elementos corrosivos, possibilidade de produ??o de areia e de parafina??o s?o levados em considera??o na escolha da bomba de fundo, coluna de hastes e unidade de bombeio, bem como as caracter?sticas de opera??o dos mesmos. Ele ? capaz de aproximar seu processo de infer?ncia da forma do racioc?nio humano, o que gera resultados mais pr?ximos daqueles obtidos por um especialista. Para tanto, suas regras de produ??o foram elaboradas com base na teoria dos conjuntos fuzzy, capazes de modelar conceitos imprecisos tipicamente presentes no racioc?nio humano. Os c?lculos dos par?metros operacionais do sistema de bombeio s?o feitos por meio do m?todo API RP 11L. Com base em informa??es de entrada, o sistema ? capaz de retornar ao usu?rio um conjunto de configura??es de bombeio mec?nico que atendam uma determinada vaz?o de projeto, por?m sem submeter os equipamentos selecionados a um esfor?o al?m daquele que possam suportar

Propriétés topologiques de systèmes photoniques non gappés modulés périodiquement. La photonique est une plate-forme où les ondes électromagnétiques (ou photons) se propagent à l'intérieur d'un cristal (comme les ondes de Bloch) formé par les degrés de liberté discrets sous-jacents, par exemple des réseaux de guides d'ondes. Ces ondes ne peuvent pas se propager si la fréquence incidente se situe dans la bande interdite photonique, alors ces ondes sont connues sous le nom d'ondes évanescentes. Ainsi, le cristal se comporte comme un réflecteur de ces ondes. Cependant, s'il existe des modes pour lesquels il existe des ondes limites qui relient la bande interdite, alors ces ondes peuvent exister à la limite sans s'infiltrer dans la masse. Ceci est analogue au mouvement chiral des électrons aux bords du Hall quantique, avec un ingrédient supplémentaire de symétrie d'inversion du temps qui se brise dans les cristaux photoniques via certaines propriétés gyromagnétiques de l'échantillon, ou la dépendance inhérente au temps du système. Dans ce dernier cas, lorsque le système, en particulier, est commandé périodiquement, on peut également observer les phases de non équilibre plus exotiques dans ces réseaux.Dans ce travail, nous explorons les propriétés topologiques de ces réseaux photoniques à commande périodique. Par exemple, comment les symétries fondamentales, par exemple la symétrie particule-trou, peuvent être mises en oeuvre pour concevoir la topologie en 1D. Nous trouvons un lien entre les symétries cristallines et les symétries fondamentales, qui facilitent une telle mise en oeuvre. De plus, une dimension synthétique peut être introduite dans ces treillis qui simulent la physique des dimensions supérieures. La différence entre la dimension synthétique et la dimension spatiale devient apparente lorsqu'une symétrie cristalline spécifique, comme l'inversion, est rompue dans ces systèmes. Cette rupture transforme une bande interdite directe en une bande interdite indirecte qui se manifeste par l'enroulement de bandes dans le spectre de la bande quasi-énergétique. Si elle est rompue dans la dimension synthétique, il en résulte une interaction de deux propriétés topologiques : l'une est l'enroulement des bandes de quasi-énergie, et l'autre est la présence d'états de bord chiraux dans la géométrie finie. Cette ancienne propriété de l'enroulement se manifeste par des oscillations de Bloch des paquets d'ondes, où nous montrons que les points stationnaires de ces oscillations sont liés au nombre d'enroulements des bandes. Cette propriété topologique peut donc être sondée directement dans une expérience par la technologie de pointe. Cependant, si cette symétrie est rompue dans la dimension spatiale, l'enroulement des bandes se manifeste comme une dérive quantifiée de la position moyenne, qui est toujours caractérisée par un nombre d'enroulement des bandes.En outre, nous montrons qu'un régime sans lacune différent peut également être conçu tout en préservant la symétrie d'inversion. Dans ce régime, la topologie peut être saisie en enfermant les dégénérescences dans l'espace des paramètres et en calculant le flux de Berry qui traverse la surface enfermée. Dans ce cas, certaines des dégénérescences peuvent héberger des états chiraux de bord avec d'autres protégés à la même quasi-énergie
Photonics has emerged a platform where electromagnetic waves (or photons) propagate inside a crystal (likeBloch waves) formed by the underlying discrete degrees of freedom, e.g., waveguide arrays. These waves cannotpropagate if the incident frequency lies within the so-called photonic bandgap, then these waves are known asevanescent waves. Thus, the crystal behaves as a reflector to these waves. However, if there are modes for whichthere exist boundary waves that connect the bandgap, then these waves can exist at the boundary without leakinginto the bulk. This is analogous to the chiral motion of electrons at the quantum Hall edges, with an extraingredient of time-reversal symmetry breaking in photonic crystals via some gyromagnetic properties of thesample, or inherent time dependence of the system. In the latter case, when the system, specifically, drivenperiodically then the more exotic non-equilibrium phases can also be observed in these lattices.In this work, we explore the topological properties in these periodically driven photonic lattices. For instance,how fundamental symmetries, e.g., particle-hole symmetry, can be implemented to engineer topology in 1D. Wefind a connection between crystalline symmetries and the fundamental symmetries, which facilitate suchimplementation. Moreover, a synthetic dimension can be introduced in these lattices that simulate higherdimensional physics. The difference between synthetic and spatial dimension becomes apparent when a specificcrystalline symmetry, like inversion, is broken in these systems. This breaking changes a direct bandgap to anindirect one which manifests in the winding of bands in the quasienergy band spectrum. If it is broken in thesynthetic dimension, it results in an interplay of two topological properties: one is the winding of the quasienergybands, and the other one is the presence of chiral edge states in the finite geometry. This former property ofwinding manifests as Bloch oscillations of wavepackets, where we show that the stationary points in theseoscillations are related to the winding number of the bands. This topological property can thus be probed directlyin an experiment by the state-of-art technology. However, if this symmetry is broken in the spatial dimension, thewinding of bands manifest as a quantized drift of mean position, which is still characterized by a winding numberof the bands.Furthermore, we show that a different gapless regime can also be engineered while preserving the inversionsymmetry. In this regime, the topology can be captured by enclosing the degeneracies in parameter space andcalculating the Berry flux piercing through the enclosed surface. In this case, some of the degeneracies can hostchiral edge states along with other protected ones at the same quasienergy

Fluid power technology has been widely used in industrial practice; however, its energy efficiency became a big concern in the recent years. Much progress has been made to improve fluid power energy efficiency from many aspects. Among these approaches, using a valve-less system to replace a traditional valve-controlled system showed eminent energy reduction. This thesis studies the valve-less solution-pump displacement controlled actuators- from the view of controls background. Singular perturbations have been applied to the fluid power to account for fluid stiffness; and a novel hydraulic circuit for single rod cylinder has been presented to increase the hydraulic circuit stabilities. Recursive Least Squares has been applied to account for measurement noise thus the parameters have fast convergence rate, square root algorithm has further applied to increase the controller's numerical stability and efficiency. It was showed that this technique is consistent with other techniques to increase controller's robustness. The developed algorithm is further extended to a hybrid adaptive control scheme to achieve desired trajectory tracking for general cases. A hardware test-bed using the invented hydraulic circuit was built up. The experimental results are presents and validated the proposed algorithms and the circuit itself. The end goal of this project is to develop control algorithms and hydraulic circuit suitable for industrial practice.

The flooded meadows of the Pamarys region permanently are an object of increased attention and require new solutions using grasslands for farming and sustainable development of the area. During the last decade's new environmental regulations has more tighten restrictions for farming and especially in protected areas. Nemunas delta Regional Park is one of the biggest protected areas in this region. The status of protected area fundamentally changed the farming conditions in polder systems. Summer polders (these are flooded in spring time) are the main chain in the plenty of problems, and proper farming and use of polder systems not only decrease expenses for maintenance, but also essentially improve ecological situation of the ecosystem in such areas. The most important problem still remains fish killing in pumping stations of polder systems. More the 10 years before the Sysa pumping station was modernized installing here screw pumps. It was experimental pumping station for several years ad latter the same pumps were installed in more three pumping stations. Today we have already 14 years experience and can do some conclusions about the use of screw pumps. The history of screw pumps, some practical experiments, analysis of collected data in three different polder systems (with screw pumps and conventional pumps) a comprised in this final Msc. degree work.

A system able to simultaneously separate and pump a gas-liquid mixture was developed.

It works efficiently and can be used in many applications (nuclear power plants,

pulp and paper processing, petroleum extraction, etc.). However, this pump and separator

system (PASS) was especially designed to handle air-oil mixture generated in

aero-engine lubrication systems. The PASS combines three important functions of the

scavenge part of the lubrication system: the deaeration and deoiling of the air-oil mixture

generated in the bearing and gearbox sumps and the pumping of the oil towards

the tank. These are critical functions for the engine. Indeed, a poor deoiling efficiency

leads to a high oil consumption. This reduces the flight endurance, increases the size

and weight of the oil tank and has a negative impact on the environment. Poor deaeration

and pumping characteristics lead to problems in the cooling and the lubrication of

the engine bearings.

Integrating a PASS into the lubrication system allows considerable improvements

(and simplification) to the lubrication system architecture. An important number of

components are suppressed: the vent lines, the deoiler, the cyclone deaerator and the

scavenge pumps. This reduces the size and the weight of the lubrication system and

increases its reliability. Furthermore, an important part of this PhD thesis focuses on

reducing the oil consumption in the PASS. This improves the flight endurance, reduces

engine maintenance and working costs and is profitable to the environment.

In addition to the development of an advanced PASS design system, the objective of

this thesis was to obtain a good understanding of the separation processes occurring in

the PASS and to develop theoretical models able to predict the separation performance

for every working condition encountered in a typical aircraft flight. To achieve this

goal, three main tasks were performed: the development of different two-phase measurement

systems, the experimental tests of four different PASS architectures and the

theoretical development (after an extensive literature review) of correlations predicting

the performance of the PASS in function of the working conditions. Five specific aspects

of the PASS were studied: the inlet flow, the deoiling efficiency, the deaeration efficiency,

the pumping efficiency and the pressure drop. Finally, the models that have been developed

with the help of the measurement systems and of the experiments have been

integrated in a complete model of the lubrication system (under the EcosimPro modelling

environment). This helps to predict real in flight PASS working conditions and

performance. Indeed, the PASS is very sensitive to the engine working conditions and

an optimisation of the prototype size and performance is only feasible with an accurate

knowledge of these working conditions and a complete lubrication system model.

Finally, with the results of this PhD thesis, a new PASS design, optimised for different

aero-engine lubrication systems, is presented.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

Terminal heme-copper oxidases (HCuOs) are transmembrane proteins that catalyze the final step in the respiratory chain - the reduction of O₂ to H₂O, coupled to energy conservation by generation of an electrochemical proton gradient. The most extensively investigated of the HCuOs are the aa₃-type oxidases, to which cytochrome c oxidase (CytcO) belongs, which uses energy released in the O₂-reduction for proton pumping. The bacterial nitric oxide reductases (NORs) have been identified as divergent members of the HCuO-superfamily and are involved in the denitrification pathway where they catalyze the reduction of NO to NO₂. Although as exergonic as O₂-reduction, this reaction is completely non-electrogenic. Among the traditional HCuOs, the cbb₃-type oxidases are the closest relatives to the NORs and as such provide a link between the aa₃ oxidases and the NORs. The cbb₃ oxidases have been shown to pump protons with nearly the same efficiency as the aa₃ oxidases, despite low sequence similarity.

This thesis is focused on measurements of membrane potential generating reactions during catalysis in the CytcO and the cbb₃ oxidase from Rhodobacter sphaeroides, and the NOR from Paracoccus denitrificans, using a time resolved electrometric technique. The pH dependence of the membrane potential generation in CytcO showed that only one proton is taken up and that no protons are pumped, at high pH. An additional kinetic phase was also detected at high pH that presumably originates to from charge-transfer within the K-pathway. Possible reasons for uncoupling, and the extent of charge-transfer, were studied using structural variants of CytcO. The measurements established that electrons and protons are taken up from the same side of the membrane in NOR. In addition, the directionality for proton uptake in cbb₃ oxidase appeared to be dependent on the choice of substrate while proton pumping was indicated to occur only during O₂-reduction.

Projetos piloto com sistemas fotovoltaicos de irrigação foram implementados ao redor do mundo para avaliar a confiabilidade e a viabilidade desta aplicação frente a outras opções de bombeamento. O presente trabalho dedicou atenção à compilação de informações sobre projetos com sistemas fotovoltaicos de bombeamento para uso na irrigação. A partir dessa compilação foi realizada uma síntese das experiências com identificação das principais barreiras e potencialidades de seu uso no Brasil. Levando em conta as lições aprendidas em projetos anteriores, o trabalho é finalizado com recomendações e orientações para implantação de projetos de sistemas fotovoltaicos de bombeamento para irrigação em pequenas propriedades rurais.
Pilot projects with photovoltaic irrigation systems have been implemented around the world to evaluate the reliability and feasibility of this application. This paper has devoted attention to compiling information about projects with photovoltaic pumping systems for use in irrigation. From this compilation, a synthesis of experience, the key barriers and the potential for their use in Brazil were made. Taking into account the lessons learned in previous projects the work shows recommendations and guidelines for implementation of projects for photovoltaic pumping systems for irrigation on small farms.

A presente dissertação aborda a avaliação de três sistemas fotovoltaicos de bombeamento, que compreendem duas configurações com equipamentos dedicados à tecnologia fotovoltaica e um com equipamentos alternativos com potências entre 0,75 CV e 1,0 CV. Os resultados mostram que a configuração alternativa apresenta menor eficiência diária do sistema motobomba. A avaliação econômica revela a competitividade da configuração alternativa frente aos sistemas importados dedicados à tecnologia fotovoltaica. Alia-se a isso a disponibilidade dos equipamentos de condicionamento de potência e a facilidade de reposição. Verificou-se também que a configuração alternativa, conversor de freqüência WEG CFW08 e motobomba SOMAR de 1,0 CV e 8 estágios, trabalha com eficiência diária próxima aos 30% na faixa de operação de 20 a 40 metros de coluna dágua. Portanto, com uma adequada escolha da motobomba para a configuração alternativa, podem-se obter desempenhos semelhantes aos obtidos com sistemas importados dedicados à tecnologia fotovoltaica. Para 30 metros, a configuração alternativa bombeou somente 1% a menos do que o sistema Grundfos. O custo do volume bombeado para 30m de altura manométrica total do sistema alternativo é 22% menor do que o sistema Grundfos e 51% mais econômico do que o sistema Solarjack (Sun Pumps).
The present dissertation shows the evaluation of three Photovoltaic Pumping Systems, which involves two configurations: the equipment dedicated to the photovoltaic technology and the alternative equipment with nominal powers between 0.75 CV and 1.0 CV. The results show that the alternative configuration attained minor daily efficiency of the motopump system. The economic evaluation reveals the competitiveness of the alternative configuration in comparison with imported photovoltaic technology dedicated systems. It also should be considered the availability of equipment for power conditioning and the facility of replacement. It was also verified that the alternative configuration, variable speed drive WEG CFW08 and 1.0 CV SOMAR motor pump with 8 stages, works with daily efficiency near 30% in the 20 to 40 meters operation range. Therefore, with an adequate choice of the motor pump for the alternative configuration, performances similar to the imported photovoltaic technology dedicated systems can be obtained. For 30 meters, the alternative configuration pumped only 1% less than the Grundfos system. The cost of pumped volume for 30 meters of manometer total height of the alternative system is 22% cheaper than the system Grundfos and 51% cheaper than the system Solarjack (Sun Pumps).

This thesis studies the optimal design for a photovoltaic-powered medium-head (30 meters) water pumping system, with the emphasis on improving the efficiency and reducing the maintenance requirements of the electrical subsystem. The reduction of maintenance requirements is realized by replacing the conventional brush-type permanent magnet dc motor with a brushless dc (BLDC) motor. Different BLDC motor control techniques such as position-sensorless operation, sinusoidal and trapezoidal excitations are investigated. The improvement in efficiency is achieved by maximizing the output power from the photovoltaic array and by minimizing the losses in various parts of the electrical sub-system. A microprocessor-based double-loop maximum power tracking scheme is developed for maximization of the photovoltaic array output power. Over 99% utilization factor is achieved for a typical clear day regardless of the season of the year. The system losses are minimized mainly by performing loss analysis and selecting most suitable switching topologies and switching components. Experimental results show that the combined converter-motor efficiency is comparable to those of high-efficiency brush-type dc motor systems.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate