Unreliable and unsustainable electricity supply has been experienced in South Africa since 2007. Eskom implemented Demand Side Management (DSM) as a short-term solution to alleviate this problem. Several compressed-air DSM projects were implemented to help reduce the strain on the electrical network. Compressed air is an integral part of production in deep-level mining, and is extensively utilised. Problems are encountered with the effective management and repairing of leaks, since the majority of mines have little to no procedures in place for leak management. Awareness of the condition of the compressed-air system and leaks needed to be created at management level in order to achieve the best results. The purpose of this study is to investigate the effect of proper leak management on compressed-air systems in the mining industry. Peak-clipping DSM projects implemented in the mining industry were used for evaluation of results. Contribution to the sustainability of compressed-air DSM projects savings through successful leak documentation was the prime focus of this study. This was achieved through the development of a Compressed Air Leakage Documentation System (CALDS). This entailed the electronic field-data capture and record keeping of field data, using rugged PDA devices suitable for the extreme environmental conditions encountered in deep-level mining. Report generation on the status of detected leaks created awareness of compressedair- system performance and leak-repair tracking at management level. Audible detection was sufficient for this study, since the focus was on the larger more-severe leaks. Leaks were expressed in monetary terms to indicate the severity. It was found that successful management of leaks could contribute to an increase of as much as 85% in project savings. The results also showed that creating awareness through documentation of leaks, and the effect this has on the system, resulted in regular repairing of these leaks. Sustainability of projects was maintained during an evaluation period of ten months, with projects achieving on average 125% of target savings. The study showed that effective reporting on compressed-air leaks resulted in increased system efficiency and sustainable DSM project savings. It was also seen that leak detection by outsourced companies did not necessarily result in financial savings. When the mine took responsibility for its own leak detection and repairs, significant savings were realised. / Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2011.

Demand Side Management (DSM) is one of the most viable and sustainable short term methods to address the shortfall in electricity generation in South Africa. This is because DSM projects can be implemented relatively quickly and inexpensively when compared with alternative generation options. This specifically applies to the mining industry. South African mines presently consume 15% of Eskom-generated electricity. Mine compressed air systems are some of the biggest users, consuming approximately 21% of mine electricity consumption. Electricity savings on compressed air systems are therefore important. With this study, various Energy Efficiency methods on compressed air systems were investigated. These methods include variable speed drives on compressor motors, temperature control of compressor discharge, minimising pressure drops in the air distribution systems, eliminating compressed air leaks, and optimising compressor selection and control. The most efficient strategies were identified, taking into account factors such as financial viability, sustainability, and ease of implementation. The best strategies were found to be the optimised control and selection of compressors, minimising compressed air leaks, and the optimal control of system pressure. These strategies were implemented and tested on large compressed air systems in gold and platinum mines. Savings of between 10% and 35% on the maximum demand of the systems were achieved. In present monetary terms this translates to as much as R108 million savings for the mines per year at the end of 2009 tariffs. If total mine compressed air electricity consumption can reduce by 30%, it will result in nearly a 1% reduction in total Eskom demand. This shows that mine compressed air savings can make a significant contribution to the drive for Energy Efficiency in South Africa. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

O torneamento radial é um processo de usinagem usado na indústria metal mecânica para o corte de peças, abertura de canais ou faceamento. Esta pode ser considerada uma operação crítica devido à forma geométrica da ferramenta e aos movimentos de corte. Isto gera a necessidade de aplicação de fluidos de corte, normalmente em abundância, na região de corte. Considerando como funções destes fluidos o arrefecimento, a lubrificação e a expulsão do cavaco, sua aplicação durante essa operação é de suma importância. Várias pesquisas visam restringir o uso de tais fluidos, seja por critérios econômicos, ambientais ou sanitários. Neste contexto, o uso da técnica de mínima quantidade de lubrificante (MQL) vem ganhando espaço nos meios produtivos. Embora seja aplicada há anos em diferentes processos de usinagem, existem poucos relatos sobre a aplicação de MQL em operações de torneamento radial; no mesmo seguimento, a aplicação de ar comprimido (ACO) vai ao encontro do conceito de usinagem ambientalmente amigável. Assim, este trabalho apresenta uma análise comparativa na aplicação de lubrificantes em abundância (ABD), em MQL e o uso de ACO no torneamento radial do aço SAE 1045 para diferentes condições de corte. Na investigação, foram consideradas as forças geradas durante o processo, as rugosidades e o desvio dimensional das superfícies usinadas, e o desgaste da ferramenta. Observou-se que os esforços gerados com MQL foram similares ou inferiores aos gerados com ABD. A mesma tendência foi observada no perfil de rugosidade, predominando valores inferiores. O MQL possibilita um corte mais estável durante a vida da ferramenta, reduzindo a ocorrência de desgaste e prolongando sua vida útil, minimiza a oscilação axial e a flexão da ferramenta, reduz as rugosidades e minimiza os desvios dimensionais. Assim, pode-se afirmar que a aplicação da técnica por MQL é viável no torneamento radial do aço SAE 1045. / Radial turning is a machining process used in the metalworking industry for parting off, grooving or facing operations. This can be considered a critical operation due to the geometric shape of the tool and the cutting movements. This generates the need for application of cutting fluids, usually in abundance, in the cutting region. Considering as functions of these fluids the cooling, lubrication and expulsion of the chip, their application during this operation is of paramount importance. Several researches aim to restrict the use of such fluids, either by economic, environmental or sanitary criteria. In this context, the use of the minimum quantity of lubricant (MQL) technique has been gaining ground in the productive media. Although it has been applied for years in different machining processes, there are few reports on the application of MQL in radial turning operations; at the same time, the application of compressed air (ACO) meets the concept of environmentally friendly machining. Thus, this work presents a comparative analysis on the application of abundant lubricants (ABD) in MQL and the use of ACO in radial turning of SAE 1045 steel for different cutting conditions. In the investigation, the forces generated during the process, the roughness and the dimensional deviation of the machined surfaces and the tool wear were considered. It was observed that the machining forces generated with MQL were similar or inferior to those generated with ABD. The same tendency was observed in the profile of roughness, predominating lower values. MQL enables a more stable cut during tool life, reducing the occurrence of wear and extending tool life, minimizes axial oscillation and tool flexion, reduces roughness and minimizes dimensional deviations. Thus, it can be indicated that the application of the technique by MQL is feasible in the radial turning of SAE 1045 steel.

O torneamento radial é um processo de usinagem usado na indústria metal mecânica para o corte de peças, abertura de canais ou faceamento. Esta pode ser considerada uma operação crítica devido à forma geométrica da ferramenta e aos movimentos de corte. Isto gera a necessidade de aplicação de fluidos de corte, normalmente em abundância, na região de corte. Considerando como funções destes fluidos o arrefecimento, a lubrificação e a expulsão do cavaco, sua aplicação durante essa operação é de suma importância. Várias pesquisas visam restringir o uso de tais fluidos, seja por critérios econômicos, ambientais ou sanitários. Neste contexto, o uso da técnica de mínima quantidade de lubrificante (MQL) vem ganhando espaço nos meios produtivos. Embora seja aplicada há anos em diferentes processos de usinagem, existem poucos relatos sobre a aplicação de MQL em operações de torneamento radial; no mesmo seguimento, a aplicação de ar comprimido (ACO) vai ao encontro do conceito de usinagem ambientalmente amigável. Assim, este trabalho apresenta uma análise comparativa na aplicação de lubrificantes em abundância (ABD), em MQL e o uso de ACO no torneamento radial do aço SAE 1045 para diferentes condições de corte. Na investigação, foram consideradas as forças geradas durante o processo, as rugosidades e o desvio dimensional das superfícies usinadas, e o desgaste da ferramenta. Observou-se que os esforços gerados com MQL foram similares ou inferiores aos gerados com ABD. A mesma tendência foi observada no perfil de rugosidade, predominando valores inferiores. O MQL possibilita um corte mais estável durante a vida da ferramenta, reduzindo a ocorrência de desgaste e prolongando sua vida útil, minimiza a oscilação axial e a flexão da ferramenta, reduz as rugosidades e minimiza os desvios dimensionais. Assim, pode-se afirmar que a aplicação da técnica por MQL é viável no torneamento radial do aço SAE 1045. / Radial turning is a machining process used in the metalworking industry for parting off, grooving or facing operations. This can be considered a critical operation due to the geometric shape of the tool and the cutting movements. This generates the need for application of cutting fluids, usually in abundance, in the cutting region. Considering as functions of these fluids the cooling, lubrication and expulsion of the chip, their application during this operation is of paramount importance. Several researches aim to restrict the use of such fluids, either by economic, environmental or sanitary criteria. In this context, the use of the minimum quantity of lubricant (MQL) technique has been gaining ground in the productive media. Although it has been applied for years in different machining processes, there are few reports on the application of MQL in radial turning operations; at the same time, the application of compressed air (ACO) meets the concept of environmentally friendly machining. Thus, this work presents a comparative analysis on the application of abundant lubricants (ABD) in MQL and the use of ACO in radial turning of SAE 1045 steel for different cutting conditions. In the investigation, the forces generated during the process, the roughness and the dimensional deviation of the machined surfaces and the tool wear were considered. It was observed that the machining forces generated with MQL were similar or inferior to those generated with ABD. The same tendency was observed in the profile of roughness, predominating lower values. MQL enables a more stable cut during tool life, reducing the occurrence of wear and extending tool life, minimizes axial oscillation and tool flexion, reduces roughness and minimizes dimensional deviations. Thus, it can be indicated that the application of the technique by MQL is feasible in the radial turning of SAE 1045 steel.

O objetivo deste trabalho é realizar uma análise paramétrica do processo de desumidificação de ar comprimido em trocadores de calor compactos com superfícies intensificadoras do tipo aletas deslocadas. A umidade contida no ar comprimido precisa ser retirada do sistema para evitar a formação de condensado nas linhas de distribuição, nos atuadores ou nos dispositivos finais. Utiliza-se o processo de desumidificação por resfriamento onde a temperatura do ar é diminuída até alcançar o ponto de orvalho, resultando em formação de condensado. O desumidificador é constituído por dois trocadores de calor (recuperador e evaporador), sendo cada um deles dividido em duas regiões. Realizou-se a modelagem do processo de transferência de calor para cada um dos trocadores. Utilizou-se o método do potencial de entalpias para determinar os coeficientes globais de transferência de calor de cada trocador. Para a realização da simulação numérica, foi implementado um programa utilizando como ferramenta computacional o programa “Engineering Equation Solver” (EES). O estudo foi feito variando-se os parâmetros geométricos do trocador de calor e verificando sua influência nos coeficientes de transferência de calor, nos calores trocados e nas condições de saída do ar. Primeiramente, cada parâmetro foi analisado individualmente e depois com algumas combinações. Concluiu-se que as dimensões das aletas no recuperador e os comprimentos do recuperador e do evaporador são os parâmetros que mais influenciam nas propriedades do ar comprimido na saída do desumidificador. / The objective of this work is to conduct a parametric analysis of the dehumidification process of compressed air in compact heat exchangers with Offset Strip Fins. The humidity carried by the compressed air should be removed from the system to prevent the condensation in the distribution lines and in the actuators or the final devices. The dehumidification process by cooling occurs when the temperature of the air is diminished until reaching the dew point, resulting in condensation of water vapor. The dehumidifier is constituted by two heat exchangers (recuperator and evaporator), each one of them being divided in two regions. A modeling of the heat and mass transfer process for each heat exchangers, was performed. The enthalpy driving potential method was used to determine the overall heat transfer coefficients of each heat exchanger. The numerical simulation was implemented by using the computational software "Engineering Equation Solver"(EES). The study was made varying the geometric parameters of the heat exchanger and verifying its influences on the heat transfer coefficients, the heat transfer and pressure drop, and the air exit conditions. First, each parameter was analyzed individually and then with some combinations. Its was concluded that the fins dimensions in both regions of the lengths of the recuperator and the evaporator are the parameters that have larger influence on the exit compressed air properties.

A escassez de água e a grande geração de esgoto doméstico com necessidade de tratamento estimulam o uso de águas residuárias na agricultura. A irrigação por gotejamento caracteriza-se como um sistema seguro para esta finalidade, mas possui como barreira tecnológica o entupimento dos gotejadores. Neste trabalho, objetivou-se selecionar modelos de gotejadores e manejos mitigadores do entupimento por uso de água residuária oriunda de tratamento secundário de esgoto doméstico. Desenvolveu-se o estudo em três etapas: (I) a caracterização de 15 modelos de gotejador novos, (II) a préseleção dos emissores e (III) a seleção da combinação manejo e modelo. Os manejos foram controle, cloração a 0,5 mg L-1 de cloro residual livre ao final da irrigação medido ao final do sistema, ar comprimido a 1,96 kPa na entrada dos emissores e a combinação de cloração e ar comprimido, utilizando-se filtragem de areia (De = 0,59 mm), disco (120 mesh) e tela (200 mesh) em todos os tratamentos. Procederam-se avaliações de vazão e cálculos de coeficiente de variação de vazão (CVq) e de grau de entupimento (GE). Os modelos apresentaram coeficiente de variação de fabricação aceitável e diferentes sensibilidades ao entupimento. O entupimento foi parcial, ocorreu de maneira desuniforme, independente da uniformidade de distribuição de água (UD) do emissor novo, e surgiu pela formação de biofilme bacteriano associado a sólidos dissolvidos. Houve aumentos de vazão em alguns modelos. A cloração reduziu o grau de entupimento ao longo do tempo e evitou o entupimento total em emissores. O modelo B associado à cloração apresentou a maior probabilidade de encontrar emissores na faixa de 5 % de variação de vazão em relação aos novos e o modelo M associado à filtragem ou a tratamentos com ar comprimido, as menores probabilidades. Os manejos mostraram-se semelhantes quanto ao GE e ao CVq e obtiveram-se valores de UD inferiores a 60 %, CVq superiores a 20 % e GE superiores a 5 %. Finalmente, de acordo com o objetivo, selecionou-se o modelo B associado à cloração como a combinação que melhor atenuou o entupimento dos emissores. / The sustainable management of water resources, given the current and projected severe water shortages, requires that appropriate methods of water usage be implemented. One of these is the application of treated wastewater to agricultural land using drip irrigation systems, which is safe and among the most resource efficient methods of irrigation. However, the use of drip irrigation with wastewater is constrained by the potential for clogging in the emitters. To elucidate the mechanism of clogging, fifteen drip emitters models from different manufacturers were tested with secondary treated wastewater in the laboratory and two field experiments were conducted to evaluate emitters and treatments according to the degree of clogging (DC) and flow rate coefficient of variation (CVq). The treatments were control (filtrage only), chlorination (0.5 mg L-1 free residual chlorine injected at the end of each irrigation cycle), compressed air (1.96 kPa in the inlet drippers) and the chlorine and compressed air combination. The manufacture coefficient of variation was acceptable and different clogging susceptibility. The clogging was partial, non-uniform and was caused by biofilm with dissolved solids. Some drippers with overflow rates were noted. The chlorination decreased clogging overtime and reduced the complete clogging. The dripper model B (pressure compensated, flat and inserted in the line, with rectangular elastic membrane over a 30 mm passageway, 0.8 mm narrowest aperture, 1.61 L h-1 under 98 kPa) with chlorination was identified as having the best performance, with the highest number of emitters with a flow rate within five percent of the flow rate when new, and the dripper model M with chlorination was the worst performance with the lowest percent. The filtrage, chlorine and air treatments did not have a statistically significant affect in the DC or CVq. Distribution uniformities higher than 60 %, CVq higher than 20 % and DC higher then 5 % were found. Finally, according to the purposed, It was selected the dripper model B with chlorination as the best combination to mitigate the clogging

Le stockage de l’énergie constitue un enjeu majeur pour garantir la sécurité des réseaux électriques et favoriser le développement des énergies renouvelables. Véritable alternative aux stations de transfert d’énergie par pompage (STEP), le stockage d’énergie par air comprimé (CAES pour Compressed Air Energy Storage) fait partie des technologies les plus intéressantes. Dans les systèmes classiques utilisés actuellement, l’énergie de compression est perdue et l'air est préchauffé lors de la détente. Il en résulte une émission de CO2 et un rendement faible de l’ordre de 50%. Le système AA-CAES (Advanced Adiabatic Compressed Air Energy Storage) vise à pallier ces deux inconvénients en stockant la chaleur de compression dans un régénérateur thermique et en la restituant avant la détente dans la turbine. Compte tenu des fortes sollicitations thermiques, mécaniques et cycliques que subit cet ouvrage, la conception d'un revêtement capable d'assurer la stabilité, l'isolation et l'étanchéité constitue un enjeu principal du système. Ce point crucial constitue l'axe principal autour duquel s'articule cette thèse. Une campagne d'essais en laboratoire a été mise en oeuvre pour étudier les comportements thermique, hydraulique et mécanique de tous les matériaux impliqués dans un régénérateur souterrain creusé dans une roche cristalline. Pour l'air humide, dont le comportement thermodynamique est mal connu dans la gamme des fortes températures et des pressions envisagées, un nouveau modèle théorique a été développé. De la même façon, un modèle thermo-hydro-mécanique a été développé pour un milieu poreux déformable saturé traversé par un fluide compressible. L'intégration de ce modèle dans un logiciel de calcul de structures par éléments finis a permis d’examiner plusieurs configurations de revêtement et d'étudier l’effet des mécanismes de couplage sur le champ de température et sur la stabilité mécanique. Afin de valider les développements effectués et les solutions de revêtement proposées, un prototype d’un régénérateur à échelle réduite combinant pression et température a été construit dans le laboratoire LITEN du CEA à Grenoble. Les résultats des expériences et des modélisations effectuées ont mis en évidence l'importance du phénomène de convection dans les briques isolantes du revêtement et la nécessité d'assurer l'étanchéité du système avant l'isolation thermique. / Energy storage is a major challenge to ensure the safety of electrical networks and to promote the development of renewable energies. Veritable alternative to Pumped Storage Hydropower (PSH), the energy storage using compressed air (for CAES Compressed Air Energy Storage) is one of the most interesting technologies. In conventional systems currently in use, the compression energy is lost and the air is preheated during the expansion phase. This results in emission of CO2 and a low efficiency of about 50%. The AA-CAES (Advanced Adiabatic Compressed Air Energy Storage) aims to overcome these two drawbacks by storing the heat of compression in a thermal regenerator and restoring it before expansion in the turbine. Given the high thermal, mechanical and cyclic loading subject to the regenerator, the design of a lining capable of ensuring stability, insulation and sealing is a main issue of the system. This crucial point is the main axis around which this research is articulated. A laboratory testing campaign has been conducted to study the thermal, mechanical and hydraulic behavior of all materials involved in the underground regenerator excavated in a crystalline rock. For the humid air, whose thermodynamic behavior is not well studied within the range of the high foreseen temperatures and pressures, a new theoretical model was developed. In the same way, a thermo-hydro-mechanical model was developed for a deformable porous medium saturated with a compressible fluid. The implementation of this last model into a finite element numerical code was used to examine several lining configurations and to study the effect of coupling mechanisms on the temperature field and the mechanical stability. To validate the developments made and the proposed lining solutions, a prototype of a small scale regenerator combining temperature and pressure was built in the LITEN laboratory of CEA in Grenoble. The results of the conducted experiments and modeling revealed the importance of the convection phenomenon in the insulating bricks of the lining and the need to seal the system before thermal insulation.

Shock tubes have been used extensively to study shock wave structures and high speed flow features. The purpose of constructing this open end shock tube was to have the ability to produce shock waves in a laboratory setting but also understand the exit flow coming out which can be applied to future studies that are beyond the scope of this work. This undertaking would require that an open end shock tube be built and instrumented with PCB Integrated Circuit Piezoelectric (ICP) Pressure Sensor Model 113B24 that would then be connected to a PCB Model 482C05 Signal Conditioner with the purpose of measuring the the pressure jumps as well as the speed of the shock wave. The data was acquired using National Instruments NI PXIe-1071 chassis with a PXI 1088 Embedded Controller as well as three PXI 5114 digitizer cards with the Virtual Instrument coded using LabView. The data was written to a text file that was then transferred to MATLAB for post processing using a Savitzy-Golay filter to clean up the signal noise. The shock tube was driven using compressed air and a diaphragm burst was achieved through spontaneous rupture of a 0.003" Mylar diaphragm. The open shock tube built for this undertaking fits in a lab space and successfully produces a shock wave that propagates down the tube that exits at the open end to reproduce a blast wave. Additionally the available pressure sensors and DAQ were integrated into the shock tube to measure the different predicted shock structures in each run. The experimental runs at the exit of the shock tube demonstrate the expected exit flow features, but a flow visualization is necessary to get a better understanding of the exit flow

The subject of master’s thesis "The study of the operating production management” is to rationalize production and distribution of compressed air. The thesis deals with the description of the current state, the analysis of compressed air production and the proposal for rationalization. The basis of this work is to implement lean manufacturing method in the company DI Industrial. The proposed steps are primarily designed for implementation in this firm but their principles and methods could be used in any company that uses compressed air technology. The study includes theoretical knowledge in the range of Lean manufacturing, Six Sigma tools and a pneumatics.

Description of present state of compressed air production in Motorpal a.s. Jihlava. Toll used for production procedure and output improvement, quality problems solving and improvement implemantation. Problem define, measure, analyse, iprovement proposals and improvement implementation, improved process control via Lean Six Sigma methodics.