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Orientador: Alberto Adade Filho / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-18T21:11:42Z (GMT). No. of bitstreams: 1 Iskandar_MarcoAntonio_M.pdf: 4356371 bytes, checksum: 8b89db3b0ba0eb163732c9073c792ae9 (MD5) Previous issue date: 2011 / Resumo: A tecnologia de motores diesel tem sido guiada por legislações cada vez mais severas. Para cumprir com estas legislações os sistemas de controle de emissões estão se desenvolvendo rapidamente visando à disponibilização no mercado de produtos que atendam às normas de emissões, mas com economia no consumo de combustível e maior durabilidade e competitividade nos mercados internacionais, em suma melhoria na relação custo x benefício. Neste contexto, é colocada a análise e projeto de um sistema de controle de arrefecimento do motor Diesel, que objetiva controlar a temperatura de água do motor visando à economia de combustível e redução dos níveis de emissões. Assim, o presente trabalho tem como objetivo a análise e projeto de um sistema substituto ao tradicional sistema de arrefecimento (cooling) do motor Diesel disponível e comumente utilizado no mercado atualmente. O sistema mecatrônico em estudo é composto por uma bomba elétrica de água, um ventilador acionado eletricamente, uma válvula termostática eletronicamente controlada e um algoritmo de controle. Este conjunto visa propiciar um controle preciso da temperatura de água do motor Diesel, dessa forma reduzindo as emissões de poluentes e o consumo de combustível, permitindo, ainda, uma resposta rápida no aquecimento em partida a frio e maior durabilidade do motor. Os ajustes do controlador foram calculados por meio de algoritmos de otimização e co-simulação computacional utilizando dois softwares distintos: GT-Cool (GT-SUITE é marca registrada da Gamma Technologies) e Matlab / Simulink (MATLAB/Simulink é marca registrada da Mathworks) / Abstract: The diesel engine technology has been driven by increasingly stringent laws. To comply with these laws the emissions control systems are rapidly developing in the market aimed at providing products that meet future emissions standards, but savings in fuel consumption and greater durability and competitiveness in international markets, improving cost-benefit ratio. In this context, design and analysis of a control system for cooling the diesel engine, aiming to control the engine water temperature accurately, to save fuel and reduce emissions. The present work has as objective to design a mechatronic system as a substitute to the traditional cooling system of the diesel engine commonly used in the market today. The system under study consists of an electric water pump, an electrically driven fan, an electronically controlled thermostatic valve and a control algorithm. This system is intended to provide a control in water temperature of the diesel engine, thereby reducing pollutant emissions and fuel consumption, allowing also a rapid response to heating in cold start. Controller tuning was calculated by algorithmic through optimization and co-simulation using two distinct computational software GT-Cool (GT-SUITE is a registered trademark of Gamma Technologies) and Matlab / Simulink (MATLAB / Simulink is a registered trademark of Mathworks) / Mestrado / Eletrônica / Mestre em Engenharia Automobilistica

Reliability of emergency Diesel generator systems, or indeed any Diesel engines in a wide range of fields is critical. Traditional maintenance procedures for these engines follow time based or statistical based methods. Due to the wide variety of uses of Diesel engines it is not possible for these forms of maintenance to be as effective as condition based monitoring. Condition based monitoring holds many advantages over traditional maintenance methods. It allows for the earlier detection and diagnosis of a fault and allows for planned maintenance work avoiding costly and unexpected downtime. It also reduces the overall maintenance costs as parts need only be replaced when they are worn or faulty, not based on a time schedule. The ability to unobtrusively monitor the engines also has many advantages in- cluding reduced sensor cost and negating the need to tamper permanently with the engine. Acoustic monitoring has been identified as the most prominent and effective way in which to achieve this goal. As such, extensive experimentation was carried out on both large and small Diesel engines over a wide range of speeds, loads and faults and the data was then analysed. The data was first investigated statistically and then processed using Independent Component Analysis after the statistical re- sults were found to be poor. A program was written for the automatic comparison of the collected data and the results presented in this thesis show that ICA and acoustic emissions have the ability to aid in engine fault detection and diagnosis. The results have shown to be reliable, consistent and able to distinguish when the engine is healthy or faulty.

Neste trabalho pretende-se desenvolver o dispositivo para a fixação de cabeçotes e acionamento de válvulas em um equipamento para medição de swirl, que é um dos movimentos do ar dentro da câmara de combustão nos motores de ignição por compressão. Este desenvolvimento tem como objetivos facilitar a montagem do cabeçote no equipamento e desenvolver o avanço automático das válvulas, visando a redução do tempo total do ensaio. No desenvolvimento, foi feito um comparativo das características e componentes montados nos cabeçotes e nos diferentes modelos que serão testados no equipamento, para que não fossem necessários retrabalhos no cabeçote ou desmontagens de componentes para a realização dos ensaios, abrangendo a maior gama possível de produtos. Foram definidos os métodos de posicionamento do cabeçote no dispositivo e o sistema de fixação. Para garantir a precisão no acionamento das válvulas, foi definido um fuso de esferas recirculantes, acionadas por um motor de passo. O projeto foi concluído e o dispositivo foi fabricado e instalado no equipamento de medição. Testes realizados mostraram resultados de medição de swirl conforme esperado, além da diminuição no tempo total do teste. A partir de observações feitas após a fabricação e os testes no dispositivo, algumas melhorias estão sendo propostas, como, por exemplo, acionamentos por balancins independentes para cada válvula. / In this work, the aim is to develop the device for the fixture of the cylinder head and the valve actuation in a swirl meter test bench. Swirl is a movement inside the combustion chamber in a compression ignition engine. The development aims to facilitate the assembling of the cylinder head in the equipment and develop the valve lift device, focusing in decreasing the total time for the test. Also, the valve actuator shall be able to perform the continuous valve lift in the swirl measurement. During the development of this work, a comparative of the main features and the components assembled in the different cylinder head types to be tested in the equipment was done, to avoid rework or disassembling of components for the test, including the most variety of types. It was defined the positioning method for cylinder head in the device and the fixation system. To ensure the precision in the valve actuation, it was defined a ball screw, driven by a step motor. The project was finalized, manufactured and installed in the measurement equipment. Performed tests have showed results of swirl measurement according to expected, and the total time of test was decreased. After this first project, some improvements are proposed in the device, for example, individual actuation per valve.

Variable valve actuation remains one of the most studied technologies for diesel engines for fuel benefits, efficiency improvements and emission control. The same can be implemented on natural gas engines however presence of throttle valve in the spark ignited natural gas engine leads to different set of challenges and outcomes. In this document, focus is on GT power led analyses for a mid-range natural gas engine and the VVA strategy applied is modulation of intake valve closure timing. The simulations are run for early intake valve closure and late intake valve closure, both applied independently and run for steady state conditions. The focus is on the low torque range to study the impact of IVC modulation on throttling losses for low torque region. The simulation studies showed that IVC strategies both early as well as late IVC do benefit in terms of thermal efficiency improvements by up to 3% and reduction in brake specific fuel efficiency by up to 13%.It also showed considerable reduction in pumping loop and increase in open cycle efficiency when IVC modulation is applied. Validating the model further with real on-engine data and then calibrating the existing GT power with the on-engine data to validate the conclusions drawn would be the next set of goals for this project.<div><br></div><div>Second part of this document is focused on real life testing of soy biodiesel fueled heavy duty on-road engine with modern exhaust aftertreatment system with SCR. Soybean based biodiesel remains one of the most sought-after alternate fuel and biofuel to be used in on-road engines. Burning biodiesel leads to a cleaner exhaust compared to conventional diesel as the biofuel is oxygenated fuel leading to more complete combustion and lower amount of emission species such as CO, CO2and PM in the exhaust. The experiments discussed in this document consisted of developing torque curve envelopes and steady state tests (RMC set points). Three soy biodiesel blends were studied which included B20-20% biodiesel, B50 –50% biodiesel and B100 –100% biodiesel. NOx emissions were observed to be considerably higher for B100 at engine outlet by up to80% as well as at tailpipe outlet increased by up to380%, compared to that of conventional diesel which is attributed to the thermal mechanism of NO production. The exhaust gas temperatures were observed to be lower by up to40-degreeC while the urea dosing was considerably higher by up to83% when using biodiesel blend B100.Thisresearch paves the way to testing further using varying biodiesel blends for regulation certification trials, for tuning the diesel engines for different biodiesel blends and for developing the control strategy for the existing diesel engines to accommodate biodiesel.<br><div><br></div></div>

Neste trabalho, pretendeu-se obter as características da movimentação do ar no início do tempo de admissão em um motor diesel, partindo de sua entrada no cabeçote, passando pelos pórticos de admissão e válvulas, até a câmara de combustão, utilizando dados reais da geometria e do processo de sobrealimentação de um motor diesel. Para tanto, utilizou-se da abordagem clássica da dinâmica dos fluidos para o desenvolvimento de um modelo matemático constituído por equacionamentos que representassem o consumo de ar, a rotacionalidade do movimento do ar nos pórticos e a movimentação de ar no cilindro, descrita por linhas de corrente obtidas a partir da aplicação da teoria de escoamento potencial plano. Os cálculos foram efetuados usando planilhas eletrônicas geradas em aplicativo Excel e, tanto a avaliação dos efeitos da geometria dos condutos quanto a determinação das linhas de corrente, foram realizadas usando o aplicativo gráfico Rhinoceros. Neste trabalho foram estudadas seis condições associadas a seis ângulos de virabrequim do início do tempo de admissão e que geraram seis conjuntos de linhas de corrente. Os resultados foram comparados com ensaios de PIV - particle image velocimetry e apresentaram semelhanças relevantes nos formatos e nos sentidos das linhas de corrente. Concluiu-se que o procedimento utilizado, por sua simplicidade de implementação, não é prático quando há a necessidade de alteração de uma das variáveis envolvidas. Porém, ao desenvolver o equacionamento para os casos apresentados, foi possível estudar o fenômeno em profundidade satisfatória, mesmo com as hipóteses simplificadoras utilizadas. / In this work, the aim was to obtain the air flow characteristics in the beginning of the intake stroke in a diesel engine, considering the inlet in head, its passiage by intake runners and valves, up to the combustion chamber, using values obtained from geometry and supercharging process observed in a specific diesel engine. It was used a classical fluid dynamics approach to develop a mathematical model which represent the air consumption, the rotation of the air at intake runners and the air flow within the cylinder, described by streamlines obtained by the use of potential flow theory. The calculation used Excel electronic spreadsheets and both the effects from geometry of intake runners evaluation and the streamlines generation were conducted in drawing software Rhinoceros. In this work six different conditions, associated at six crankshaft angles in the beginning of the intake stroke were studied, resulting in six streamlines set. The results were compared to a PIV test - particle image velocimetry - and relevant similarities was observed both in shapes and rotation sense of streamlines. The conclusion was that the methodology, considering its simplicity in implementation, it is not the most practical method when a modification in variables involved is necessary. However, this methodology was enough to study the phenomenon in satisfactory depth, even using the simplifying assumptions.

Biodiesel is an alternative fuel that can be produced from a variety of lipid feedstocks. It has a number of perceived advantages over conventional petroleum diesel and as a result world production of biodiesel has increased dramatically since the turn of the century. Amongst its reported disadvantages is a widely observed increase in emissions of oxides of nitrogen, or NOx. Several explanations have been proposed for this phenomenon; in reality it is likely to be due to a combination of factors. The interplay of multiple factors affecting NOx emissions means that the increase in NOx when fuelling on biodiesel is not consistent or ubiquitous, but is instead dependent upon operating conditions and the specifics of the fuels being compared. The work documented in this thesis explores the nature and causes of the change in NOx emissions associated with biodiesel. The intention was that, by adjusting operating conditions, and using a wide range of fuels, doped with additives to achieve an even broader range of combustion characteristics, the impact of important variables would be made clearer, making it possible to reduce the problem to its lowest common denominators. In early experiments it was found that NOx emissions from biodiesel tended to be lower than those of petrodiesel under conditions where combustion was relatively highly premixed, but higher under more conventional diesel conditions where diffusion combustion constituted a larger proportion of heat release. The main experimental set revealed a definite increase in NOx emissions when fuelling on biodiesel, for a fixed start of combustion and equivalent degree of premixing. The addition of an oxygenate to petrodiesel elicited comparable NOx emissions to biodiesel, as a function of fuel-bound oxygen content; the data implies that the like-for-like biodiesel NOx increase may be a direct result of fuelbound oxygen. However, the like-for-like biodiesel NOx increase varies dependent upon operating conditions. In part, this may be related to higher apparent heat release rate (AHRR) through the diffusion burn phase when fuelling on biodiesel. This may result from the extended biodiesel injection duration. Across operating conditions, the extent to which smoke emissions when fuelling on petrodiesel exceeded those when fuelling on biodiesel was generally correlated with the magnitude of the biodiesel NOx increase; where the difference in smoke emissions was small, the biodiesel NOx increase was small, and where the difference in smoke emissions was more substantial, so was the difference in NOx emissions. This suggests a possible connection to changes in mixture stoichiometry. When differentiating between fuels, increased cetane number reduces NOx, and increased oxygen content increases NOx. Biodiesel does not necessarily have higher NOx emissions than petrodiesel: the biodiesel NOx increase exists where the difference in cetane number is insuffi cient to counteract the effects of fuel-bound oxygen content.

No description available.

This study was motivated by a need to better understand the sprays that can develop when oil leaks occur in gas turbine engines. Current gas turbine engines incorporate an extensive network of oil distribution pipes which deliver lubrication oil to bearings and seals at various locations across the engine. Parts of the oil pipe network are situated in hot, high pressure engine cavities where an oil leak, from a fractured pipe or leaking seal, could ignite and lead to an engine fire. Oil leaks in gas turbine engines create liquid injection in cross-airstream situations, a subject which has been widely studied for combustion systems. However, previous studies are almost exclusively based on circular nozzle geometries. For a fractured oil pipe, the geometry through which the oil leaks approximates to a slot shape rather than a circular nozzle. Sprays which develop in cross-airstreams are most sensitive to the parameters of Weber number (Weg eq) and momentum flux ratio (q). A wide range for these parameters are considered to be possible in engine oil leak scenarios because of the variety of crack dimensions possible and range of airflow conditions across the different sections of the engine; from zero to in excess of We g eq = 4000 and q = 300 could be possible in extreme cases. The aim of this study was to generate and then characterise sprays in representative conditions. The main focus was the characterisation of the droplets which formed in the sprays, with the key objective of providing validation data for CFD codes. Droplet characterisation was performed using a phase Doppler particle analysis system. High speed video as well as pulsed laser sheet digital imaging were also used in the study to provide insight into upstream features of the spray field. A 0.5 x 5.38 mm slot shaped nozzle geometry was used in two orientations; perpendicular alignment ↓↓⦶ and parallel alignment ↓↓⦶ . Water was injected into a cross-airstream over a twelve point test matrix with momentum flux ratios (q) values within the range of 4 ≳ q ≳ 32 and Weber number (We g eq) values within the range of 300 ≳ We g eq ≳ 1600. The position of the spray was highly dependent on slot nozzle orientation. The spray was considerably further offset from the nozzle injection wall in parallel alignment ↓↓⦶ , compared to the perpendicular alignment ↓↓⦶. However, the centre-line distribution of Arithmetic Mean Diameter (AMD) was similar for both orientations, albeit offset further from the injection wall for the parallel slot nozzle. The underlying structure of droplet size distribution was consistent with results for sprays from circular nozzles. At low liquid injection pressures the sprays produced by the perpendicular aligned slot ↓↓⦶ exhibited impingement, producing large droplets in the near wall region. Where impingement was not present, the data showed that AMD was not significantly influenced by the orientation of the slot nozzle; with all tests generating results in the range of 16 μm ≳ AMD ≳ 80 μm.

Current gas turbine technology for power generation is generally optimised for natural gas. On the basis of current instabilities in natural gas price and supply, the use of alternative fuels, such as syngas, has recently gained high interest. Due to the different thermodynamic properties of syngas compared to natural gas the behaviour of existing gas turbine components may significantly change. From practical and economic points of view, it is generally considered that in order to meet the new fuel properties, the main effort should be put on the adaptation of conventional gas turbines in integrated gasification combined cycle (IGCC) plants rather than producing a new generation of gas turbine designs from scratch. In addition to the requirement of new combustion technologies, main critical issues are represented by the reduction of compressor surge margin and turbine blade overheating. Solutions might include thermodynamic cycle as well as turbine geometry modifications. The latter would be preferred in terms of power plant performance. The main aim of this thesis is to explore suitable solutions to be applied to gas turbine compressors in order to accommodate syngas combustion. Among others, the use of variable stator vanes (VSVs) and blade radial stacking line modifications are considered. These are investigated on reference geometries available in the public domain. A baseline compressor geometry representative of a conventional heavy-duty gas turbine fueled with natural gas is generated and modified according to the understating gained during this study. The re-designed machine is a result of the application of stator vanes re-staggering in the front stages and blade sweep in the rear stages in order to cope with compressor air supply control and critical flow separation regions respectively. The obtained results show that efficient and stable operation during power modulation can be achieved, while reducing the need of other modifications to the combined cycle plant. It was therefore concluded that the proposed option can be considered a viable option to satisfy some important technical and economic constraints imposed by the integration of an existing gas turbine within an IGCC plant.