The demands on tomorrows diesel engines regarding fuel consumption and emission levels keep getting more difficult to fulfill. Due to this fact, the control demand is getting bigger and bigger. To be able to comply with the Euro 6 standards, it is believed that engine control need to be conducted individually from cylinder to cylinder if the need for after-treatment systems should be minimized. Scania’s approach to handle emission levels so far has been to use exhaust gas recirculation (EGR). To be able to optimize the use of EGR it is necessary to know how the inert gases, water and carbon dioxide, are distributed between the cylinders. The distribution variation become even more difficult to predict since the EGR is cooled, sometimes leading to condensation of some of the water content. The condensation of water and its behavior in the inlet manifold is studied in this thesis. Different ways of measuring non-uniformity in the gas composition between cylinders with respect to EGR in general and water content in particular are evaluated. Using these results, measurements have been conducted on an engine and conclusions are drawn from them. The conclusions are that uneven distribution of above all liquid water, due to puddle formation, have an impact on emission formation that should be accounted for in some of the examined operating conditions.

No description available.

No description available.

The work presented in this thesis is the result of the KTH CICERO project “Dynamic Engine Performance” in which the main objective was to develop simple models foremission formation. The demand for such models is increasing, mainly due to the tightening emission legislation for diesel engines which has lead to more complex engines and thereby more laborious development and calibration processes. Simple emission models can be a valuable tool during the development phase, e.g. when used with models for gas exchange - and after-treatment systems, and for precalibration of the engine control settings. Since engines in automotive application typically work under dynamic load, the main prerequisites were that the models should be comprehensive enough to handle the extreme conditions that can occur in engines during load transients but still simple enough to be used for calibration. Two main approaches have been used; one where the combustion and emission formation processes were modeled from the flame front and downstream using equilibrium chemistry. In the other approach, the entire mixing/entrainment process was modeled and emission formation was modeled with kinetic chemistry. Both approaches were found to meet the requirements but had different advantages; the first, simpler approach had shorter calculation time while the latter was more comprehensive and required less tuning. The latter also resulted in a model for heat release rate which can be useful as a stand-alone model and allows the emission models to be used for untested conditions. Another objective in this project was to identify techniques/instruments that can be used for emission measurements during transient operation since these are essential for understanding of emission formation in these conditions and as validation data for the emission models. / QC 20110502

This research work characterises diesel engine soot physiochemical properties and engine performance and emissions for the combustion of two common mineral diesel fuels (low and medium sulphur) and a RME B100 biodiesel fuel at two geometric compression ratios (19.5:1 and 16.5:1) and a broad range of EGR (10 to 55%) for an otherwise unmodified VW 1.9TDI 130PS engine. The principal focus of the research is the physiochemical characterisation of soot sampled from the engine exhaust manifold and also a DPF in the exhaust and exploring how the fuel type, compression ratio and EGR influence the soot properties and how these properties then influence the evolution of the soot in the exhaust.

O emprego de óleos vegetais como combustível em motores ciclo diesel tem se demonstrado viável após diversos estudos de desempenho já desenvolvidos em diversos motores e configurações, porém apresentando algumas restrições quanto ao seu uso contínuo, dentre as quais se destacam a ocorrência de quebras do motor devido ao excesso de carbonização no cabeçote. No Brasil, a abundância de óleos de origem vegetal constitui um incentivo para a realização de estudos visando ao aproveitamento desses combustíveis alternativos, neste contexto, este trabalho apresenta um estudo das características macroestruturais da formação de sprays de óleo vegetal de soja in natura em um atomizador utilizado em motores diesel em condições de pressão semelhantes às de um motor. Para isso foi montada uma bancada que é constituída de uma câmara pressurizada projetada e fabricada para simular as mesmas condições de massa específica do ar obtidas dentro da câmara de combustão do motor ciclo diesel no instante do início da injeção do combustível. Também é dotada de um sistema de injeção de combustível projetado para que as pressões de funcionamento do conjunto porta injetor mecânico utilizado fosse atingido. O registro da formação do spray é realizado por meio de uma câmara de alta velocidade e alta taxa de aquisição de imagens, como o qual é possível avaliar o comportamento dos jatos de óleo de soja e óleo diesel quanto a distância de quebra, penetração da ponta, velocidade e ângulo de abertura de spray. Das propriedades físico-químicas do óleo vegetal de soja, a que mais se destaca com relação às propriedades do óleo diesel é a viscosidade, que para os líquidos utilizados nesse trabalho foi verificado que é aproximadamente 15 vezes maior que a viscosidade do óleo diesel. Essa grande diferença nas mesmas condições de temperatura produziram resultados de atomização bem distinta entre os líquidos e verifica-se a necessidade de modificação de mais parâmetros do que somente a densidade do gás para que a atomização seja mais próxima do óleo diesel e o óleo vegetal in natura possa ser utilizado nos motores, pois os regimes de atomização observados condizem com o previsto considerando as propriedades dos dois óleos nas condições testadas. / The use of vegetable oils as fuel in diesel engines has proven to be viable after several performance studies already developed in several engines and settings, but presenting some restrictions on its continued use, among which stand out the occurrence of engine failures due to over-charred on the head. In Brazil, plenty of vegetable oils is an incentive to carry out studies for the use of these alternative fuels, in this context, this work presents a study of macro-structural characteristics of the formation of vegetable oil sprays soy in kind in an atomizer used in diesel engines into pressure conditions similar to those of an engine. To this it was mounted on a stand which consists of a pressure chamber designed and manufactured to simulate the same conditions of air density obtained within the combustion chamber of the diesel engine cycle at the time of start of fuel injection. It is also equipped with a fuel injection system designed for operating pressures of the whole mechanical door gun used was reached. The record of the formation of the spray is carried out by means of a camera high speed and high rate of image acquisition, as which it is possible to evaluate the behavior of soybean oil jets and diesel oil as the distance break, tip penetration , speed and spray opening angle. From the physico-chemical properties of vegetable soybean oil, which excels in respect of diesel fuel properties is viscosity, as for liquids used in this work was found that it is approximately 15 times greater than the viscosity of diesel oil. This great difference in the same conditions of temperature produced very different atomization results between the liquid and there is a need for more parameters change than just the density of the gas for atomization is closer to diesel oil and vegetable oil in nature can be used in engines, because atomization schemes observed consistent with the expected considering the properties of both oils under the conditions tested.

To control the combustion in an engine, an accurate estimation of the air mass flow is required. Due to strict emission legislation and high demands on fuel consumption from customers, a technology called variable valve timing is investigated. This technology controls the amount of air inducted to the engine cylinder and the amount of gases pushed out of the cylinder, via the inlet and exhaust valves. The air mass flow is usually estimated by large look-up tables but when introducing variable valve timing, the air mass flow also depends on the angles of the inlet and exhaust valves causing these look-up tables to grow with two dimensions. To avoid this, models to estimate the air mass flow have been derived. This has been done with grey-box models, using physical equations together with unknown parameters estimated by solving a linear least-squares optimization problem. To be able to implement the models in the electronic control unit in the future, only sensors implemented in a commercial vehicle are used as much as possible. The work has been done using an inline 6-cylinder diesel engine with measurements from steady-state conditions. All four models derived in this project are based on the estimation methods in use today with fix cam phasing, and are derived from the ideal gas law together with a volumetric efficiency factor. The first three models derived in this work only include sensors provided in commercial engines. The measurements needed as input signals are engine rotational speed, crank angle resolved pressure in the intake manifold, intake and exhaust valve angles and intake manifold temperature. The fourth and last model is divided into three sub-models to model different parts of the four-stroke engine cycle. This model also includes crank angle resolved exhaust manifold pressure and exhaust manifold temperature, where the temperature is the only sensor used in this project that is not provided in a commercial engine. It has been concluded how influential it is to use correctly measured values for the input signals. Since the manifold pressure and the cylinder volume vary during one four-stroke cycle, it is essential that these signal measurements are taken at the right crank angle degree. With wrong crank angle degree, the estimation is worse than if the cylinder volume is constant for all operating points and the pressure signals are taken as a mean value over the whole four-stroke cycle. Further development to reach better estimation results with lower relative error is needed. However, for the work in this thesis, the model with best model fit is estimating the air mass flow well enough to use it as a basis for further control.

Com os grandes avanços ocorridos na disponibilização de computadores, existe uma tendência contínua para a utilização de técnicas computacionais auxiliando no projeto de equipamentos de engenharia. Cada vez mais estão se obtendo resultados bastante próximos às condições reais, incluindo a simulação de motores de combustão interna. Neste sentido o presente trabalho tem o objetivo de analisar o escoamento turbulento no processo de admissão de ar em um motor operando em ciclo Diesel. A investigação é focada na determinação da influência do passo de tempo no cálculo do coeficiente de descarga e razão de swirl. Adicionalmente, o campo de velocidades, pressão, energia cinética turbulenta e outros parâmetros são apresentados e analisados, com o objetivo de auxiliar no entendimento da dinâmica envolvida. Essencialmente, dois modelos de turbulência são empregados, juntamente com dois tratamentos de parede. Seus resultados também são confrontados e discutidos. A geometria considerada é de um motor Fiat 1.9 L quatro tempos com duas válvulas. A análise é concentrada em um único cilindro. O pacote computacional utilizado é o Star-cd, e seu aplicativo es-ice. A independência de malha foi obtida, chegando a 1.672.056 volumes. Os resultados são apresentados de duas formas. A primeira delas refere-se a resultados de simulações em regime permanente, realizadas em boa parte por outros autores, com ênfase na determinação do coeficiente de descarga e razão de swirl, estes confrontados com valores experimentais, visando à validação da metodologia. Fica evidente a importância da escolha do modelo de turbulência na simulação de motores de combustão interna, assim como das funções de interpolação utilizadas. Na segunda parte os resultados referem-se a uma análise transiente, considerando o movimento do pistão e válvulas, a 1500 RPM. Observa-se a grande exigência quanto ao passo de tempo requerido no transiente real, ficando demonstrado que para esta velocidade o menor passo de tempo utilizado, 0,05° (5.5555E-6 s), ainda é insuficiente para alguns momentos do ciclo. É possível notar maior influência no coeficiente de descarga do que na razão de swirl, em relação aos passos de tempo utilizados. A forte dependência do modelo de turbulência nos resultados obtidos é mais uma vez confirmada, conforme o esperado, já que as hipóteses sobre a física do fenômeno são diferentes em cada modelo. Os resultados quanto ao tratamento na parede não apresentaram significantes diferenças, quando aplicados junto ao modelo de turbulência k-ω SST. / Considering the increase in the availability of computers, there is a continuing trend toward the use of computational simulation aiding in the design of engineering equipments. Reasonable results, close to the real conditions, are obtained, including the simulation of internal combustion engines. In this way, the present work has the objective of analyzing the turbulent flow in the air intake process of an engine operating in Diesel cycle. The investigation focuses on the determination of the time step in the calculation of the air discharge coefficient and swirl ratio. Additionally, the turbulent kinetic energy, pressure and velocity fields, besides other parameters, are presented and analyzed, with the objective of aiding in the understanding of the involved dynamics. Essentially, two turbulence models are employed, together with two wall treatments. Their results are also confronted and discussed. The considered geometry is a four-stroke, 1.9-L FIAT engine, with two valves. The analysis is concentrated on a single cylinder. The software package used is the Star-cd, and its application es-ice. The mesh independence is carried out, arriving in 1.672.056 volumes. The results are presented in two ways. The first one refers to simulation results of the steady state, also accomplished by other authors, with emphasis in the determination of the discharge coefficient and swirl ratio. These data are confronted with experimental values, aiming to validate the applied methodology. The importance of the choice of the turbulent model becomes evident in the simulation of internal combustion engines, as well as the interpolation functions used. In the second part the results refer to a transient analysis, considering the valves and piston movement, at 1500 rpm. It is observed the great demand on time step required is observed for the real transient, demonstrating that, for this speed, the smallest time step used, 0.05º (5.5555E-6 s), is still insufficient for some moments of the cycle. Also regarding the time step, it is possible to notice a greater influence in the discharge coefficient than in the swirl ratio. The strong dependence of the turbulence model on the results is once again confirmed, as expected, since the hypotheses about the physics of the phenomenon are different in each model. The results, regarding the wall treatment, presented no significant differences, when applied together with the SST k-ω turbulence model.

Com os grandes avanços ocorridos na disponibilização de computadores, existe uma tendência contínua para a utilização de técnicas computacionais auxiliando no projeto de equipamentos de engenharia. Cada vez mais estão se obtendo resultados bastante próximos às condições reais, incluindo a simulação de motores de combustão interna. Neste sentido o presente trabalho tem o objetivo de analisar o escoamento turbulento no processo de admissão de ar em um motor operando em ciclo Diesel. A investigação é focada na determinação da influência do passo de tempo no cálculo do coeficiente de descarga e razão de swirl. Adicionalmente, o campo de velocidades, pressão, energia cinética turbulenta e outros parâmetros são apresentados e analisados, com o objetivo de auxiliar no entendimento da dinâmica envolvida. Essencialmente, dois modelos de turbulência são empregados, juntamente com dois tratamentos de parede. Seus resultados também são confrontados e discutidos. A geometria considerada é de um motor Fiat 1.9 L quatro tempos com duas válvulas. A análise é concentrada em um único cilindro. O pacote computacional utilizado é o Star-cd, e seu aplicativo es-ice. A independência de malha foi obtida, chegando a 1.672.056 volumes. Os resultados são apresentados de duas formas. A primeira delas refere-se a resultados de simulações em regime permanente, realizadas em boa parte por outros autores, com ênfase na determinação do coeficiente de descarga e razão de swirl, estes confrontados com valores experimentais, visando à validação da metodologia. Fica evidente a importância da escolha do modelo de turbulência na simulação de motores de combustão interna, assim como das funções de interpolação utilizadas. Na segunda parte os resultados referem-se a uma análise transiente, considerando o movimento do pistão e válvulas, a 1500 RPM. Observa-se a grande exigência quanto ao passo de tempo requerido no transiente real, ficando demonstrado que para esta velocidade o menor passo de tempo utilizado, 0,05° (5.5555E-6 s), ainda é insuficiente para alguns momentos do ciclo. É possível notar maior influência no coeficiente de descarga do que na razão de swirl, em relação aos passos de tempo utilizados. A forte dependência do modelo de turbulência nos resultados obtidos é mais uma vez confirmada, conforme o esperado, já que as hipóteses sobre a física do fenômeno são diferentes em cada modelo. Os resultados quanto ao tratamento na parede não apresentaram significantes diferenças, quando aplicados junto ao modelo de turbulência k-ω SST. / Considering the increase in the availability of computers, there is a continuing trend toward the use of computational simulation aiding in the design of engineering equipments. Reasonable results, close to the real conditions, are obtained, including the simulation of internal combustion engines. In this way, the present work has the objective of analyzing the turbulent flow in the air intake process of an engine operating in Diesel cycle. The investigation focuses on the determination of the time step in the calculation of the air discharge coefficient and swirl ratio. Additionally, the turbulent kinetic energy, pressure and velocity fields, besides other parameters, are presented and analyzed, with the objective of aiding in the understanding of the involved dynamics. Essentially, two turbulence models are employed, together with two wall treatments. Their results are also confronted and discussed. The considered geometry is a four-stroke, 1.9-L FIAT engine, with two valves. The analysis is concentrated on a single cylinder. The software package used is the Star-cd, and its application es-ice. The mesh independence is carried out, arriving in 1.672.056 volumes. The results are presented in two ways. The first one refers to simulation results of the steady state, also accomplished by other authors, with emphasis in the determination of the discharge coefficient and swirl ratio. These data are confronted with experimental values, aiming to validate the applied methodology. The importance of the choice of the turbulent model becomes evident in the simulation of internal combustion engines, as well as the interpolation functions used. In the second part the results refer to a transient analysis, considering the valves and piston movement, at 1500 rpm. It is observed the great demand on time step required is observed for the real transient, demonstrating that, for this speed, the smallest time step used, 0.05º (5.5555E-6 s), is still insufficient for some moments of the cycle. Also regarding the time step, it is possible to notice a greater influence in the discharge coefficient than in the swirl ratio. The strong dependence of the turbulence model on the results is once again confirmed, as expected, since the hypotheses about the physics of the phenomenon are different in each model. The results, regarding the wall treatment, presented no significant differences, when applied together with the SST k-ω turbulence model.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-22Bitstream added on 2014-06-13T20:27:40Z : No. of bitstreams: 1 kimura_rk_me_ilha.pdf: 3286814 bytes, checksum: 4a971a0f369c4d68e65570bcb2276b61 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A manutenção atualmente é observada como um fator importante para uma empresa que busca destacar-se no mercado cada vez mais competitivo. Para que isso aconteça o uso de ferramentas estratégicas que proporcionam uma melhoria do parque industrial são fundamentais. A análise do óleo lubrificante é uma dessas ferramentas capazes de indicar a vida útil das partes internas de um equipamento. Acompanhando essa evolução, o uso de novas fontes de energia também ganha espaço, destacando-se as fontes de energia ecologicamente corretas, chamadas de fontes de energia “limpa” como é o caso do Biodiesel, combustível substituto do Diesel mineral, que pode ser produzido a partir de plantas oleaginosas ou gorduras animais. Em motores de combustão interna que trabalham com o ciclo Diesel (ignição por compressão) os resultados de testes com o uso do Biodiesel ainda estão sendo realizados, pois a regulamentação do uso obrigatório ainda é recente no país. Atualmente está regulamentada a mistura 4% de Biodiesel em volume misturado no Diesel derivado de petróleo. Para um bom funcionamento de um motor de ignição por compressão o uso de um lubrificante que segue as especificações do fabricante é essencial, pois o lubrificante possui muitas funções, sendo a principal delas manter as partes móveis do motor com o mínimo de atrito entre si. O uso de um lubrificante fora das especificações ou com contaminantes (água, combustível, etc) acarreta uma série de danos ao motor como desgaste, superaquecimento e baixo rendimento. Neste trabalho é utilizada a técnica de análise de óleo, onde se busca averiguar as possíveis influências que o uso do Biodiesel pode ter sobre as propriedades físico-químicas do lubrificante. Para tanto, a ferrografia analítica, a espectrografia por absorção atômica, ponto de fulgor, filtragem por membrana de celulose e análise... / Maintenance is now seen as an important factor for a company that seeks to stand out in the market increasingly competitive. For that purpose the use of strategic tools that provides an improvement in the industrial park are key. The lubricant analysis is one of those tools that indicate the life of internal parts of equipment. Following those developments, the use of new sources of energy is also increasing; especially energy sources environmentally friendly, called sources of clean energy such as biodiesel-fuel substitute for mineral diesel, which can be produced from plant oil or animal fats. In internal combustion engines that work with the Diesel cycle (compression ignition) tests with the use of biodiesel is still being performed, since the regulation on the mandatory use is still young in the country. Nowadays it is currently regulated mixture of 4% biodiesel by volume mixed in diesel derived from petroleum. For good function of an ignition engine the use of a lubricant following the manufacturer's specifications is essential, since the lubricant has many functions, the main one being to keep the moving parts of the engine with minimal friction between it others. The use of a lubricant out of specification or with contaminants (water, fuel, etc.) has some kind of engine damage and wear, overheating and low income. This work uses the oil analysis technique, where it is tried the possible influence that the use of Biodiesel might have on the physical and chemical properties of the lubricant. Therefore, the analytical ferrography, the atomic absorption spectrometry, flash point, membrane filtration and viscosity analysis are examples of tests carried out at work. The results show that morphology and the concentration of particles found by atomic absorption espectrography in lubricant are considered normal and that a technique alone does not translate a real situation inside a mechanical system