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In this thesis various aspects of the diesel engine fuel injection, combustion and emission formation processes have been evaluated. Several types of evaluation tools and methods have been applied. Fuel spray momentum was used to characterize injection rate and hole-to-hole variations in fuel injectors. Using both instantaneous fuel impulse rates and instantaneous mass flow measurements, spray velocity and nozzle flow parameters were evaluated. Several other hole-to-hole resolved injector characterization methods were used to characterize a set of fuel injectors subjected to long term testing. Fuel injector nozzle hole-to-hole variations were found to have a large influence on engine efficiency and emissions. The degree of hole-to-hole variations for an injector has been shown to correlate well with the performance deterioration of that injector. The formation and atomization of fuel sprays, ignition onset and the development of diffusion flames were studied using an optical engine. Flame temperature evaluations have been made using two different methods. NO-formation depends strongly on flame temperature. By applying a NO-formation evaluation method based on both heat release rate and flame and gas temperature it was possible to achieve a reasonable degree of correlation with measured exhaust emissions for very varying operating conditions. The prediction capability of the NO-formation evaluation method was utilized to evaluate spatially and temporally resolved NO-formation from flame temperature distributions. This made it possible to pinpoint areas with a high degree of NO-formation. It was found that small hot zones in the flames can be responsible for a large part of the total amount of NO that is produced, especially in combustion cases where no EGR is used to lower the flame temperature. By applying optical diagnostics methods the combustion and emission formation phenomena encountered during production engine transients were evaluated. The transient strategy of the engine involved reducing the EGR-rate to zero during the initial parts of the transient. Increased general flame temperature and the occurrence of small hot zones were found to explain the increase in NO-emissions during these transients. / QC 20110530

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No description available.

No description available.

Ever growing population and increased energy consumption across all industries has resulted in higher atmospheric concentration of the greenhouse gases (GHG) and therefore an increase in the planet's average temperature, which has led to increasingly demanding and more strict legislations on pollutant sources, and more specifically, the automotive industry. As a consequence of all this, the demand for research into alternative energy sources has greatly increased. In this study combustion characteristics, engine performance, and exhaust emission of diesel-ethanol and diesel-gasoline are investigated in an optical direct injection diesel engine. In particular, effects of different substitution ratios and diesel injection strategies are studied when the total fuel energy is kept constant. The three main substitution ratios used in this study include 45% (45% of fuel energy from port-injected ethanol/gasoline and 55% from direct injection diesel), 60%, and 75%. The engine used for this investigation is a Ricardo Hydra single cylinder optical engine running at 1200 rpm. In-cylinder pressure measurement is used for calculating all engine parameters, heat release rate, and efficiency. In addition to the thermodynamic analysis of the combustion parameters, high speed camera was used alongside with a copper vapor laser or the high speed image intensifier in the high speed video imaging for the optical analysis of the effect of the above-mentioned parameters on autoignition and combustion processes, while Horiba particulate analyser and AVL smoke meter were utilized in monitoring and recording emissions for every tested condition. Depending on the testing conditions, such as injection strategy and intake conditions, both dual-fuel operations were able to deliver high efficiency and improved emissions compared to that of a pure diesel engine operation, with the diesel-gasoline operation offering more consistency in improved thermal efficiency, and the diesel-ethanol operation delivering lower emission output. The optical analysis of the combustion represents the main difference in the flame propagation, distribution and quality for each substitute fuel and its substitution percentage, as well as the condition under examination.

The development of Environmentally Adapted Lubricants (EALs) and their use has been gaining momentum over the last decade. It has been shown that raw EALs degrade in the environment in about one tenth the time of an equivalent mineral based lubricant. Estimates and findings such as these serve to highlight the potential benefits of the EAL products, it is also important however to investigate the by-products of their use to ensure that the benefits are not cancelled by an increase of, for instance, combustion by-products. This thesis compares the emissions from a two-stroke outboard engine when using an EAL and an equivalent mineral lubricant, where the primary objective of the study is to characterise and quantify the pollutants that remain within the water column after combustion. To accomplish this, tests were conducted both in the laboratory (freshwater) and in the field (seawater) for a range of throttle settings. A 1.9kW two-stroke outboard engine was set-up in a test tank and water samples were taken from the tank after the engine had been run for a period at each of the throttle settings. The tests were repeated for a 5.9kW four-stroke engine, however, the experiments were only conducted in the laboratory (freshwater) and using only a standard mineral lubricant. Statistical analyses of the results were conducted using a Principal Components Analysis (PCA). A simple dilution model was used to estimate the initial outboard engine emission concentrations, which was extended to determine the concentrations at distances of 1, 10 and 100 metres from the source. An investigation of the Total Toxicity Equivalence of the PAH pollutant concentrations (TEQPAH) was conducted using Toxicity Equivalent Factors (TEFs). Results for both types of engine and in both fresh and seawater showed that even the initial concentrations at the source, in almost all instances, were well below the ANZECC water quality guidelines trigger levels. At a distance of 1 metre from the source all concentrations were well below, and therefore, the Total Toxicity Equivalents of the PAHs were found to be even lower. It is concluded that the emissions from a single outboard engine when using either an EAL or a mineral based lubricant are similar. However, the use of EALs has further reaching advantages in that spilt raw lubricants will degrade in the environment up to 10 times faster than a mineral lubricant. Also EALs are less toxic to aquatic and marine organisms and therefore the benefits of using them has to be viewed from a wider perspective. The results in this thesis for a single outboard engine now form the basis for a more detailed environmental assessment of their impacts.

Internal combustion engine emissions are currently a major source of air pollution. The harmful impact of engine emissions can be reduced when engines are fuelled by alternatives to petrol and diesel such as natural gas. The use of lean burn technology in spark-ignition engines has been dominant; however, the lean burn technique can not economically satisfy the increasingly restricted future emission standards particularly for NOx emissions. In this thesis, the use of the stoichiometric air-fuel mixture with exhaust gas recirculation (EGR) technique in a spark ignition natural gas engine is investigated. The aim of the research is to optimize the key engine operating conditions in order to obtain the lowest NO emissions accompanied with low fuel consumption and high power. This is achieved via both experimental and computer simulation research. / PhD Doctorate

Um die beiden Hypothesen, dass (1) die Anzahl der Doppelbindungen der veresterten Fettsäuren einen Einfluss auf die Mutagenität der DME hat, und (2) dass die Oxidation (künstliche Alterung) verschiedener FAME und Blends höhere Mutagenität der DME bewirkt, zu untersuchen, wurden Abgasproben der folgenden Kraftstoffe verwendet: DK, PME, RME, LME, B20, B20alt, B20E2, B20altE2, RMEalt. Die Abgasproben wurden über Testläufe mit einem Mercedes-Benz OM 906 Euro-IIIMotor, der im ESC Testzyklus betrieben wurde, gewonnen. Die Mutagenität der Abgasproben wurde mittels des Ames-Tests untersucht. Sowohl die Positiv- als auch die Negativkontrollen bestätigten, dass die Reagenzien und Teststämme für die Versuche geeignet waren. Die Ergebnisse zeigten, dass sich die unter Punkt 1.5.1 (S. 17) beschriebene Hypothese, dass die Anzahl der Doppelbindungen der veresterten Fettsäuren einen Einfluss auf die Mutagenität der DME hat, bestätigte. Sowohl bei den Kondensaten, als auch den Partikulaten konnte gezeigt werden, dass die DME der FAME mit der geringeren Anzahl an mehrfach ungesättigten Fettsäuren signifikant geringer mutagen waren, als die DME der FAME mit der höheren Anzahl an mehrfach ungesättigten Fettsäuren. So ergab sich eine Reihenfolge der FAME mit aufsteigender Mutagenität ihrer DME: PME < RME < LME. Dieses Ergebnis war vor allem bei den Kondensaten in beiden Teststämmen (TA98, TA100) mit als auch ohne metabolische Aktivierung und bei den Partikulaten im Stamm TA98 ohne metabolische Aktivierung zu sehen. Die zweite Hypothese, dass die Oxidation (künstliche Alterung) verschiedener FAME und Blends höhere Mutagenität der DME bewirkt, wurde widerlegt. Zur Untersuchung dieser Hypothese wurden neben FAME (RME, RMEalt) folgende Blends verwendet: B20, B20alt, B20E2, B20altE2. Es konnten zwei signifikante Unterschiede erzielt werden, die jedoch für einen Beweis nicht ausreichten. Zusätzlich traten die signifikanten Unterschiede nicht im selben Teststamm auf und die Abgase der gealterten Form waren nicht durchgängig mutagener als die Abgase der nicht gealterten Form. Der Beweis eines signifikanten Unterschiedes, dass die Oxidation von FAME höhere Mutagenität der DME der dadurch gealterten FAME hervorruft, war daher nicht möglich. Weiterhin wurde ein Blend mit 2% Ethanol und 2% Butanol verschnitten. Der erhoffte Effekt der Alkoholadditivierung, eine Homogenisierung des FAME-Anteils durch Sedimentauflösung von oxidativen Abbauprodukten von FAME-Blends zu bewirken, blieb ebenso aus. Bei der Betrachtung der GPM zeigte sich, dass die FAME nicht die höchste GPM, aber die größte LOF besitzen. Dies spiegelte sich in der Mutagenität der DME der FAME verglichen mit denen des DK wieder. DK hatte zwar einen höheren Wert der GPM, aber einen kleineren Anteil der LOF. Die Abgase der FAME zeigten sich tendenziell mutagener als die des DK, jedoch ohne signifikante Ergebnisse. Dieser Effekt war v.a. bei den Kondensaten zu sehen. Die erhöhte Mutagenität der FAME-Abgase gegenüber den DK-Abgasen lässt sich anhand verschiedener Hypothesen erklären, die aber noch nicht ausreichend untersucht oder bewiesen sind.

The complexity of engineered systems has increased remarkably to meet customer needs. In the continuously growing global market, it is essential for engineered systems to keep their productivities which can be achieved by higher reliability and availability. Integrated health management based on diagnostics and prognostics provides significant benefits, which includes increasing system safety and operational reliability, with a significant impact on the life-cycle costs, reducing operating costs and increasing revenues. Characteristics of complex systems such as nonlinearity, dynamicity, non-stationarity, and non-Gaussianity make diagnostics and prognostics more challenging tasks and decrease the application of classic reliability methods remarkably – as they cannot address the dynamic behaviour of these systems. This research has focused on detecting, predicting and isolating faults in engineered systems, using operational data with multifarious data characteristics. Complexities in the data, including non-Gaussianity and high nonlinearity, impose stringent challenges on fault analysis. To deal with these challenges, this research proposed an integrated data-driven methodology in which hidden Markov modelling (HMM) and Bayesian network (BN) were employed to detect, predict and isolate faults in a system. The fault detection and prediction were based on comparing and exploiting pattern similarity in the data via the loglikelihood values generated through HMM training. To identify the root cause of the faults, the probability values obtained from updating the BN were used which were based on the virtual evidence provided by HMM training and log-likelihood values. To set up a more accurate data-driven model – particularly BN structure – engineering analyses were employed in a structured way to explore the causal relationships in the system which is essential for reliability analysis of complex engineered systems. The automotive exhaust gas Aftertreatment system is a complex engineered system consisting of several subsystems working interdependently to meet emission legislations. The Aftertreatment system is a highly nonlinear, dynamic and non-stationary system. Consequently, it has multifarious data characteristics, where these characteristics raise the challenges of diagnostics and prognostics for this system, compared to some of the references systems, such as the Tennessee Eastman process or rolling bearings. The feasibility and effectiveness of the presented framework were discussed in conjunction with the application to a real-world case study of an exhaust gas Aftertreatment system which provided good validation of the methodology, proving feasibility to detect, predict, and isolate unidentified faults in dynamic processes.