Dissertations / Theses on the topic 'Motor vehicles Pollution control devices'

Climate change has become a discussion topic of exponentially increasing urgency and importance amoung world leaders of all disciplines. These changes are brought about by the emission of so-called Greenhouse gases from various human activities. The primary cause of CO2 emissions is the burning of the Earth’s supply of nonrenewable natural fossil fuels like coal, oil and natural gas. The world first agreed on the prevention of “dangerous” climatic changes at the Earth Summit in 1992. The Kyoto Protocol of 1997 was the first step toward protection of the atmosphere and prescribes restrictions on emission pollutants. Since then the vehicle gas emissions are being controlled by means of different gas emissions norms, like the European Union Norm in Europe. The automotive manufacturers and suppliers are collectively working on reducing overall vehicle emissions. They are focusing on several different emission limiting possibilities, for example improved engine design, special fuel development and exhaust gas treatment systems. The exhaust gas treatment process requires continuous controlling and management of the exhaust gas emissions while driving a vehicle. Certain factors such as high emission temperatures have a negative influence on the life span of these systems. Their functionality and durability is also known to be reduced by the presence of chemical poisoning species like sulphur, phosphorus, zinc and calcium. The chemical poisoning species are produced during combustion of fuel and engine oil. They are therefore contained in the exhaust emissions and can poison the catalyst when passing over it. Phosphorous poisoning is particularly problematic and should be reduced considerably. This study involves the investigation of the phosphorous poisoning process and aims to provide clarity regarding the influences of different fuel and oil compositions on the severity of the process. Engine oil and biodiesel are two major sources of phosphorous poisoning. The phosphorus contained in biodiesel fuel is a natural component and can be minimized during the refining procedure. In contrast to others studies, the biodiesel fuel used during this project was SME (Soya Methyl Ester) with a 20% biodiesel content. This choice of fuel was made because of the increasingly important role that this type of biodiesel is playing in the European market and the future tendency to increase the percentage of biodiesel in the mixture with standard diesel fuel. The phosphorus contained in engine oil is a necessary additive to retain the antioxidant and anti-wear properties of the oil. This study examined the poisoning influences from the most commonly used phosphorus containing oil additive, Zinc Dithiophosphates (ZDDP), as well as a Zn-free, phosphorus containing anti-wear oil additive. This formulation provides information about the phosphorus poisoning process as caused by the engine oil in the absence of Zn in the oil additives. The results show how the phosphorus content in biodiesel fuel affects the functionality of the exhaust gas treatment systems and the importance of reducing the permitted content of phosphorus contained in the fuel. Reducing the phosphorus content in the fuel will conserve the functionality of the exhaust gas treatment systems during their operational life and thereby protect the environmental from emission pollutants. It also provides insight into the differences in the poisoning processes when the phosphorus deposited on the catalyst comes from biodiesel fuel and when it comes from the engine oil. Finally the results also illustrate the influence of different phosphorous forms contained in engine oil additives on the catalyst poisoning process. This information could be used for the development of new oil additive formulations.

Thesis (Ph.D)--Public Policy, Georgia Institute of Technology, 2009.
Committee Chair: Noonan, Douglas; Committee Member: Castillo, Marco; Committee Member: Chang, Michael; Committee Member: Cozzens, Susan; Committee Member: Rodgers, Michael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

An experimental investigation examined the capability of dielectric barrier discharge (DBD) actuators to control a high-lift device system. Aerodynamic tests investigated the potential of utilising the actuator to control the flap side-edge vortex flow field. Acoustic tests examined the attenuation of slat noise with a DBD actuator. The sparse knowledge related to the control of a vortex flow field with a DBD actuator necessitated a more fundamental study that used a NACA 0015 wing. From this study, it was shown that the application of control resulted in a more diffused tip vortex. The actuator's ability to control the evolving vortex flow field was weakly dependent on the Reynolds number but strongly dependent on the angle of attack. Consequently, a DBD actuator was applied to a flap side edge. However, it was concluded that the actuator had no discernible effect on the flow field due to its addition of momentum being too low to destabilise the formation of the flap side-edge vortex. The slat research concerned the attenuation of the leading-edge component of high-lift device noise. At an angle of attack of two degrees, several tonal noise components with broadband content appeared in the slat noise spectrum. These noise features were successfully suppressed with a DBD actuator operating in open-loop control. For closedloop control, a quasi-static feedback controller was implemented. Comparable levels of performance were obtained for both control methods with more than a 20 dB reduction achieved in the dominant tonal noise feature. The research conducted shed new light on the application of DBD actuators to control the high-lift device system. However, further research is needed if the device is to be utilised to control flap side-edge flow field. The attenuation of slat tonal noise with broadband content was achieved with the actuator.

The tractive force has to be interrupted during a gear-shifting operation in a manual vehicle transmission, leading into a decrease of speed while changing gears during the acceleration process. Therefore in a racing application, the shifting time has to be as short as possible so that the required performance of a racing car can be achieved. The following dissertation describes the development of a transmission control system to enable gear changes within a manual gearbox, which was designed for the Formula Student racing series. Various solutions were developed on the basis of reviewed literature, technical data of components and experiences of Formula Student teams. Following this, a comparison of the concepts by means of a utility analysis identified the pneumatic actuation of selector forks to be the most suitable concept. This was mainly due to the expected shifting time, the weight, and its advantageous energy supply requirement. After the selection of the actuators and the position sensors, the system was implemented into the drivetrain to check the tment and the technical feasibility. To draw conclusions regarding the shifting time and to prove the functionality of the system, an open test bench was constructed. Additionally, the hardware and software had to be developed to enable the test run. After the manufacturing and assembling of the test bench, the optimal settings for the test run were determined. By comparing the achieved shifting time of alternative solutions, an improvement in the driving performance of a Formula Student race car is probable.

This report describes a feasibility study investigating dynamic denting of members using pyrotechnic devices to engineer favourable energy absorption characteristics into thin walled tubes. A tube of sufficiently low slenderness ratio and wall thickness, when loaded axially to failure, will collapse in the progressive buckling mode. After the ultimate buckling load has been exceeded, and as the tube continues to compress, the load oscillates between loads considerably lower than the ultimate buckling load. The object of introducing an advantageous deformation is to decrease the ultimate buckling load to a magnitude comparable with the subsequent peak loads, but at the same time avoiding a change in the buckling mode which is not advantageous. Testing was limited to thin walled square mild steel tubes. The test procedure began with a process to determine the limitations imposed on the geometric imperfections that could be achieved by the use of explosive. It was found that all the explosively induced deformations were rounded, i.e. the dents were hemi-spherical in shape. It was also found that a smooth edged round hole could be created in the centre of the dent with the use of a round, flat explosive charge. Geometric imperfections that could be induced explosively in the specimens (as well as other deformation shapes, tested for comparative purposes) were mechanically formed in the specimens. The tubes were then quasi - statically crushed to determine the energy absorption characteristics induced by the deformations. When spherical dents were induced, the deformation affected the tube beyond the immediate spherical dent and hence the distance between the plastic hinges was increased and instabilities in the crushing process were introduced. Holes (without any visible denting) decreased the distance between the plastic hinges and thus also induced instabilities. In both cases the tubes tended to skew over to one side and in extreme cases Euler buckling ensued.

This thesis describes an investigation into the spatial species conversion profiles of a Cu-zeolite SCR under engine conditions at low exhaust gas temperatures; this was then compared with a CFD model that models the catalyst via a porous medium measuring 5 x 5 x 91 cells assuming a uniform cross-sectional flow distribution. Species conversion rates were sampled at fixed points in the axial direction. The analysis of the spatial conversion profiles is a more rigorous method in assessing the ability of a mathematical model to predict the experimental data. It can also assist in the optimisation of the catalyst size, minimising packaging requirements and manufacturing costs. The experiments were undertaken on a light-duty diesel engine at a speed of 1500rpm, and at a load of 6bar BMEP; this provided exhaust gas temeraqtures between 200 and 220°C. NO2:NOx ratios were controlled by changing the size and position of the diesel oxidation catalyst, the inlet NH3: NOx ratio was also also varied, ammonia gas was used instead of urea for the purposes of simlicity. The advantage of testing on an actual engine over lab-babed studies is that the conditions such as exhaust gas composition are more realistic. A 1D CFD model was constructed using the ‘porous medium approach’ with kinetics obtained from open literature. Results from the simulations were then compared with the experimental data for the same engine conditions. It was observed that the majority of the NOx conversion took place in the first half of the brick for all NH3: NOx ratios investigated, and that the formation of N2O via NO2 and ammonia had the same influence as the ‘fast’ SCR reaction just after the inlet, which the CFD model failed to predict for the base case analyses. The influence of the inlet ammonia on the model was also noticed to be greater than in the experiments. Simple transient analyses were also undertaken on the short SCR bricks for NO2: NOx ratios of 0.6 and 0.07, and it was observed that the response time to steady-state was noticeably higher in the experiments than in the model. Modifications made to the model, including decreasing the influence of the ‘fast’ SCR reaction, and the addition of an empirical term onto the ammonia adsorption provided a noticeably better agreement for different NH3: NOx injection ratios. The desorption kinetics in the model were also altered by increasing the strength of the bonding of the ammonia onto the adsorption sites. This improved the transient agreement between the model and the experiments, but reduced the steady-state concentrations at the exit of the brick for all NH3:NOx ratios investigated.

According to the current governmental regulations, all diesel buses will be replaced in the United States and the European market within the next ten years. There are over 60,000 buses in the United States and each year over 3,000 new buses of approximately 40 feet in length are purchased. The bus market has a growth rate of four to five percent per year over the last two years. The improvements in technology offered by United States companies prove unsatisfactory in terms of bus performance and the emissions of new buses. The energy crisis in the United States and concern over the health hazards of the diesel fuel exhaust gases and particulates, alternative fuel vehicles are in great demand in the transit market world wide.

South Africa is coming under increasing pressure to conform to the rest of the world in terms of emissions regulations. The pressure is caused by a number of factors: international organisations requiring local companies to adhere to environmental conservation policies, evidence from within South Africa that efforts are being made to reduce environmental pollution in line with other countries and keeping abreast of the latest technologies that have been incorporated into vehicles to reduce emissions. In light of these problems associated with emiSSions, a study was initiated by the Department of Transport and the School of Bioresources Engineering and Environmental Hydrology at the University of Natal to investigate and develop a method of predicting emissions from a diesel engine. The main objective of this research was to incorporate this model into SimTrans in order to estimate emissions generated from a vehicle while it is travelling along specific routes in South Africa. SimTrans is a mechanistically based model, developed at the School, that simulates a vehicle travelling along a route, requiring input for the road profile and vehicle and engine specifications. After a preliminary investigation it was decided to use a neural network to predict emissions, as it provides accurate results and is more suitable for a quantitative analysis which is what was required for this study. The emissions that were predicted were NOx (Nitric oxide-NO and Nitric dioxide-N02), CO (carbon monoxide), HC (unbumt hydrocarbons) and particulates. The neural netWork was trained on emissions data obtained from an ADE 447Ti engine. These neural networks were then integrated into the existing SimTrans. Apart from the neural network, an algorithm to consider the effect of ambient conditions on the output of the engine was also included in the model. A sensitivity analysis was carried out using the model to prioritise the factors affecting emissions. Finally using the data for the ADE 447Ti engine, a trip with a Mercedes Benz 2644S-24 was simulated using different scenarios over the routes from Durban to Johannesburg and Cape Town to Johannesburg in South Africa to quantify the emissions that were generated.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

This thesis presents an analysis of air quality control initiatives in the GVRD. Starting with an examination of deteriorating regional air quality, oxides of nitrogen emissions (NOx), are the focus (as a precursor to ground level ozone.) The research demonstrates that if the status quo is maintained, episodes of ground level ozone will get worse and the effects will be far reaching and expensive. The Greater Vancouver Regional District's Air Quality Management Plan is reviewed, with emphasis on analysis and evaluation of emission reduction strategies. Emission Reduction Measures (ERMs) are various methods of reducing air pollution (including scrubbers on smoke stacks, transportation demand management, alternative fuels and motor vehicle inspection/maintenance programs.) Emission Reduction Measures are viewed as the tools that must be implemented to solve air quality problems. Environmentally, the most desirable solution would be to implement all ERMs. However, factors such as cost effectiveness and social, financial, political and customer service impacts must be considered and the best measures should be implemented first. The best solutions are those that meet as many objectives as possible while causing the least amount of negative impacts on the economy, society, government and the environment. Finding optimal solutions is a task that requires formalization of common sense. Analytical frameworks such as the cost/benefit analysis, decision analysis and the multiple account/objective analysis are considered as potential tools to help "make sense" of the complexity of air quality policy decisions. The intent is to provide useful and readily understandable information to decision makers. The Multiple Account Analysis (as used by The Crown Corporations Secretariat) is applied to an assortment of Emission Reduction Measures to help identify the "best" order for implementation. This method provides results that compare accounts of importance (such as cost effectiveness and emission reduction potential) and presents decision makers with quality information highlighting tradeoffs and preferences. In the scope of this paper, four ERMs are analyzed across accounts and the results presented in a matrix. The AirCare Program appears as the best choice for effective reduction of oxides of nitrogen when compared to alternative fuels, vanpooling and the Burrard thermal generating plant rebuild.