To improve the performance of the three-way catalytic (TWC) converter, advanced control strategies and onboard diagnostics (OBD) systems are needed. Both rely on a relatively accurate but computationally efficient TWC converter model. This thesis aims to develop a control-oriented model that can be employed to develop the control strategies and OBD systems of the TWC converter. The thesis consists of two parts, i.e., the high-fidelity model development and the model reduction. Firstly, a high-fidelity model is built using the energy and mass conservation principles. In this model, a constant inlet simulation is used to validate the warming-up characteristics, and a driving cycle simulation is used to calibrate the reaction rate parameters. The results of the simulation show that the high-fidelity model has adequate accuracy. Secondly, a reduced-order model is developed based on phase and reaction simplifications of the high-fidelity model. The aim of the development of the reduced-order model is to propose a computationally efficient model for further development of control strategies and state estimators for OBD systems. The accuracy of the reduced-order model is then validated by means of simulations. / Thesis / Master of Science (MSc)

My dissertation addresses how engineers, scientists, and bureaucrats generated knowledge about pollution, crafted an institution for environmental protection, and constructed a collective identity for themselves. I show an important shift in regulators\' priorities, from stringent health-based standards to flexible technology-based ones through the development of end-of-pipeline pollution control devices, which contributed to the emergence of economic incentives and voluntary management programs. Drawing on findings from archival documents, published sources, and oral history interviews, I examine the first decade of the EPA amid constant organizational changes that shaped the technological and managerial character of environmental policy in the United States. Exploring the EPA\'s internal research and development processes and their relationship with scientific and engineering communities sheds light on how the new fields of environmental engineering and policy were co-produced in the 1970s. I argue that two competing approaches for environmental management, a community health approach and a control technology approach, developed from EPA\'s responses to bureaucratic, geographical, and epistemic challenges. I focus on researchers and managers from the Office of Research and Development at Research Triangle Park, North Carolina, as they were engaged in (1) controversy about integrated aerometry and epidemiology research intended to correlate air pollution and health, (2) intra-agency debate about the government\'s responsibility for introducing catalytic converters for tailpipe emissions reduction and responding to the potential environmental and social consequences, and (3) inter-agency activities for the demonstration of scrubbers for smokestack emissions and further application of the control technology approach in energy-related environmental problems. My principal conceptual contribution is "regulatory engineering." I define regulatory engineering as an approach to sociotechnical problems in which engineering practices are incorporated into regulatory and organizational changes, which in turn influences technical knowledge and identity formation. As EPA activities became closely associated with energy and economic issues toward the end of the 1970s, I argue that engineers took the initiative in demonstrating and evaluating control technologies for pollution abatement and energy development, scientists carefully studied environmental and health effects of these technologies, and regulators set up pollution standards and attainment deadlines accordingly. Studying the co-production of knowledge, institution, and identity through the lens of regulatory engineering helps us to understand technoscientific and managerial aspects of environmental governance beyond the 1970s EPA where technical feasibility considerations, economic incentives, and cooperative management expanded into legislation and regulation. / Ph. D.

The life cycle analysis compares the environmental impacts of catalytic converters and the effects of not using these devices. To environmentally evaluate the catalytic converter, the emissions during extraction, processing, use of the product are considered. All relevant materials and energy supplies are evaluated for the catalytic converter. The goal of this life cycle is to compare the pollutants of a car with and without a catalytic converter. Pollutants examined are carbon monoxide (CO), carbon dioxide (CO2), hydrocarbons (HC), and nitrogen oxides (NOx). The main finding is that even considering materials and processing, a catalytic converter decreases the CO, HC and NOx pollutant emissions. The CO2 emissions are increased with a catalytic converter, but this increase is small relative to the overall CO2 emissions. The majority of catalytic converter pollutants are caused by the use phase, not extraction or processing. The life cycle analysis indicates that a catalytic converter decreases damage to human health by almost half, and the ecosystem quality damage is decreased by more than half. There is no damage to resources without a converter, as there are no materials or energy required; the damages with a converter are so small that they are not a significant factor. Overall, catalytic converters can be seen as worthwhile environmental products when considering short term effects like human health effects of smog, which are their design intent. If broader environmental perspectives that include climate change are considered, then the benefits depend on the weighting of these different environmental impacts. / Master of Science

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010. / AFRIKAANSE OPSOMMING:Die navorsing wat hier uiteengesit word ondersoek die hipotese dat kondensasie en die gevolglike verdamping van water wat teenwoordig is in die uitlaatgas van ‘n binnebrandenjin, plaasvind in die gedeeltes van die uitlaatstelsel tussen die uitlaatklep en die katalitiese-omsetter se uitlaat. Daar word verder veronderstel dat hierdie tweefasevloeieffekte die tydafhanklike temperatuurprofiele in die uitlaatstelsel beïnvloed, wat moontlik kan lei tot ‘n vertraging in die tydsduur vir die katalitiese omsetter om temperature van 200-300 °C te bereik, wat nodig is om noemenswaardige omsetting te bewerkstellig. Om hierdie veronderstelling te evalueer is ‘n tydafhanklike, eendimensionele wiskundige model van die termo-vloei gedrag in die uitlaatstelsel gedurende ‘n koue inwerktreeding, insluitende vogtigheidseffekte, opgestel en opgelos deur van ‘n rekenaaralgoritme gebruik te maak. Warmte- en massaoordragsteorie was gebruik om die ongestadigde massa-, energie- en momentumbehoudsvergeleikings te formuleer. Die tweefasige vogeffekte was gemodelleer deur gebruik te maak van die verhouding tussen warmte- en massaoordrag, wat verdamping en heterogeniese kondensasie (die kondensasie van damp teen die pypwand) voorspel as gevolg van die dampdrukgradient tussen die grootmaat damp en die versadigde damp by die oppervlak van die vloeistoffilm. Homogene kondensasie (die kondensasie van vloeistof in die vorm van druppels in die dampstroom) was ook in aanmerking geneem indien die grootmaatgas temperatuur onder die versadigingstemperatuur van die grootmaatdamp gedaal het. ’n Eksperimentele ondersoek was gedoen deur van twee enjins gebruik te maak, ’n 1.6 L Volkswagen Bora en ’n 1.6 L Ford RoCam, in die toetsselle van Cape Advanced Engineering Pty (Ltd). Om die gastemperature so akkuraat moontlik te meet, was spesiale radiasiegeskermde sensore met vinnige reaksietyd ontwerp en installer in die pypseksies van die uitlaatstelsels van beide enjins. Die geskermde sensore het temperature van tot 50 °C hoër as konvensionele termokoppels in dieselfde areas gemeet. Dit is in koers is met resultate wat deur die foutbeperkingsteorie, geassosieer met die meet van temperature in vloeïende gas in uitlaatstelsels, voorspel word. Vergelyking van die numeriese simulasie met die eksperimenteel gemete temperature het aangedui dat in dele van die uitlaatstelsel voor die katalitieseomsetter, die vog min uitwerking het op die termiese gedrag van die stelsel. In hierdie gedeeltes is die konveksie warmte-oordrag dominant. In die katalitieseomsetter was die vogeffekte invloedryk. Die eksperimentele resultate toon ‘n duidelike vroeë toename in die gastemperature, gevolg deur ‘n tydperk van konstante temperature by nagenoeg die versadigingstemperatuur van die grootmaatdamp (verwys na as die temperatuurplato) by die katalitiese-omsetter se kern en uitlaat. Die numeries gesimuleerde gastemperature het ook hierdie gedrag getoon, maar ‘n baie hoë en skerp piek by die begin van die plato het voorgekom. Hierdie piek was nie te sien by die eksperimentele resultate nie en is toegeskryf aan nie-ewewigstoestande in die verdampingsproses, wat aandui dat die tempo van verdamping wat deur die massa-oordragmodel voorspel word te hoog is vir die model en dat dit verfyn moet word. Verdere ondersoek van die invloed van die individuele massa-oordragprosesse het getoon dat die homogene kondensasie die dominante proses is in die vorming van vloeistof in die katalitiese-omsetter. Heterogeniese kondensasie het plaasgevind, maar ‘n kleiner massa vloeistof is produseer. Die maksimum hoeveelheid vloeistof wat voorspel is om in die katalitiese-omsetter te vorm was 12 g/cm wat gelykstaande is aan ‘n film van 0.05.mm dik indien eweredig versprei oor die binneoppervlak van die monoliet. Daar was in die simulasie gevind dat beide verdamping en kondensasie benodig word om die temperatuurplato te simuleer, vanwaar die gevolgtrekking gemaak kan word dat beide prosesse wel plaasvind en dat die eerste stelling in die oorspronklike hipotese wel geldig is. Daar was egter teen die einde van die toetsperiode gevind dat beide temperature wat met en sonder vogeffekte simuleer was, die eksperimentele temperature nagevolg het, wat aandui dat die invloed van vog beperk is tot die vroeë stadiums van die katalitiese-omsetter se opwarmingstydperk. Die tweede gedeelte van die hipotese wat veronderstel dat die voggedrag ‘n vertraging in die tydsduur om omsetting te bewerkstellig veroorsaak, is dus bevind om ongeldig te wees. Die wiskundige model wat opgestel is tydens die ondersoek is weens noodsaaklikheid ‘n vereenvoudigde simulasie van komplekse termo-vloei prosesse. Dit dien as nuttige grondwerk vir verdere in-diepte ondersoeke en afronding van die teorie met betrekking tot voggedrag en die uitwerking daarvan op die tydsafhanklike temperature in ‘n uitlaatstelsel. / ENGLISH ABSTRACT: The research presented here investigates the hypothesis that condensation and subsequent evaporation of water vapour present in the exhaust gas of an internal combustion engine occur in the sections of the exhaust system between the exhaust port and the catalytic converter exit. It is further hypothesised that these two-phase moisture effects influence the transient temperature profiles in the exhaust system, and potentially cause a delay in the time it takes for the catalytic converter to reach temperatures of 200-300 °C, which are required for light-off to occur. In order to evaluate this hypothesis a transient, one-dimensional mathematical model of the thermo-fluid behaviour in the exhaust system during a cold start, including moisture effects, was created and solved by means of a computer algorithm. Heat and mass transfer theory was used to formulate the unsteady conservation equations for mass, energy and momentum. The two phase moisture effects were modelled using the analogy between heat and mass transfer, which predicts evaporation and heterogeneous condensation (the condensation of vapour against the pipe wall) due to a vapour pressure gradient between the bulk vapour and a saturated vapour at the surface of the liquid film. Homogeneous condensation (the condensation of liquid in the form of droplets in the gas stream) was also accounted for if the bulk gas temperature dropped below the bulk vapour saturation temperature. An experimental investigation was performed using two engines, a 1.6.L Volkswagen Bora and a 1.6.L Ford RoCam, in the test cells of Cape Advanced Engineering Pty (Ltd). In order to measure the gas temperatures as accurately as possible specialised radiation shielded sensors with fast time response were designed and installed in the pipe sections of the exhaust systems of both engines. The shielded sensors measured temperatures up 50 °C higher than the conventional thermocouples installed at the same positions, which is in keeping with the results predicted by the theory governing errors associated with temperature measurement in the flowing gas in the exhaust system. Comparison of the numerically simulated and experimentally measured temperatures indicated that in the sections of the exhaust system leading up to the catalytic converter the moisture has little influence on the temperature behaviour of the exhaust system. In these sections the convective heat transfer is dominant. In the catalytic converter the moisture effects were found to be influential. The experimental results clearly show an early rise in the gas temperatures, followed by a period of constant temperature at approximately the saturation temperature of the bulk vapour (referred to as the temperature plateau) at the catalytic converter mid-bed and exit. The numerically simulated gas temperatures also exhibited this plateau, but an initial very high and sharp peak in the simulated gas temperatures occurred at the start of the plateau. This was not seen in the experimental results and is attributed to non-equilibrium in the evaporation process, indicating that the rate of evaporation predicted by the mass transfer model used is too high for this application and that the model needs to be refined. Further investigation of the influence of the individual mass transfer processes indicated that the homogeneous condensation is the dominant process in the formation of liquid in the catalytic converter. Heterogeneous condensation was found to occur, but produced a smaller mass of liquid. The maximum amount of liquid predicted to form in the catalytic converter was 12 g/cm, which translates to a film 0.05 mm thick if evenly distributed over the inner surface of the monolith. In the simulation it was found that both evaporation and condensation are needed in order to simulate the temperature plateau, from which it was concluded that both these processes do occur and the first statement in the original hypothesis is valid. However, by the end of the test period temperatures simulated both with or without the moisture effects closely approached the final temperatures of the experimental investigation, indicating that the influence of the moisture is limited to the early stages of the catalytic converter warm-up. The second part of the hypothesis, postulating that the moisture behaviour caused a delay in the time taken to reach light-off temperature, is therefore concluded to be invalid. The mathematical model constructed in this research is by necessity a simplified solution to complex thermo-fluid processes. It serves as useful groundwork for further elaboration and refinement of the theory related the moisture behaviour and its influence on the transient temperatures in the exhaust system.

This thesis work has been conducted in the Handheld Laboratory at Husqvarna AB with the purpose of finding the parameters responsible for the performance of the catalytic converters used in the test rig. The catalytic converters are used in the test rig during the long term testing of the chain saws to reduce the hydrocarbon content from the exhaust before it enters into the environment.   To perform this research two approaches were carried out. One with Design of Experiment (DOE) and another using Scanning Electron Microscope (SEM) analysis. In Design of Experiments parameters that are suspected to be influencing the performance of the catalytic converter were refined. Using these parameters a test plan is made with the help of statistical analysis application Minitab and the tests were carried out in the test rig. Using SEM the effects of aging and its effect on microstructure and chemical composition on the catalyst surface was analyzed. The results from the DoE shows that the exhaust flow, collector diameter and distance to the muffler are responsible for the collection of exhaust. Distance to the muffler and collector length are the factors affecting the conversion of the exhaust. In addition to that exhaust flow is also responsible for the duration of heating coil running time.        The results from the SEM analysis shows that the operating temperature is high due to which there is thermal degradation of catalyst and there is also deactivation due to fouling. Another finding is that the flow on to the catalyst is not uniformly distributed

This thesis deals with optimization of conditions for the determination of platinum by electrothermal atomic absorption spectrometry. The theoretical part describes the occurrence of platinum in different part of the environment, its physical and chemical properties, transport and bioavailability. There is also evaluated appropriate method for determination and preconcentration of platinum. The experimental part describes advance of optimize the measurement conditions for ETA-AAS, further is describes optimization of condition for SPE and work with real samples on which are applied this conditions.

The diploma thesis focuses on identifying the presence of platinum in soil samples by absorption spectroscopy. The work is divided into two parts, the theoretical part is focused on the occurrence and behavior of platinum in the environment, the fundamental chemical and physical properties of platinum, its importance in catalytic converters in cars, on solid phase extraction method and the method for the determination of atomic absorption spectrometry. The second part is the practical part, focused on the determination of the platinum amount in the soil samples in the city of Brno.

No description available.

The main automotive catalytic media, precious metal-doped ceria-zirconia oxides, fundamental system character is unknown. Understanding the catalytic system properties should allow for the production of an optimal model catalyst. This goal of this study is to gain understanding of ceria-zirconia-palladium systems and to determine a reproducible method for preparing catalysts with minimal surface-carbon. This study investigates ceria-zirconia-palladium catalyst preparation via aqueous chemistry methods and a sputter deposition technique for doping ceria-zirconia oxide mixtures. Prepared catalysts are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XPS allows the surface species, after catalyst doping and annealing, to be evaluated. Prepared catalyst EM analysis allows for surface morphology and particle characteristic evaluation. Prepared catalysts are exposed to UHV conditions, palladium sputtered-coated, and annealed at various temperatures. Temperature dependency is observed in both percentage of carbon, metal, and oxygen species present. This study led to a reproducible, low-carbon content, doping method for use in future pollutant reaction studies.

<p>Avgasmängden som bensindrivna fordon tillåts släppa ut minskas hela tiden. Ett sätt att möta framtida krav, är att förbättra katalysatorns effektivitet. För att göra detta kan luft-bränsle-förhållandet regleras med avseende på syrelagringen i katalysatorn, istället för som idag, reglera mot stökiometriskt blandningsförhållande. Eftersom syrelagringen inte går att mäta med en givare behövs en modell som beskriver katalysatorns dynamiska egenskaper. Tre sådana modeller har undersökts, utvärderats och jämförts.</p><p>Två av modellerna har implementerats i Matlab/Simulink och anpassats till mätningar från en experimentuppställning. För att kunna observera syrelagringen online valdes slutligen en av modellerna ut, och implementerades i ett Extended Kalman filter.</p><p>Ytterligare arbete behöver läggas ner på den mest lovande modellen, och detsamma gäller för Kalmanfiltret, men på sikt förväntas resultaten kunna bli bra.</p> / <p>The legal amount of emissions that vehicles with spark ignited engines are allowed to produce are steadily reduced over time. To meet future emission requirements it is desirable to make the catalytic converter work in a more efficient way. One way to do this is to control the air-fuel-ratio according to the oxygen storage level in the converter, instead of, as is done today, always trying to keep it close to stoichiometric. The oxygen storage level cannot be measured by a sensor. Hence, a model describing the dynamic behaviors of the converter is needed to observe this level. Three such models have been examined, validated, and compared.</p><p>Two of these models have been implemented in Matlab/Simulink and adapted to measurements from an experimental setup. Finally, one of the models was chosen to be incorporated in an extended Kalman filter (EKF), in order to make it possible to observe the oxygen storage level online.</p><p>The model that shows best potential needs further work, and the EKF is working with flaws, but overall the results are promising.</p>