Thesis (M.S.)--Michigan State University. School of Criminal Justice, 2008. / Title from PDF t.p. (viewed on Aug. 5, 2009) Includes bibliographical references (p.158-160). Also issued in print.

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.

No description available.

Air pollution is a threat to the environment and human health. Freight trucking in particular is the main source of freight transportation emissions. Heavy-duty trucks emit large amounts of toxic air pollutants that cause serious diseases and harm public health. In addition, heavy-duty trucks emit great amounts of greenhouse gas (GHG), which is the leading cause of global warming. Despite increased environmental restrictions on air pollution and rising trucking greenhouse gas emissions in the past decades, no economic study has examined the potential GHG and air pollution reductions in the trucking sector and the associated private abatement costs to the industry. This study accounts for GHG emissions and toxic air pollutants in measuring and evaluating efficiency and productivity for the trucking industry in the 48 contiguous states. Moreover, the private costs of abatement to the industry were also estimated. When only GHG was incorporated in the production model, the results showed that each state could expand desirable output and reduce GHG by an average of 11 percent per year between 2000 and 2007. The Malmquist-Luenberger productivity indexes showed that omitting or ignoring GHG in trucking service production yielded biased estimates. On the other hand, due to increased environmental regulations, most of the toxic air pollutants decreased dramatically between 2002 and 2005. The analytical results showed that inefficiency decreased during this period. The private costs of abatement averaged $73 million per state in 2005. When GHG and six toxic air pollutants were incorporated in the production model, the estimated private abatement cost was $76 million per state, which was equivalent to 0.7 percent of the industry output in 2005.

No / Since the beginning of time, energy has pervaded our earth. We rely on it to advance in any development. As the energy sources become scarcer, it is important to learn how to save and economize energy. A perfect energy should be cheap and efficient. Bi-Fuel system is such a concept, which combines the best of Diesel and Gas driven engines. Diesel driven engines though provide high power density but own the drawback of high cost and high on-site fuel storage. Gas driven engines provide low cost but own the drawback of low power density. A Bi-Fuel system is Compression ignited engine, which runs on the simultaneous combustion of Diesel and Natural gas. It works by introducing gas to the engine via various technologies and then electronically controlling flow dependent on output. This greatly extends the runtimes and limits the amount of diesel fuel that must be stored on site.

Within this body of work several series of experiments will investigate the nature of complex combustion in an experimental single-cylinder engine emulating a modern passenger car size compression-ignition (CI) engine. Regimes of single, piloted single and piloted split-main injections will be tested and compared in terms of combustion characteristics, specific emission output and cyclic behaviour to determine how increased injection complexity affects the emissions and output of the modern CI engine. Through these tests, the effect of fuel-line stationary waves will be demonstrated and investigated, showing conclusively that optimised engine calibration is essential to account for injector-generated waves in any multiple injection scenario. This data will then be confirmed with a dedicated analysis using an injector rate measuring tube. The tests will then be expanded to include examination into the behaviour of injector needle-lift standard deviation over its operating cycle, in-cylinder pressure standard deviation behaviour and trends over the combustion cycle as well as IMEP variability. Through these tests a novel method to detect start of combustion will be proposed and compared to conventional methods. Low temperature combustion (LTC) will be tested under incremental injection complexity. Tests will be optimised for combustion phasing and injection pressure, with a view to analysis of emissions, output and cyclic behaviour to establish whether the knowledge gained about conventional combustion holds true under LTC. Optimization of engine parameters will be shown to result in easier to implement LTC regimes with superior emissions characteristics. Finally, LTC tests will be expanded to include 30% and 50% by volume gas-to-liquid fuel (GTL) blends in order to determine whether fuel characteristics further influence emissions, output and cyclic behaviour in LTC through complex injection regimes. How GTL-blend ratio affects trends in emissions and cyclic behaviour will also be examined and compared to conventional diesel fuel.

[pt] O objetivo desse trabalho é avaliar o potencial técnico- econômico nacional da autogeração de energia elétrica. O levantamento desse potencial é realizado a partir do desenvolvimento de uma metodologia determinística para os clientes de alta tensão da concessionária LIGHT no estado do Rio de Janeiro, extrapolando-a para a estimativa do potencial brasileiro, através dos dados de consumo nacional. A geração distribuída é analisada a partir do atual estado da arte da tecnologia disponível para motores alternativos de combustão interna, ciclos Diesel e Otto. Os motores alternativos possuem tecnologia amplamente difundida, alta escala de produção, alta eficiência e baixo custo de investimento de aquisição, principalmente quando comparado a outras tecnologias de geração elétrica de pequeno e médio porte. Dessa forma, optou-se pela tecnologia dos motores alternativos como o mais adequado para a autogeração. Os motores alternativos têm grande potencial para servir de base para expansão da geração distribuída nacional. São considerados como alternativas de fontes energéticas para a autogeração, o óleo diesel e o gás natural. Para a operação dos motores ciclo Diesel foi considerada, além da hipótese de funcionamento pelo modo tradicional a óleo diesel, sua operação com um kit de conversão para combustível dual. Este permite uma substituição do óleo diesel pelo gás natural em torno de 80 por cento. Já para os motores alternativos ciclo Otto foi apenas considerada a utilização do energético gás natural. A viabilidade econômica do investimento em centrais de geração distribuída, é obtida quando traçado um paralelo entre o atual custo da energia elétrica que é fornecida pela concessionária e o custo da aquisição e operação do sistema de autogeração. O cálculo de viabilidade será dado por uma ótica estritamente econômica. Considerando-se que a atratividade do empreendimento seja dada por uma taxa interna de retorno do investimento mínima de 15 por cento a.a para um horizonte de 15 anos, é estimado que a geração distribuída possa representar 2,6 por cento da energia elétrica gerada nacionalmente ou cerca de 7.173 GWh/ano, concentrada principalmente para geração de horário de ponta. Os geradores a diesel representam 44,6 por cento desse total, os geradores dieselgás 55,2 por cento e os geradores a gás cerca de 0,2 por cento. Isto significa um consumo diário de 2,2 MMm3 de gás natural e 2.800 m3 de óleo diesel. De uma maneira geral a autogeração não se viabiliza economicamente para geração fora de ponta, em virtude do baixo custo da energia elétrica neste período. Em função da penetração do gás natural no mercado nacional, é realizada uma análise de sensibilidade entre custo desse energético e o aumento do potencial de geração distribuída nacional. Conclui-se, que a queda do preço do gás natural pode aumentar ainda mais o potencial de geração distribuída baseado nos geradores diesel-gás, além de também viabilizar os geradores gás. Finalmente são abordados e analisados os impactos e benefícios trazidos pela geração distribuída ao sistema atual de geração e transmissão nacional. / [en] The objective of this work is to evaluate the technical- economic potential of electric energy self-generation in Brazil. A deterministic methodology will be built for market evaluation. It will be based on a developed model for high voltage customers from LIGHT, located in state of Rio de Janeiro and extrapolated to establish the national market. The extrapolation will be made through the national consumption data. The distributed generation is analyzed from the state of the art of reciprocating internal combustion engines, Diesel and Otto cycles. These engines have widespread technology, high efficiency and offer low acquisition cost when compared with other small and medium scale gensets technologies. In that way, they were chosen, to be the alternatives for the distributed generation. The reciprocating engines have great potential to support the expansion of the distributed generation in Brazil. Diesel oil and natural gas are considered as the fuel alternatives for the gensets. Besides the usual diesel oil, used as fuel for diesel engines, it was considered the mix between diesel oil and natural gas. The mix is handled with an auxiliary conversion kit. It allows diesel oil being substituted around 80% by natural gas. It was only considered natural gas fuel for the gas engines. The economic feasibility of the investment in distributed generation is achieved when a comparison is made between the current cost of the electric energy, which is supplied by the local utility company, and the cost of acquisition and operation of the self generation system. The feasibility will be given by a strict economic aspect. Considering the attractiveness for the enterprise, it is given by a minimum internal rate of return of 15 percent per year in a horizon of 15 years. It is estimated that the national distributed generation can represent 2.6 percent of all national electric generation or 7,173 GWh/year. Mainly for generation at peak hours. The diesel oil gensets represents 44.6 percent of that total, the diesel-gas gensets 55.2 percent and the gas gensets around 0.2 percent. Meaning a daily consumption of 2.2 MMm3 of natural gas and 2,800 m3 of oil diesel. Self generation isn`t economic feasible at off-peak hours, because the low tariff value. For the perspective of expansion of the natural gas net distribution in Brazil, a sensibility analysis was accomplished between the natural gas cost and increase of the national distributed generation market. It is concluded that if the natural gas cost less, the national distributed generation market would grow, based mainly in diesel-gas and gas gensets. Finally, the impacts and benefits brought by distributed generation in the current scenery of national generation and transmission systems were analyzed.

La Réduction Catalytique Sélective (SCR) par l'ammoniac, ou l'urée, est un procédé connu de post-traitement permettant de réduire efficacement les oxydes d'azote émis par les motorisations Diesel, en azote et en eau. Les zéolithes échangées au cuivre sont parmi les meilleures formulations pour une application sur véhicules légers, puisque efficaces sur une large zone de température. Le but de cette thèse était d'étudier la stabilité hydrothermale de ce type de catalyseur. L'approche utilisée au cours de ce travail repose sur l'étude des différentes fonctionnalités d'un catalyseur commercial de NH3-SCR présent sous forme de monolithe, à l'état frais et pour différentes conditions de vieillissement, au Banc Gaz Synthétique couplée à une analyse physico-chimique précise de la phase active du catalyseur. Ceci nous a permis de comprendre les phénomènes de désactivation intervenant au cours d'un vieillissement hydrothermal et de mesurer leur impact sur l'activité et la sélectivité de ce type de catalyseur. Après traitement hydrothermal, on assiste à une désalumination plus ou moins importante de la zéolithe, pouvant conduire à l'effondrement de sa structure, ainsi que d'importantes modifications au niveau du cuivre dès les plus faibles températures de vieillissements. Les résultats ont montré l'importance de maintenir une teneur minimal de cuivre en position d'échange, afin de conserver une capacité de stockage en ammoniac suffisante, mais surtout pour garantir une bonne efficacité à basse température en SCR du NO. Le maintien de la structure de la zéolithe semble essentiel pour que le catalyseur conserve une bonne efficacité et sélectivité au cours du temps. / The Selective Catalytic Reduction (SCR) by ammonia, or urea, is a well-known after-treatment process used for converting efficiently the nitrogen oxides, emitted by Diesel engines, into nitrogen and water. Copper-exchanged zeolites are among the most efficient formulations for light-duty applications, since effective over a wide temperature-range. The aim of this thesis is to study the hydrothermal stability of this type of catalyst. The approach used is this work is based on the study of the catalytic properties of a fresh commercial monolith catalyst for NH3-SCR in fresh and after different ageing conditions, at synthetic gas test bench, coupled with a comprehensive physicochemical analysis of the catalyst active phase. This allowed us to understand the deactivation phenomena occurring during a hydrothermal ageing and the impact on the catalyst activity and selectivity. A hydrothermal treatment induces a dealumination of the zeolite, into a more or less significant extent, which can lead to its collapse, as well as important modifications of the copper sites, even at low ageing. The results showed the importance to maintain a minimal copper content into exchanged sites, in order to retain a sufficient ammonia storage capacity, and especially to provide a good efficiency for the SCR of NO at low temperature. The preservation of the zeolite structure seems to be essential in order to maintain the catalyst efficiency and selectivity over time.

The growing municipal solid waste generation rates have necessitated more efficient, optimized waste collection facilities. The majority of the US collection fleet is composed of diesel-fueled vehicles which contribute significant atmospheric emissions including greenhouse gases. In order to reduce emissions to the atmosphere, more collection agencies are investigating alternative fuel technologies such as natural gas, biofuels (bio-gas and bio-diesel), and hybrid electric technology. This research is an in-depth environmental analysis of potential alternative fuel technologies for waste collection vehicles. This study will evaluate the use of alternative fuels by waste collection vehicles. Lifecycle emissions, cost, fuel and energy consumption were evaluated for a wide range of fossil and bio-fuel technologies. Moreover, the energy consumption and the tail-pipe emissions of dieselfueled waste collection vehicles were estimated using MOVES 2010a software. Emission factors were calculated for a typical waste collection driving cycle as well as constant speed. Finally, the selection of fuel type by the waste collection industry requires consideration of environmental, security, financial, operational, and safety issues. In this study, a qualitative comparison between alternative fuels was performed; a multifactorial assessment of these factors was conducted taking into account the opinion of the waste collection industry of the importance of each factor. Liquid-petroleum fuels have higher life-cycle emissions compared to natural gas; however landfill natural gas has the lowest life-cycle emissions compared to all other fuel categories. Compressed natural gas waste collection vehicles have the lowest fuel cost per collection vehicle mile travel compared to other fuel categories. Moreover, the actual driving cycle of waste collection vehicles consists of repetitive stops and starts during waste collection; iv this generates more emissions than constant speed driving. Finally, the multifactorial assessment indicates that natural gas and landfill gas have better environmental, economical, and energy security performance than current liquid-petroleum fuels.

No description available.