In emissions catalyst applications, an axial distribution of reaction, surface chemistry, and temperature all exist on or along the surface of the catalyst. Understanding these distributions is very important in developing physically relevant models of such systems. One focus of this work was developing a technique to obtain accurate temperature measurements from a catalyst during exothermic or endothermic reaction steps. IR thermography was tested as a method to evaluate spatial temperature distributions as a function of time on a diesel NOX adsorber catalyst. The technique proved accurate, relatively simple to interpret and operate, and efficient to the extent it can be used for data generation. As a continuation of the technique development, the temperature changes and gradients formed during simulated operation of a Pt/Ba/Al2O3 NOX adsorber catalyst (NAC) for diesel exhaust applications were monitored using IR thermography and standard thermocouples. NACs operate in a cyclic manner; during the lean phase, when the engine is in normal operation, the catalyst traps entering NOX; once the catalyst nears saturation, the catalyst is exposed to a rich exhaust phase, in reductant relative to oxygen, where the trapped NOX is reduced to N2; and finally the exhaust returns to the normally lean conditions thereby completing the cycle. During the rich phase, previous work has suggested that significant temperature changes might be occurring along the length of the catalyst. In this study, temporally and spatially resolved temperature distributions were obtained throughout the cycle in order to evaluate the significance of these temperature changes and their effects on the reaction chemistry. The effects of (1) reactor in the possible reaction pathways, (2) CO and O2 levels in the regeneration phase, (3) NO and NO2 as the source of NOX in the lean cycle and (4) nominal operating temperature on these temperature distributions were evaluated. The temperature gradient and distribution measurements are being used to characterize the reactions and as input into models.

In emissions catalyst applications, an axial distribution of reaction, surface chemistry, and temperature all exist on or along the surface of the catalyst. Understanding these distributions is very important in developing physically relevant models of such systems. One focus of this work was developing a technique to obtain accurate temperature measurements from a catalyst during exothermic or endothermic reaction steps. IR thermography was tested as a method to evaluate spatial temperature distributions as a function of time on a diesel NOX adsorber catalyst. The technique proved accurate, relatively simple to interpret and operate, and efficient to the extent it can be used for data generation. As a continuation of the technique development, the temperature changes and gradients formed during simulated operation of a Pt/Ba/Al2O3 NOX adsorber catalyst (NAC) for diesel exhaust applications were monitored using IR thermography and standard thermocouples. NACs operate in a cyclic manner; during the lean phase, when the engine is in normal operation, the catalyst traps entering NOX; once the catalyst nears saturation, the catalyst is exposed to a rich exhaust phase, in reductant relative to oxygen, where the trapped NOX is reduced to N2; and finally the exhaust returns to the normally lean conditions thereby completing the cycle. During the rich phase, previous work has suggested that significant temperature changes might be occurring along the length of the catalyst. In this study, temporally and spatially resolved temperature distributions were obtained throughout the cycle in order to evaluate the significance of these temperature changes and their effects on the reaction chemistry. The effects of (1) reactor in the possible reaction pathways, (2) CO and O2 levels in the regeneration phase, (3) NO and NO2 as the source of NOX in the lean cycle and (4) nominal operating temperature on these temperature distributions were evaluated. The temperature gradient and distribution measurements are being used to characterize the reactions and as input into models.

A methodology was developed to dissect diesel particulate filters to study the time effect of loading for two different fuels: ULSD and a biodiesel blend. Filters loaded with soot from a diesel engine for exposure times of 1, 2, 5 and 10 hours were fractured and samples of filter substrates were analyzed using Raman spectroscopy and scanning electron microscopy. Observations revealed the sharp rise in pressure drop to be attributable to the clogging of the pores in the channel wall, leading to the formation of a pore-bridge. Cross sectional imaging of wall sections revealed this pore-bridge to be shallow, with significant particulate depositions limited to the first quarter of the depth of the filter walls. Images revealed increasingly dense deposits and the formation of coarse particles and soot cakes. Raman spectroscopy revealed no significant graphitization of the soot cake. The dissection methodology exhibits significant potential for future studies on DPFs.

A methodology was developed to dissect diesel particulate filters to study the time effect of loading for two different fuels: ULSD and a biodiesel blend. Filters loaded with soot from a diesel engine for exposure times of 1, 2, 5 and 10 hours were fractured and samples of filter substrates were analyzed using Raman spectroscopy and scanning electron microscopy. Observations revealed the sharp rise in pressure drop to be attributable to the clogging of the pores in the channel wall, leading to the formation of a pore-bridge. Cross sectional imaging of wall sections revealed this pore-bridge to be shallow, with significant particulate depositions limited to the first quarter of the depth of the filter walls. Images revealed increasingly dense deposits and the formation of coarse particles and soot cakes. Raman spectroscopy revealed no significant graphitization of the soot cake. The dissection methodology exhibits significant potential for future studies on DPFs.

Low temperature combustion (LTC) is an appealing new method of combustion that promises low nitric oxides and soot emissions while maintaining or improving on engine performance. The three main points of this study were to develop and validate an engine model in GT-Power capable of implementing LTC, to study parametrically exhaust gas recirculation (EGR) and injection timing effects on performance and emissions, and to investigate methods to decrease pressure rise rates during LTC operation. The model was validated at nine different operating points, 3 speeds and 3 loads, while the parametric studies were conducted on 6 of the 9 operating points, 3 speeds and 2 loads. The model consists of sections that include: cylinders, ports, intake and exhaust manifolds, EGR system, and turbocharger. For this model, GT-Power calculates the combustion using a multi-zone, quasi-dimensional model and a knock-induced combustion model. The main difference between them is that the multi-zone model is directly injected while the knock model is port injected. A variety of sub models calculate the fluid flow and heat transfer. A parametric study varying the EGR and the injection timing to determine the optimal combination was conducted using the multi-zone model while a parametric study that just varies EGR is carried out using the knock model. The first parametric study showed that the optimal EGR and injection timing combination for the low loads occurred at high levels of EGR (60 percent) and advanced injection timings (30 to 40 crank angle degrees before top dead center). The optimal EGR and injection timing combination for the high loads occurred at low levels of EGR (30 percent to 40 percent) and retarded injection timings (7.5 to 5 crank angle degrees before top dead center). The knock model determined that the ideal EGR ratio for homogeneous charge compression ignition (HCCI) operation varied from 30 percent to 45 percent, depending on the operating condition. Three methods were investigated as possible ways to reduce pressure rise rates during LTC operation. The only feasible method was the multiple injection strategy which provided dramatically reduced pressure rise rates across all EGR levels and injection timings.

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In 2009, Cobb County School District (CCSD) and Georgia Institute of Technology (Georgia Tech) received a competitive federal grant to implement an idle and tailpipe emission reduction program in the CCSD bus fleet. The project is designed to reduce school bus idling by installing GPS and idle detection systems in the bus, providing bus dispatchers with a web system to track vehicle activity and idling in real-time, and to automatically shut off the engine when idle thresholds at specific locations are exceeded. A team of Georgia Tech researchers is implementing the anti-idle program and estimating the emissions and fuel savings from the project using approved modeling methods. This thesis presents the results of the emission modeling process, as well as an analysis of baseline school bus idling activity. EPA's MOVES mobile source emission model was used to develop emission rates for school buses for each operating mode, which are defined by the instantaneous vehicle speed, acceleration and scaled tractive power. Local data for Cobb County and Atlanta were collected and input into the MOVES model. The pollutants modeled include carbon dioxide, carbon monoxide, particulate matter (coarse and fine), oxides of nitrogen, and gaseous hydrocarbons. The vehicle activity data collected through the GPS and communications equipment installed in the buses were classified into the operating mode bins for each second of recorded data, and multiplied by the corresponding emission rate to determine the total modal emissions before and after project implementation. Preliminary results suggest that thousands of gallons of diesel fuel and thousands of dollars can be saved with the project, improving overall fleet fuel efficiency by 2%, as well as reducing emissions in some categories by as much as 38%.

Hohe Partikelemissionen und starke mutagene Wirkungen wurden nach der Verbrennung von Pflanzenöl in Dieselmotoren beobachtet. Diese Studie untersuchte die Hypothese, dass diese Ergebnisse durch die Menge der ungesättigten oder mehrfach ungesättigten Fettsäuren aus pflanzlichen Ölen beeinflusst werden und dass Mischungen aus Dieselkraftstoff und Pflanzenöl mutagen sind. Drei verschiedene Pflanzenöle (Leinöl, LÖ; Palmöl, PÖ; Rapsöl, RÖ), Mischungen von 20% Pflanzenöl und 80% Dieselkraftstoff (B20) und 50% Pflanzenöl und 50% Dieselkraftstoff (B50) sowie herkömmlicher Dieselkraftstoff (DK) wurden in einem Dieselmotoren verbrannt. Die Abgase wurde auf partikuläre Emissionen und die mutagene Wirkung im Vergleich zu Emissionen von DK untersucht. Der Motor wurde im European Stationary Cycle betrieben. Die Partikelmasse wurde gravimetrisch gemessen während die Mutagenität unter Verwendung des bakteriellen Rückmutationsversuchs mit Tester Stämmen TA98 und TA100 bestimmt wurde. Bei der Verbrennung von LÖ entstand die größte Partikelmasse (PM). Im Vergleich zu DK war die lösliche organische Fraktion (LOF) besonders hoch. RO präsentiert die zweithöchste PM und LOF, gefolgt von PÖ, die kaum über DK lag. B50 zeigte die niedrigste Menge an PM während B20 so hoch lag wie DK. RÖ zeigte die höchste Anzahl an Mutationen der Pflanzenöle gefolgt von LÖ. PÖ war weniger mutagen, aber immer noch stärker als DK. B50 zeigte ein höheres mutagenes Potential als B20. Während PM und LOF stark mit dem Gehalt an mehrfach ungesättigten Fettsäuren in den Pflanzenölen korrelierten hatte die Mutagenität eine signifikante Korrelation mit der Menge der gesamten vorhandenen ungesättigten Fettsäuren. Pflanzenölblends scheinen weniger mutagen als die reinen Öle zu sein und das mutagene Maximum im Vergleich zu Blends mit Biodiesel und DK verschobenen. Diese Studie unterstützt die Hypothese, dass die Zahl der Doppelbindungen in ungesättigten Fettsäuren von Pflanzenölen Bei Verbrennung in Dieselmotoren die Menge der emittierten Partikel und die Mutagenität des Abgases beeinflussen. Das Maximum der Mutagenität verschiebt sich bei Pflanzenölblends im Vergleich zu Biodieselblends. Weitere Untersuchungen müssen die kausalen Zusammenhang aufzuklären und wo das Maximum der Pflanzenölblends liegt.