Dissertations / Theses on the topic 'Exhaust gas analysis'

This dissertation describes the known formation mechanisms of pollutant emissions for spark ignition internal combustion engines, the most common pollutants emitted by spark ignition engines, current methods to reduce pollutants emissions and a comparison of industry procedures with one and three-dimensional modeling including detailed surface reaction chemistry model, all used to estimate catalytic converter efficiency. Also, experimental tests were performed to provide exhaust gas composition boundary conditions, and to provide values for current catalytic converter efficiency. The detailed surface reaction chemistry model presented problems into implementation for one and three-dimensional analyzes, presenting zero conversion into one-dimensional analysis and continuous reduction in conversion efficiency for three-dimensional analysis. The industry procedure has been used for a long time, and presented the more realist values and behavior, not justifying the replacement for an analysis that includes chemistry reaction models, either one or three-dimensional.

Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains viii, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-73).

Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains xi, 133 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 129-133).

The main purpose of the AOD-converter is to lower the carbon content in stainless steel production. The carbon content can be estimated by static theoretical models. It can also be estimated through dynamic models based on analysis of the exhaust gases from the converter. This master thesis is a study on an extended use of exhaust gas analysis data on the AOD-converter at Outokumpu’s stainless steel plant in Avesta, Sweden. There are two main methods of predicting the carbon content based on exhaust gas analysis, mass balance and a linear regression between decarburization rate and carbon content. This master thesis mainly focuses on the development of the linear regression model for steel grades ASTM 304L, 316L, S32101 and S32205 for the last step of the decarburization, as well as ASTM S32205 and S30815 for the second last step of the decarburization. The results showed that the linear regression model can predict the carbon content at the last step of decarburization with a standard deviation between 0,00626 %C and 0,0109 %C for the different steel grades. An equation for carbon prediction dependent on the steel composition was also developed in the master thesis, making it theoretically possible to use for all steel grades, it has however not yet been tested on other steel grades. The CRE measured from the exhaust gases was also studied to find out if it is possibleto use as basis for step changes during the decarburization, but the resultswere inconclusive.
Huvudsyftet med AOD-konvertern är att sänka kolhalten i produktionen av rostfritt stål. Kolhalten kan uppskattas av statiska teoretiska modeller. Den kan också uppskattas av dynamiska modeller baserade på analys av avgaserna från konvertern. Det här examensarbetet handlar om utvidgning av användandet av avgasanalysdata på AOD-konvertern på Outokumpus stålverk i Avesta, Sverige. Det finns i huvudsak två metoder för att bestämma kolhalten med hjälp av avgasanalys, massbalans och en linjär regression mellan kolfärskningshastigheten och kolhalten. Det här examensarbetet fokuserar i huvudsak på utvecklingen av den linjära modellen för stålsorterna ASTM 304L, 316L, S32101 och S32205 för sista steget i kolfärskningen. Samt stålsorterna ASTM S32205 och S30815 för näst sista steget i kolfärskningen. Resultaten visade att den linjära modellen kunde uppskatta kolhalten i sista steget av kolfärskningen med en standardavvikelse mellan 0,00626 %C och 0,0109 %C för de fyra olika stålsorterna. En ekvation som anger sambandet mellan sammansättningen på stålet under kolfärskningen och ekvationen för den linjära regressionen togs också fram i examensarbetet. Teoretiskt kan ekvationen användas för alla stålsorter men den har inte än blivit testad på andra stålsorter. CRE uppmätt med hjälp av avgasanalys undersöktes också för att ta reda på om CRE kan användas för att bestämma när stegbytena ska ske, det gick dock inte att utgöra från resultaten.

Thesis (M.S.)--West Virginia University, 2008.
Title from document title page. Document formatted into pages; contains vi, 78 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 42-44).

The member states of European Union aim to promote the reduction of harmful emissions. Emissions from combustion processes cause effects on human health and pose environmental issues, for example by increasing greenhouse effect. There are two ways to reduce emissions; one is to promote renewable energy sources and the other to utilize more effectively the available fossil fuels until a long-term solution is available. Hence, it is necessary to strive for CO2 mitigation technologies applied to fossil fuels. Low natural gas prices together with high energy efficiency have made gas turbines popular in the energy market. But, gas turbine fired with natural gas come along with emissions of CO2, NOx and CO. However, these disadvantages can be eliminated by using gas turbine with precombustion CO2 capture, separating carbon from the fuel by using fuel reforming process and feeding pure hydrogen as a fuel. Hydrogen fired gas turbines are used in two applications such as a gas turbine with pre-combustion CO2 capture and for renewable power plants where hydrogen is stored in case as a backup plan. Although the CO2 emissions are reduced in a hydrogen fired gas turbine with a pre-combustion CO2 capture, there are still several challenges such as high flame temperatures resulting in production of thermal NOx. This project suggests a method for application of hydrogen fired gas turbine, using exhaust gas recirculation to reduce flame temperature and thus reducing thermal NOx. A NOx emission model for a hydrogen-fired gas turbine was built from literature data and used to select the best operating conditions for the plant. In addition, the economic benefits of switching from natural gas to pure hydrogen are reported. For the techno-economic analysis, investment costs and operating costs were taken from the literature, and an economic model was developed. To provide sensitivity analysis for the techno-economic calculation, three cases were studied. Literature review was carried out on several journal articles and websites to gain understanding on hydrogen and natural gas fired gas turbines. Results showed that, in the current state, pure hydrogen has high delivery cost both in the US and Europe. While it’s easy to access natural gas at low cost, therefore in the current state gas turbine fired with natural gas are more profitable than hydrogen fired gas turbine. But, if targeted hydrogen prices are reached while fuel reforming process technology are developed in the coming future the hydrogen fired gas turbine will compete seriously with natural gas.

Local exhaust (LE) ventilation is a ventilation technique where contaminated air is locally extracted close to the contaminant source usually with the purpose to reduce the exposure of workers to dust, fumes or vapour, which can be hazardous to their health. The performance of a LE installation depends however on many influential factors, and there is not yet an international standardized way to test LE constructions. The present study is the natural continuation of some previous studies at the University of Gävle that aimed at contributing to the establishment of such tests. The study entails full scale experimental measurements that include 3-D air velocity measurements and tracer gas tests in a controlled air turbulence environment generated through physical movements of a vertical, human-sized cylinder. These measurements were focused on human exposure, which was analysed by means of a seated human simulator for different configurations in which the exhaust flow rate, turbulence level, the exhaust hood arrangement and the measuring/injecting distance varied. The use of a sonic 3-D anemometer, that yielded both magnitude and direction of the air movement, proved very useful in analysing the generated air turbulence. As a measure of the LE performance, PNV value (Percentage of Negative Velocities) was used. This measure represents the percentage of time when the air flow at the measuring point in front of the exhaust hood is directed away from the nozzle, i.e. when the velocity component in the direction towards the exhaust hood opening is negative. Regarding the results obtained, in an otherwise undisturbed environment, measurement data showed that the natural convection from the human simulator sitting in front of the LE introduces some disturbances of the air flow in the suction region, proportional to the exhaust flow rate. However, when additional turbulence was generated through the controlled movements of the human-sized cylinder, thus creating a controlled turbulence setting, natural human convection leaded to a lower percentage of negative velocities (PNV) in comparison with the case in which human simulator was not present, especially for low exhaust air flow rates and when the exhaust hood was raised from the table. The tracer gas tests implied injection of a neutrally buoyant tracer gas through a perforated sphere placed in front of the exhaust hood. The amount of tracer gas that escaped from the suction flow was measured both in the room air and in the breathing zone. The first measurements yielded a sensitive method for measuring the capture efficiency (CE) of the exhaust hood. The CE is the percentage of injected tracer gas that is directly captured by the exhaust hood. This parameter showed that although the  convection flow generated by the human simulator leads to low PNV values, it seems that the tracer gas is not actually being captured, but trapped in that convection flow. As a consequence, PNV and CE get a strong correlation, which is even more intense when injection and capture point are closer together. Hence, PNV represents a good alternative to tracer gas measurements only if the relationship between the correlation of PNV and CE with respect to the distance from the injection to the capture point is known. Finally, measurements of tracer gas in the breathing zone showed random, short and high exposures when turbulence was generated and those exposures got worse by natural human convection.

Thesis (M.S.)--West Virginia University, 2007.
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Thesis (Ph. D.)--West Virginia University, 2002.
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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%.

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.

Mobile source emissions are a major contributor to global and local air pollution. Governments and regulatory agencies have been increasing the stringency of regulations in the transportation sector for the last ten years to help curb transportation sector air pollution. The need for regulations has been emphasized by scientific research on the impacts from ambient pollution, especially research on the effect of particulate matter on human health. The particulate emissions from diesel vehicles, diesel particulate matter (DPM) is considered a known or probable carcinogen in various countries and increased exposure to DPM is linked to increased cardiovascular health problems in humans. The toxicity of vehicle emissions and diesel particulate emissions in particular, in conjunction with an increased awareness of potential petroleum fuel shortages, international conflict over petroleum fuel sources and climate change science, have all contributed to the increase of biodiesel use as an additive to or replacement for petroleum fuel. The goal of this research is to determine how this increased use of biodiesel in the particular emission testing setup impacts urban air quality. To determine if biodiesel use contributes to a health or climate benefit, both the size range and general composition were investigated using a comprehensive comparison of the particulate component of the emissions in real time. The emissions from various biodiesel and diesel mixtures from a common diesel passenger vehicle were measured with a cavity ring-down transmissometer (CRDT) coupled with a condensation particle counter, a SMPS, a nephelometer, NOx, CO, CO2, and O3 measurements. From these data, key emission factors for several biodiesel and diesel fuel mixtures were developed. This approach reduces sampling artifacts and allows for the determination of optical properties, particle number concentration, and size distributions, along with several important gas phase species' concentrations. Findings indicate that biodiesel additions to diesel fuel do not necessarily have an air quality benefit for particulate emissions in this emission testing scenario. The often cited linear decrease in particulate emissions with increasing biodiesel content was not observed. Mixtures with half diesel and half biodiesel tended to have the highest particulate emissions in all size ranges. Mixtures with more than 50% biodiesel had slightly lower calculated mass for light absorbing carbon, but this reduction in mass is most likely a result of a shift in the size of the emission particles to a smaller size range, not a reduction in the total number of particles. Evaluation of the extensive optical properties from this experimental set-up indicates that biodiesel additions to diesel fuel has an impact on emission particle extinction in both visible and near-IR wavelengths. The B99 mixture had the smallest emission factor for extinction at 532 nm and at 1064 nm. For the extinction at 532 nm, the trend was not linear and the emission factor peaked at the B50 mixture. Results from intensive properties indicate that emissions from B5 and B25 mixtures have Ångström exponents close to 1, typical for black carbon emissions. The mixtures with a larger fraction of biodiesel have Ångström exponent values closer to 2, indicating more absorbing organic matter and/or smaller particle size in the emissions. Additional experimental testing should be completed to determine the application of these results and emission factors to other diesel vehicles or types of diesel and biodiesel fuel mixtures.

[ES] Los objetivos son 2: 1- Determinar el efecto de la dispersión de la recirculación de gases de escape de alta presión (HP EGR) en las emisiones de NOx y humos en motores diésel de automoción en operaciones de funcionamiento constantes. La investigación cuantifica las emisiones de NOx y humos en función del nivel de dispersión de EGR de alta presión entre cilindros. 2- Explorar los límites del modelado 1D para predecir el movimiento del flujo de los gases en la compleja situación en la que estos entran en los cilindros desde el colector de admisión. Los experimentos se realizaron en un banco de pruebas con un motor diésel de 1.6 litros. Para detectar la dispersión de EGR de alta presión se instaló un sistema de válvulas en los conductos de admisión de cada cilindro para medir la concentración de CO2, por tanto la tasa de EGR, en cada conducto. Se instaló también un sistema de válvulas en el escape para medir las emisiones de NOx en cada cilindro. Se instaló un sensor de humos en la línea de escape, aguas abajo de la turbina, para medir el efecto de la dispersión de EGR de alta presión en las emisiones de humos además del sensor para medir el resto de las emisiones contaminantes aguas abajo de la turbina. Se han estudiado 9 puntos de funcionamiento diferentes con distintas velocidades y niveles de carga. El mapa motor se ha estudiado en profundidad, desde 1250 hasta 3000 rpm y entre 3 y 20 bar de presión media efectiva (BMEP). La tasa de EGR varía entre 5 y 42%, dependiendo del punto de funcionamiento. La geometría del modelo reproduce la del motor diésel de automoción de 1.6 litros en el que se realizaron los ensayos experimentales. Incluyendo la línea de EGR de alta presión que fue instalada para controlar los niveles de dispersión durante los ensayos experimentales. La metodología centrada en las herramientas experimentales combina aparatos de medida tradicional con un sistema de válvulas específico que ofrecen una información precisa en cuanto a la concentración de especies tanto en el colector de admisión como en el de escape. El estudio se realizó a emisiones de NOx constantes para observar el efecto de la dispersión de EGR en los valores de opacidad. La metodología está centrada en las herramientas de modelado, las condiciones de contorno y toda la información necesaria para poner en marcha el modelo proviene de los resultados de los ensayos experimentales medidos con los diferentes sensores y aparatos mencionados anteriormente. Muchos de ellos necesarios para ajustar el modelo. La parte más importante para estudiar la capacidad de predicción del modelo es el diseño del colector de admisión. Es necesario poner especial atención en la orientación de los conductos, y en la estructura interna y la superficie para tratar de ser muy fiel a la geometría real, ya que ello determina la predicción de la dispersión. Esta aproximación de modelado cuasi tridimensional (3D) es posible gracias a un programa específico que importa la información necesaria desde un archivo CAD al programa de modelado 1D. Respecto a la parte experimental, el estudio concluye que cuando la dispersión de EGR es baja, los niveles de opacidad se reducen en todos los puntos de funcionamiento. Sin embargo, por encima de ciertos niveles de dispersión de EGR, la opacidad crece seriamente con diferentes pendientes según el punto de operación. El estudio permite cuantificar este límite de dispersión de EGR. La dispersión de EGR incrementa el consumo de combustible por encima del 6.9%. Respecto a la parte de modelado, el estudio concluye que cuando la distribución de EGR entre conductos medida experimentalmente es asimétrica y presenta un alto patrón de concavidad o convexidad, el modelo no predice adecuadamente la distribución del EGR. El estudio concluye que, aunque en los ensayos experimentales la tasa de EGR afecta a la dispersión de EGR, el modelo 1D no es tan sensible como para predecir esta influencia cuando la tasa de EGR está por debajo del 10%.
[CA] L'objectiu de l'estudi és doble. Per una banda, determinar l'efecte de la dispersió de la recirculació de gasos d'escapament d'alta pressió (HP EGR per les seues sigles en anglès) en les emissions d'òxids de nitrogen (NOx) i fums en motors dièsel d'automoció en operacions de funcionament constants. La investigació quantifica les emissions de NOx i fums en funció del nivell de dispersió d'EGR d'alta pressió entre cilindres. Per una altra banda, l'objectiu és explorar els límits del modelatge unidimensional (1D) per predir el moviment del flux dels gasos en la complexa situació en què aquests entren als cilindres des del col·lector d'admissió. Els experiments van ser realitzats en un banc de proves amb un motor dièsel de 1.6 litres. Per detectar la dispersió d'EGR d'alta pressió es va instal·lar un sistema de vàlvules en els conductes d'admissió de cada cilindre per mesurar el percentatge de CO2 i per tant la taxa d'EGR. De la mateixa manera es va instal·lar també un sistema de vàlvules d'escapament, cilindre a cilindre, per mesurar les emissions de NOx. A més també es va instal·lar un sensor de fums en la línia d'escapament, aigües avall de la turbina, per mesurar l'efecte de la dispersió d'EGR d'alta pressió en les emissions de fums, així com el sensor de mesura de la resta d'emissions aigües avall de la turbina. S'han estudiat 9 punts de funcionament diferents amb distintes velocitats i nivells de càrrega, per la qual cosa el mapa motor s'ha estudiat en profunditat, des de 1250 fins a 3000 rpm i entre 3 i 20 bar de pressió mitjana efectiva (BMEP per les seues sigles en anglès). La taxa d'EGR varia entre 5 i 42 %, depenent del punt de funcionament. La geometria del model reprodueix la geometria del motor dièsel d'automoció d'1.6 litres en el qual es van realitzar tots els assajos experimentals. La metodologia centrada en les ferramentes experimentals combina aparells de mesura tradicional amb un sistema de vàlvules específic que ofereixen una informació precisa quant a la concentració d'espècies tant al col·lector d'admissió com al d'escapament. L'estudi es va realitzar a emissions de NOx constants per observar l'efecte de la dispersió d'EGR en els valors d'opacitat. Quant a la metodologia centrada en les ferramentes de modelatge, les condicions de contorn i tota la informació necessària per posar en marxa el model prové dels resultats dels assajos experimentals mesurats amb els diferents sensors i aparells mencionats anteriorment, molts d'ells necessaris per ajustar el model. La part més important per estudiar la capacitat de predicció del model és el disseny del col·lector d'admissió. És necessari posar especial atenció a l'orientació dels conductes, i a l'estructura interna i la superfície per tractar de ser molt fidel a la geometria real, ja que determina la predicció de la dispersió. Esta aproximació del model quasi-tridimensional (3D) és possible gràcies a un programa específic que importa la informació necessària des d'un arxiu de disseny assistit per ordinador (CAD) al programa de modelat 1D. Respecte a la part experimental, l'estudi conclou que quan la dispersió d'EGR és baixa, els nivells d'opacitat es redueixen en tots els punts de funcionament. Tanmateix, per damunt de certs nivells de dispersió d'EGR, l'opacitat creix seriosament amb diferents pendents segons el punt d'operació. L'estudi permet quantificar aquest límit de dispersió d'EGR. A més, la dispersió d'EGR podria contribuir a incrementar el consum de combustible per damunt del 6.9%. Respecte a la part de modelatge, l'estudi conclou que quan la distribució d'EGR entre conductes mesurada experimentalment és asimètrica i presenta un alt patró de concavitat o convexitat, el model no prediu adequadament la distribució d'EGR. A més, l'estudi conclou que, tot i que en els assajos experimentals la taxa d'EGR afecta a la dispersió d'EGR, el model 1D no és tan sensible com per predir aquesta influència quan la taxa d’EGR està per baix del 10%.
[EN] The objective of the study is twofold. On the one hand, it is to determine the effect of the high pressure (HP) exhaust gas recirculation (EGR) dispersion in automotive diesel engines on NOx and smoke emissions in steady engine operation. The investigation quantifies the smoke emissions as a function of the dispersion of the HP EGR among cylinders. On the other hand, it is to explore the limits of the one-dimensional (1D) modeling to predict the movement of the flow in a complex situation as the gases get into the cylinders from the intake manifold. The experiments are performed on a test bench with a 1.6 liter automotive diesel engine. In order to track the HP EGR dispersion in the intake pipes, a valves system to measure CO2, hence EGR rate, pipe to pipe was installed. In the same way, a valves device to measure NOx emissions cylinder to cylinder in the exhaust was installed too. Moreover a smoke meter device was installed in the exhaust line, downstream the turbine, to measure the effect of the HP EGR dispersion on smoke emissions. A probe to measure the other raw emissions was installed downstream the turbine, too. Nine different engine running conditions were studied at different speed and load, thus the engine map was widely studied, from 1250 rpm to 3000 rpm and between 3 and 20 bar of BMEP. The EGR rate variates between 5 and 42 % depending on the working operation point. The geometry of the model reproduces the geometry of a 1.6 liter diesel automotive engine where the tests were performed. It includes an HP-EGR line and the device that was installed to perform the experiments to control the dispersion. The methodology focused on experimental tools combining traditional measuring devices with a specific valves system which offers accurate information about species concentration in both the intake and the exhaust manifolds. The study was performed at constant raw NOx emissions to observe the effect of the EGR dispersion in the opacity values. Regarding the methodology focused on modeling tools, the boundary conditions and all the necessary information to run the model comes from experimental results measured with the different sensors and devices mentioned before. Much of them were needed to adjust the model. The most important part of the modeling to study the capacity of the prediction of the EGR dispersion is the layout of the intake manifold. It is necessary put special attention to the orientation of the pipes, and the internal structure and surface trying to mimic the real geometry because it determinates the prediction of the dispersion. This approximation to quasi-three-dimensional (3D) modeling is possible thanks to a specific software that imports the necessary information from a computer-aided design (CAD) file to the 1D modeling software. Concerning the experimental results, the study leads to conclude that when the EGR dispersion is low, the opacity presents reduced values in all operation points. However, above a certain level of EGR dispersion, the opacity increases dramatically with different slopes depending on the engine running condition. This study allows quantifying this EGR dispersion threshold. In addition, the EGR dispersion could contribute to an increase in the engine fuel consumption up to 6.9%. Regarding to the modeling part, the study concludes that when the experimental EGR distribution among pipes is asymmetric and presents high concavity or convexity spatial pattern, the model does not predict properly the EGR distribution. In addition, the study concludes that, although in the experimental tests the EGR rate affects to the EGR dispersion, the 1D model is not too sensitive to predict this influence when the EGR rate is lower than 10%.
The respondent wishes to acknowledge the financial support received by contract FPI 2015 S2 3101 of Programa de Apoyo a la Investigación y Desarrollo (PAID) from Universitat Politècnica de València (UPV).
Miguel García, J. (2021). Analysis of the high pressure EGR dispersion among cylinders in automotive diesel engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/161889
TESIS

This thesis deals with turbulent mixing processes occurring in internal combustion engines, when applying exhaust gas recirculation (EGR). EGR is a very efficient way to reduce emissions of nitrogen oxides (NOx) in internal combustion engines. Exhaust gases are recirculated and mixed with the fresh intake air, reducing the oxygen con- centration of the combustion gas and thus the peak combustion temperatures. This temperature decrease results in a reduction of NOx emissions. When applying EGR, one is often faced with non-uniform distribution of exhaust among and inside the cylinders, deteriorating the emission performance. The mixing of exhaust gases and air is governed by the flow in the engine intake manifold, which is characterized by unsteadiness due to turbulence and engine pulsations. Moreover, the density cannot be assumed to be constant due to the presence of large temperature variations.Different flow cases having these characteristics are computed by compressible Large Eddy Simulations (LES). First, the stationary flows in two T-junction type geometries are investigated. The method is validated by comparison with experimental data and the accuracy of the simulations is confirmed by grid sensitivity studies. The flow structures and the unsteady flow modes are described for a range of mass flow ratios between the main and the branch inlet. A comparison to RANS computations showed qualitatively different flow fields.Thereafter, pulsating inflow conditions are prescribed on the branch inlet in or- der to mimic the large pulsations occurring in the EGR loop. The flow modes are investigated using Dynamical Mode Decomposition (DMD).After having established the simulation tool, the flow in a six-cylinder engine is simulated. The flow is studied by Proper Orthogonal Decomposition (POD) and DMD. The mixing quality is studied in terms of cylinder-to-cylinder non-uniformity and temporal and spatial variances. It was found that cycle-averaging of the concentration may give misleading results. A sensitivity study with respect to changes in the boundary conditions showed that the EGR pulsations, have large influence on the results. This could also be shown by POD of the concentration field showing the significance of the pulses for the maldistribution of exhaust gases.Finally, the flow in an intake manifold of a four-cylinder engine is investigated in terms of EGR distribution. For this geometry, pipe bends upstream of the EGR inlet were found to be responsible for the maldistribution.

QC 20130207

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Guensler, Randall; Committee Member: Rodgers, Michael; Committee Member: Russell, Armistead.

Increasing the efficiency of conventional power plants is a crucial aspect in the quest of reducing the energy consumption of the world and to having sustainable energy systems in the future. Thus, within the scope of this thesis the possible efficiency improvements for the Wärtsilä 18V50DF model gas engine based combine power generation options are investigated by recovering waste heat of the engine via Organic Rankine cycle (ORC).  In order to this, four different ORC models are simulated via Aspen Plus software and these models are optimized for different objective functions; power output and price per unit of electricity generation. These ORC models are: regenerative Organic Rankine cycle (RORC), cascaded Organic Rankine cycle with an economizer (CORCE), cascaded Organic Rankine cycle with two heat sources (CORC2) and cascaded Organic Rankine cycle with three heat sources (CORC3). In the cascaded cycle models there are two loops which are coupled with a common heat exchanger that works as a condenser for the high temperature (HT) loop and as a preheater for the low temperature (LT) loop. By using this common heat exchanger, the latent heat of condensation of the HT loop is utilized. The engine’s hot exhaust gases are used as main heat source in all the ORC models. The engine’s jacket water is utilized in the CORC2 models as an additional heat source to preheat the LT working fluid. In the CORC3 models engine’s lubrication oil together with the jacket water are used as additional sources for preheating the LT loop working fluid. Thus, the suitability of utilizing these two waste heat sources is examined. Moreover, thermodynamic and economic analyses are performed for each model and the results are compared to each other. The effect of different working fluids, condenser cooling water temperatures, superheating on cycles performance is also evaluated. The results show that with the same amount of fuel the power output of the engine would be increased 2200 kW in average and this increases the efficiency of the engine by 6.3 %. The highest power outputs are obtained in CORC3 models (around 2750 kW) whereas the lowest are in the RORC models (around 1800 kW). In contrast to the power output results, energetic efficiencies of the RORC models (around 30 %) are the highest and CORC3 models (around 22 %) are the lowest. In terms of exergetic efficiency, the highest efficiencies are obtained in CORC2 (around 64.5 %) models whereas the lowest in the RORC models (around 63 %). All the models are found economically feasible since thermodynamically optimized models pay the investment costs back in average of 2 years whereas the economically optimized ones in 1.7. The selection of the working fluid slightly affects the thermodynamic performance of the system since in all the ORC configurations Octamethyltrisiloxane (MDM) working fluid cycles achieve better thermodynamic performances than Decamethyltetrasiloxane (MD2M) working fluid cycles. However, the choice of working fluid doesn’t affect the costs of the system since both working fluid cycles have similar price per unit of electricity generation. The CORC2 models obtain the shortest payback times whereas the CORC3 models obtain the longest Thus the configuration of the ORC does affect the economic performance. It is observed from the results that increasing the condenser cooling water temperature have negative impact on both thermodynamic and economic performances. Also, thermodynamic performances of the cycles are getting reduced with the increasing degree of superheating thus superheating negatively affects the cycle’s performances. The engine’s jacket water and lubrication oil are found to be sufficient waste heat sources to use in the ORC models.

La lutte contre la pollution et le respect de normes strictes en matiere d'emission sont des soucis tres actuels pour les constructeurs automobiles; dans ce contexte, il est primordial pour eux de disposer d'un systeme fiable et precis d'analyse des gaz d'echappement. La sensibilite de ce systeme doit permettre de mesurer, dans des melanges riches en co#2 et vapeur d'eau, des teneurs de l'ordre du ppm pour la plupart des especes tout en envisageant des analyses plus critiques encore pour les vehicules possedant des equipements catalytiques. Le but de la presente etude, menee au cea en association avec le gie peugeot renault, est la conception d'un systeme base sur un spectrometre irtf permettant le suivi, quasiment en temps reel, de l'evolution de la composition des gaz d'echappement. Le travail a consiste: 1) a determiner les parametres de travail adequats, 2) a realiser une cellule originale particulierement adaptee; 3) a creer plusieurs programmes d'analyse susceptibles de prendre en compte les differentes configurations rencontrees dans les gaz d'echappement; 4) a observer les constituants isoles pour determiner les parametres specifiques d'analyse de chacun, 5) a etudier les phenomenes apparaissant dans les melanges; 6) a envisager des solutions pour la mesure des constituants particulierement critiques. La fin de cette etude a donne lieu a l'evaluation sur site chez les constructeurs automobiles de plusieurs systemes commerciaux specialement dedies a l'analyse des gaz d'echappement des vehicules pour profiter des competences acquises dans ce domaine

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. Life-cycle 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 diesel-fueled 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; 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.
ID: 030646260; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.Env.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 72-77).
M.S.Env.E.
Masters
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Environmental Engineering

Thesis (M.S.C.E.)--University of Toledo, 2008.
Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science in Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 81-92.

Spark ignited engines are still important for conventional as well as for hybrid power trains and are thus objective to optimization. Today a lot of functionalities arise from software solutions, which have to be calibrated. Modern engine technologies provide an extensive variability considering their valve train, fuel injection and load control. Thus, calibration efforts are really high and shall be reduced by introduction of virtual methods. In this work a physical 0D combustion model is set up, which can cope with a new generation of spark ignition engines. Therefore, at first cylinder thermodynamics are modeled and validated in the whole engine map with the help of a real-time capable approach. Afterwards an up to date turbulence model is introduced, which is based on a quasi-dimensional k-epsilon-approach and can cope with turbulence production from large scale shearing. A simplified model for ignition delay is implemented which emphasizes the transfer from laminar to turbulent flame propagation after ignition. The modeling is completed with the calculation of overall heat release rates in a 0D entrainment approach with the help of turbulent flame velocities. After validation of all sub-models, the 0D combustion prediction is used in combination with a 1D gas exchange analysis to virtually calibrate the modern engine torque structure and the ECU function for exhaust gas temperature with extensive simulations
Moderne Ottomotoren spielen heute sowohl in konventionellen als auch hybriden Fahrzeugantrieben eine große Rolle. Aktuelle Konzepte sind hochvariabel bezüglich Ventilsteuerung, Kraftstoffeinspritzung und Laststeuerung und ihre Optimierungspotentiale erwachsen zumeist aus neuen Softwarefunktionen. Deren Applikation ist zeit- und kostenintensiv und soll durch virtuelle Methoden unterstützt werden. In der vorliegenden Arbeit wird ein physikalisches 0D Verbrennungsmodell für Ottomotoren aufgebaut und bis zur praktischen Anwendung geführt. Dafür wurde zuerst die Thermodynamik echtzeitfähig modelliert und im gesamten Motorenkennfeld abgeglichen. Der Aufbau eines neuen Turbulenzmodells auf Basis der quasidimensionalen k-epsilon-Gleichung ermöglicht anschließend, die veränderlichen Einflüsse globaler Ladungsbewegung auf die Turbulenz abzubilden. Für den Brennverzug wurde ein vereinfachtes Modell abgeleitet, welches den Übergang von laminarer zu turbulenter Flammenausbreitung nach der Zündung in den Vordergrund stellt. Der restliche Brennverlauf wird durch die physikalische Ermittlung der turbulenten Brenngeschwindigkeit in einem 0D Entrainment-Ansatz dargestellt. Nach Validierung aller Teilmodelle erfolgt die virtuelle Bedatung der Momentenstruktur und der Abgastemperaturfunktion für das Motorsteuergerät

Petroleum powered vehicles emit volatile organic compounds (VOCs) through combustion that contributes to the pollution of the environment. A technique in the 1970s was developed to decrease these emissions, especially for nitrogen oxides (NOx) and sulphuric oxides (SOx) which is called exhaust gas recirculation (EGR). The technique works by recirculating a portion of the combusted gas back into the engine, this limits the NOx and SOx emissions because of lower temperatures and less available oxygen. The problems that follow these effects is the formation and condensation of acids that corrode the material of the EGR system, which are created by many different reactions. It is of importance to understand how the compounds in the EGR system behaves through analysis of authentic and simulated condensates, which is why a quantitative method for these compounds are of interest. The aim of the project was to develop a simple quantitative analysis method for formic acid, acetic acid, and lactic acid in aqueous solution, which was done at Gränges Sweden AB. The technique used for detection and quantification was gas chromatography (GC) coupled to a flame ionization detector (FID) and a water compatible polyethylene glycol (PEG) column. Fractional factorial design (FFD) was used for determination of adequate operating parameters of the GC method and the sample preparation. Sample preparation only required filtration and pH adjustment prior to direct aqueous injection (DAI) to the chromatographic instrument. Detection of the analytes was very difficult because of non-compatibility with the FID, and quantification of asymmetric peak shapes made this problem worse, omitting lactic acid from further analysis. Limit of detection (LOD) and limit of quantification (LOQ) was 490 and 1640 ppm for formic acid and 120 and 400 ppm for acetic acid, with an injection volume of 0.3 μL and split ratio 10:1. Limits were too high for every EGR sample leaving no peaks detected for the sample preparation used. Further development should be done with complementary techniques and sample reprocessing in order to quantify the compounds.

This research studied the effects of evaporative spray cooling on air-air ejector performance. Experimental data was collected for the purpose of validating computational simulations. This was done by modifying an existing air-air ejector to accommodate four spray flow nozzles which were used to atomize cooling water. The only parameter that was varied throughout the study was the mass flow rate of cooling water. One single phase (air) case and four spray flow cases where performed and analyzed. The purpose of the single phase experiment was to have a baseline for the air-air ejector performance and isolate the sources of experimental error contributed by spray flow. Three specialized multiphase flow instruments were designed and fabricated by the author to measure, gas phase temperatures, spray mass flow rates, and mixture total pressures. A computational study was performed using the collected experimental data for inlet continuous phase and spray mass flow as boundary conditions for equivalent simulations. A temperature gradient modified turbulence model was written by the author to better predict the mixing rates found experimentally which was used for the duration of this research. Secondary droplet breakup was modeled by the author using empirical correlations following preliminary simulations recognizing the deficiencies of commercially available breakup models. Comparison of experimental and computational cases produced mixed results. It was found that the experimental gas temperature instrument performed poorly for the local droplet fluxes encountered during testing. The spray sampling probe showed more promising results with two integrated mass flows agreeing within 6% of computational simulations. The total pressure probe solved the issue of pressure port clogging, but measurements were representative of mixture density which made an inferred velocity calculation difficult. It was found that evaporation of spray flow before the nozzle exit plane caused a reduction in dynamic pressure and a reduction in back pressure. A full scale simulation was performed to determine the effects of scaling on evaporative spray cooling performance. It was found that for the geometrically similar full scale model, the total droplet surface area and particle residence times scaled up with the model which increased cooling performance.
Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-05-18 14:47:50.52

碩士
崑山科技大學
環境工程研究所
96
This research is focus on analyzing the Tedlar bag test of NIEA A734.70, published by Environmental Protection Administration, Taiwan. However, this method only focus on 24 species VOCs (C5-C10), because of considering the complex factor of discharging gas, and the compound which including high carbon. It causes the condensation on analyzing C11-C14 VOCs with the higher molecular weight, which are low evaporating for collecting the coagulation on the bag in the room temperature. Meanwhile, the method of non-extreme organic compound environmental assay never mentions the avail of cylinder technology. This research focuses on the cylinder method and verifies the avail of its assay technology and collecting the alkane, terpene, alkyne, hydrocarbon and other compounds in the pipe. The result shows that there are the affections on cold coagulation and compound diosmose by the Tedlar Bag method to collect the extreme and non-extreme compounds. Comparing the quality control line (above 0.985), precision around ±30% and the accuracy ±25% by cylinder draw out method and NIEA A715.12B canister method. However, draw out of cylinder method focus the C5-C10 However, cylinder accuracy and precision for C5-C10 VOC analysis, R-squre between 0.985-0.996, the accuracy of 70% -135%, the precision of 2.8% -14.0%, but obviously the species of C11-C14 VOCs; R-squre of n-tridecane and n-tetradecane between 0.95-0.96, the accuracy of the C11-C14 VOCs between 53%-161%, the precision is no excess of ± 25% but as well as high In the ± 20%. By the circulating method of cylinder, the accuracy of C5-C8 VOCs is less than ± 10%, and precision of less than ±3%, opposite the draw out of cylinder high than many. C9-C14 species the accuracy of 101%-201% and precision of ±9.42%-±16.67%. C9-C14 species change over of the higher reasons, may be due to the circulating method of cylinder sampling into the GC/FID of pressure is not to agree with more higher variation. In addition, exhaust gas of stacks collection of detection compared by circulating and draw out of cylinder method due to sampling into methods and chemical characteristics of the same species, resulting in GC / FID analysis is relatively low.

碩士
國立成功大學
機械工程學系碩博士班
95
The thermal-hydraulic characteristics for both inside and outside tubes of a recuperator were discussed in this study. The radiation effect was considered between the tube wall and the working fluid for evaluating the outside tube performance. For inside tube, the heat transfer and pressure drop data for turbulent flow were discussed for different kinds of tube inserts including longitudinal strip inserts with and without holes and twisted-tape inserts with varied twist angle (α=15.3o, 24.4o and 34.3o). Form the simulation results, it is found that the heat transfer coefficient of the tube bank with strip inserts, strip inserts with holes, triangular prism, circular cylinder and twisted-tape inserts of α=15.3o, 24.4o, and 34.3o are respectively 5-16%, 12-27%, 3-16%, 3-19%, 6-32%, 12-43% and 25-61% than those for tube bank without using inserts. And pressure drop are respectively 90-140%, 220-250%, 130-160%, 200-350%, 130-170%, 240-280% and 290-330% than those for tube bank without using inserts. The numerical results of heat transfer coefficient for tube bank without using inserts, strip inserts without and with holes, triangular prism, circular cylinder, and twisted-tape inserts (α=15.3o) are respectively agreed with the experimental data within 3.6%, 4.1%, 4.5%, 6.9%, 4.8% and 8.5%. Furthermore, the results indicate that it is possible to obtain a reduction in area of approximately 20%.

A system intended to detect, classify, and track radioactive sources in moving vehicle traffic is under development at Lawrence Livermore National Laboratory (LLNL). This system will fuse information from a network of sensor suites to provide real time tracking of the location of vehicles emitting gamma and/or neutron radiation. This work examined aspects of the source terms of interest and applicable gamma detection technologies for passive detection of emitted gamma radiation. The severe restriction placed on the length of count due to motion of the source is presented. Legitimate gamma sources expected in traffic are discussed. The requirement to accurately classify and discriminate against these "nuisance" sources and cost restraints dictate the choice of NaI(Tl) detectors for this application. The development of a capability to automatically analyze short duration, low signal-to-noise NaI(Tl) spectra collected from vehicles passing a large, stationary detector is reported. The analysis must reliably discriminate between sources commonly transported in motor vehicles and alert on the presence of sources of interest. A library of NaI(Tl) spectra for 33 gamma emitting sources was generated with MCNP4B Monte Carlo modeling. These simulated spectra were used as parent distributions, from which multiple realizations of short duration spectra were sampled. Principal component analysis (PCA) of this data set yielded eigenvectors that enable the conversion of unknown spectra into principal component space (PCS). An algorithm using least squares fitting of the positions of library sources in PCS as basis functions, capable of identifying library nuclides in unidentified spectra, is reported. Analysis results for experimental spectra are compared against those achieved using simulated spectra. A valuable characteristic of this method is its ability to identify sources despite unknown shielding geometries. The successful identification of radionuclides and false identification rates found were excellent for the signal levels involved. For many of the sources, identification performance against experimental spectra was somewhat poorer than found using simulated spectra. The results demonstrate that the PCA-based algorithm is capable of high success rates in identifying sources in short duration, low signal-to-noise NaI(Tl) spectra.
Graduation date: 2001

碩士
國立高雄海洋科技大學
輪機工程研究所
104
This experiment by vertical single cylinder four stroke diesel generator set as the experimental machine, and use the current domestic general type of fishing boats as diesel engine fuel. Oil type by burning oil for fishing vessels and fishing boats oil mixed pure ethyl ether, according to the proportion (0.5%, 1%, 1.5%, 2%) mixed way. In the four kinds of resistive loads measuring the physical properties of exhaust gas temperature and burning diesel engine exhaust product quantity and remaining oxygen content. Test results can understand the four different load conditions, different ether added, four type combustion boat pure ether of diesel oil and adding different ratios of prime mover caused by physical and chemical conditions. Explore ether added to diesel oil to the improving effect of air pollution, and the choice of additives for the future reference.

博士
國立成功大學
機械工程學系碩博士班
90
In Taiwan, many existing simple-cycle gas turbine generation sets (GENSET) that were originally designated as peak load units can be started up in a very short time(say 15 minutes), but suffer from very low efficiency (around 26%). Unfortunately, the simple-cycle units are forced to operate entire summer daytime due to the power shortage in Taiwan. In addition, the power generation of gas turbine degrades significantly during summer peaking hours (when electricity is most needed) due to the hot ambient temperatures. The aim of this research is to evaluate the feasibility of retrofitting these simple-cycle units into more advanced cycle with higher power output and efficiency. A computer code was developed to evaluate the performance improvement of different modifications for simple cycle GENSETs. The accuracy of our developed code was validated by simulating the actual GE Frame 6B and 7B simple-cycle GENSETs. The results from computer simulation indicated that the steam injection gas turbine (STIG) cycle with regenerator was found to be the most effective in boosting both the power output and thermal efficiency among many proven technologies. From thermoeconomic analysis, the retrofitting project with STIG and regeneration features also has the best rate of return. In the consideration of local hot/humid weather and the complication of retrofitting, the integration of STIG and inlet air cooling (IAC) was also proposed in this study. This integrated system can boost 60% of power output under hot and humid weather condition and greatly depress the emission of NOx. The performance of this system is less sensitive to ambient temperature, and its heat-to-power ratio can be swiftly adjusted to meet the actual demand.

Indiana University-Purdue University Indianapolis (IUPUI)
This paper presents a novel approach of particulate material (soot) measurement in a Diesel particulate filter using Electrical Capacitance Tomography. Modern Diesel Engines are equipped with Diesel Particulate Filters (DPF), as well as on-board technologies to evaluate the status of DPF because complete knowledge of DPF soot loading is very critical for robust efficient operation of the engine exhaust after treatment system. Emission regulations imposed upon all internal combustion engines including Diesel engines on gaseous as well as particulates (soot) emissions by Environment Regulatory Agencies. In course of time, soot will be deposited inside the DPFs which tend to clog the filter and hence generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot build-up, regeneration of the DPF must be done as an engine exhaust after treatment process at pre-determined time intervals. Passive regeneration use exhaust heat and catalyst to burn the deposited soot but active regeneration use external energy in such as injection of diesel into an upstream DOC to burn the soot. Since the regeneration process consume fuel, a robust and efficient operation based on accurate knowledge of the particulate matter deposit (or soot load)becomes essential in order to keep the fuel consumption at a minimum. In this paper, we propose a sensing method for a DPF that can accurately measure in-situ soot load using Electrical Capacitance Tomography (ECT). Simulation results show that the proposed method offers an effective way to accurately estimate the soot load in DPF. The proposed method is expected to have a profound impact in improving overall PM filtering efficiency (and thereby fuel efficiency), and durability of a Diesel Particulate Filter (DPF) through appropriate closed loop regeneration operation.