Selective Exhaust Gas Recirculation (S-EGR) consists of selectively transferring CO2 from the exhaust gas stream of a gas-fired power plant into the air stream entering the gas turbine compressor. Unlike in “non-selective” Exhaust Gas Recirculation (EGR) technology, recirculation of, principally, nitrogen does not occur, and the gas turbine still operates with a large excess of air. Two configurations are proposed: one with the CO2 transfer system operating in parallel to the post-combustion carbon capture (PCC) unit; the other with the CO2 transfer system operating downstream of, and in series to, the PCC unit. S-EGR allows for higher CO2 concentrations in the flue gas of approximately 13-14 vol%, compared to 6.6 vol% with EGR at 35% recirculation ratio. The oxygen levels in the combustor are approximately 19 vol%, well above the minimum limit of 16 vol% with 35% EGR reported in literature. At these operating conditions, process model simulations show that the current class of gas turbine engines can operate without a significant deviation in the compressor and the turbine performance from the design conditions. Compressor inlet temperature and CO2 concentration in the working fluid are critical parameters in the assessment of the effect on the gas turbine net power output and efficiency. A higher turbine exhaust temperature allows the generation of additional steam which results in a marginal increase in the combined cycle net power output of 5% and 2% in the investigated configurations with S-EGR in parallel and S-EGR in series, respectively. With aqueous monoethanolamine scrubbing technology, S-EGR leads to operation and cost benefits. S-EGR in parallel operating at 70% recirculation, 97% selective CO2 transfer efficiency and 96% PCC efficiency results in a reduction of 46% in packing volume and 5% in specific reboiler duty, compared to air-based combustion CCGT with PCC, and of 10% in packing volume and 2% in specific reboiler duty, compared to 35% EGR. S-EGR in series operating at 95% selective CO2 transfer efficiency and 32% PCC efficiency results in a reduction of 64% in packing volume and 7% in specific reboiler duty, compared to air-based, and of 40% in packing volume and 4% in specific reboiler duty, compared to 35% EGR. An analysis of key performance indicators for selective CO2 transfer proposes physical adsorption in rotary wheel systems as an alternative to selective CO2 membrane systems. A conceptual design assessment with two commercially available adsorbent materials, activated carbon and Zeolite X13, shows that it is possible to regenerate the adsorbent with air at near ambient temperature and pressure. Yet, a significant step change in adsorbent materials is necessary to design rotary adsorption systems with dimensions comparable to the largest rotary gas/gas heat exchanger used in coal-fired power plants, i.e. approximately 24 m diameter and 2 m height. An optimisation study provides guidelines on the equilibrium parameters for the development of materials. Finally, a technical feasibility study of configuration options with rotary gas/gas heat exchangers shows that cooling water demand around the post-combustion CO2 capture system can be drastically reduced using dry cooling systems where gas/gas heat exchangers use ambient air as the cooling fluid. Hybrid cooling configurations reduce cooling and process water demand in the direct contact cooler of a wet cooling system by 67% and 35% respectively, and dry cooling configurations eliminate the use of process and cooling water and achieve adequate gas temperature entering the absorber.

Legislators steadily increase the demands on lowered emissions from heavy duty vehicles. To meet these demands it is necessary to integrate technologies like Exhaust Gas Recirculation (EGR) and Variable Geometry Turbochargers (VGT) together with advanced control systems. A control structure with PID controllers and selectors is proposed and investigated for coordinated control of EGR valve and VGT position in heavy duty diesel engines. Main control goals are to fulfill the legislated emission levels, to reduce the fuel consumption, and to fulfill safe operation of the turbocharger. These goals are achieved through regulation of normalized oxygen/fuel ratio and intake manifold EGR-fraction. These are chosen as main performance variables since they are strongly coupled to the emissions, compared to manifold pressure or air mass flow, which makes it easy to adjust set-points depending on e.g. measured emissions during an emission calibration process. In addition a mechanism for fuel efficient operation is incorporated in the structure, this is achieved by minimizing the pumping work. To design a successful control structure, a mean value model of a diesel engine is developed and validated. The intended applications of the model are system analysis, simulation, and development of model-based control systems. Model equations and tuning methods for the model parameters are described for each subsystem in the model. Static and dynamic validations of the entire model show mean relative errors that are less than 12%. Based on a system analysis of the model, a key characteristic behind the control structure is that oxygen/fuel ratio is controlled by the EGR-valve and EGR-fraction by the VGT-position, in order to handle a sign reversal in the system from VGT to oxygen/fuel ratio. For efficient calibration an automatic controller tuning method is developed. The controller objectives are captured in a cost function, that is evaluated utilizing a method choosing representative transients. The performance is evaluated on the European Transient Cycle. It is demonstrated how the weights in the cost function influence behavior, and that the tuning method is important in order to improve the control performance compared to if only a standard method is used. It is also demonstrated that the controller structure performs well regarding all control objectives. In combination with its efficient tuning, the controller structure thus fulfills all requirements for successful application. / Report code: LiU-TEK-LIC-2006:52.

Orientador: Marcelino Pereira do Nascimento / Resumo: Estudos recentes mostram tendência de desenvolvimento de sistemas capazes de recuperar energia dos gases de escape. Apesar de ser de fato uma fonte de energia, os sistemas para recuperação instalados na linha de exaustão mostram grande complexidade e necessidade de muito espaço de instalação. O presente estudo demonstra a viabilidade de recuperação de energia do sistema de arrefecimento com espaço de instalação reduzido. O estudo propõe a geração de vapor através de perfis instalados nas paredes da câmara de combustão e sua aplicação em um ciclo Rankine para gerar trabalho através de expansor. A simulação realizada com o software GT-Power demonstra a possibilidade de extrair calor das câmaras com a mesma eficiência de um sistema convencional de arrefecimento por água e aditivo. Paralelamente, o estudo propõe um sistema de recirculação de gases de exaustão sem o uso de um trocador de calor, patenteado pela empresa patrocinadora, complementando a estratégia para evitar o uso desnecessário de energia em um motor a combustão. Os gases provenientes da linha de baixa pressão da exaustão são admitidos pela linha de ar limpo, em alta pressão, através do uso de uma válvula Laval. Os resultados são provenientes de uma rotina de cálculo em Excel, base VBA. O sistema permite que os gases fluam por fora da turbina e elimina a necessidade de um trocador de calor, resolvendo o maior problema dos sistema convencionais de recirculação de gases em baixa pressão. A combinação das duas soluções,... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

La evidente generalización durante los últimos años del uso de turbocompresores en motores de combustión interna ha sido debida a un aumento necesario de la concienciación sobre las emisiones contaminantes y sus efectos sobre el medio ambiente y las personas. Las normativas sobre emisiones contaminantes se han endurecido, generalizando el uso de técnicas como la Recirculación de Gases de Escape de Ruta Larga bajo unas condiciones de operación más amplias, con una mayor tasa e incluso bajo condiciones ambiente frías, lo que ha generado potenciales problemas de condensación de agua y daño en el compresor. Además, la tendencia actual de reducir el tamaño del motor para reducir el consumo, llamada " downsizing", ha provocado que el compresor tenga que funcionar muy cerca del límite de bombeo, lo que ha provocado, junto al descrito aumento de recirculación de gases de escape, una mayor exigencia en cuanto a durabilidad y funcionalidad del mismo. Los problemas comentados están claramente condicionados por la configuración geométrica de la entrada del compresor, ya sea por la condensación causada por los gases de escape al ser mezclados con aire fresco o por la influencia sobre el límite de bombeo y el resto de prestaciones. En este trabajo se propone un modelo de predicción de condensación para ser integrado en un código comercial de mecánica de fluidos computacional (STAR-CCM+). Dicho modelo se plantea de forma que aumente en la menor medida posible el coste computacional, asumiendo ciertas limitaciones como la ausencia de caracterización de las gotas de agua. Una vez implementado, se contrastan los resultados frente a datos experimentales de ensayos de durabilidad: se correlacionan las predicciones del modelo frente al impacto de la condensación sobre el rodete del compresor en diferentes configuraciones geométricas y condiciones de operación. Posteriormente se estudia el impacto del propio compresor sobre el proceso de mezcla y la condensación, lo que permite después desacoplar el problema y reducir en dos órdenes de magnitud el tiempo de cálculo al poder obviar la simulación del compresor. En cuanto a la influencia de la geometría en el margen de bombeo y resto de parámetros, se proponen varias geometrías sencillas y se analiza su impacto. Primero, se realizan ensayos experimentales en banco motor, tanto estacionarios para medir rendimiento y ruido como transitorios para definir el bombeo. Después, se ejecutan simulaciones CFD y se estudian los fenómenos locales que aparecen, en los que se evidencia una sensibilidad elevada de la geometría sobre el margen de bombeo y el resto de parámetros. Se puede destacar el desempeño de la geometría de entrada cónica, que produce un aumento considerable del margen de bombeo sin repercusiones en el resto de condiciones de operación; y la tobera convergente-divergente, que aumenta el margen de bombeo pero, además, también aumenta ligeramente el rendimiento en el resto del mapa del compresor, aunque a costa de reducir moderadamente las prestaciones a alto gasto másico. / Popularization of turbochargers in internal combustion engines has been produced in the recent years due to a needful increase of awareness of pollutant emissions and their repercussion on the environment and the population. Pollutant emission regulations have tightened, causing techniques such Long Route Exhaust Gas Recirculation to operate under a wider range of operating conditions, with higher rates and even under very cold ambient conditions, which generates a potential problem of water condensation and compressor damaging. Additionally, the actual trend consisting in reducing the size of the engine to reduce fuel consumption, known as "downsizing", has caused the compressor to have to work close to the surge limit. Together with the aforementioned extension of LR-EGR usage range, these phenomena have induced an increase of the compressor design requirements, concerning durability and functionality. Both problems are governed by the geometrical configuration of the compressor inlet and can be, then, studied accordingly. In this work, a predictive condensation model is proposed for being embedded in a computational fluid dynamics commercial code (STAR-CCM+). To allow a potential optimization of a given geometry, the model should introduce as low additional computational effort as possible, assuming certain limitations, though. For example, the characterization of water droplets is neglected. Once the model is implemented and verified, the results are compared with experimental data obtained from durability tests performed to assess the erosion of the compressor wheel under condensation generated by different LR-EGR T-joint configurations and operating conditions. After, the influence of the compressor on the mixing process and generation of condensates is addressed, proving that the simulation of the compressor can be decoupled from the T-joint numerical domain and reducing by two orders of magnitude the simulation time. Concerning the impact of the inlet geometry on the surge margin and the other important compressor parameters, several simple geometries are proposed, and their influence is assessed. First, experimental tests performed on an engine test bench are carried out: steady measurements for obtaining efficiency and noise emission and transient tests for characterizing the surge limit. Then, 3D-CFD simulations are performed using similar geometries, studying the local phenomena that appear and proving thus the sensitivity of the inlet geometry to the surge margin and the performance of the compressor. It may be highlighted the performance of the tapered duct, that produces a considerable positive shift of the surge margin without worsening the rest of the parameters and the convergent-divergent nozzle, which in addition to considerably improving the surge margin also enhances the isentropic efficiency of the compressor at low and mid mass flow rates. Nevertheless, the throat becomes a drawback at high mass flow rates, decreasing the compression ratio and efficiency under such conditions. / L'evident generalització durant els últims anys de l'ús de turbocompressors en motors de combustió interna ha estat deguda a un augment necessari de la conscienciació sobre les emissions contaminants i els seus efectes sobre el medi ambient i les persones. Les normatives sobre emissions contaminants s'han fet més restrictives, generalitzant l'ús de tècniques com la Recirculació de Gasos d'Escap de Ruta Llarga sota unes condicions d'operació més àmplies, amb una major taxa i fins i tot sota condicions ambient fredes, fet que ha generat potencials problemes de condensació d'aigua i danys al compressor. A més, la tendència actual de reduir la grandària del motor per millorar el consum, anomenada " downsizing", ha provocat que el compressor haja de funcionar molt a prop del límit de bombeig, fet que ha provocat, junt amb el descrit augment de recirculació de gasos d'escap, una major exigència quant a la seua durabilitat i funcionament. Els problemes esmentats estan clarament condicionats per la configuració geomètrica de l'entrada del compressor, ja siga per la condensació causada pels gasos d'escap al ser barrejats amb aire fresc o per la influència sobre el límit de bombeig i la resta de prestacions. En aquest treball es proposa un model de predicció de condensació per a ser integrat en un codi comercial de mecànica de fluids computacional (STAR-CCM+). Dit model es planteja de manera que augmente en la menor mesura possible el cost computacional, assumint certes limitacions com l'absència de caracterització de les gotes d'aigua. Una vegada implementat, es contrasten els resultats enfront de dades experimentals d'assajos de durabilitat: correlacionen les prediccions del model enfront de l'impacte de la condensació sobre el rodet del compressor en diferents configuracions geomètriques i condicions d'operació. Posteriorment, s'estudia l'impacte del mateix compressor sobre el procés de barreja i la condensació, cosa que permet després desacoblar el problema i reduir en dos ordres de magnitud el temps de càlcul, ja que pot obviar-se la simulació del compressor. Quant a la influència de la geometria en el marge de bombeig i la resta de paràmetres, es proposen diverses geometries senzilles i s'analitza el seu impacte. Primerament, es realitzen assajos experimentals en banc motor, tant estacionaris per mesurar rendiment i soroll com transitoris per definir el bombeig. Després, s'executen simulacions CFD i s'estudien els fenòmens locals que apareixen, en els quals s'evidencia una sensibilitat elevada de la geometria sobre el marge de bombeig i la resta de paràmetres. Es pot destacar el rendiment de la geometria d'entrada cònica, que produeix un augment considerable del marge de bombeig sense repercussions en la resta de condicions d'operació; i la tovera convergent-divergent, que augmenta el marge de bombeig però, a més, també augmenta lleugerament el rendiment en la resta del mapa del compressor, encara que a costa de reduir moderadament les prestacions a alt flux màssic. / Tarí De Paco, D. (2018). Effect of inlet configuration on the performance and durability of an automotive turbocharger compressor [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/104410 / TESIS

En la actualidad, la industria del transporte es la encargada de satisfacer las necesidades logísticas del mundo. Los combustibles fósiles continúan siendo la principal fuente de energía de esta industria, y el motor Diésel, una de las tecnologías principales en la transformación de la energía química de estos combustibles en energía mecánica a través del proceso de combustión. Asociado a este proceso de transformación de la energía, un conjunto de efectos indeseados como las emisiones contaminantes o los gases de efecto invernadero han hecho movilizar a la comunidad científica. Dicha comunidad, ha realizado importantes esfuerzos en la investigación de soluciones limpias y eficientes que ayuden a minimizar los efectos indeseados del uso del motor Diésel. Sumado a los esfuerzos en la investigación, diferentes organizaciones gubernamentales han generado normativas que regulan estas emisiones contaminantes y la industria del motor ha reaccionado integrando soluciones tecnológicas que han hecho evolucionar la configuración original del motor Diésel. Debido a razones principalmente geopolíticas, el desarrollo económico a nivel mundial no se ha dado de manera homogénea, y en la actualidad, existe una disparidad global en cuanto a las exigencias en normativa de emisiones y la implementación de tecnologías para su control, siendo estas afectadas principalmente por sus costos. Es en este contexto donde se enmarca esta tesis doctoral, cuyo objetivo principal es el estudio de diferentes estrategias de inyección y de renovación de la carga como herramienta de control de emisiones en motores de encendido por compresión, teniendo en cuenta el costo de su integración. Se busca poder definir los límites de estas estrategias de bajo costo, determinando así su potencial real en la futura normativa de los mercados emergentes. Para abordar dicho objetivo, la tesis se ha desarrollado en tres etapas. En la primera, se ha realizado una aproximación teórico-experimental a las estrategias de inyección mediante modelado 3D-CFD y ensayos paramétricos en motor que permiten establecer como los parámetros de inyección responden al objetivo planteado. En la segunda etapa, se han estudiado las estrategias de renovación de la carga. Primero desde el modelado 1D para luego su posterior evaluación mediante su ensayo experimental en motor definiendo de esta manera las ventajas e inconvenientes de cada estrategia. En la tercera y última etapa, se han combinado todas las estrategias previamente estudiadas desde una aproximación experimental. De esta manera se puede alcanzar el objetivo de la tesis doctoral donde se ha comprobado la viabilidad de estas estrategias de bajo costo y se ha determinado su verdadero potencial como herramientas de control de las emisiones contaminantes. / En l'actualitat, la indústria del transport és l'encarregada de satisfer les necessitats logístiques del món. Els combustibles fòssils continuen sent la principal font d'energia d'aquesta indústria, i el motor Diésel, una de les tecnologies principals en la transformació de l'energia química d'aquests combustibles en energia mecànica a través del procés de combustió. Associat a aquest procés de transformació de l'energia, un conjunt d'efectes indesitjats com les emissions contaminants o els gasos d'efecte hivernacle han fet mobilitzar a la comunitat científica. Aquesta comunitat, ha realitzat importants esforços en la recerca de solucions netes i eficients que ajuden a minimitzar els efectes indesitjats de l'ús del motor Diésel. Sumat als esforços en la recerca, diferents organitzacions governamentals han generat normatives que regulen aquestes emissions contaminants i la indústria del motor ha reaccionat integrant solucions tecnològiques que han fet evolucionar la configuració original del motor Diésel. A causa de raons principalment geopolítiques, el desenvolupament econòmic a nivell mundial no s'ha donat de manera homogènia, i en l'actualitat, existeix una disparitat global quant a les exigències en normativa d'emissions i la implementació de tecnologies per al seu control, sent aquestes afectades principalment pels seus costos. És en aquest context on s'emmarca aquesta tesi doctoral, que el seu objectiu principal és l'estudi de diferents estratègies d'injecció i de renovació de la càrrega com a eina de control d'emissions en motors d'encès per compressió, tenint en compte el cost de la seua integració. Se cerca poder definir els límits d'aquestes estratègies de baix cost, determinant així el seu potencial real en la futura normativa dels mercats emergents. Per a abordar dita objectiva, la tesi s'ha desenvolupat en tres etapes. En la primera, s'ha realitzat una aproximació teòric-experimental a les estratègies d'injecció mitjançant modelatge 3D-CFD i assajos paramètrics en motor que permeten establir com els paràmetres d'injecció responen a l'objectiu plantejat. En la segona etapa, s'han estudiat les estratègies de renovació de la càrrega. Primer des del modelatge 1D per a després la seua posterior avaluació mitjançant el seu assaig experimental en motor definint d'aquesta manera els avantatges i inconvenients de cada estratègia. En la tercera i última etapa, s'han combinat totes les estratègies prèviament estudiades des d'una aproximació experimental. D'aquesta manera es pot aconseguir l'objectiu de la tesi doctoral on s'ha comprovat la viabilitat d'aquestes estratègies de baix cost i s'ha determinat el seu vertader potencial com a eines de control de les emissions contaminants. / Nowadays, the transport industry is responsible for accomplish the world's logistics requirements. Fossil fuels continue to be the main source of energy for this industry, and the Diesel engine, one of the main technologies in the transformation of the chemical energy of these fuels into mechanical energy through combustion. Associated with this process of energy transformation, a set of undesired effects such as pollutant emissions or greenhouse gases have challenged the scientific community that has made significant research efforts aiming clean and efficient solutions. Added to the scientific community efforts, different governmental organizations have created regulations in order to control these pollutant emissions and the engine industry has reacted by integrating technological solutions that have evolved the original configuration of the Diesel engine. Due mainly to geopolitical reasons, economic development worldwide has not occurred in a homogeneous manner, and currently, there is a global disparity regarding the requirements in emission regulations and the implementation of technologies for their control, mainly driven by their costs. It is in this framework where is set this doctoral thesis, with the main objective to study different injection and air management strategies as a tool for emission control in compression ignition engines, taking into account the cost of their integration. The aim is to be able to define the limits of these low-cost strategies, thus determining their real potential in the future regulations of emerging markets. To address this objective, the thesis has been developed in three stages. In the first one, a theoretical-experimental approach to the injection strategies has been carried out using 3D-CFD modeling and parametric engine tests which allow us to establish how the injection parameters help to reach the depicted thesis objective. In the second stage, the air management strategies have been studied. First, from the 1D modeling point of view in order to select the best option for this platform, and later to proceed with the experimental validation of this selection. Through the described approach is possible defining the advantages and disadvantages of each air management strategy. In the third and final stage, all previously studied strategies have been combined from an experimental approach. In this way, the evaluation of these cost-effective strategies has been defined and the fully potential as a tool for emissions control has been determined thus the objective of the doctoral thesis could be achieved. / Estepa Ruiz, D. (2018). Study of different fuel injection and air management strategies as a tool for emissions control in a compression ignition engine (Diesel engine) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113076 / TESIS

The scope of this thesis investigates value added by a turbocharger with an associated motor-generator unit to a diesel engine used by a commercial vehicle. A thermodynamic model of the engine was prepared in GT-SUITE software. Case studies were primary focused on a reduction of specific fuel consumption as well as a nitrogen oxides production using an energy recuperation of exhaust gas. Furthermore, there are described potential benefits of using an electric assistance in order to increase an exhaust gas temperature during a steady state engine operation. Additionally, there is an investigation of potential benefits of a turbocharger assistance in a transition engine mode operating during rapid acceleration of the vehicle. The results of individual analysis will be taken into account for a selection of turbocharger regarding specific engine implementation. The results of simulation suggest that it is possible to lower specific fuel consumption, production of nitrogen oxides, as well as accelerate turbocharger response.

No description available.

The pathophysiology of cytokines released by infiltrating white blood cells upon pancreatic beta cells is not fully understood. Early growth response gene-1 (Egr-1) expression is specifically and transiently up regulated in pancreatic beta cells in response to glucose. We hypothesized that interleukin-1 beta (IL-1▀) induction of nitric oxide alters glucose induced Egr-1 transcription levels. Egr-1 levels were assessed via western blot, nitric oxide was measured with a Griess Reagent kit and insulin levels via ELISA. Glucose induced both insulin and Egr-1 production in INS-1 cells. IL-1▀ dose dependently increased nitric oxide production over time and significantly attenuated glucose induced Egr-1 expression. Sodium nitroprusside dose dependently reduced glucose induced Egr-1 production. The data suggest a strong relationship between IL-1▀ induced nitric oxide production and the reduction of glucose stimulated Egr-1 production. The pathways altered by this cytokine could provide a better understanding of the pathophysiology leading to pancreatic beta cell death.

<p dir="ltr">An EGR Pump and High-Efficiency turbo were installed on a 13.6 L John Deere diesel engine. The main objective of this study was to examine how a high-efficiency turbocharger and an electric EGR pump can work together to improve fuel efficiency in engines without increasing the emission of NOx. The focus is on finding a balance, between enhancing efficiency and controlling emissions which will ultimately contribute to making vehicles eco-friendly and fuel-efficient.</p>

No description available.