Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications

[EN] On the last years engine researchers has been focused on improving engine efficiency in order to decrease CO2 emissions and fuel consumption, while fulfilling the increasingly stringent pollutant emissions regulations. In this framework, engine downsizing arises as a promising solution, and 2-stroke cycle operation offers the possibility of reducing the number of cylinders without incurring in NVH penalties. An experimental investigation has been performed to evaluate the performance of a newly-designed poppet valves 2-stroke engine, in terms of finding the proper in-cylinder conditions to fulfill the emission limits in terms of NOx and soot, keeping competitive fuel consumption levels. Moreover, present research work aims to improve the existing knowledge about the gas exchange processes in a 2-stroke engine with poppet valves architecture, and its impact over the combustion conditions, final exhaust emissions levels and engine efficiency. The experimental results confirm how this engine architecture presents high flexibility in terms of air management control to substantially affect the in-cylinder conditions. The in-cylinder oxygen concentration and density, which are the product of a given trapping ratio and delivered mass flow, were linked to pollutant emissions and performance by their impact on instantaneous adiabatic flame temperature and spray mixing conditions. After the optimization process, it was possible to minimize simultaneously NOx, soot and indicated fuel consumption, without observing a critical trade-off between the pollutant emissions and the fuel consumption. (C) 2013 Elsevier Ltd. All rights reserved.This research has been sponsored by the European Union in framework of the POWERFUL project, seventh framework program FP7/2007-2013, theme 7, sustainable surface transport, grant agreement No. SCP8-GA-2009-234032. The authors gratefully appreciate this support.Benajes Calvo, JV.; Novella Rosa, R.; De Lima Moradell, DA.; Tribotte, P.; Quechon, N.; Obernesser, P.; Dugue, V. (2013). Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications. Applied Thermal Engineering. 58(1-2):181-193. https://doi.org/10.1016/j.applthermaleng.2013.03.050S181193581-

An adapted heat transfer model for engines with tumble motion

In the last years, a growing interest about increasing the engine efficiency has led to the development of new engine technologies. The accurate determination of the heat transfer across the combustion chamber walls is highly relevant to perform a valid thermal balance while evaluating the potential of new engine concepts. Several works dealing with heat transfer correlations that consider the swirl motion are found in the literature; however, there is a lack of works dealing with heat transfer correlations which take into account the effect of the tumble movement. In this work, a new heat transfer model accounting for the tumble motion is presented. A two stroke HSDI Diesel engine with high tumble and no swirl is used to perform the theoretical study, the model development and its final calibration. Initially, a theoretical analysis of the gas movement phenomena is carried out based on CFD results and then, a model is developed and calibrated based on a skip-fire testing technique. Finally, a sensitivity study focused on evaluating the model robustness is performed. The results confirm an average RMSE reduction of 70% with respect to the Woschni model, being this consistent improvement qualitatively evidenced in the instantaneous heat transfer evolutionThe support of the Spanish Ministry of Economy and Competitiveness (TRA2013-41348-R) is greatly acknowledged.Olmeda González, PC.; Martín Díaz, J.; Novella Rosa, R.; Carreño, R. (2015). An adapted heat transfer model for engines with tumble motion. Applied Energy. 158:190-202. https://doi.org/10.1016/j.apenergy.2015.08.051S19020215

Analysis of combustion concepts in a newly designed two-stroke high-speed direct injection compression ignition engine

[EN] Two research paths are being followed to develop compression ignition engines, the extreme optimization of the conventional diesel combustion concept and the development of alternative combustion concepts. The optimization of the conventional diesel combustion concept focuses on controlling the combustion development in an attempt to improve pollutant emissions and efficiency. Additionally, extensive research in four-stroke engines already demonstrated the benefits of the partially premixed combustion concept in terms of emissions and efficiency when using high volatility and low reactivity fuels, such as gasoline-like fuels, from medium-to-high engine loads. A detailed optimization of the conventional diesel combustion concept has been performed in an innovative two-stroke poppet valves high speed direct injection compression ignition engine, in order to find the real limits of this engine configuration. Later, its compatibility with the partially premixed combustion concept using a high octane fuel (Research Octane Number 95) with a triple injection strategy for reducing pollutant emissions at medium-to-low load conditions has been evaluated considering also the impact on engine efficiency. Results confirm the potential for attaining state-of-the-art emission levels operating with diesel combustion, and how emissions and efficiency can be optimized by adjusting the air management settings without facing any additional trade-off aside from that usual between NOX and soot. The feasibility of combining this engine configuration with the gasoline partially premixed combustion concept for controlling pollutant emissions has been also corroborated and, with a fine tuned triple injection strategy, engine efficiency even improves compared to that obtained operating with well-optimized diesel combustion.This research has been partially sponsored by the European Union in framework of the POWERFUL project, FP7/2007-2013, theme 7, sustainable surface transport, grant agreement no. SCP8-GA-2009-234032.Benajes Calvo, JV.; Novella Rosa, R.; De Lima Moradell, DA.; Tribotté, P. (2015). Analysis of combustion concepts in a newly designed two-stroke high-speed direct injection compression ignition engine. International Journal of Engine Research. 16(1):52-67. https://doi.org/10.1177/1468087414562867S5267161Tribotte, P., Ravet, F., Dugue, V., Obernesser, P., Quechon, N., Benajes, J., … De Lima, D. (2012). Two Strokes Diesel Engine - Promising Solution to Reduce CO2 Emissions. Procedia - Social and Behavioral Sciences, 48, 2295-2314. doi:10.1016/j.sbspro.2012.06.1202Wang, X., Huang, Z., Zhang, W., Kuti, O. A., & Nishida, K. (2011). Effects of ultra-high injection pressure and micro-hole nozzle on flame structure and soot formation of impinging diesel spray. Applied Energy, 88(5), 1620-1628. doi:10.1016/j.apenergy.2010.11.035Payri, R., Gimeno, J., Viera, J. P., & Plazas, A. H. (2013). Needle lift profile influence on the vapor phase penetration for a prototype diesel direct acting piezoelectric injector. Fuel, 113, 257-265. doi:10.1016/j.fuel.2013.05.057Macian, V., Payri, R., Ruiz, S., Bardi, M., & Plazas, A. H. (2014). Experimental study of the relationship between injection rate shape and Diesel ignition using a novel piezo-actuated direct-acting injector. Applied Energy, 118, 100-113. doi:10.1016/j.apenergy.2013.12.025Manente, V., Johansson, B., Tunestal, P., & Cannella, W. (2009). Effects of Different Type of Gasoline Fuels on Heavy Duty Partially Premixed Combustion. SAE International Journal of Engines, 2(2), 71-88. doi:10.4271/2009-01-2668Kaiadi, M., Johansson, B., Lundgren, M., & Gaynor, J. A. (2013). Sensitivity Analysis Study on Ethanol Partially Premixed Combustion. SAE International Journal of Engines, 6(1), 120-131. doi:10.4271/2013-01-0269Sellnau, M. C., Sinnamon, J., Hoyer, K., & Husted, H. (2012). Full-Time Gasoline Direct-Injection Compression Ignition (GDCI) for High Efficiency and Low NOx and PM. SAE International Journal of Engines, 5(2), 300-314. doi:10.4271/2012-01-0384Benajes, J., Novella, R., De Lima, D., Tribotté, P., Quechon, N., Obernesser, P., & Dugue, V. (2013). Analysis of the combustion process, pollutant emissions and efficiency of an innovative 2-stroke HSDI engine designed for automotive applications. Applied Thermal Engineering, 58(1-2), 181-193. doi:10.1016/j.applthermaleng.2013.03.050Benajes, J., Molina, S., Novella, R., & De Lima, D. (2014). Implementation of the Partially Premixed Combustion concept in a 2-stroke HSDI diesel engine fueled with gasoline. Applied Energy, 122, 94-111. doi:10.1016/j.apenergy.2014.02.013Payri, R., Salvador, F. J., Gimeno, J., & Novella, R. (2011). Flow regime effects on non-cavitating injection nozzles over spray behavior. International Journal of Heat and Fluid Flow, 32(1), 273-284. doi:10.1016/j.ijheatfluidflow.2010.10.001Payri, R., Salvador, F. J., Gimeno, J., & Bracho, G. (2008). A NEW METHODOLOGY FOR CORRECTING THE SIGNAL CUMULATIVE PHENOMENON ON INJECTION RATE MEASUREMENTS. Experimental Techniques, 32(1), 46-49. doi:10.1111/j.1747-1567.2007.00188.xPAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84(5), 551-561. doi:10.1016/j.fuel.2004.10.009Payri, R., García, A., Domenech, V., Durrett, R., & Plazas, A. H. (2012). An experimental study of gasoline effects on injection rate, momentum flux and spray characteristics using a common rail diesel injection system. Fuel, 97, 390-399. doi:10.1016/j.fuel.2011.11.065Payri, F., Molina, S., Martín, J., & Armas, O. (2006). Influence of measurement errors and estimated parameters on combustion diagnosis. Applied Thermal Engineering, 26(2-3), 226-236. doi:10.1016/j.applthermaleng.2005.05.006Lapuerta, M., Armas, O., & Hernández, J. J. (1999). Diagnosis of DI Diesel combustion from in-cylinder pressure signal by estimation of mean thermodynamic properties of the gas. Applied Thermal Engineering, 19(5), 513-529. doi:10.1016/s1359-4311(98)00075-1Tree, D. R., & Svensson, K. I. (2007). Soot processes in compression ignition engines. Progress in Energy and Combustion Science, 33(3), 272-309. doi:10.1016/j.pecs.2006.03.002Benajes, J., Novella, R., García, A., & Arthozoul, S. (2011). The role of in-cylinder gas density and oxygen concentration on late spray mixing and soot oxidation processes. Energy, 36(3), 1599-1611. doi:10.1016/j.energy.2010.12.071Benajes, J., García-Oliver, J. M., Novella, R., & Kolodziej, C. (2012). Increased particle emissions from early fuel injection timing Diesel low temperature combustion. Fuel, 94, 184-190. doi:10.1016/j.fuel.2011.09.014Arrègle, J., López, J. J., Garcı́a, J. M., & Fenollosa, C. (2003). Development of a zero-dimensional Diesel combustion model. Part 1: Analysis of the quasi-steady diffusion combustion phase. Applied Thermal Engineering, 23(11), 1301-1317. doi:10.1016/s1359-4311(03)00079-6Musculus, M. P. B., Miles, P. C., & Pickett, L. M. (2013). Conceptual models for partially premixed low-temperature diesel combustion. Progress in Energy and Combustion Science, 39(2-3), 246-283. doi:10.1016/j.pecs.2012.09.00

Study of different Exhaust Gas Recirculation Configurations and their Impact on Turbocharged Spark Ignition Engines

[ES] Esta tesis doctoral se encuadra en el contexto de una creciente concienciación y preocupación en la sociedad por la contaminación y su efecto sobre la salud de las personas, así como la influencia de los gases de efecto invernadero en el cambio climático. En este sentido, el sector transporte no ha sido una excepción, y se ha legislado para regular tanto las emisiones contaminantes como las de efecto invernadero de manera cada vez más estricta, retando continuamente a las empresas del sector y fabricantes de motores a aumentar la eficiencia y limpieza de sus sistemas propulsivos. Este trabajo tiene por objetivo estudiar el impacto que tienen distintos sistemas de recirculación de gases de escape (exhaust gas recirculation o EGR) en un motor de encendido provocado, de inyección directa, sobrealimentado, con distribución variable y dentro de la tendencia del downsizing. Cabe resaltar que el motor bajo estudio es un modelo sin EGR empleado actualmente en aplicaciones de transporte por carretera de turismos utilitarios, por lo que el proyecto ha estado en todo momento ligado a la actualidad del sector, y los avances y descubrimientos de los estudios aquí presentados pueden resultar de una enorme utilidad y ser empleados en aplicaciones reales. Estos sistemas de recirculación de gases de escape pretenden aumentar la eficiencia de los motores de encendido provocado con el objetivo de reducir la desventaja que estos presentan con respecto a los motores de encendido por compresión, mientras que se mantienen los niveles de emisiones. Dicha desventaja en eficiencia radica principalmente en una menor relación de compresión del motor de encendido provocado para evitar la autoignición y en el uso del dosado estequiométrico para el correcto funcionamiento del postratamiento.[CA] Aquesta tesi doctoral s'enquadra en el context d'una creixent conscienciació i preocupació en la societat per la contaminació i el seu efecte sobre la salut de les persones, així com la inuència dels gasos d'efecte d'hivernacle en el canvi climàtic. En aquest sentit, el transport no ha sigut una excepció, i s'ha legislat per a regular tant les emissions contaminants com les d'efecte d'hivernacle de manera cada vegada més estricta, reptant contínuament a les empreses del sector i fabricants de motors a augmentar l'eficiència dels seus sistemes propulsius. Aquest treball té per objectiu estudiar l'impacte que tenen diferents sistemes de recirculació de gasos d'escapament (exhaust gas *recirculation o EGR) en un motor d'encesa provocada, d'injecció directa, sobrealimentat, amb distribució variable i dins de la tendència del downsizing. Cal ressaltar que el motor sota estudi és un model sense EGR empleat actualment en aplicacions de transport per carretera de turismes utilitaris, per la qual cosa el projecte ha estat en tot moment lligat a l'actualitat del sector, i els avanços i descobriments dels estudis presentats poden resultar d'una enorme utilitat i ser emprats en aplicacions reals. Aquests sistemes de recirculació de gasos d'escapament pretenen augmentar l'eficiència dels motors d'encesa provocada amb l'objectiu de reduir el desavantatge que aquests presenten respecte als motors d'encesa per compressió, mantenint els nivells d'emissions. Aquest desavantatge en eficiència radica principalment en una menor relació de compressió del motor d'encesa provocada per a evitar l'autoignició i en l'ús del dosatge estequiomètric per al correcte funcionament del postractament[EN] This PhD-Thesis is framed in the context of a growing awareness and concern in society about pollution and its effect on people's health, as well as the influence of greenhouse gases on climate change. In this sense, transportation has not been an exception, and legislation has been reated to regulate both polluting emissions and greenhouse gases in an increasingly strict manner, continually challenging companies in the sector and engine manufacturers to increase efficiency and cleanliness of their propulsive systems. The objective of this work is to study the impact that different exhaust gas recirculation (EGR) systems have on a spark ignition, direct injection, turbocharged engine, with a variable timing and within the downsizing trend. It should be noted that the engine under study is mass-produced without EGR and is currently used in passenger utility cars, so the project has been always linked to current events in the sector, and the advances and discoveries of the studies presented here can be useful in real applications. These exhaust gas recirculation systems aim to increase the efficiency of spark ignition engines, reducing the disadvantage they present with respect to compression ignition engines, while maintaining emission levels. Said disadvantage in efficiency lies mainly in a lower compression ratio in order to avoid autoignition and in the use of stoichiometric operation for the optimal operation of the aftertreatment system.Pitarch Berná, R. (2023). Study of different Exhaust Gas Recirculation Configurations and their Impact on Turbocharged Spark Ignition Engines [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19809

Assessment of air management strategies on particulate number and size distributions from a 2-stroke compression-ignition engine operating with gasoline Partially Premixed Combustion concept

[EN] The newly designed partially premixed combustion concept has demonstrated its potential to reduce nitrogen oxides and particulate matter emissions combined with highly indicated efficiencies. However, it is highly dependent of the ignition characteristics of the fuel and the air/fuel mixture preparation. Therefore, the proper selection of an injection strategy, of the combustion chamber design and of the air management strategy are critical to ensuring successful partially premixed combustion operation in the full engine map. The objective of the present investigation is to evaluate the use of multiple air management strategies over the air/fuel effective equivalence ratio (feff) and cylinder charge reactivity and its consequent impact on particle number emissions and particle size distribution. Tests were carried out in a newly designed 2-stroke high-speed direct-injection compression-ignition engine operating with partially premixed combustion concept using 95-research-octane-number gasoline fuel. A scanning mobility particle sizer was used to measure the size distribution of engine-exhaust particles in the range from 6.3 to 237 nm. Three different steady-state operation modes in terms of indicated mean effective pressure and engine speed were investigated. The experiments showed an increase in the particle number emissions and a progressive shift in the particle size toward larger sizes, increasing the accumulation-mode particles and reducing the nucleation-mode particles with the decrease in the differential pressure between intake and exhaust (DP) and the valve overlap period. Finally, the particle formation process was limited by the increase in the exhaust gas recirculation rate.Bermúdez, V.; Ruiz, S.; Novella Rosa, R.; Soto-Izquierdo, L. (2018). Assessment of air management strategies on particulate number and size distributions from a 2-stroke compression-ignition engine operating with gasoline Partially Premixed Combustion concept. International Journal of Engine Research. 1-22. https://doi.org/10.1177/1468087418802706S12

Internal Combustion Engines and Powertrain Systems for future Transport 2019

Internal Combustion Engines and Powertrain Systems for Future Transport 2019 provides a forum for IC engine, fuels and powertrain experts, and looks closely at developments in powertrain technology required to meet the demands of the low carbon economy and global competition in all sectors of the transportation, off-highway and stationary power industries

Optimization of dual-fuel engine utilizing flexible valve train technology

This research aims to optimize the performance and emissions of a dual-fuel marine engine by a flexible valve train approach. A mathematical model for the flexible valve train strategy including its two sub-mechanisms (Flexible Camshaft Technology (FCT) and Multi-segment Camshaft) is developed in MATLAB. After that, a phenomenological combustion model based on fractal combustion principle is developed in AVL CRUISE-M. The combustion model includes many sub-models and allows the valve timing positions to be imported to investigate their influence on the engine performance and emissions.Das Ziel dieser Arbeit ist, die Leistung und Emissionen eines Dual-Fuel-Schiffsmotors durch einen flexiblen Ventiltriebansatz zu optimieren. In MATLAB wird ein mathematisches Modell der Strategie des flexiblen Ventiltriebs einschließlich seiner beiden Teilmechanismen (Flexible Camshaft Technology (FCT) und Multi-Segment Camshaft) entwickelt. Danach wird ein phänomenologisches Verbrennungsmodell basierend auf dem fraktalen Verbrennungsprinzip in AVL CRUISE-M implementiert. Das Verbrennungsmodell importiert die Ventilsteuerzeiten und untersucht deren Auswirkung auf Motorleistung und Emissionen

Analysis and Optimization of the Transient Operation of Gasoline Turbocharged Direct Injection Engines Under High EGR Conditions

[ES] El transporte por carretera es uno de los sectores que más contribuyen al cambio climático. Por ello, muchos gobernantes a nivel mundial están promoviendo una transición hacia medios de transporte sostenibles que no dependan de combustibles fósiles. Sin embargo, debido a la falta de competitividad de las alternativas actuales, no parece factible, en el corto plazo, reducir significativamente el uso de los motores de combustión. Así pues, es probable que los motores de gasolina (MEP) mantengan su papel dominante en el sector automotriz durante los próximos años. De ahí que sea crucial seguir mejorando estos motores a fin de reducir su huella de carbono. Actualmente, es habitual fabricar motores MEP de pequeña cilindrada ("downsizing") con sistemas de sobrealimentación e inyección directa, a fin de reducir el consumo de combustible y las emisiones de CO2. Además, en la última década, se ha demostrado que la recirculación de gases de escape (EGR) puede mejorar la eficiencia de los motores MEP entre un 3 % y un 6 %, dependiendo del grado de carga. Como desventaja, para poder extraer todo el potencial de la estrategia EGR, es necesario trabajar con altas tasas de EGR, lo que puede causar ciertos problemas en condiciones transitorias. En esta tesis, se ha demostrado que el uso de altas tasas de EGR a través de sistemas de baja presión en motores MEP turboalimentados puede ralentizar la respuesta del motor y provocar fallos de encendido durante maniobras de aceleración y desaceleración, respectivamente. Con la entrada en vigor de nuevos procedimientos de homologación de vehículos, como el WLTP (Worldwide harmonized Light vehicle Test Procedure), donde las operaciones transitorias tienen un peso importante, los fabricantes buscan que sus motores consuman y emitan menos en un amplio rango de condiciones de operación, tanto estacionarias como transitorias. Por ello, el objetivo principal de esta tesis es analizar y optimizar el funcionamiento, en condiciones transitorias, de los motores MEP que operan con altas tasas de EGR. Para ello, se ha empleado un motor de gasolina (Euro 6) de 1.3l turboalimentado con inyección directa, distribución variable y turbina de geometría variable. Se ha desarrollado un modelo unidimensional (1D) del motor para el estudio de la fluidodinámica y los fenómenos de transporte en su interior. Por otro lado, se ha ensayado el motor para calibrar el modelo 1D y evaluar aspectos difícilmente predecibles con dicho modelo, como las emisiones contaminantes y la estabilidad de la combustión. Previo al estudio en condiciones transitorias, el motor fue calibrado con EGR, y se realizaron simulaciones para determinar el consumo de un vehículo convencional y otro híbrido, ambos con EGR, durante un ciclo WLTP. Finalmente, se concluyó que ciertas estrategias orientadas a mejorar el proceso de renovación de la carga pueden resolver la problemática del uso del EGR en condiciones transitorias. Eso sí, implementar dichas estrategias conllevaría un aumento en complejidad y costes.[CA] El transport per carretera és un dels sectors que més contribueixen al canvi climàtic. Per això, molts governants a nivell mundial estan promovent una transició cap a mitjans de transport sostenibles que no depenguen de combustibles fòssils. No obstant això, a causa de la falta de competitivitat de les alternatives actuals, no sembla factible, en el curt termini, reduir significativament l'ús dels motors de combustió. Així doncs, és probable que els motors de gasolina (MEP) mantinguen el seu paper dominant en el sector automotriu durant els pròxims anys. D'ací ve que siga crucial continuar millorant aquests motors a fi de reduir la seua petjada de carboni. Actualment, és habitual fabricar motors MEP de xicoteta cilindrada ("downsizing") amb sistemes de sobrealimentació i injecció directa, a fi de reduir el consum de combustible i les emissions de CO2. A més, en l'última dècada, s'ha demostrat que la recirculació de gasos d'escapament (EGR) pot millorar l'eficiència dels motors MEP entre un 3% i un 6%, depenent del grau de càrrega. Com a desavantatge, per a poder extraure tot el potencial de l'estratègia EGR, és necessari treballar amb altes taxes de EGR, la qual cosa pot causar uns certs problemes en condicions transitòries. En aquesta tesi, s'ha demostrat que l'ús d'altes taxes de EGR a través de sistemes de baixa pressió en motors MEP turboalimentats pot alentir la resposta del motor i provocar fallades d'encesa durant maniobres d'acceleració i desacceleració, respectivament. Amb l'entrada en vigor de nous procediments d'homologació de vehicles, com el WLTP (Worldwide harmonized Light vehicle Test Procedure), on les operacions transitòries tenen un pes important, els fabricants busquen que els seus motors consumisquen i emeten menys en un ampli rang de condicions d'operació, tant estacionàries com transitòries. Per això, l'objectiu principal d'aquesta tesi és analitzar i optimitzar el funcionament, en condicions transitòries, dels motors MEP que operen amb altes taxes de EGR. Per a això, s'ha emprat un motor de gasolina (Euro 6) de 1.3l turboalimentat amb injecció directa, distribució variable i turbina de geometria variable. S'ha desenvolupat un model unidimensional (1D) del motor per a l'estudi de la fluidodinàmica i els fenòmens de transport en el seu interior. D'altra banda, s'ha assajat el motor per a calibrar el model 1D i avaluar aspectes difícilment predictibles amb aquest model, com les emissions contaminants i l'estabilitat de la combustió. Previ a l'estudi en condicions transitòries, el motor va ser calibrat amb EGR, i es van realitzar simulacions per a determinar el consum d'un vehicle convencional i un altre híbrid, tots dos amb EGR, durant un cicle WLTP. Finalment, es va concloure que unes certes estratègies orientades a millorar el procés de renovació de la càrrega poden resoldre la problemàtica de l'ús del EGR en condicions transitòries. Això sí, implementar aquestes estratègies comportaria un augment en complexitat i costos.[EN] Road transport is a major contributor to climate change. However, given the lack of competitiveness of fossil fuel-free alternatives, it does not seem possible to reduce the dependence on the internal combustion engine (ICE) as rapidly as planned by the authorities. Advanced gasoline engines will therefore hold a high market share in the automobile industry in the following years, at least during the next decade, either working in conventional or hybrid powertrains. Hence it is essential to keep improving these engines to reduce the negative impact of light-duty vehicles on the environment. The most used strategy to reduce fuel consumption and CO2 emissions in current spark-ignition (SI) gasoline engines is downsizing combined with direct injection (DI). Besides, downsizing must go hand in hand with turbocharging to maintain peak power. It is also proven that exhaust gas recirculation (EGR) can improve fuel economy in SI engines by 3-6% at medium and high loads. As a disadvantage, extracting the full benefit from EGR requires operating with high recirculation rates (close to the EGR dilution limit), leading to some issues under transient conditions. In this thesis, it is demonstrated that high EGR operation through long-route systems in turbocharged engines can potentially originate combustion instabilities and poor engine response during load-decrease (tip-out) and load-increase (tip-in) maneuvers, respectively. Transient operations are especially important for manufacturers since the implementation of the Worldwide harmonized Light vehicle Test Procedure (WLTP). The present thesis is therefore devoted to analyzing and optimizing the gasoline engine performance under high EGR conditions during relevant transient maneuvers. To this end, a Euro-6 1.3L turbocharged DI SI gasoline engine with a variable geometry turbine was employed. A 1D model of this ICE was developed to assess fluid dynamics and transport phenomena. Engine tests were also performed to validate the 1D model and evaluate torque response, combustion stability, and raw exhaust emissions. Before addressing the study of transient maneuvers, the engine calibration with EGR was carried out, and 0D conventional and hybrid vehicle simulations were done to determine the EGR benefit in fuel economy under WLTP driving conditions. Finally, tip-in and tip-out results revealed that some air management strategies are effective in meeting the transient EGR challenges in SI engines, but at the expense of increased complexity and costs.González Domínguez, D. (2023). Analysis and Optimization of the Transient Operation of Gasoline Turbocharged Direct Injection Engines Under High EGR Conditions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19385

Internal Combustion Engines and Powertrain Systems for future Transport 2019

Internal Combustion Engines and Powertrain Systems for Future Transport 2019 provides a forum for IC engine, fuels and powertrain experts, and looks closely at developments in powertrain technology required to meet the demands of the low carbon economy and global competition in all sectors of the transportation, off-highway and stationary power industries