Dual-Fuel Dual-Mode combustion strategy to achieve high thermal efficiency, low NOx and smoke emissions in compression ignition engines

Elevada eficiencia térmica y mínimas emisiones contaminantes impuestas por las restrictivas normativas anticontaminación en motores alternativos representan el principal objetivos de los fabricantes de motores. La estrategia de combustión diésel convencional es ampliamente utilizada en el mundo gracias a su excelente economía en el consumo de carburante. Esta estrategia permite operar con mezclas pobres de combustible y aire proporcionando elevada eficiencia térmica. Además, este tipo de combustión puede ser aplicada desde motores tanto para vehículos ligeros como en motores marinos. Sin embargo, este proceso de combustión conlleva a la generación de elevadas emisiones de NOx y emisiones de partículas (comúnmente llamado hollín en los diésel), siendo imposible reducir ambos contaminantes de forma simultánea. Por tanto, los fabricantes han incorporado sistemas de post-tratamiento con el objetivo de cumplir con las normativas de emisiones, cuya intención es la de proveer emisiones más limpias y elevada eficiencia. Por el contrario, este tipo de sistemas para mitigar las emisiones contaminantes incrementan la complejidad del motor dado el complejo proceso llevado a cabo durante el post-tratamiento y una aumento en los costes tanto de producción como operativos a lo largo del ciclo de vida del motor. La comunidad científica continua desarrollando soluciones alternativas a la combustión diésel convencional manteniendo los beneficios de este proceso de combustión mientras que las emisiones son reducidas (principalmente NOx y hollín). La comunidad científica ha encontrado en las estrategias de combustión de baja temperatura un proceso de combustión capaz de proporcionar elevada eficiencia térmica y emisiones ultra bajas de NOx y humo. En este sentido, la revisión bibliográfica dice que estos tipos de combustión permiten la reducción simultánea de ambas emisiones, rompiendo así el tradicional "trade-off" existente en la combustión diésel convencional. Sobre todas las estrategias, la que muestra un potencial superior es la estrategia conocida como combustión dominada por la reactividad del combustible. Este proceso de combustión se caracteriza por emplear dos combustibles, siendo capaz de solucionar los principales problemas de las estrategias de baja temperatura tales como el fasado de la combustión. Sin embargo, esta estrategia de combustión también presenta algunos inconvenientes como el elevado nivel de monóxido de carbono e hidrocarburos inquemados a baja carga y elevado gradiente de presión y presión en cámara a elevada carga que limitan el rango de operación. El objetivo general de la presente investigación es proveer de una estrategia de combustión "dual-fuel" capaz de operar sobre todo el rango de operación de un motor proporcionando igual o mejores eficiencia térmica que el diésel convencional y emisiones ultra bajas de NOx y humos. Adicionalmente, esta investigación implica una exploración delas emisiones de las partículas del concepto de combustión ya que el número de partículas se encuentra actualmente regulado por la normativa anticontaminante. El proceso de combustión que responde a este objetivo es "Dual-Mode Dual-Fuel". Este concepto de combustión emplea dos combustibles y cambia de combustión premezclada a baja carga a combustión de naturaleza difusiva a plena carga. Con el deseo de explorar las capacidades de la estrategia de combustión, se han empleado dos configuraciones de "hardware" y se ha realizado un estudio de la distribución por tamaños de las partículas. Finalmente, considerando los principales resultados de la investigación, el último capítulo pretende resumir las principales bondades del concepto de combustión así como sus limitaciones y trabajos futuros.Elevada eficiència tèrmica i mínimes emissions contaminants impostes per les normatives anticontaminants en motores alternatius representen el principal objectiu dels fabricants de motors. La estratègia de combustió diésel convencional es àmpliament utilitzada per tot el mon gracies al excel·lent consum de carburant. Esta estratègia permet operar el motor amb dosatges pobres que resulten en elevada eficiència tèrmica. A més, aquest tipus de combustió pot ser aplicada tant a els motor mes lleugers con als motor per aplicacions marines. No obstant això, aquest procés de combustió implica la generació de elevats nivells de emissió de NOx i sutja, que no es poden reduir simultàniament. Per tant, els fabricants han incorporat sistemes de post-tractament amb el objectiu de acomplir les normatives anticontaminació, que pretenen obtindre motors en emissions mes netes i mes eficients. Per el contrari, aquest tipus de sistemes per a reduir les emissions incrementen la complexitat del motor i els costos tant de producció com operatius al llarg del cicle de vida del motor. La comunitat científica continua desenvolupant solucions alternatives a la combustió dièsel mantenint els beneficis d¿aquest tipus de combustió però reduint les emissions (principalment NOx i sutja). La comunitat científica ha trobat a les estratègies de combustió de baixa temperatura un procés de combustió que te elevada eficiència tèrmica i extremadament baixes emissions de NOx y partícules. En aquest sentit, la revisió bibliogràfica constata que aquests tipus de combustions permeten la reducció simultània dels contaminants NOx i sutja, trencant el tradicional "trade-off" existent a la combustió dièsel. De entre totes les estratègies proposades de baixa temperatura, la estratègia combustió dominada per la reactivitat del combustible presenta mes potencial que les altres. Aquest procés de combustió es caracteritza per utilitzar dos combustibles, lo que li permet solventar els principals problemes que han aparegut al llarg de la investigació de les estratègies de baixa temperatura com el control de la combustió. No obstant, aquest concepte de combustió també presenta algunes limitacions com el excessiu nivell de monòxid de carbó e inquemats a baixa càrrega i el elevat gradient de pressió i elevada pressió en càmera a elevada càrrega que limiten el rang de operació del motor. El objectiu de la investigació es proposar un concepte de combustió "dual-fuel" que puga operar en tot el rang de operació de un motor proporcionant el mateix o millorant la eficiència tèrmica que el dièsel amb emissions ultra baixes de NOx y partícules. A més, aquesta investigació també implica realitzar una exploració de les partícules emitides per el concepte ja que actualment està regulat per les normatives anticontaminants. El procés de combustió que compleix el objectiu es diu "Dual-Mode Dual-Fuel". Aquest concepte de combustió utilitza dos combustibles de diferent reactivitat y modifica la combustió de totalment premesclada a baixa càrrega a combustió de natura difusiva a plena càrrega. Amb el desig de explorar les capacitats del concepte, s¿han arribat a provar dos configuracions de pistons diferent per a adequar la relació de compressió i també un anàlisi per tamanys de les partícules. Finalment, considerant els principals resultats obtinguts, el últim capítol pretén resumir les principals avantatges del concepte ací com les principals limitacions y , per tant, els treballs futurs.High thermal efficiency coupled to minimum pollutants emissions imposed by the stringent standard emissions limitations in reciprocating engines represent the main target of the engine manufacturers industry. Conventional diesel combustion strategy is widely used worldwide due to its excellent fuel economy. This combustion strategy allows operating under lean mixtures of fuel and air that provide high thermal efficiency. In addition, this type of combustion can be applied from light-duty engines to large bore marine engines. However, the combustion process leads to high NOx and particle matter emissions, being impossible to reduce both pollutants simultaneously. Hence, manufactures have incorporated aftertreatment systems in order to meet the imposed standard emissions limitations, which are aimed to provide cleaner emissions and high efficiency. By contrast, these systems required for the emissions mitigation result in a very complex processes and an increase in the engine production and operational costs. The research community continues developing alternative solutions to the conventional diesel combustion concept keeping the benefits of this combustion process while the emissions are reduced (mainly focused on NOx and soot). Research community have found in the low temperature combustion strategies the combustion process able to provide excellent high thermal efficiency and ultra-low NOx and smoke emissions. In this sense, the literature review states that this types of combustion processes allow the simultaneous reduction of NOx and smoke, breaking the traditional trade-off found in diesel engines. Amongst others, the most promising strategy is the reactivity controlled compression ignition. This combustion process is characterized by using two fuels and is able to solve the main challenges of the low temperature combustion processes such as combustion phasing control. Nonetheless, the reactivity controlled strategy also presents some challenges such as excessive carbon monoxide and unburned hydrocarbons during low load operation and high pressure rise rate and in-cylinder pressure that limit the engine range operation. The general objective of this investigation is to provide a dual-fuel strategy able to operate over the whole range providing similar or better thermal efficiency that the conventional diesel combustion and ultra-low values of NOx and smoke. In addition, the investigation also explores the particle emissions of the concept since it is regulated by the standard emissions. The combustion process that responds to the target provided at the general objective is the Dual-Fuel Dual-Mode concept. This concept uses two fuels and switches from a dual-fuel fully premixed strategy (based on the RCCI concept) during low load operation to a diffusive nature during high load operation. In order to explore the capabilities of the concept, two hardware configurations are used and a particle size distribution exploration is performed. Finally, considering the main findings of the investigation, the last chapter is aimed to provide the benefits of the combustion process developed as well as the main limitations or future works of the concept.Boronat Colomer, V. (2018). Dual-Fuel Dual-Mode combustion strategy to achieve high thermal efficiency, low NOx and smoke emissions in compression ignition engines [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113413TESI

A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio

Reactivity Controlled Compression Ignition concept offers an ultra-low nitrogen oxide and soot emissions with a high thermal efficiency. This work investigates the capabilities of this low temperature combustion concept to work on the whole map of a medium duty engine proposing strategies to solve its main challenges. In this sense, an extension to high loads of the concept without exceeding mechanical stress as well as a mitigation of carbon oxide and unburned hydrocarbons emissions at low load together with a fuel consumption penalty have been identified as main Reactivity Controlled Compression Ignition drawbacks. For this purpose, a single cylinder engine derived from commercial four cylinders medium-duty engine with an adapted compression ratio of 12.75 is used. Commercial 95 octane gasoline was used as a low reactivity fuel and commercial diesel as a high reactivity fuel. Thus, the study consists of two different parts. Firstly, the work is focused on the development and evaluation of an engine map trying to achieve the maximum possible load without exceeding a pressure rise rate of 15 bar/CAD. The second part holds on improving fuel consumption and carbon oxide and unburned hydrocarbons emissions at low load. Results suggest that it is possible to achieve up to 80% of nominal conventional diesel combustion engine load without overpassing the constraints of pressure rise rate (below 15 bar/CAD) and maximum pressure peak (below 190 bar) while obtaining ultra-low levels of nitrogen oxide and soot emissions. Regarding low load challenges, it has developed a particular methodology sweeping the gasoline-diesel blend together with intake temperature or exhaust gas recirculation maintaining constant the combustion phasing and ultra-low nitrogen oxide and soot emissions. As a result a drastic decrease carbon oxide and unburned hydrocarbons emissions is obtained with a slight fuel consumption improvement.The authors would like to thank VOLVO Group Trucks Technology for supporting this research.Benajes Calvo, JV.; Pastor Soriano, JV.; García Martínez, A.; Boronat-Colomer, V. (2016). A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio. Energy Conversion and Management. 126:497-508. doi:10.1016/j.enconman.2016.08.023S49750812

Gaseous emissions and particle size distribution of dual-mode dual-fuel diesel-gasoline concept from low to full load

[EN] Low temperature combustion concepts are in focus of study nowadays as a method to avoid the NOx-soot trade-off existing with conventional diesel combustion. One of the most promising strategy is known as reactivity controlled compression ignition because of its high thermal efficiency and the ultra-low nitrogen oxides and soot emissions. However, this concept presents several challenges such as the high levels of carbon monoxide and unburned hydrocarbons promoted at low load and unacceptable levels of pressure rise rate at high load. Therefore, to mitigate these shortcomings the dual-mode dual-fuel concept, combining reactivity controlled compression ignition and diffusive dual-fuel diesel-gasoline combustion, has been developed. Total number of particles is also limited by the emission standards. Previous studies focused in particles emissions carried out by the research community present particle size distribution, composition and mass of the particles on reactivity controlled compression ignition combustion mode. Additional studies were carried out in order to identify the components of these particles, being partially formed of volatiles, and reflects that particles are smaller than at conventional diesel combustion, presenting higher number of particles from nucleation mode than from accumulation mode. Dual-Mode Dual-Fuel concept may present a different behavior for particle distribution with respect to the conventional diesel combustion or the traditional low temperature concepts due to the nature of the particles. The objective of the present study is to measure the particle size distribution as well as gaseous emissions of this new Dual-Mode Dual-Fuel concept from low load to full load for a representative engine speed of 1200 rpm. Main results of this study suggest that Dual-Mode Dual-Fuel concept promotes higher quantity of particles than conventional diesel combustion despite of providing less smoke. In addition, nucleation mode particles dominate the particle size distribution for the new combustion concept at low load and moves towards accumulation mode domination at full load. (C) 2017 Elsevier Ltd. All rights reserved.This investigation has been funded by VOLVO Group Trucks Technology. The authors also acknowledge the Spanish economy and competitiveness ministry for partially supporting this research (HiReCo TRA2014-58870-R). The predoctoral contract of the author V. Boronat (FPI-S2-2017-2882) is granted by the Programa de Apoyo para la Investigacion y Desarrollo (PAID) of the Universitat Politecnica de Valencia. The author J. Monsalve-Serrano acknowledges the financial support from the Universitat Politecnica de Valencia under the grant "Ayudas Para la Contratacion de Doctores para el Acceso al Sistema Espahol de Ciencia, Tecnologia e Innovacion".Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Boronat-Colomer, V. (2017). Gaseous emissions and particle size distribution of dual-mode dual-fuel diesel-gasoline concept from low to full load. Applied Thermal Engineering. 120:138-149. https://doi.org/10.1016/j.applthermaleng.2017.04.005S13814912

Achieving clean and efficient engine operation up to full load by combining optimized RCCI and dual-fuel diesel-gasoline combustion strategies

[EN] This experimental work investigates the capabilities of the reactivity controlled compression ignition combustion concept to be operated in the whole engine map and discusses its benefits when compared to conventional diesel combustion. The experiments were conducted using a single-cylinder medium duty diesel engine fueled with regular gasoline and diesel fuels. The main modification on the stock engine architecture was the addition of a port fuel injector in the intake manifold. In addition, with the aim of extending the reactivity controlled compression ignition operating range towards higher loads, the piston bowl volume was increased to reduce the compression ratio of the engine from 17.5:1 (stock) down to 15.3:1. To allow the dual-fuel operation over the whole engine map without exceeding the mechanical limitations of the engine, an optimized dual-fuel combustion strategy is proposed in this research. The combustion strategy changes as the engine load increases, starting from a fully premixed reactivity controlled compression ignition combustion up to around 8 bar IMEP, then switching to a highly premixed reactivity controlled compression ignition combustion up to 15 bar IMEP, and finally moving to a mainly diffusive dual-fuel combustion to reach the full load operation. The engine mapping results obtained using this combustion strategy show that reactivity controlled compression ignition combustion allows fulfilling the EURO VI NOx limit up to 14 bar IMEP. Ultra-low soot emissions are also achieved when the fully premixed combustion is promoted, however, the soot levels rise notably as the combustion strategy moves to a less premixed pattern. Finally, the direct comparison of reactivity controlled compression ignition versus conventional diesel combustion using the nominal engine settings, reveals that reactivity controlled compression ignition can be a potential solution to reduce the selective catalyst reduction and diesel particulate filter aftertreatment necessities with a simultaneous improving of the thermal efficiency. (C) 2017 Elsevier Ltd. All rights reserved.This investigation has been funded by VOLVO Group Trucks Technology. The authors also acknowledge the Spanish economy and competitiveness ministry for partially supporting this research (HiReCo TRA2014-58870-R). The predoctoral contract of the author J. Monsalve-Serrano (FPI-S2-2015-1531) is granted by the Programa de Apoyo para la Investigación y Desarrollo (PAID) of the Universitat Politècnica de València.Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Boronat-Colomer, V. (2017). Achieving clean and efficient engine operation up to full load by combining optimized RCCI and dual-fuel diesel-gasoline combustion strategies. Energy Conversion and Management. 136:142-151. https://doi.org/10.1016/j.enconman.2017.01.010S14215113

Particulates Size Distribution of Reactivity Controlled Compression Ignition (RCCI) on a Medium-Duty Engine Fueled with Diesel and Gasoline at Different Engine Speeds

[EN] This work investigates the particulates size distribution of reactivity controlled compression ignition combustion, a dual-fuel concept which combines the port fuel injection of low-reactive/gasoline-like fuels with direct injection of highly reactive/diesel-like fuels. The particulates size distributions from 5-250 nm were measured using a scanning mobility particle sizer at six engine speeds, from 950 to 2200 rpm, and 25% engine load. The same procedure was followed for conventional diesel combustion. The study was performed in a single-cylinder engine derived from a stock medium-duty multi-cylinder diesel engine of 15.3:1 compression ratio. The combustion strategy proposed during the tests campaign was limited to accomplish both mechanical and emissions constraints. The results confirms that reactivity controlled compression ignition promotes ultra-low levels of nitrogen oxides and smoke emissions in the points tested. However, in spite of having similar or lower smoke emissions, the number of particles in some conditions is higher for the reactivity controlled compression ignition than for conventional diesel combustion. Nucleation mode dominates the particle formation for the reactivity controlled compression ignition mode, while accumulation mode dominates the particle formation for conventional diesel combustion. Thus, it is confirmed that the smoke measurement in filter smoke number units cannot be used to correlate the total particle mass for the reactivity controlled compression ignition mode, as typically done for conventional diesel combustion.This investigation has been funded by VOLVO Group Trucks Technology. The authors also acknowledge the Spanish economy and competitiveness ministry for partially supporting this research (HiReCo TRA2014-58870-R). The predoctoral contract of the author V. Boronat (FPI-S2-2017-2882) is granted by the Programa de Apoyo para la Investigacion y Desarrollo (PAID) of the Universitat Politecnica de Valencia. The author J. Monsalve-Serrano acknowledges the financial support from the Universitat Politecnica de Valencia under the grant "Ayudas Para la Contratacion de Doctores para el Acceso al Sistema Espanol de Ciencia, Tecnologia e Innovacion".Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Boronat-Colomer, V. (2017). Particulates Size Distribution of Reactivity Controlled Compression Ignition (RCCI) on a Medium-Duty Engine Fueled with Diesel and Gasoline at Different Engine Speeds. SAE International Journal of Engines. 10(5):2382-2391. https://doi.org/10.4271/2017-24-0085S2382239110

An investigation on the particulate number and size distributions over the whole engine map from an optimized combustion strategy combining RCCI and dual-fuel diesel-gasoline

[EN] Literature demonstrates that, for premixed low temperature combustion concepts, particulate matter cannot be directly extrapolated from soot emissions measurements, as typically done for conventional diesel combustion. This is because the particulate matter from low temperature combustion has low fraction of carbonaceous compounds and great amount of soluble organic fraction, which is not captured by the smoke measurement techniques such as the optical reflectometry. By this reason, the study of the particulate matter characteristics from this combustion techniques requires using specific equipment. The aim of the current work is to gain understanding on the particulate matter characteristics from the dual-mode dual-fuel combustion, which is an optimized combustion strategy that combines fully and highly premixed RCCI regimes at low and medium loads, and switches to dual-fuel diffusion combustion at full load. The study was performed over the whole engine map, using a 15.3:1 compression ratio medium-duty EURO VI diesel engine. In particular, the particulate number and size distributions were sampled using a scanning mobility particle sizer and a condensation particle counter, which allow measuring the size distribution and total number of particles from 5 to 250 nm. Results demonstrate that the fully premixed RCCI combustion is dominated by small particles (less than 30 nm in mobility diameter), the dual-fuel diffusion mode is dominated by larger particles (around 100 nm in mobility diameter) showing more diesel-like particle size distributions, and the highly premixed reactivity controlled compression ignition regime shows a transitional particle size distribution with two peaks of mobility diameters around 20 and 80 nm. (C) 2017 Elsevier Ltd. All rights reserved.This investigation has been funded by VOLVO Group Trucks Technology. The authors also acknowledge the Spanish economy and competitiveness ministry for partially supporting this research (HiReCo TRA2014-58870-R). The predoctoral contract of the author V. Boronat (FPI-S2-2017-2882) is granted by the Programa de Apoyo para la Investigación y Desarrollo (PAID) of the Universitat Politècnica de València. The author J. Monsalve-Serrano acknowledges the financial support from the Universitat Politècnica de València under the Grant Ayudas Para la Contratación de Doctores para el Acceso al Sistema Español de Ciencia, Tecnología e Innovación .Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Boronat-Colomer, V. (2017). An investigation on the particulate number and size distributions over the whole engine map from an optimized combustion strategy combining RCCI and dual-fuel diesel-gasoline. Energy Conversion and Management. 140:98-108. https://doi.org/10.1016/j.enconman.2017.02.073S9810814

Dual-Fuel Combustion for Future Clean and Efficient Compression Ignition Engines

[EN] Stringent emissions limits introduced for internal combustion engines impose a major challenge for the research community. The technological solution adopted by the manufactures of diesel engines to meet the NOx and particle matter values imposed in the EURO VI regulation relies on using selective catalytic reduction and particulate filter systems, which increases the complexity and cost of the engine. Alternatively, several new combustion modes aimed at avoiding the formation of these two pollutants by promoting low temperature combustion reactions, are the focus of study nowadays. Among these new concepts, the dual-fuel combustion mode known as reactivity controlled compression ignition (RCCI) seems more promising because it allows better control of the combustion process by means of modulating the fuel reactivity depending on the engine operating conditions. The present experimental work explores the potential of different strategies for reducing the energy losses with RCCI in a single-cylinder research engine, with the final goal of providing the guidelines to define an efficient dual-fuel combustion system. The results demonstrate that the engine settings combination, piston geometry modification, and fuel properties variation are good methods to increase the RCCI efficiency while maintaining ultra-low NOx and soot emissions for a wide range of operating conditions.The authors acknowledge VOLVO Group Trucks Technology for supporting this research and express their gratitude to the Spanish economy and competitiveness ministry for partially funding this investigation under the project HiReCo (TRA2014-58870-R). The author J. Monsalve-Serrano thanks the Universitat Politecnica de Valencia for his predoctoral contract (FPI-S2-2015-1531), which is included within the framework of Programa de Apoyo para la Investigacion y Desarrollo (PAID).Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Boronat-Colomer, V. (2017). Dual-Fuel Combustion for Future Clean and Efficient Compression Ignition Engines. Applied Sciences. 7(1):1-16. https://doi.org/10.3390/app7010036S11671Zheng, M., Asad, U., Reader, G. T., Tan, Y., & Wang, M. (2009). Energy efficiency improvement strategies for a diesel engine in low-temperature combustion. International Journal of Energy Research, 33(1), 8-28. doi:10.1002/er.1464Jacobs, T. J., & Assanis, D. N. (2007). The attainment of premixed compression ignition low-temperature combustion in a compression ignition direct injection engine. Proceedings of the Combustion Institute, 31(2), 2913-2920. doi:10.1016/j.proci.2006.08.113Zhu, L., Cheung, C. S., Zhang, W. G., & Huang, Z. (2011). Effect of charge dilution on gaseous and particulate emissions from a diesel engine fueled with biodiesel and biodiesel blended with methanol and ethanol. Applied Thermal Engineering, 31(14-15), 2271-2278. doi:10.1016/j.applthermaleng.2011.03.023Wang, Y., Zhao, Y., Xiao, F., & Li, D. (2014). Combustion and emission characteristics of a diesel engine with DME as port premixing fuel under different injection timing. Energy Conversion and Management, 77, 52-60. doi:10.1016/j.enconman.2013.09.011Payri, F., Desantes, J. M., & Pastor, J. V. (1996). LDV measurements of the flow inside the combustion chamber of a 4-valve D.I. diesel engine with axisymmetric piston-bowls. Experiments in Fluids, 22(2), 118-128. doi:10.1007/s003480050029Qiu, L., Cheng, X., Liu, B., Dong, S., & Bao, Z. (2016). Partially premixed combustion based on different injection strategies in a light-duty diesel engine. Energy, 96, 155-165. doi:10.1016/j.energy.2015.12.052Mathivanan, K., J. M. Mallikarjuna, & Ramesh, A. (2016). Influence of multiple fuel injection strategies on performance and combustion characteristics of a diesel fuelled HCCI engine – An experimental investigation. Experimental Thermal and Fluid Science, 77, 337-346. doi:10.1016/j.expthermflusci.2016.05.010Singh, A. P., & Agarwal, A. K. (2012). Combustion characteristics of diesel HCCI engine: An experimental investigation using external mixture formation technique. Applied Energy, 99, 116-125. doi:10.1016/j.apenergy.2012.03.060Maurya, R. K., & Agarwal, A. K. (2011). Experimental investigation on the effect of intake air temperature and air–fuel ratio on cycle-to-cycle variations of HCCI combustion and performance parameters. Applied Energy, 88(4), 1153-1163. doi:10.1016/j.apenergy.2010.09.027Zhang, X., Wang, H., Zheng, Z., Reitz, R., & Yao, M. (2016). Experimental investigations of gasoline partially premixed combustion with an exhaust rebreathing valve strategy at low loads. Applied Thermal Engineering, 103, 832-841. doi:10.1016/j.applthermaleng.2016.04.147Kalghatgi, G. T., Kumara Gurubaran, R., Davenport, A., Harrison, A. J., Hardalupas, Y., & Taylor, A. M. K. P. (2013). Some advantages and challenges of running a Euro IV, V6 diesel engine on a gasoline fuel. Fuel, 108, 197-207. doi:10.1016/j.fuel.2012.10.059Leermakers, C. A. J., Bakker, P. C., Nijssen, B. C. W., Somers, L. M. T., & Johansson, B. H. (2014). Low octane fuel composition effects on the load range capability of partially premixed combustion. Fuel, 135, 210-222. doi:10.1016/j.fuel.2014.06.044Benajes, J., Molina, S., García, A., Monsalve-Serrano, J., & Durrett, R. (2014). Conceptual model description of the double injection strategy applied to the gasoline partially premixed compression ignition combustion concept with spark assistance. Applied Energy, 129, 1-9. doi:10.1016/j.apenergy.2014.04.093Benajes, J., Molina, S., García, A., Monsalve-Serrano, J., & Durrett, R. (2014). Performance and engine-out emissions evaluation of the double injection strategy applied to the gasoline partially premixed compression ignition spark assisted combustion concept. Applied Energy, 134, 90-101. doi:10.1016/j.apenergy.2014.08.008Park, S. H., Youn, I. M., Lim, Y., & Lee, C. S. (2013). Influence of the mixture of gasoline and diesel fuels on droplet atomization, combustion, and exhaust emission characteristics in a compression ignition engine. Fuel Processing Technology, 106, 392-401. doi:10.1016/j.fuproc.2012.09.004Bessonette, P. W., Schleyer, C. H., Duffy, K. P., Hardy, W. L., & Liechty, M. P. (2007). Effects of Fuel Property Changes on Heavy-Duty HCCI Combustion. SAE Technical Paper Series. doi:10.4271/2007-01-0191Inagaki, K., Fuyuto, T., Nishikawa, K., Nakakita, K., & Sakata, I. (2006). Dual-Fuel PCI Combustion Controlled by In-Cylinder Stratification of Ignitability. SAE Technical Paper Series. doi:10.4271/2006-01-0028Kokjohn, S. L., Hanson, R. M., Splitter, D. A., & Reitz, R. D. (2011). Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion. International Journal of Engine Research, 12(3), 209-226. doi:10.1177/1468087411401548Dempsey, A. B., Das Adhikary, B., Viswanathan, S., & Reitz, R. D. (2012). Reactivity Controlled Compression Ignition Using Premixed Hydrated Ethanol and Direct Injection Diesel. Journal of Engineering for Gas Turbines and Power, 134(8). doi:10.1115/1.4006703Benajes, J., Molina, S., García, A., Belarte, E., & Vanvolsem, M. (2014). An investigation on RCCI combustion in a heavy duty diesel engine using in-cylinder blending of diesel and gasoline fuels. Applied Thermal Engineering, 63(1), 66-76. doi:10.1016/j.applthermaleng.2013.10.052Hanson, R. M., Kokjohn, S. L., Splitter, D. A., & Reitz, R. D. (2010). An Experimental Investigation of Fuel Reactivity Controlled PCCI Combustion in a Heavy-Duty Engine. SAE International Journal of Engines, 3(1), 700-716. doi:10.4271/2010-01-0864Benajes, J., Pastor, J. V., García, A., & Monsalve-Serrano, J. (2015). The potential of RCCI concept to meet EURO VI NOx limitation and ultra-low soot emissions in a heavy-duty engine over the whole engine map. Fuel, 159, 952-961. doi:10.1016/j.fuel.2015.07.064Ma, S., Zheng, Z., Liu, H., Zhang, Q., & Yao, M. (2013). Experimental investigation of the effects of diesel injection strategy on gasoline/diesel dual-fuel combustion. Applied Energy, 109, 202-212. doi:10.1016/j.apenergy.2013.04.012Reitz, R. D., & Duraisamy, G. (2015). Review of high efficiency and clean reactivity controlled compression ignition (RCCI) combustion in internal combustion engines. Progress in Energy and Combustion Science, 46, 12-71. doi:10.1016/j.pecs.2014.05.003Payri, F., Olmeda, P., Martín, J., & García, A. (2011). A complete 0D thermodynamic predictive model for direct injection diesel engines. Applied Energy, 88(12), 4632-4641. doi:10.1016/j.apenergy.2011.06.005Lapuerta, M., Ballesteros, R., & Agudelo, J. R. (2006). Effect of the gas state equation on the thermodynamic diagnostic of diesel combustion. Applied Thermal Engineering, 26(14-15), 1492-1499. doi:10.1016/j.applthermaleng.2006.01.001Lapuerta, 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)00075-1Woschni, G. (1967). A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine. SAE Technical Paper Series. doi:10.4271/670931Payri, F., Margot, X., Gil, A., & Martin, J. (2005). Computational Study of Heat Transfer to the Walls of a DI Diesel Engine. SAE Technical Paper Series. doi:10.4271/2005-01-0210Torregrosa, A., Olmeda, P., Degraeuwe, B., & Reyes, M. (2006). A concise wall temperature model for DI Diesel engines. Applied Thermal Engineering, 26(11-12), 1320-1327. doi:10.1016/j.applthermaleng.2005.10.021Payri, F., Olmeda, P., Martin, J., & Carreño, R. (2014). A New Tool to Perform Global Energy Balances in DI Diesel Engines. SAE International Journal of Engines, 7(1), 43-59. doi:10.4271/2014-01-0665Cheng, A. S. (Ed), Upatnieks, A., & Mueller, C. J. (2007). Investigation of Fuel Effects on Dilute, Mixing-Controlled Combustion in an Optical Direct-Injection Diesel Engine. Energy & Fuels, 21(4), 1989-2002. doi:10.1021/ef0606456Kono, M., Basaki, M., Ito, M., Hashizume, T., Ishiyama, S., & Inagaki, K. (2012). Cooling Loss Reduction of Highly Dispersed Spray Combustion with Restricted In-Cylinder Swirl and Squish Flow in Diesel Engine. SAE International Journal of Engines, 5(2), 504-515. doi:10.4271/2012-01-0689Splitter, D., Wissink, M., Kokjohn, S., & Reitz, R. D. (2012). Effect of Compression Ratio and Piston Geometry on RCCI Load Limits and Efficiency. SAE Technical Paper Series. doi:10.4271/2012-01-0383Hanson, R., Curran, S., Wagner, R., Kokjohn, S., Splitter, D., & Reitz, R. D. (2012). Piston Bowl Optimization for RCCI Combustion in a Light-Duty Multi-Cylinder Engine. SAE International Journal of Engines, 5(2), 286-299. doi:10.4271/2012-01-0380Tutak, W. (2014). Bioethanol E85 as a fuel for dual fuel diesel engine. Energy Conversion and Management, 86, 39-48. doi:10.1016/j.enconman.2014.05.016Desantes, J. M., Lopez, J. J., Garcia, J. M., & Pastor, J. M. (2007). EVAPORATIVE DIESEL SPRAY MODELING. Atomization and Sprays, 17(3), 193-231. doi:10.1615/atomizspr.v17.i3.10Desantes, J. M., Arregle, J., Lopez, J. J., & Cronhjort, A. (2006). SCALING LAWS FOR FREE TURBULENT GAS JETS AND DIESEL-LIKE SPRAYS. Atomization and Sprays, 16(4), 443-474. doi:10.1615/atomizspr.v16.i4.6

Influencia de la geometría de entrada en el funcionamiento del compresor centrífugo de sobrealimentación

Proyecto confidencial (Riunet)Boronat Colomer, V. (2014). Influencia de la geometría de entrada en el funcionamiento del compresor centrífugo de sobrealimentación. http://hdl.handle.net/10251/39320.Archivo delegad

Estudio de emisiones gaseosas y prestaciones en el modo de combustión RCCI mediante el uso de gasolina/diésel aplicado en un motor medium-duty de combustión interna

Reactivity controlled compression ignition (RCCI) concept offers ultra-low NOx and smoke emissions with a thermal efficiency. The present work investigates the capabilities of this new Low Temperature Combustion (LTC) concept on the whole engine map of a medium-duty engine proposing strategies to solve its main challenges. Therefore, in order to extent the engine operation up to full load, several constraints must be accomplished. These constraints are summarized in two groups: Mechanical constraints: ¿ Maximum pressure rise rate <15bar/CAD ¿ In-cylinder pressure < 190 bar Emissions constraints: ¿ NOx emissions <0.4 g/kWh ¿ Smoke emissions < 1.5 FSN Despite of not having any specific constraint regarding carbón monoxide (CO) and unburned hydrocarbons (HC), during the tests these emissions have been taken in account to control them due to the high quantity of CO and uHC emissions promoted by this concept. From the tests standpoint, the experiments of this investigation were carried out in a single-cylinder engine (SCE) derived from a commercial medium-duty four cylinders engine which is able to meet EURO VI limitation standard. A SCE is required in this kind of investigation due to the precise control of the variables which take part in the combustion process. Additional modifications were performed in the SCE with the aim to improve the engine conditions to apply the RCCI concept. In this sense, different compressions ratios (CR) were tested apart from the stock configuration (CR12.75 and CR15.3). RCCI concept requires two different reactivity fuels. Therefore, gasoline 95 RON (EN228) was used as the low reactivity fuel and diesel (EN 590) was used as a high reactivity fuel. These fuels were chosen due to they can be obtained in any petrol station and thereby, it is possible to implement this LTC concept with conventional fuels. Regarding the fuel injection systems, a double injection system was developed to manage the injection of both fuels independently. In this sense, a port fuel injection (PFI) was installed at the intake manifold to inject the gasoline. Additionally, a fuel conditioner was installed to measure also the fuel mass and a controller was developed to manage the fuel injection. Diesel fuel was injected directly in the cylinder with the stock direct injector. Nonetheless, a fuel conditioner was installed and an injector controller was developed to operate the diesel injection independently from the engine ECU and the gasoline injection. In order to operate the engine under RCCI mode, a strategy has been developed to stablish the procedure for RCCI implementation. The procedure has been divided in three steps. First step consists of obtaining the desired engine load while the integrity of the engine is guaranteed not overpassing the mechanical constraints and get a stable operation. The second step is focused on reducing the NOx and smoke emissions below the emissions constraints aforementioned. Finally, the last step focuses in a fine optimization in order to reduce fuel consumption up to diesel values or lower and thereby, a reduction in CO and unburned HC emissions also. Results suggest that this concept can be applied up to the 80% engine load with ultra-low NOx and smoke emissions which are able to meet EURO VI limitations without aftertreatment at steady state operating points when a CR of 12.75 is used. However, CO and unburned HC emissions levels are unacceptable at low load and require aftertreatment. Regarding the CR of 15.3, the maximum engine load achieved has been 100%. However, the emissions have been increased with the aim to allow the concept to achieve the whole engine map operation. In this sense, a variation of the concept has been applied to operate at high load despite of increasing both NOx and smoke emissions. This variation has been named dual-mode dual-fuel (DMDF) mode. From the efficiency standpoint, both CR tested provides lower fuel consumption than CDC for alEl modo de combustion reactivity controlled compression ignition (RCCI) produce emisiones de óxidos de nitrógeno (NOx) y humo sumamente reducidas con respecto al diésel convencional mientras que es capaz de mantener o superar su eficiencia térmica. Éste trabajo estudia las capacidades potenciales de este nuevo concepto de combustión de baja temperatura (LTC- Low Temperature Combustion) para ser extrapolado a todo el rango de operación de un motor médium-duty de combustión interna. Para ello, se han investigado diversas configuraciones de motor con la intención de superar los posibles inconvenientes de este tipo de modo de combustión y así poder alcanzar los objetivos de la investigación. Adicionalmente, se han de cumplir una serie de restricciones: Restricciones mecánicas: ¿ Gradiente de presión <15bar/CAD ¿ Presión en el cilindro < 190 bar Restricciones en emisiones: ¿ Emisiones de óxidos de nitrógeno <0.4 g/kWh ¿ Emisiones de humo < 1.5 FSN Por otro lado, se ha tenido en cuenta las emisiones de monóxido de carbono (CO) e hidrocarburos (HC) inquemados, especialmente elevados en este tipo de combustión y que no son foco del principal interés de este estudio. Para realizar este trabajo, se han llevado a cabo una serie de ensayos en un motor monocilíndrico derivado de un motor de 4 cilindros médium-duty de producción en serie. El uso de un motor monocilíndrico es necesario para poder obtener un control preciso del proceso de combustión. Para poder emplear este modo de combustión en el motor, se han probado diferentes relaciones de compresión (RC), la original de 17,5 y dos modificadas de 12,75 y 15,3. El concepto de combustión RCCI requiere el uso de combustibles con diferente reactividad. Con el fin de disponer de las condiciones más reales posibles, se ha optado por gasolina 95 RON (EN 228) como combustible de baja reactividad y diésel (EN 590) como combustible de alta reactividad, combustibles que son muy fáciles de adquirir en cualquier estación de servicio. Para realizar la inyección de los combustibles se ha implementado un sistema de inyección doble. El combustible de alta reactividad (diésel) se ha inyectado a través del inyector original al que se le ha acoplado una nueva bomba de combustible y una serie de elementos para acondicionar el combustible para poder medirlo correctamente. Además, se ha provisto de un software específico para gobernar el inyector en función de los requerimientos de cada punto. Por otro lado, la inyección del combustible de baja reactividad (gasolina) se ha llevado a cabo mediante un inyector de inyección indirecta colocado en el colector de admisión (PFI-port fuel injector) y un sistema acondicionador de combustible para su correcta medición. Éste inyector también está gobernado por un controlador desarrollado para este estudio similar al del inyector diésel. Para poder operar el motor mediante este sistema de combustión, se ha desarrollado una estrategia de operación compuesta de tres pasos. El primer paso consiste en obtener la carga de motor deseada sin producir daños en el motor, es decir, comprobando que las restricciones mecánicas no son sobrepasadas en ningún momento y garantizar así la vida del motor. El segundo paso consiste en reducir emisiones en términos de NOx y humo hasta los niveles que se han citado anteriormente, en la enumeración de las restricciones, y por último un tercer paso dedicado a optimizar la combustión con el fin de obtener consumos iguales o mejores a los obtenidos en el motor de referencia (configuración diésel original) operando con diésel convencional. Por último, los resultados obtenidos hasta ahora sugieren que este concepto de combustión se puede emplear hasta una carga del 80% en todo el rango de motor manteniendo las emisiones de NOx y de humos por debajo de lo exigido por la normativa anticontaminación EURO VI para una RC12.75. Sin embargo las emisiones de CO e inquemadosBoronat Colomer, V. (2017). Estudio de emisiones gaseosas y prestaciones en el modo de combustión RCCI mediante el uso de gasolina/diésel aplicado en un motor medium-duty de combustión interna. http://hdl.handle.net/10251/86058TFG