Dual-fuel compression ignition: towards clean, highly efficient combustion

The more and more stringent emissions regulations, together with the greater fuel economy demanded by vehicle users, impose a clear objective to researchers and engine manufacturers: look for the maximum efficiency with the minimum pollutant emissions levels. The conventional diesel combustion is a highly efficient process, but also leads to high levels of NOx and soot emissions that require using aftertreatment systems to reduce the final levels released to the environment. Since these systems incur in higher costs of acquisition and operation of the engine, the scientific community is working on developing alternative strategies to reduce the generation of these pollutants during the combustion process itself. The literature shows that the new combustion modes based on promoting low temperatures during this process, offer high efficiency and very low NOx and soot levels simultaneously. However, after years of investigation, it can be concluded that these techniques cannot be applied in the whole engine operating range due to, among others, factors like the low control of the combustion process. In recent years, it has been demonstrated that the dual-fuel combustion technique allows to overcome this limitation thanks to the additional degree of freedom provided by the capacity of modulating the fuel reactivity depending on the engine operating conditions. This characteristic, together with the near-zero NOx and soot levels obtained with this technique, has encouraged the scientific community to deeply investigate the dual-fuel combustion. In this sense, former works confirm the advantages previously described, concluding that still exist some limitations to be tackled, as well as some margin for improving the potential of this combustion concept. The general objective of the present Doctoral Thesis is to contribute to the understanding of the dual-fuel combustion mode, with the particular aim of exploring different ways to improve its efficiency. For this purpose, it has been experimentally evaluated different options such as the modification of the engine operating parameters, specific designs of the piston geometry or the use of alternative fuels. With the aim of answering some of the questions found in the literature, the first part of each study has been dedicated to perform a detailed analysis of the influence of each particular strategy on the dual-fuel operation at low load. Later, it has been checked the ability of each option to extend the dual-fuel operating range towards higher engine loads. It is interesting to note that the analysis of some results has been supported by CFD calculations, which have allowed to understand some local phenomena occurring during the dual-fuel combustion process, which cannot be confirmed only from the experimental point of view. Finally, taking into account the knowledge acquired during the different studies performed, the last chapter of results has been devoted to evaluate the ability of the dual-fuel concept to operate over the whole engine map, as well as to identify the possible limitations that this technique presents from the technological point of view.Las cada vez más restrictivas normativas anticontaminantes, junto con la demanda de motores con menor consumo de combustible por parte de los usuarios, imponen un claro objetivo a investigadores y fabricantes de motores: la búsqueda de la máxima eficiencia con los mínimos niveles de emisiones contaminantes. La combustión diésel convencional ofrece una alta eficiencia, pero a su vez da lugar a elevadas emisiones de NOx y hollín que requieren del uso de sistemas de postratamiento para reducir los niveles finales emitidos al ambiente. Dado que estos sistemas incurren en mayores costes de adquisición y operación del motor, la comunidad científica está trabajando en el desarrollo distintas estrategias para reducir la generación de estos contaminantes durante el propio proceso de combustión. La literatura demuestra que los nuevos modos de combustión basados en promover bajas temperaturas durante este proceso, ofrecen simultáneamente una elevada eficiencia y muy bajos niveles de NOx y hollín. Sin embargo, tras años de investigación, se puede llegar a la conclusión de que estas técnicas no pueden ser aplicadas en todo el rango de operación del motor debido a, entre otros, factores como el escaso control sobre el proceso de combustión. En los últimos años, se ha demostrado que la técnica de combustión dual-fuel permite superar esta limitación gracias al grado de libertad adicional que supone la capacidad de modular la reactividad del combustible en función de las condiciones de operación del motor. Esta característica, junto con los casi nulos niveles de NOx y hollín que proporciona, ha despertado un gran interés sobre la comunidad científica. En este sentido, trabajos precedentes confirman las ventajas que este modo de combustión ofrece, demostrando a su vez que aún existen una serie de limitaciones por abordar, así como cierto margen por explotar para mejorar el potencial de este concepto. La presente Tesis Doctoral plantea como objetivo general el contribuir a la comprensión del modo de combustión dual-fuel, y de manera particular explorar distintas vías con objeto de mejorar su eficiencia. Para ello, se han evaluado de manera experimental diferentes opciones que van desde la modificación de los parámetros de operación del motor, hasta diseños específicos de la geometría del pistón o el uso de combustibles alternativos. Tratando de responder algunas de las cuestiones encontradas en la literatura, en cada uno de los estudios se ha realizado un análisis detallado de la influencia del parámetro en cuestión sobre la operación del motor a baja carga, y a su vez se ha comprobado la capacidad de cada una de estas opciones de extender la operación del motor hacia cargas más elevadas. Cabe destacar que el análisis de ciertos resultados se ha apoyado en cálculos numéricos CFD, los cuales han permitido entender ciertos fenómenos locales que ocurren durante el proceso de combustión dual-fuel, y que no pueden ser confirmados únicamente desde el punto de vista experimental. Finalmente, teniendo en cuenta el conocimiento adquirido en los diferentes estudios realizados, el último capítulo de resultados se ha dedicado a evaluar la capacidad de operación del concepto dual-fuel en todo el rango de funcionamiento del motor, así como a identificar las posibles limitaciones que esta técnica presenta desde el punto de vista tecnológico.Les cada vegada més restrictives normatives anticontaminants, juntament amb la demanda de motors amb menor consum de combustible per part dels usuaris, imposen un clar objectiu a investigadors i fabricants de motors: la cerca de la màxima eficiència amb els mínims nivells d'emissions contaminants. La combustió dièsel convencional ofereix una alta eficiència, però al seu torn dóna lloc a elevades emissions de NOx i sutge que requereixen de l'ús de sistemes de postractament per a reduir els nivells finals emesos a l'ambient. Aquests sistemes incorren en majors costos d'adquisició i operació del motor, per la qual cosa de forma paral·lela, la comunitat científica està treballant en el desenvolupament de diferents estratègies per a reduir la generació d'aquests contaminants durant el propi procés de combustió. La literatura demostra que les noves tècniques de combustió basades a promoure baixes temperatures durant aquest procés, ofereixen simultàniament una elevada eficiència i molt baixos nivells de NOx i sutge. No obstant açò, després d'anys de recerca, es pot arribar a la conclusió que aquestes tècniques no poden ser aplicades en tot el rang d'operació del motor a causa de, entre uns altres, factors com l'escàs control sobre el procés de combustió. En els últims anys, s'ha demostrat que la tècnica de combustió dual-fuel permet superar aquesta limitació gràcies al grau de llibertat addicional que suposa la capacitat de modular la reactivitat del combustible en funció de les condicions d'operació del motor. Aquesta característica, juntament amb els quasi nuls nivells de NOx i sutge que proporciona, ha despertat un gran interès sobre la comunitat científica. En aquest sentit, treballs precedents confirmen els avantatges que aquesta tècnica de combustió ofereix, demostrant al seu torn que encara existeixen una sèrie de limitacions per abordar, així com cert marge per explotar per a millorar el potencial d'aquest concepte. La present Tesi Doctoral planteja com a objectiu general el contribuir a la comprensió de la tècnica de combustió dual-fuel, i de manera particular explorar diferents vies a fi de millorar la seua eficiència. Per a açò, s'han avaluat de manera experimental diferents opcions que van des de la modificació dels paràmetres d'operació del motor, fins a dissenys específics de la geometria del pistó o l'ús de combustibles alternatius. Tractant de respondre algunes de les qüestions trobades en la literatura, en cadascun dels estudis s'ha realitzat una anàlisi detallada de la influència del paràmetre en qüestió sobre l'operació del motor a baixa càrrega, i al seu torn s'ha comprovat la capacitat de cadascuna d'aquestes opcions d'estendre l'operació del motor cap a càrregues més elevades. Cal destacar que l'anàlisi de certs resultats s'ha recolzat en càlculs numèrics CFD, els quals han permès entendre certs fenòmens locals que ocorren durant el procés de combustió dual-fuel, i que no poden ser confirmats únicament des del punt de vista experimental. Finalment, tenint en compte el coneixement adquirit en els diferents estudis realitzats, l'últim capítol de resultats s'ha dedicat a avaluar la capacitat d'operació del concepte dual-fuel en tot el rang de funcionament del motor, així com a identificar les possibles limitacions que aquesta tècnica presenta des del punt de vista tecnològic.Monsalve Serrano, J. (2016). Dual-fuel compression ignition: towards clean, highly efficient combustion [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/75109TESI

High efficiency two stroke opposed piston engine for plug-in hybrid electric vehicle applications: evaluation under homologation and real driving conditions

[EN] The potential of plug-in hybrid electric vehicles (PHEV) to reduce greenhouse gas emissions highly depends on the vehicle usage and electricity source. In addition, the high costs of the battery pack and electric components suppose a challenge to the vehicle manufacturers. However, the internal combustion engine complexity can be reduced due to its lower use as compared to the no-hybrid vehicles. This work evaluates the use of a new opposed piston 2-stroke engine, based on rod-less innovative kinematics, in a series PHEV architecture based on rod-less innovative kinematics along different driving routes in Europe. A 0D-vehicle model fed with experimental tests is used. The battery size is optimized under homologation conditions for two different vehicle types. The optimum case is tested in several real driving conditions under different vehicle modes and battery states of charge. The main contribution of this work is the demonstration of the potential to reduce the vehicle CO2 emissions and cost with an innovative 2-stroke engine. The results show that 24 kWh is the optimum battery size for both vehicle platforms. Charge depleting mode shows 70% of CO2 tailpipe reduction in urban cycles and 22% in long travels compared to the no-hybrid version. Charge sustaining mode results show a CO2 tailpipe reduction of 20% in urban cycles and 2% in long distance travels with respect to the no-hybrid version. In spite of the CO2 contribution of the battery manufacturing, the results show a reduction of LCA CO2 emissions in 52% in charge depleting and 7% charge sustaining against the no-hybrid case.This work has been partially supported by "Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital de la Generalitat Valenciana" through grant number GV/2020/017. The authors acknowledge FEDER and Spanish Ministerio de Economia y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R). The authors want to thank INNengine for providing the engine and the help in the experimental campaign. Lastly, acknowledge to Gamma Technologies for the numerical simulation support and provide the GT-RealDrive licensesSerrano, J.; García Martínez, A.; Monsalve-Serrano, J.; Martínez-Boggio, SD. (2021). High efficiency two stroke opposed piston engine for plug-in hybrid electric vehicle applications: evaluation under homologation and real driving conditions. Applied Energy. 282(Part A):1-17. https://doi.org/10.1016/j.apenergy.2020.116078S117282Part

Computational optimization of the dual-mode dual-fuel concept through genetic algorithm at different engine loads

[EN] The diesel/gasoline dual-mode dual-fuel (DMDF) combustion concept was optimized in a compression-ignition engine by combining the computational fluid dynamics (CFD) simulations with the genetic algorithm. Seven operating parameters with remarkable influences on the engine performance were chosen as the variables to be optimized for simultaneously minimizing the fuel efficiency, nitrogen oxides (NOx), and soot emissions. Moreover, the potential of the further improvement of the DMDF combustion concept was discussed, and the rationality of this strategy was demonstrated. The results indicate that, at low load, simultaneous improvement of the fuel economy and emissions can be realized by strengthening the homogeneous combustion. At mid load, the fuel economy can be improved by reducing the heat transfer losses, while the NOx emissions are sacrificed to some extent. At high load, improved fuel economy can be realized by transferring a part of diffusion combustion to premixed reactivity-controlled compression ignition (RCCI) combustion. Concerning the operating parameters, lower intake temperature is beneficial to decrease the transfer losses, and the control of intake temperature is crucial for the stable operation of DMDF combustion under wide load conditions. Overall, gross indicated thermal efficiency above 45% is achieved, and the NOx and soot emission can be maintained under the Euro 6 standard for the test load range.This work was partially supported by the National Natural Science Foundation of China (Grant Nos. 51961135105 and 91641117) and China Postdoctoral Science Foundation (Grant No. 2019M661094). The experimental results used in this investigation were obtained in a project funded by VOLVO Group Trucks Technology. The authors also acknowledge FEDER and Spanish Ministerio de Economia y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R) and the Universitat Politecnica de Valencia for partially supporting this research through Convocatoria de ayudas a Primeros Proyectos de Investigacion (PAID-06-18).Xu, G.; Monsalve-Serrano, J.; Jia, M.; García Martínez, A. (2020). Computational optimization of the dual-mode dual-fuel concept through genetic algorithm at different engine loads. Energy Conversion and Management. 208:1-13. https://doi.org/10.1016/j.enconman.2020.112577S113208Johnson TV. Diesel emission control in review. SAE Technical Paper. 2009; no. 2009-01-0121.Reitz, 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.2014.05.003Lim, J. H., & Reitz, R. D. (2014). High Load (21 Bar IMEP) Dual Fuel RCCI Combustion Using Dual Direct Injection. Journal of Engineering for Gas Turbines and Power, 136(10). doi:10.1115/1.4027361Splitter, D. A., & Reitz, R. D. (2014). Fuel reactivity effects on the efficiency and operational window of dual-fuel compression ignition engines. Fuel, 118, 163-175. doi:10.1016/j.fuel.2013.10.045Xu, Z., Jia, M., Li, Y., Chang, Y., Xu, G., Xu, L., & Lu, X. (2018). Computational optimization of fuel supply, syngas composition, and intake conditions for a syngas/diesel RCCI engine. Fuel, 234, 120-134. doi:10.1016/j.fuel.2018.07.003D.F. Chuahy, F., & Kokjohn, S. L. (2017). Effects of the direct-injected fuel’s physical and chemical properties on dual-fuel combustion. Fuel, 207, 729-740. doi:10.1016/j.fuel.2017.06.039Murugesa Pandian, M., & Anand, K. (2018). Comparison of different low temperature combustion strategies in a light duty air cooled diesel engine. Applied Thermal Engineering, 142, 380-390. doi:10.1016/j.applthermaleng.2018.07.047Li, Y., Jia, M., Chang, Y., Kokjohn, S. L., & Reitz, R. D. (2016). Thermodynamic energy and exergy analysis of three different engine combustion regimes. Applied Energy, 180, 849-858. doi:10.1016/j.apenergy.2016.08.038Gong, C., Li, Z., Yi, L., & Liu, F. (2019). Comparative study on combustion and emissions between methanol port-injection engine and methanol direct-injection engine with H2-enriched port-injection under lean-burn conditions. Energy Conversion and Management, 200, 112096. doi:10.1016/j.enconman.2019.112096Tong, L., Wang, H., Zheng, Z., Reitz, R., & Yao, M. (2016). Experimental study of RCCI combustion and load extension in a compression ignition engine fueled with gasoline and PODE. Fuel, 181, 878-886. doi:10.1016/j.fuel.2016.05.037Agarwal, A. K., Singh, A. P., & Maurya, R. K. (2017). Evolution, challenges and path forward for low temperature combustion engines. Progress in Energy and Combustion Science, 61, 1-56. doi:10.1016/j.pecs.2017.02.001Dempsey, A. B., Walker, N. R., Gingrich, E., & Reitz, R. D. (2014). Comparison of Low Temperature Combustion Strategies for Advanced Compression Ignition Engines with a Focus on Controllability. Combustion Science and Technology, 186(2), 210-241. doi:10.1080/00102202.2013.858137Wang, Y., Zhu, Z., Yao, M., Li, T., Zhang, W., & Zheng, Z. (2016). An investigation into the RCCI engine operation under low load and its achievable operational range at different engine speeds. Energy Conversion and Management, 124, 399-413. doi:10.1016/j.enconman.2016.07.026Dempsey AB, Reitz RD. Computational optimization of reactivity controlled compression ignition in a heavy-duty engine with ultra low compression ratio. SAE Technical Paper. 2011; no. 2011-24-0015.Hanson R, Curran S, Wagner R, Kokjohn S, Splitter D, Reitz R. Piston bowl optimization for RCCI combustion in a light-duty multi-cylinder engine. SAE Technical Paper. 2012; no. 2012-01-0380.Eichmeier, J., Wagner, U., & Spicher, U. (2012). Controlling Gasoline Low Temperature Combustion by Diesel Micro Pilot Injection. Journal of Engineering for Gas Turbines and Power, 134(7). doi:10.1115/1.4005997Molina, S., García, A., Pastor, J. M., Belarte, E., & Balloul, I. (2015). Operating range extension of RCCI combustion concept from low to full load in a heavy-duty engine. Applied Energy, 143, 211-227. doi:10.1016/j.apenergy.2015.01.035Benajes, J., Pastor, J. V., García, A., & Boronat, 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.2016.08.023Benajes, J., García, A., Monsalve-Serrano, J., & Boronat, 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. doi:10.1016/j.enconman.2017.01.010García, A., Monsalve-Serrano, J., Villalta, D., & Sari, R. (2019). Fuel sensitivity effects on dual-mode dual-fuel combustion operation for different octane numbers. Energy Conversion and Management, 201, 112137. doi:10.1016/j.enconman.2019.112137Amsden AA. KIVA-3V: A block structured KIVA program for engines with vertical and canted valves. USA: Los Alamos National Laboratory Technical Report; 1997. LA-13313-MS.Wang, B.-L., Lee, C.-W., Reitz, R. D., Miles, P. C., & Han, Z. (2012). A generalized renormalization group turbulence model and its application to a light-duty diesel engine operating in a low-temperature combustion regime. International Journal of Engine Research, 14(3), 279-292. doi:10.1177/1468087412465379Zhang, Y., Jia, M., Liu, H., Xie, M., Wang, T., & Zhou, L. (2014). DEVELOPMENT OF A NEW SPRAY/WALL INTERACTION MODEL FOR DIESEL SPRAY UNDER PCCI-ENGINE RELEVANT CONDITIONS. Atomization and Sprays, 24(1), 41-80. doi:10.1615/atomizspr.2013008287Zhang, Y., Jia, M., Liu, H., & Xie, M. (2016). Development of an improved liquid film model for spray/wall interaction under engine-relevant conditions. International Journal of Multiphase Flow, 79, 74-87. doi:10.1016/j.ijmultiphaseflow.2015.10.002Yi, P., Long, W., Jia, M., Tian, J., & Li, B. (2016). Development of a quasi-dimensional vaporization model for multi-component fuels focusing on forced convection and high temperature conditions. International Journal of Heat and Mass Transfer, 97, 130-145. doi:10.1016/j.ijheatmasstransfer.2016.01.075Zhang, Y., Jia, M., Yi, P., Liu, H., & Xie, M. (2017). An efficient liquid film vaporization model for multi-component fuels considering thermal and mass diffusions. Applied Thermal Engineering, 112, 534-548. doi:10.1016/j.applthermaleng.2016.10.046Cao, J., Jia, M., Niu, B., Chang, Y., Xu, Z., & Liu, H. (2019). Establishment of an improved heat transfer model based on an enhanced thermal wall function for internal combustion engines operated under different combustion modes. Energy Conversion and Management, 195, 748-759. doi:10.1016/j.enconman.2019.05.046Ricart, L. M., Reltz, R. D., & Dec, J. E. (1999). Comparisons of Diesel Spray Liquid Penetration and Vapor Fuel Distributions With In-Cylinder Optical Measurements. Journal of Engineering for Gas Turbines and Power, 122(4), 588-595. doi:10.1115/1.1290591Kee RJ, Rupley FM, Meeks E, Miller JA. CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas phase chemical and plasma kinetics. USA: Sandia National Laboratory Technical Report; 1996. SAND96-8216.Chang, Y., Jia, M., Li, Y., & Xie, M. (2015). Application of the Optimized Decoupling Methodology for the Construction of a Skeletal Primary Reference Fuel Mechanism Focusing on Engine-Relevant Conditions. Frontiers in Mechanical Engineering, 1. doi:10.3389/fmech.2015.00011Xu, G., Jia, M., Li, Y., Chang, Y., Liu, H., & Wang, T. (2019). Evaluation of variable compression ratio (VCR) and variable valve timing (VVT) strategies in a heavy-duty diesel engine with reactivity controlled compression ignition (RCCI) combustion under a wide load range. Fuel, 253, 114-128. doi:10.1016/j.fuel.2019.05.020Li, Y., Jia, M., Chang, Y., Xu, Z., Xu, G., Liu, H., & Wang, T. (2018). Principle of determining the optimal operating parameters based on fuel properties and initial conditions for RCCI engines. Fuel, 216, 284-295. doi:10.1016/j.fuel.2017.12.010García, A., Monsalve-Serrano, J., Villalta, D., & Lago Sari, R. (2019). Performance of a conventional diesel aftertreatment system used in a medium-duty multi-cylinder dual-mode dual-fuel engine. Energy Conversion and Management, 184, 327-337. doi:10.1016/j.enconman.2019.01.069Benajes, 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.2015.07.064Splitter D, Wissink M, Kokjohn S, Reitz RD. Effect of compression ratio and piston geometry on RCCI load limits and efficiency. SAE Technical Paper. 2012; no. 2012-01-0383.Broatch, A., Olmeda, P., García, A., Salvador-Iborra, J., & Warey, A. (2017). Impact of swirl on in-cylinder heat transfer in a light-duty diesel engine. Energy, 119, 1010-1023. doi:10.1016/j.energy.2016.11.040Olmeda, P., García, A., Monsalve-Serrano, J., & Lago Sari, R. (2018). Experimental investigation on RCCI heat transfer in a light-duty diesel engine with different fuels: Comparison versus conventional diesel combustion. Applied Thermal Engineering, 144, 424-436. doi:10.1016/j.applthermaleng.2018.08.082Kim M, Reitz RD, Kong SC. Modeling early injection processes in HSDI diesel engines. SAE Technical Paper. 2006; no. 2006-01-0056.Xu, G., Jia, M., Li, Y., Chang, Y., & Wang, T. (2018). Potential of reactivity controlled compression ignition (RCCI) combustion coupled with variable valve timing (VVT) strategy for meeting Euro 6 emission regulations and high fuel efficiency in a heavy-duty diesel engine. Energy Conversion and Management, 171, 683-698. doi:10.1016/j.enconman.2018.06.034Xu G, Jia M, Xu Z, Chang Y, Wang T. Numerical investigation of the potential of late intake valve closing (LIVC) coupled with double diesel direct-injection strategy for meeting high fuel efficiency with ultra-low emissions in a heavy-duty reactivity controlled compression ignition (RCCI) engine at high load. SAE Technical Paper. 2019; no. 2019-01-1166.Deb, K., Pratap, A., Agarwal, S., & Meyarivan, T. (2002). A fast and elitist multiobjective genetic algorithm: NSGA-II. IEEE Transactions on Evolutionary Computation, 6(2), 182-197. doi:10.1109/4235.996017Shi, Y., & Reitz, R. D. (2008). Optimization study of the effects of bowl geometry, spray targeting, and swirl ratio for a heavy-duty diesel engine operated at low and high load. International Journal of Engine Research, 9(4), 325-346. doi:10.1243/14680874jer00808Li, Y., Jia, M., Chang, Y., Liu, Y., Xie, M., Wang, T., & Zhou, L. (2014). Parametric study and optimization of a RCCI (reactivity controlled compression ignition) engine fueled with methanol and diesel. Energy, 65, 319-332. doi:10.1016/j.energy.2013.11.059Nieman DE, Dempsey AB, Reitz RD. Heavy-duty RCCI operation using natural gas and diesel. SAE Technical Paper. 2012; no. 2012-01-0379.Xu, G., Jia, M., Li, Y., Xie, M., & Su, W. (2017). Multi-objective optimization of the combustion of a heavy-duty diesel engine with low temperature combustion under a wide load range: (I) Computational method and optimization results. Energy, 126, 707-719. doi:10.1016/j.energy.2017.02.126Leermakers CAJ, Somers LMT, Johansson BH. Combustion phasing controllability with dual fuel injection timings. SAE Technical Paper. 2012; no. 2012-01-1575.Gingrich E, Ghandhi J, Reitz RD. Experimental investigation of piston heat transfer in a light duty engine under conventional diesel, homogeneous charge compression ignition, and reactivity controlled compression ignition combustion regimes. SAE Technical Paper. 2014; no. 2014-01-1182

An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS)

[EN] Recent investigations demonstrated that real-world emissions usually exceed the levels achieved in the laboratory based type approval processes. By means of on-board emissions measurements, it has been shown that nitrogen oxides emitted by diesel engines substantially exceed the limit imposed by the Euro 6 regulation. Thus, with the aim of complementing the worldwide harmonized light vehicles test cycle, the real driving emissions cycle will be introduced after 1 September 2017 to regulate the vehicle emissions in real-world driving situations. This paper presents on-board gaseous emissions "measurements from a Euro 6 light-duty diesel vehicle in a real-world driving route using a portable emissions measurement system. The test route characteristics follow the requirements imposed by the RDE regulation. The analysis of the raw emissions results suggests that the greatest amount of nitrogen oxides and nitrogen dioxide are emitted during the urban section of the test route, confirming that lower speeds with more accelerations and decelerations lead to higher nitrogen oxides emissions levels than constant high speeds. Moreover, the comparison of the two calculation methods proposed by the real driving emissions regulation has revealed emissions rates differences ranging from 10% to 45% depending on the pollutant emission and the trip section considered (urban or total). Thus, the nitrogen oxides emissions conformity factor slightly varies from one method to the other.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".Luján, JM.; Bermúdez, V.; Dolz, V.; Monsalve-Serrano, J. (2018). An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS). Atmospheric Environment. 174:112-121. https://doi.org/10.1016/j.atmosenv.2017.11.056S11212117

Optimization of the parallel and mild hybrid vehicle platforms operating under conventional and advanced combustion modes

[EN] The stringent regulations, increased global temperature and customer demand for high fuel economy have led to rapid developments of different alternative propulsion solutions in the last decade, with special attention to the electrified vehicles. The combination of electric machines with conventional powertrains allows to diversify the powertrain architectures. In addition, alternative combustion modes as reactivity controlled compression ignition (RCCI) have been shown to provide simultaneous ultra-low NOx and soot emissions with similar or better thermal efficiency than conventional diesel combustion (CDC). Therefore, the combination of both technologies creates a promising horizon to be implemented in commercial vehicles of the near future. In this work, experimental and numerical simulations were combined to study the potential of the parallel full hybrid electric vehicle (P2-FHEV) and mild hybrid vehicle (MHEV) to obtain lower fuel consumption and NOx emissions than a conventional powertrain in the Worldwide Harmonized Light Vehicles Cycle (WLTC). The hybrid vehicles are simulated with both CDC and diesel-gasoline RCCI combustion engines as power source. Each powertrain was optimized in terms of components (battery, electric motors...) capacity, internal combustion engine operative points, energy management strategy and gear ratios. The results show a significant fuel consumption reduction as the complexity of the hybrid system increases. The parallel architecture, which represents the most complex hybrid system tested in this work, allows obtaining a fuel consumption reduction of around 20% as compared to CDC. The dual-mode CDC-RCCI concept showed improvements in NOx and soot emissions with comparable values in terms of energy consumption and CO2 emissions than CDC. Additionally, the mild hybrid technology with the functionality of start-stop, torque assist and regenerative braking showed an acceptable balance between complexity and fuel consumption gain.The authors want to express their gratitude to General Motors Global Research & Development for providing the engine used to acquire the experimental data used in this investigation. The authors acknowledge FEDER and Spanish Ministerio de Economia y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R). The authors also acknowledge the Universitat Politecnica de Valencia for partially supporting this research through Convocatoria de ayudas a Primeros Proyectos de Investigation (PAID-06-18).Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Martínez-Boggio, S. (2019). Optimization of the parallel and mild hybrid vehicle platforms operating under conventional and advanced combustion modes. Energy Conversion and Management. 190:73-90. https://doi.org/10.1016/j.enconman.2019.04.010S739019

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

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

Potential of a Two-Stage Variable Compression Ratio Downsized Spark Ignition Engine for Passenger Cars under different driving conditions

[EN] With the aim of reducing pollutant emissions from internal combustion engines (ICE), the application of stoichiometrically operated spark ignition (SI) engines, for light-duty vehicles, has been overcoming the compression ignition (CI) engines market share throughout the past years. The ability of a substantial reduction of the primary harmful emissions (HC, CO, and NOx) through the use of the simple three-way catalyst (TWC) is the main reason for that. Nonetheless, with increasing attention to CO2 emissions, the development of highly efficient downsized SI engines turn to be of enormous interest. The synergies of multiple systems such as direct injection, turbocharger, and variable valve actuation are able to lead the SI efficiencies closer to those of CI engines. However, to enable high load operation on such downsized engines, the compression ratio (CR) must be reduced due to knock limitations, reducing the partial-load operations efficiency. The implementation of two-stage variable compression ratio (VCR) systems enables the extraction of high thermal efficiency with high CR at lower loads and extended knock-free high load operation with low CR. In this study, the evaluation of a two-stage VCR system applied to a state-of-the-art downsized SI engine was made through standard driving cycle simulations. The VCR mechanism is composed of an eccentric element in the small end of the connecting rod, which is rotated to increase/decrease the effective connecting rod length, achieving the CRs of 12.11:1 and 9.56:1. The engine was run in an eddy-current dynamometer test bench throughout the essential operating range to obtain the brake specific fuel consumption (BSFC) map. The VCR mechanism CR switching delay was also experimentally characterized to derive a function of the operating conditions. The measured map was entered into the map-based driving cycle simulation with a sub-model to account for the isolated effects of the transient period encompassing the compression ratio switching. The results show that slow CR transitions lead to fuel consumption penalties, which suggests the need for optimizing the control strategies of the VCR system. Even though this penalty, once the gear up-shift speed is optimized for each driving cycle, the VCR system still enables fuel consumption reductions up to 3% on the WLTC driving cycle, up to 4% on the proposed urban driving cycles and up to 3% on highway driving cycles with respect to the fixed CR.This research has been partially funded by FEDER and the Spanish Government through project RTI2018-102025-B-I00. The authors also acknowledge the Universitat Politecnica de Valencia for partially supporting this research through Convocatoria de ayudas a Primeros Proyectos de Lnvestigacion (PAID-06-18).López, JJ.; García Martínez, A.; Monsalve-Serrano, J.; Vielmo-Cogo, V.; Wittek, K. (2020). Potential of a Two-Stage Variable Compression Ratio Downsized Spark Ignition Engine for Passenger Cars under different driving conditions. Energy Conversion and Management. 203:1-15. https://doi.org/10.1016/j.enconman.2019.112251S115203Amelang S, Wehrmann B. Dieselgate – a timeline of Germany’s car emissions fraud scandal | Clean Energy Wire n.d. https://www.cleanenergywire.org/factsheets/dieselgate-timeline-germanys-car-emissions-fraud-scandal (accessed September 2, 2019).Luján, J. M., Bermúdez, V., Dolz, V., & Monsalve-Serrano, J. (2018). An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS). Atmospheric Environment, 174, 112-121. doi:10.1016/j.atmosenv.2017.11.056E, J., Pham, M., Zhao, D., Deng, Y., Le, D., Zuo, W., … Zhang, Z. (2017). Effect of different technologies on combustion and emissions of the diesel engine fueled with biodiesel: A review. Renewable and Sustainable Energy Reviews, 80, 620-647. doi:10.1016/j.rser.2017.05.250Jurić, F., Petranović, Z., Vujanović, M., Katrašnik, T., Vihar, R., Wang, X., & Duić, N. (2019). Experimental and numerical investigation of injection timing and rail pressure impact on combustion characteristics of a diesel engine. Energy Conversion and Management, 185, 730-739. doi:10.1016/j.enconman.2019.02.039E, J., Zhao, X., Qiu, L., Wei, K., Zhang, Z., Deng, Y., … Liu, G. (2019). Experimental investigation on performance and economy characteristics of a diesel engine with variable nozzle turbocharger and its application in urban bus. Energy Conversion and Management, 193, 149-161. doi:10.1016/j.enconman.2019.04.062E, J., Zuo, W., Gao, J., Peng, Q., Zhang, Z., & Hieu, P. M. (2016). Effect analysis on pressure drop of the continuous regeneration-diesel particulate filter based on NO 2 assisted regeneration. Applied Thermal Engineering, 100, 356-366. doi:10.1016/j.applthermaleng.2016.02.031Huang, Y., Ng, E. C. Y., Yam, Y., Lee, C. K. C., Surawski, N. C., Mok, W., … Chan, E. F. C. (2019). Impact of potential engine malfunctions on fuel consumption and gaseous emissions of a Euro VI diesel truck. Energy Conversion and Management, 184, 521-529. doi:10.1016/j.enconman.2019.01.076Deng, Y., Liu, H., Zhao, X., E, J., & Chen, J. (2018). Effects of cold start control strategy on cold start performance of the diesel engine based on a comprehensive preheat diesel engine model. Applied Energy, 210, 279-287. doi:10.1016/j.apenergy.2017.10.093García, A., Monsalve-Serrano, J., Heuser, B., Jakob, M., Kremer, F., & Pischinger, S. (2016). Influence of fuel properties on fundamental spray characteristics and soot emissions using different tailor-made fuels from biomass. Energy Conversion and Management, 108, 243-254. doi:10.1016/j.enconman.2015.11.010Benajes, J., Pastor, J. V., García, A., & Boronat, 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.2016.08.023Benajes, J., García, A., Monsalve-Serrano, J., & Villalta, D. (2018). Benefits of E85 versus gasoline as low reactivity fuel for an automotive diesel engine operating in reactivity controlled compression ignition combustion mode. Energy Conversion and Management, 159, 85-95. doi:10.1016/j.enconman.2018.01.015Wang, Z., Liu, H., & Reitz, R. D. (2017). Knocking combustion in spark-ignition engines. Progress in Energy and Combustion Science, 61, 78-112. doi:10.1016/j.pecs.2017.03.004Santos, H., & Costa, M. (2008). Evaluation of the conversion efficiency of ceramic and metallic three way catalytic converters. Energy Conversion and Management, 49(2), 291-300. doi:10.1016/j.enconman.2007.06.008Heck, R. M., & Farrauto, R. J. (2001). Automobile exhaust catalysts. Applied Catalysis A: General, 221(1-2), 443-457. doi:10.1016/s0926-860x(01)00818-3Feng, D., Wei, H., & Pan, M. (2018). Comparative study on combined effects of cooled EGR with intake boosting and variable compression ratios on combustion and emissions improvement in a SI engine. Applied Thermal Engineering, 131, 192-200. doi:10.1016/j.applthermaleng.2017.11.110European Environment Agency (EEA). Monitoring CO2 emissions from new passenger cars and vans in 2017. 2018. doi:10.2800/74986.Society of Motor Manufacturers and Traders (SMMT). Fall in new car market wake up call to policy makers as environmental goals at risk. 2019.Kalghatgi, G. T. (2015). Developments in internal combustion engines and implications for combustion science and future transport fuels. Proceedings of the Combustion Institute, 35(1), 101-115. doi:10.1016/j.proci.2014.10.002Su, J., Xu, M., Li, T., Gao, Y., & Wang, J. (2014). Combined effects of cooled EGR and a higher geometric compression ratio on thermal efficiency improvement of a downsized boosted spark-ignition direct-injection engine. Energy Conversion and Management, 78, 65-73. doi:10.1016/j.enconman.2013.10.041Zhen, X., Wang, Y., Xu, S., Zhu, Y., Tao, C., Xu, T., & Song, M. (2012). The engine knock analysis – An overview. Applied Energy, 92, 628-636. doi:10.1016/j.apenergy.2011.11.079Zhuang, Y., Qian, Y., & Hong, G. (2017). The effect of ethanol direct injection on knock mitigation in a gasoline port injection engine. Fuel, 210, 187-197. doi:10.1016/j.fuel.2017.08.060Zhou, L., Dong, K., Hua, J., Wei, H., Chen, R., & Han, Y. (2018). Effects of applying EGR with split injection strategy on combustion performance and knock resistance in a spark assisted compression ignition (SACI) engine. Applied Thermal Engineering, 145, 98-109. doi:10.1016/j.applthermaleng.2018.09.001Luján, J. M., Climent, H., Novella, R., & Rivas-Perea, M. E. (2015). Influence of a low pressure EGR loop on a gasoline turbocharged direct injection engine. Applied Thermal Engineering, 89, 432-443. doi:10.1016/j.applthermaleng.2015.06.039Li, T., Wang, B., & Zheng, B. (2016). A comparison between Miller and five-stroke cycles for enabling deeply downsized, highly boosted, spark-ignition engines with ultra expansion. Energy Conversion and Management, 123, 140-152. doi:10.1016/j.enconman.2016.06.038Lanzanova, T. D. M., Dalla Nora, M., Martins, M. E. S., Machado, P. R. M., Pedrozo, V. B., & Zhao, H. (2019). The effects of residual gas trapping on part load performance and emissions of a spark ignition direct injection engine fuelled with wet ethanol. Applied Energy, 253, 113508. doi:10.1016/j.apenergy.2019.113508Noce, T., da Silva, R. R., Morais, R., Sales, L. C. M., Hanriot, S. de M., & Sodré, J. R. (2018). Energy factors for flexible fuel engines and vehicles operating with gasoline-ethanol blends. Transportation Research Part D: Transport and Environment, 65, 368-374. doi:10.1016/j.trd.2018.09.002Wittek K, Geiger F, Andert J, Martins MES, Oliveira M. An Overview of VCR Technology and Its Effects on a Turbocharged DI Engine Fueled with Ethanol and Gasoline. SAE Tech Pap 2017:2017-36-0357. doi:10.4271/2017-36-0357.Hiyoshi R. Variable compression ratio engine. US2013/0327302A1, 2013.Moteki K, Fujimoto H, Aoyama S. Variable compression ratio mechanism of reciprocating internal combustion engine. US6505582B2, 2003.Larsen GJ. Reciprocating piston engine with a varying compression ratio. US5025757A, 1991.Wittek K. Hydraulic freewheel for an internal combustion engine with variable compression ratio. US9677469B2, 2017.Rao VDN, German DJ, Vrsek GA, Chottiner E, Madin MM. Variable compression ratio pistons and connecting rods. US6568357B1, 2003.Kleeberg H, Tomazic D, Dohmen J, Wittek K, Balazs A. Increasing Efficiency in Gasoline Powertrains with a Two-Stage Variable Compression Ratio (VCR) System. SAE Tech Pap 2013:2013-01-0288. doi:10.4271/2013-01-0288.Shelby MH, Leone TG, Byrd KD, Wong FK. Fuel Economy Potential of Variable Compression Ratio for Light Duty Vehicles. SAE Int J Engines 2017;10:2017-01-0639. doi:10.4271/2017-01-0639.Boretti, A., & Scalzo, J. (2012). Novel Crankshaft Mechanism and Regenerative Braking System to Improve the Fuel Economy of Light Duty Vehicles and Passenger Cars. SAE International Journal of Passenger Cars - Mechanical Systems, 5(4), 1177-1193. doi:10.4271/2012-01-1755Teodosio L, De Bellis V, Bozza F, Tufano D. Numerical Study of the Potential of a Variable Compression Ratio Concept Applied to a Downsized Turbocharged VVA Spark Ignition Engine. SAE Tech Pap 2017:2017-24–0015. doi:10.4271/2017-24-0015.Hoyer KS, Moore WR, Confer K. A Simulation Method to Guide DISI Engine Redesign for Increased Efficiency using Alcohol Fuel Blends. SAE Int J Engines 2010:2010-01-1203. doi:10.4271/2010-01-1203.Luján, J. M., García, A., Monsalve-Serrano, J., & Martínez-Boggio, S. (2019). Effectiveness of hybrid powertrains to reduce the fuel consumption and NOx emissions of a Euro 6d-temp diesel engine under real-life driving conditions. Energy Conversion and Management, 199, 111987. doi:10.1016/j.enconman.2019.111987Wittek, K., Geiger, F., Andert, J., Martins, M., Cogo, V., & Lanzanova, T. (2019). Experimental investigation of a variable compression ratio system applied to a gasoline passenger car engine. Energy Conversion and Management, 183, 753-763. doi:10.1016/j.enconman.2019.01.037Klein P. Zylinderdruckbasierte Fuellungserfassung für Verbrennungsmotoren 2009.Taylor JR. An introduction to error analysis. 2nd ed. 1997.Gao, J., Chen, H., Li, Y., Chen, J., Zhang, Y., Dave, K., & Huang, Y. (2019). Fuel consumption and exhaust emissions of diesel vehicles in worldwide harmonized light vehicles test cycles and their sensitivities to eco-driving factors. Energy Conversion and Management, 196, 605-613. doi:10.1016/j.enconman.2019.06.038Tsokolis, D., Tsiakmakis, S., Dimaratos, A., Fontaras, G., Pistikopoulos, P., Ciuffo, B., & Samaras, Z. (2016). Fuel consumption and CO2 emissions of passenger cars over the New Worldwide Harmonized Test Protocol. Applied Energy, 179, 1152-1165. doi:10.1016/j.apenergy.2016.07.091T.J. Barlow I. S. McCrae, and P.G. Boulter SL. A reference book of driving cycles for use in the measurement of road vehicle emissions. 2009.André, M. (2004). The ARTEMIS European driving cycles for measuring car pollutant emissions. Science of The Total Environment, 334-335, 73-84. doi:10.1016/j.scitotenv.2004.04.070Wittek, K., Tiemann, C., & Pischinger, S. (2009). Two-Stage Variable Compression Ratio with Eccentric Piston Pin and Exploitation of Crank Train Forces. SAE International Journal of Engines, 2(1), 1304-1313. doi:10.4271/2009-01-1457Caton, J. A. (2017). The interactions between IC engine thermodynamics and knock. Energy Conversion and Management, 143, 162-172. doi:10.1016/j.enconman.2017.04.00

Surrogate Fuel Formulation to Improve the Dual-Mode Dual-Fuel Combustion Operation at Different Operating Conditions

[EN] Dual-mode dual-fuel combustion is a promising combustion concept to achieve the required emissions and CO2 reductions imposed by the next standards. Nonetheless, the fuel formulation requirements are stricter than for the single-fuel combustion concepts as the combustion concept relies on the reactivity of two different fuels. This work investigates the effect of the low reactivity fuel sensitivity (S=RON-MON) and the octane number at different operating conditions representative of the different combustion regimes found during the dual-mode dual-fuel operation. For this purpose, experimental tests were performed using a PRF 95 with three different sensitivities (S0, S5 and S10) at operating conditions of 25% load/950 rpm, 50%/1800 rpm and 100%/2200 rpm. Moreover, air sweeps varying ±10% around a reference air mass were performed at 25%/1800 rpm and 50%/1800 rpm. Conventional diesel fuel was used as high reactivity fuel in all the cases. Moreover, commercial 95 RON gasoline was used as reference to compare the different TRFs. The engine settings were managed to adjust the rate of heat release to that found with 95 RON gasoline. To do this, a quality index imposing a maximum deviation of 5% point-to-point between the HRR curves from both fuels was defined. The results suggest that PRF 95 with S0 has the most similar behavior compared to conventional 95 RON gasoline whatever the engine load. As the engine load increases, the sensitivity effect is more noticeable and iso-HRR operation was only possible for S0. At low and medium load, the TRFs present similar engine-out emissions with equal fuel consumption. At full load, the NOx emissions are increased with respect to the reference 95 RON gasoline without fuel consumption benefits. The results from the air variation for the different octane numbers demonstrated that the greatest differences are obtained for low air mass (i.e, higher EGR). In addition, the decrease of the octane number limits the maximum air increase due to the pressure gradients, requiring modifications in the engine settings that increase the soot formation.The authors thanks VOLVO Group Trucks Technology and ARAMCO Overseas Company for supporting this research. The authors also acknowledge FEDER and Spanish Ministerio de Economía y Competitividad for partially supporting this research through TRANCO project (TRA2017-87694-R) and the Universitat Politècnica de València for partially supporting this research through Convocatoria de ayudas a Primeros Proyectos de Investigación (PAID-06-18). The author R. Sari acknowledges the financial support from the Spanish ministry of science innovation and universities under the grant ¿Ayudas para contratos predoctorales para la formación de doctores¿ (PRE2018-085043).Benajes, J.; García Martínez, A.; Monsalve-Serrano, J.; Lago-Sari, R. (2020). Surrogate Fuel Formulation to Improve the Dual-Mode Dual-Fuel Combustion Operation at Different Operating Conditions. SAE International. 1-13. https://doi.org/10.4271/2020-01-2073S11

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