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dc.descriptionIn this work, a Continuous Variable Valve Timing (CVVT) system for load control in spark-ignition engines is proposed, analyzed, and compared with a conventional Throttle-controlled Engine. An analytical model for ideal processes is initially developed to study the performance of both cycles during part-load operation. Then, irreversibilites comprising charging dilution effects and heat losses during compression and expansion strokes are considered to approach a more realistic engine operation. At full-load, both cycles reach a maximum efficiency corresponding to that of an Otto cycle. However, a reduction in the efficiency occurs at part-load operation, with the CVVT Engine having a higher efficiency with respect to the Throttled Engine due to its unthrottled load control mechanism, which avoids power consumption caused by friction during air intake. It is found that charge dilution exerts a strong impact in the net power output and efficiency of both cycles. Additional reductions in power output and efficiency are caused by heat losses. At part-load operation, lower temperatures and pressures are reached in the CVVT Engine, which imply lower mechanical stresses that favor engine lifetime. It also represents a potential for additional efficiency enhancement via increasing combustion temperature. Finally, a fuel economy estimation analysis is carried out to provide quantitative assessment about the economic advantage of the proposed CVVT Engine. From this analysis, a fuel economy increment of up to 4.1% is obtained for a CVVT Engine with respect to a Throttled Engine at a 20%-30% load, which is typical of a real vehicle engine operation. © 2018 Elsevier Ltdspa
dc.publisherElsevier Ltdspa
dc.subjectContinuous Variable Valve Timing Engine (CVVT Engine)spa
dc.subjectEfficiency enhancementspa
dc.subjectFuel economyspa
dc.subjectIrreversible engine operationspa
dc.subjectThrottled Enginespa
dc.titleEfficiency enhancement of spark-ignition engines using a Continuous Variable Valve Timing system for load controlspa
dc.publisher.programIngeniería en Energíaspa
dc.contributor.affiliationOsorio, J.D., Universidad de Medellín; Ingeniería Térmica Ltda;Rivera-Alvarez, A., Ingeniería Térmica Ltda., Fundación Ergon, Medellínspa
dc.publisher.facultyFacultad de Ingenieríasspa
dc.relation.referencesInternational energy outlook 2016 with projections to 2040 (2016),, Accessed January 2018;Da Rosa, A.V., Fundamentals of renewable energy processes (2012), third ed. Academic Press;Cipolla, G., Bozza, F., Spark ignition engines: state-of-the-art and current technologies. Future trends and developments. Handbook of clean energy systems (2015), John Wiley & Sons, Ltd;Alagumalai, A., Internal combustion engines: progress and prospects (2014) Renew Sustain Energy Rev, 38, pp. 561-571;Fathi, M., Jahanian, O., Shahbakhti, M., Modeling and controller design architecture for cycle-by-cycle combustion control of homogeneous charge compression ignition (HCCI) engines - a comprehensive review (2017) Energy Convers Manag, 139, pp. 1-19;Lin, J.C., Hou, S.S., Performance analysis of an air-standard Miller cycle with considerations of heat loss as a percentage of fuel's energy, friction and variable specific heats of working fluid (2008) Int J Therm Sci, 47, pp. 182-191;Tavakoli, S., Jazayeri, S.A., Fathi, M., Jahanian, O., Miller cycle application to improve lean burn gas engine performance (2016) Energy, 109, pp. 190-200;Grohn, M., Wolf, K., Variable valve timing in the new mercedes-benz four-valve engines, SAE technical paper 891990 (1989);Hosaka, T., Hamazaki, M., Development of the variable valve timing and lift (VTEC) engine for the Honda NSX. SAE Technical Paper, no 910008 (1991), pp. 1-6;Zhao, J., Research and application of over-expansion cycle (Atkinson and Miller) engines - a review (2017) Appl Energy, 185, pp. 300-319;Sauer, C., Kulzer, A., Rauscher, M., Hettinger, A., Analysis of different gasoline combustion concepts with focus on gas exchange (2009) SAE Int. J. Eng, 1 (1), pp. 336-345;Taylor, A.M.K.P., Science review of internal combustion engines (2008) Energy Pol, 36, pp. 4657-4667;Zmudka, Z., Postrzednik, S., Przybyla, G., Throttleless control of SI engine load by fully flexible inlet valve actuation system (2016) Combustion Eng, 164 (1), pp. 44-48;Fontana, G., Galloni, E., Variable valve timing for fuel economy improvement in a small spark-ignition engine (2009) Appl Energy, 86, pp. 96-105;Lenz, H., Wichart, K., Gruden, D., Variable valve timing-a possibility to control engine load without throttle. SAE technical paper 880388 (1988);Mianzo, L., Peng, H., Modeling and control of a variable valve timing engine (2000) Proceedings of the American control conference, pp. 554-558. , Chicago, Illinois;Bozza, F., De Bellis, V., Teodosio, L., A numerical procedure for the calibration of a turbocharged spark-ignition variable valve actuation engine at part load (2017) Int J Engine Res, 18 (8), pp. 1-14;Gimelli, A., Muccillo, M., Pennacchia, O., Study of a new mechanical variable valve actuation system: Part II- estimation of the actual fuel consumption improvement through one-dimensional fluid dynamic analysis and valve train friction estimation (2015) Int J Engine Res, 16 (6), pp. 762-772;Stein, R., Galietti, K., Leone, T., Dual equal VCT - a variable camshaft timing strategy for improved fuel economy and emissions (1995), SAE Technical Paper 950975;Stone, R., Introduction to internal combustion engines (1999), third ed. Macmillan press LTD London, UK;Uysal, F., Sagiroglu, S., The effects of a pneumatic-driven variable valve timing mechanism on the performance of an Otto engine (2015) J Mech Eng, 61 (11), pp. 632-640;, FreeValve AB, Kelliehousevägen 73 Ängelholm S-262 74, Sweden. (Accessed January 2018);Zhao, Y., Chen, J., Performance analysis of an irreversible Miller heat engine and its optimum criteria (2007) Appl Therm Eng, 27, pp. 2051-2058;Dobrucali, E., The effects of the engine design and running parameters on the performance of a Otto-Miller Cycle engine (2016) Energy, 103, pp. 119-126;Ge, Y., Chen, L., Sun, T.F., Wu, C., Effects of heat transfer and friction on the performance of an irreversible air-standard miller cycle (2005) Int Commun Heat Mass Tran, 32 (8), pp. 1045-1056;Wang, C., Chen, L., Ge, Y., Sun, F., Comparison of air-standard rectangular cycles with different specific heat models (2016) Appl Therm Eng, 109, pp. 507-513;Wang, Y., Lin, L., Roskilly, A.P., Zeng, S., Huang, J., He, Y., Huang, X., Yang, J., An analytic study of applying Miller cycle to reduce NOx emission from petrol engine (2007) Appl Therm Eng, 27 (11-12), pp. 1779-1789;Decher, R., Energy Conversion systems, flow physics and engineering (1994), Oxford university press;Lumley, J.L., Engines: an introduction (1999), first ed. Cambridge University Press;Taylor, C.F., (1985) The Internal-combustion engine in theory and practice, 1. , second ed. The MIT press;Gupta, H.N., Fundamentals of internal combustion engines (2013), second ed. PHI;Kutlar, O.A., Arslan, H., Calik, A.T., Methods to improve efficiency of four stroke, spark ignition engines at part load (2005) Energy Convers Manag, 46 (20), pp. 3202-3220spa

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