Scaling and dimensional methods to incorporate knock and flammability limits in models of high-efficiency gasoline and ethanol engines

Lewis, Anne Marie; Ortiz-Soto, Elliott; Lavoie, George A.; Assanis, Dennis N.

doi:10.1177/1468087414530387

Cited by 12 publications

(5 citation statements)

References 32 publications

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“…14 Liu et al 14 recommend a value of c 2 between 0.2 and 0.4. This is consistent with an analysis performed by Lewis et al, 29 where a detailed study of SI flame structure for high-dilution engines indicated c 2 = 0.2 as a reasonable value. For this study, a value of c 2 = 0.2 is selected.…”

Section: Model Structure and Descriptionsupporting

confidence: 92%

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Evaluation of control-oriented flame propagation models for production control of a spark-assisted compression ignition engine

Robertson

Prucka

2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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The drive to improve internal combustion engines has led to efficiency objectives that exceed the capability of conventional combustion strategies. As a result, advanced combustion modes are more attractive for production. These advanced combustion strategies typically add sensors, actuators, and degrees of freedom to the combustion process. Spark-assisted compression ignition (SACI) is an efficient production-viable advanced combustion strategy characterized by spark-ignited flame propagation that triggers autoignition in the remaining unburned gas. Modeling this complex combustion process for control demands a careful selection of model structure to maximize predictive accuracy within computational constraints. This work comprehensively evaluates a physics-based and a data-driven model. The physics-based model produces a burn duration by computing laminar flame speed as a function of test point conditions. The crank-angle domain is intentionally excluded to reduce computational expense. The data-driven model is an artificial neural network (ANN). The candidate models are compared to a one-dimensional engine model validated to experimental SACI engine data. Though both models capture the trends in burn rates, the ANN model has a root-mean square error (RMSE) of 1.4 CAD, significantly lower than the 10.4 CAD RMSE of the physics-based model. The exclusion of the crank-angle domain results in insufficient detail for the physics-based model, while the ANN can tolerate this exclusion.

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Section: Model Structure and Descriptionsupporting

confidence: 92%

“…In this region, the flame is highly strained and quench occurs. Dai et al 28 and Lewis et al 29 both demonstrated that this turbulent flame model satisfactorily predicts misfire in SI engines. In these studies, EGR level is limited to less than 25%.…”

Section: Physics-based Model Developmentmentioning

confidence: 96%

Evaluation of control-oriented flame propagation models for production control of a spark-assisted compression ignition engine

Robertson

Prucka

2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…If τ ID < τ RES , the end gas autoignites before the flame fully consumes the charge. 61 This is a very rough approach to define the knock limit in SI engines, as knock is strongly influenced by the end gas pressure, temperature, and mixture composition but is used here for its simplicity. The residence time is a function of engine speed and residence period in crank angle degrees, and is defined by…”

Section: ■ Stable Regime Of Diluted Combustionmentioning

confidence: 99%

“…Other research used the residence time (τ RES ), as an indicator of knock occurrence. If τ ID < τ RES , the end gas autoignites before the flame fully consumes the charge . This is a very rough approach to define the knock limit in SI engines, as knock is strongly influenced by the end gas pressure, temperature, and mixture composition but is used here for its simplicity.…”

Section: Stable Regime Of Diluted Combustionmentioning

confidence: 99%

Computational Study of the Laminar Reaction Front Properties of Diluted Methanol–Air Flames Enriched by the Fuel Reforming Product

Nguyen

Verhelst

2017

Energy Fuels

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The current work investigates the flame structure and the propagation of premixed laminar flame fronts for mixtures of diluted methanol−air enriched by fuel reforming products under spark ignition engine conditions. Two engine concepts were investigated: one with external fuel reforming (EFR) and one with reformed exhaust gas recirculation (R-EGR).Here, the fuel reformate (or syngas) is a mixture of H 2 , CO, and CO 2 with a CO selectivity of 6.5%, which is used to represent the products of methanol steam reforming over a Cu−Mn/Al foam catalyst. The simulations were exercised over a wide range of dilution level and unburned gas temperature at 40 bar with a skeletal chemical kinetic mechanism using zero/one-dimensional codes. Two types of dilutionair and EGRwere compared at the same fuel-to-charge equivalence ratio (ϕ′). The results showed that the knock limit for spark-ignited operation is extended with rising dilution levels, especially when diluted by an R-EGR mixture. Syngas addition also leads to a reduced knock tendency. At the knock limit, the fraction of heat released by autoignition is greater at a higher dilution rate. At the lower flammability limit, the stable flame propagation range is expanded to a lower unburned gas temperature when using air dilution. Under stoichiometric conditions, dilution with an R-EGR mixture is recommended for partial load operation, because it provides a stable flame at high dilution levels. The influence of gas properties were also investigated, where a shorter ignition delay after compression was observed with a leaner mixture. The ignition delay increased with a higher EGR ratio, especially in the case of the R-EGR mixture. Therefore, the knock tendency increases with a leaner mixture. However, the knock ringing intensity decreases if the mixture is diluted by air. A mixture diluted by R-EGR can reduce the knock tendency, compared to the two EGR dilution cases, and can decrease the knock ringing intensity, compared to the two air dilution cases at high dilution ratios.

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“…1,2 Use of alcohol as a fuel is popular in transport sector because it offers several advantages such as cost-effectiveness, tides over energy security issue, reduces greenhouse gas (GHG) emissions, reduces toxic exhaust emissions, enhances overall energy efficiency and reduces engine knocking. 3,4 In fact, combustion knock is a major barrier in achieving higher thermal efficiency in SI engines [1][2][3][4][5][6][7] Performance of a gasoline/ alcohol blend fuelled direct injection SI engine significantly depends on fuel spray phenomenon, therefore recently many researchers have focused on resolving this issue. [8][9][10][11][12] Also, understanding spray characteristics of both 'gasoline' and 'renewable fuels' has become very important.…”

Section: Introductionmentioning

confidence: 99%

Microscopic spray characteristics of ethanol and methanol blended gasoline in a direct injection spark ignition engine

Sharma

Ágarwal

2021

International Journal of Engine Research

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Renewable fuels are continuously being refined/ upgraded for automotive applications to reduce dependence on conventional fossil fuels. However, optimized use of these renewable fuels in existing and new engines/ vehicles requires comprehensive characterization and understanding of spray atomization and fuel-air mixture formation processes. Spray atomization and mixture formation depends on fuel injection pressure (FIP), fuel injection quantity and ambient conditions. This study is aimed at exploring microscopic spray characteristics of ethanol and methanol blended gasoline for automotive applications, particularly in direct injection Spark Ignition (DISI) engines. Phase Doppler interferometer (PDI) technique was used for comparative microscopic spray characterization in a constant volume spray chamber (CVSC) at ambient pressure condition, to evaluated spray droplet size-velocity distributions and joint probability density function (JPDF) of different test fuels. In this study, two gasohol mixtures [15% v/v ethanol and methanol blended with 85% v/v gasoline] and baseline gasoline were experimentally evaluated for comparing spray droplet size-velocity distributions at two different FIPs of 80 and 160 bars, at two different fuel injection quantities of 12 and 28 mg/injection, which are typical representative conditions for a DISI engines. The results from this experimental investigation are valuable for automotive and fuel industries, and spray community, which are continuously upgrading renewable and oxygenated fuels and engine technologies for efficiency improvement and emission reduction.

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Scaling and dimensional methods to incorporate knock and flammability limits in models of high-efficiency gasoline and ethanol engines

Cited by 12 publications

References 32 publications

Evaluation of control-oriented flame propagation models for production control of a spark-assisted compression ignition engine

Evaluation of control-oriented flame propagation models for production control of a spark-assisted compression ignition engine

Computational Study of the Laminar Reaction Front Properties of Diluted Methanol–Air Flames Enriched by the Fuel Reforming Product

Microscopic spray characteristics of ethanol and methanol blended gasoline in a direct injection spark ignition engine

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