A Study of In-Cylinder Soot Oxidation by Laser Extinction Measurements During an EGR-Sweep in an Optical Diesel Engine

Gallo, Yann Le; Simonsson, Johan; Lind, Ted; Bengtsson, Per-Erik; Bladh, Henrik; Andersson, Öivind

doi:10.4271/2015-01-0800

Cited by 14 publications

(16 citation statements)

References 23 publications

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“…Natural luminosity from the flame was collected using three photo diodes with different band pass filters. These authors concluded that a drastic decrease in the oxygen intake concentration (up to 9%) implies a monotonic decrease in the cycle soot oxidation rate [15], which is consistent with the results reported in [13]. Using a similar optical approach, Lopez et al [16] also studied the in-cylinder soot oxidation process by means of the two-color method.…”

Section: Introductionsupporting

confidence: 64%

“…In spite of significant soot oxidation during the first part, only the second part is considered for calculation of KL half-life time in this study, since the oxidation during this part is the main responsible for the final engine-out soot emissions. Assuming that the last part of the curve (from EoI up to EoC) presented in Figure 5 follows an exponential decay after the KL peak [13], it would be possible to quantify the late-cycle soot oxidation rate by extracting the half-life value of the decay curve.…”

Section: Kl and Act -1 Half-life Timesmentioning

confidence: 99%

“…Measurements were made by using laser extinction under a wide range of operating conditions. Gallo et al [13], using an optical diesel engine, demonstrated that a reduction in oxygen concentration results in a decrease in incylinder soot oxidation. In their study, time resolved extinction measurements have been used to estimate soot oxidation rates during the expansion stroke.…”

Section: Introductionmentioning

confidence: 99%

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Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions

López

Martín

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Applied Thermal Engineering

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Section: Introductionsupporting

confidence: 64%

Section: Kl and Act -1 Half-life Timesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions

López

Martín

García

et al. 2017

Applied Thermal Engineering

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“…Diluting the charge by Exhaust Gas Recirculation (EGR) is a widespread method for reducing the NOx emissions by decreasing the combustion temperature. On the other hand, EGR 2 generally increases PM emissions due to deteriorating in-cylinder soot oxidation rates [1,2].…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies indicate that, under most conditions applicable to diesel engines, this oxidation has a dominating influence on the soot emission levels [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Investigation of late-cycle soot oxidation using laser extinction and in-cylinder gas sampling at varying inlet oxygen concentrations in diesel engines

Gallo

Malmborg

Simonsson

et al. 2017

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This study focuses on the relative importance of O2 and OH as oxidizers of soot during the late cycle in diesel engines. Laser-extinction measurements of soot oxidation rates are made in an optically accessible engine. These are combined with in-cylinder gas sampling data from a single-cylinder engine fitted with a fast gas sampling valve. Both measurements confirm that the in-cylinder soot oxidation slows down when the inlet concentration of O2 is reduced. A 50% decrease in intake O2 concentration reduces the soot oxidation rate by 600%, a discrepancy indicating that O2 in itself is not the main soot oxidizing species. Chemical kinetics simulations of OH concentrations in the oxidation zone and estimates of the OH-soot oxidation rate point towards OH being the dominant oxidizer.

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Swirl ratio and post injection strategies to improve late cycle diffusion combustion in a light-duty diesel engine

Benajes

Martín

García

et al. 2017

Applied Thermal Engineering

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Nitrogen oxides (NOx) and soot emissions are the most important pollutants from directinjection diesel engines. In particular, soot formation and oxidation determine the net engine-out soot emissions. These phenomena are complex and competing processes during diesel combustion. Despite many researches implicate the mechanisms of soot formation with soot emissions, the enhancement of the late cycle soot oxidation is the dominant mechanism for a reduction of engine-out soot emissions. The mixing process and the in-cylinder bulk temperature are two important parameters in the development of soot oxidation process. The current research compares different engine strategies to enhance the late cycle mixing controlled combustion process and therefore enhance soot oxidation while maintaining similar gross indicated efficiency in a light-duty engine. For this purpose, a simplified methodology has been used, which analyzes the effect of mixing process and in-cylinder bulk gas temperature on soot oxidation during the late cycle combustion. For carrying out this research, theoretical and experimental tools were used. In particular, the experimental measurements were made in a single-cylinder directinjection light-duty diesel engine varying the swirl ratio and the injection pattern as injection pressure, Start of Energizing (SoE), Energizing Time (ET) and number of injections events. To analyze soot emissions, the combustion luminosity was measured by an optoelectronic probe and the optical thickness parameter (KL) was evaluated by the two-color pyrometry method. The apparent combustion time (ACT-1) was used as mixing time tracer. Results show that an increase in swirl ratio implies an improvement on the mixing process and higher values of average bulk temperature during the late-cycle diffusion combustion. Both phenomena produce an enhancement in the soot oxidation process. In the lowest swirl ratio case, a suitable injection strategy based on multiple injections, provides similar results of soot oxidation process (and therefore, the emissions) as high swirl ratio case.

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A Study of In-Cylinder Soot Oxidation by Laser Extinction Measurements During an EGR-Sweep in an Optical Diesel Engine

Cited by 14 publications

References 23 publications

Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions

Implementation of two color method to investigate late cycle soot oxidation process in a CI engine under low load conditions

Investigation of late-cycle soot oxidation using laser extinction and in-cylinder gas sampling at varying inlet oxygen concentrations in diesel engines

Swirl ratio and post injection strategies to improve late cycle diffusion combustion in a light-duty diesel engine

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