Role of Piston Bowl Shape to Enhance Late-Cycle Soot Oxidation in Low-Swirl Diesel Combustion

Eismark, Jan; Andersson, Mats; Christensen, Magnus; Denbratt, Ingemar

doi:10.4271/03-12-03-0017

Cited by 30 publications

(16 citation statements)

References 13 publications

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“…DME can also be used for different combustion systems such as conventional ω-bowl or stepped lip bowl if the design is proper for flame-wall interaction to optimize the late-cycle oxidation process. Another example of a unique piston, Wave-type, which Volvo developed (Eismark et al, 2019) in recent years, could also allow for incylinder dilution of recirculating charge in a radial direction. This could improve DME combustion's thermal efficiency due to lower flame temperature by introducing in-cylinder dilution, which results in a lower specific heat ratio.…”

Section: Ignition and Lift-off Length: Comparison Dme And Dieselmentioning

confidence: 99%

Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

et al. 2021

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Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, DME spray combustion under several different conditions of ambient temperature (Tamb = 750–1100 K), ambient density (ρamb = 14.8–30 kg/m3), oxygen concentration (O2 = 15–21%), and injection pressure (Pinj = 75–150 MPa) were studied. The results from both experiments (constant-volume combustion vessel) and numerical simulations were used to develop empirical correlations for ignition and lift-off length. Compared to diesel, the established correlation of DME shows a similar Arrhenius-type expression. Sensitivity studies show that Tamb and Pinj have a stronger effect on DME's ignition and combustion than other parameters. Finally, this study provides a simplified conceptual mechanism of DME reacting spray under high reactivity ambient (high Tamb, high O2) and LTC conditions. Finally, this paper discusses engine operating strategies using a non-conventional fuel such as DME with different reactivity and chemical properties.

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Section: Ignition and Lift-off Length: Comparison Dme And Dieselmentioning

confidence: 99%

Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

et al. 2021

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show abstract

“…However, a better mixing process usually leads to a higher flame temperature and consequently a significant increase in NO X formation. For this reason, recent works have focused on promoting soot oxidation during late combustion stage [15] [16]. At this point, the piston geometry takes a major role as it influences both swirl and squish flows and spray-walls interaction, as well as the late-cycle mixing process [17][18] [19].…”

Section: Introductionmentioning

confidence: 99%

“…For light and mediumduty diesel engines, where the swirl number is usually higher than 1, the piston bowl design is typically re-entrant, as shown in figure 1. The purpose of this geometry is to support the swirl movement generated inside the cylinder, creating a re-circulation flow towards the bowl center during the late combustion stage [15]. Different re-entrant geometries have been developed and optimized during the last years.…”

Section: Introductionmentioning

confidence: 99%

Effect of a novel piston geometry on the combustion process of a light-duty compression ignition engine: An optical analysis

Pastor

García

Micó

et al. 2021

Energy

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“…32 Recently, the Volvo Group has presented a new piston geometry. 33 It has been named as ''wave piston'' and it has been designed for truck engines. In this piston, a kind of protrusions (waves) are located at the bowl periphery, equally spaced around the whole circumference.…”

Section: Introductionmentioning

confidence: 99%

“…The results have shown a great potential in terms of soot reduction while keeping low NO X levels due to the efficient late cycle oxidation promoted by the bowl design. 12,34 Eismark et al 33 tested this piston geometry in a high pressure/ high temperature spray chamber and in a single cylinder engine. A strong decrease of up to 80% in soot emissions without NO X emissions penalization were found by the authors during the tests.…”

Section: Introductionmentioning

confidence: 99%

Soot reduction for cleaner Compression Ignition Engines through innovative bowl templates

Pastor

García

Micó

et al. 2020

International Journal of Engine Research

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Considering the need of pollutant emissions reduction and the high cost of the after-treatment systems, in-cylinder solutions for pollutant reduction are becoming more and more relevant. Among different proposals, new piston geometries are considered an attractive solution for reducing both soot and nitrogen oxides emissions in compression ignition engines. For this reason, this paper evaluates the soot formation and combustion characteristics of a novel piston geometry proposal, called stepped lip-wave, for light-duty engines. It is compared with other two well-known bowl geometries: re-entrant and stepped lip. The study was performed in an optical single-cylinder direct injection compression ignition engine. Two optical techniques (2 color pyrometry and OH* chemiluminescence) were applied for analyzing soot formation in each piston geometry. Test were performed at different engine loads, fuel injection characteristics and exhaust gas recirculation configuration. The re-entrant piston presents higher soot formation and a slower late oxidation process in comparison with the other two geometries. Stepped lip and stepped lip-wave present similar soot formation levels. However, stepped lip-wave showed a more efficient and faster soot oxidation process during the final combustion stages. Results confirm the potential of the stepped lip-wave concept to reduce soot emissions and achieve a cleaner energy production system.

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Role of Piston Bowl Shape to Enhance Late-Cycle Soot Oxidation in Low-Swirl Diesel Combustion

Cited by 30 publications

References 13 publications

Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

Effect of a novel piston geometry on the combustion process of a light-duty compression ignition engine: An optical analysis

Soot reduction for cleaner Compression Ignition Engines through innovative bowl templates

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