Comparison of the effects of multiple injection strategy on the emissions between moderate and heavy EGR rate conditions: part 1-pilot injections

Choi, Hae-Jin; Lee, Jeongwoo; Hong, Kookeui; Lee, Sangyul; Choi, Soon-Ho; Yu, Sung Hoon; Min, Kyoungdoug

doi:10.1007/s12206-013-0220-x

Cited by 28 publications

(17 citation statements)

References 2 publications

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“…Attempts to reduce emissions and soot formation usually contradict each other; that is, retarding timing will reduce NO x but increase soot, while higher injection pressure will reduce soot but increase NO x [4]. Some multiple-injection strategies have been shown to reduce NO x emission and soot simultaneously [1,5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Reitz [5] varied the amount of fuel injected in the pilot from 10-75% of the total amount of fuel injected and was able to reduce NO x with minimal increase of soot. Other attempts to decrease the trade-off between NO x and soot include studies of splitting main injection into two, three, or four parts on HSDI diesel engines [8] as well as double injection [6].…”

Section: Introductionmentioning

confidence: 99%

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Spray–combustion interaction mechanism of multiple-injection under diesel engine conditions

Cung

Moiz

Johnson

et al. 2015

Proceedings of the Combustion Institute

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Multiple-injection has shown significant benefits in the reduction of combustion emissions and soot formation. However, there is a need to understand the secondary flow-induced air-fuel mixture formation and subsequent combustion mechanism under multiple-injection. An experiment was performed by changing the dwell time between the pilot and main injections under the conditions of 23 kg/m 3 ambient density with 0% O 2 (noncombusting) and 15% O 2 (combusting) ambient conditions, at an injection pressure of 120 MPa. The mass ratios of pilot and main injections in the study were 15%/85% and 20%/80%. A hybrid shadowgraph and Mie scattering imaging technique in a nearly simultaneous mode along the same line of sight was used to visualize the spray and flame luminosity. Pilot-main spray flame properties including ignition delay, ignition location, and lift-off length were characterized from experimental images. CFD simulation of pilot-main spray combustion was performed under the same experimental conditions to provide additional insights into the combustion process. The air-fuel mixing field and ignition process followed by main injection flame structure are significantly altered at different dwells. The spray-to-flame interaction mechanism model has been established for the development of an optimal multiple-injection scheme for, possibly, low soot formation and emissions. .

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spray–combustion interaction mechanism of multiple-injection under diesel engine conditions

Cung

Moiz

Johnson

et al. 2015

Proceedings of the Combustion Institute

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“…When the first injection portion was 40% and 50%, a diffusion flame generating soot appeared due to the short ignition delay and mixing time. Lee et al [90] investigated the effects of fuel quantity during first injection on the emissions of a DI diesel engine under moderate and heavy EGR. Under moderate EGR (~30%), the quantity of the first injection was changed from 1 to 5 mg/cycle.…”

Section: First Injection Quantitymentioning

confidence: 99%

A Review of Early Injection Strategy in Premixed Combustion Engines

Liang

Zhang

et al. 2019

Applied Sciences

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Due to the increasing awareness of environmental protection, limitations on exhaust emissions of diesel engines have become increasingly stringent. This challenges diesel engine manufacturers to find a new balance between engine performance and emissions. Advanced combustion modes for diesel engines, such as homogeneous charge compression ignition (HCCI) and premixed charge compression ignition (PCCI), which can simultaneously reduce exhaust emissions and substantially improve thermal efficiency, have drawn increasing attention. In order to allow enough time to prepare the homogeneous mixture, the early injection strategy has been utilized widely in HCCI and PCCI diesel engines. This paper is aimed at providing a comprehensive review of the effects of early injection parameters on the performance and emissions of HCCI and PCCI engines fueled by both diesel and alternative fuels. Various early injection parameters, including injection pressure, injection timing, and injection angle, are discussed. In addition, the effect of the blending ratio of alternative fuels is also summarized. Every change in parameters has its own advantages and disadvantages, which are explained in detail in order to help researchers choose the best early injection parameters for HCCI and PCCI engines.

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“…26 In the working points pertaining to the part of the engine map that is explored during the extra-urban driving cycle (EUDC) portion of the NEDC, the application of a pilot injection closely coupled or joined to the main injection can lead to an optimization of the CN-PM and NO x -PM trade-offs, compared to injection patterns with conventional DT values. 31 Even though NO x emissions generally reduce as the DT between the pilot and main injections is reduced 22 within the conventional DT range, 32 the PM emissions generally augment as this DT reduces. However, a small pilot injection, which is closely coupled to the main injection, causes an increase in the injected flow-rate of the main injection during the nozzle opening phase, 33 and this can enhance the spray atomization.…”

Section: Introductionmentioning

confidence: 99%

Exploitation of injection fusion strategies in diesel engines equipped with solenoid injectors

D’Ambrosio

Ferrari

2017

International Journal of Engine Research

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Pilot-main injection strategies are investigated in the short dwell-time range at medium load and speed conditions for a low-temperature combustion diesel engine endowed with indirect-acting solenoid injectors. Dwell-time sweeps have been carried out for pilot injections with different energizing times under steady-state working conditions and constant combustion phasing. The experimental results on the engine are combined with in-cylinder analyses of pressure, heat release rate, temperature and emission time histories. As the electric dwell time is reduced toward zero, combustion noise reaches a minimum at a dwell time of 120-140 ms, and a reduction of 1-4.5 dB is possible compared to levels at dwell time = 500 ms. This decrease in combustion noise is obtained in conjunction with a local reduction in engine-out nitrogen oxide emissions, but penalties occur for engine-out soot emissions and brake-specific fuel consumption. The pilot and main injection shots feature fusion phenomena at the shortest dwell-time values, thus giving rise to rate-shaped single injections, which resemble the boot-shaped profiles in direct-acting piezoelectric injectors. The increase in the velocity of the needle, which occurs during the nozzle opening phase pertaining to the main injection for closely coupled injections as dwell time is reduced, is shown to be not the primary cause responsible for the observed trends in combustion noise and soot emissions as dwell-time changes. The combination of simulation and experimental data supports the theory that the main injection interacts with the pilot mixture field: the relative phasing between pilot and main combustion and the in-cylinder equivalent ratio distribution are the dominant aspects in the definition of the engine performance in the short dwell-time range.

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Comparison of the effects of multiple injection strategy on the emissions between moderate and heavy EGR rate conditions: part 1-pilot injections

Cited by 28 publications

References 2 publications

Spray–combustion interaction mechanism of multiple-injection under diesel engine conditions

Spray–combustion interaction mechanism of multiple-injection under diesel engine conditions

A Review of Early Injection Strategy in Premixed Combustion Engines

Exploitation of injection fusion strategies in diesel engines equipped with solenoid injectors

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