A comparative study to evaluate the effects of pre-chamber jet ignition for engine characteristics and emission formations at high speed

Yontar, Ahmet Alper

doi:10.1016/j.energy.2020.118640

Cited by 25 publications

(7 citation statements)

References 17 publications

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“…2,4,5 The TJI has the advantages of high ignition energy, fast flame propagation, and short flame propagation distance. 6,7 After the spark ignition, the hot burnt gases and reacting compounds are ejected from the prechamber in the form of turbulent jets as driven by the pressure difference between the pre-chamber and main chamber. 8,9 The turbulent jets produce multiple spatially distributed ignition sites in the main chamber, 10 which increases the ignition energy and decreases the flame propagation distance.…”

Section: Introductionmentioning

confidence: 99%

Effect of spark ignition location on the turbulent jet ignition characteristics in a lean burning natural gas engine

Xue

Yong

Zhao

et al. 2022

International Journal of Engine Research

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The Turbulent Jet Ignition is an effective concept to achieve stable lean burning for natural gas engines due to the multiple ignition sources, high ignition energy, and fast combustion rate. A variation of the ignition location has a non-negligible effect on the ignition performance of the TJI system. The present work aims to provide more details on this effect by numerical simulations. Both factors of the additional fuel supply to the pre-chamber and the in-cylinder flow field are taken into consideration in this study. A numerical model is built based on a lean burning natural gas engine and validated by experimental results. Five different spark ignition sources are equally arranged on the vertical axis of the pre-chamber, with different distances from the connecting orifices. Simulations are carried out under the same initial and boundary conditions except for the location of the ignition source. Combustion pressure, in-cylinder flow field, fuel mass fraction distribution, and heat release rate are analyzed to study the in-cylinder ignition and combustion process. The results show that a rotational flow and a non-uniform fuel distribution are formed in the pre-chamber during the compression stroke. The turbulent jet characteristics are significantly influenced by the coupling of two factors: the combustion rate inside the pre-chamber as well as the flame propagation distance from the ignition source to the connecting orifices. Rapid combustion rate and shorter flame propagation distance both lead to the earlier ejection of cold jets and hot jets. Among five ignition sources, the one located closest to the connecting orifices generates earlier hot jets with the highest mean velocity. The jets are more effective to ignite the lean mixture and could decrease the combustion duration of the main chamber.

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Section: Introductionmentioning

confidence: 99%

Effect of spark ignition location on the turbulent jet ignition characteristics in a lean burning natural gas engine

Xue

Yong

Zhao

et al. 2022

International Journal of Engine Research

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“…Conventional spark ignition is difficult to extend the lean burn limit, which limits the fuel saving potential. 11,14–16…”

Section: Introductionmentioning

confidence: 99%

“…Conventional spark ignition is difficult to extend the lean burn limit, which limits the fuel saving potential. 11,[14][15][16] The pre-chamber jet ignition technology first ignites the combustible mixture in a small space, and the hightemperature and high-pressure mixture in the prechamber is sprayed into the main combustion chamber through small holes, thereby igniting the main combustion chamber mixture. There are three reasons why the pre-chamber achieves fast and stable combustion: the sprayed high-temperature, high-pressure mixture increases the ignition area; the flame sprayed through the small holes is extinguished, producing active combustion intermediate products and increasing the combustion rate; the turbulent kinetic energy of the main combustion chamber is increased by high-speed sprayed mixture.…”

Section: Introductionmentioning

confidence: 99%

Lean combustion and emission performance of a gasoline direct injection engine with active pre-chamber

Zhang

Huang

Wang

et al. 2022

Advances in Mechanical Engineering

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Pre-chamber jet ignition technology can effectively improve flame propagation speed and in-cylinder combustion rate, so it is conducive to the improvement of thermal efficiency and fuel economy. While, studies on the key parameters of the influence of active pre-chamber on combustion and emissions are not systematic. The influence of the key parameters of injection control in active pre-chamber on combustion and emission is not clear at present. Thus, in this paper, an active pre-chamber jet ignition system was designed and used in a single cylinder GDI engine, and the effects of compression ratio and pre-chamber injection strategy on pre-chamber jet ignition were experimentally studied, as well as the comparison of pre-chamber jet ignition and conventional spark ignition. The results show that, at 2750 r/min, IMEP 11 bar operation point, lean burn can effectively reduce the fuel consumption and increase the thermal efficiency of gasoline engine. Adopting traditional spark plug system can extend the lean burn limit to excess air ratio of 1.5 with the gross indicated thermal efficiency (GITE) of 45% limited by unstable combustion, while resembling active pre-chamber system can achieve GITE of 46.5% with the excess air ratio of 2.0 with the help of much more stable combustion. And the NOx emission of active-pre-chamber system has been reduced by 78% compared by conventional spark plug system. Increasing the compression ratio to 14.8 can further reduce the indicated fuel consumption to 177 g/kWh, and increase the GITE to 48.5% and further reduce the NOx emission to lowest 0.53 g/kWh with the excess air ratio of 2.1. With the increase of pre-chamber injection pressure, the ignition stability increases, the combustion duration decrases, and thermal efficiency increases. With the increase of the pre-chamber injection duration, the ignition delay first decreases and then increases. When the injection duration increases to 800 μs, COV is greater than 3%. If the pre-chamber injection duration further increase, the COV increases, the combustion phasing retard, and the thermal efficiency decreases. With the increase of pre-chamber injection duration and pressure, the wetting wall fuel increases, which leads to the increase of PN emission.

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“…The current research effort is focused on the active pre-chamber where auxiliary fuel is added into the prechamber. The active pre-chamber concepts are found to enhance the combustion stability and extend the lean limit to ultra-lean conditions (λ > 2.0) [5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Fuel Properties on Combustion Characteristics in a Narrow-Throat Pre-Chamber Engine

Hlaing

Marquez

Burgos

et al. 2021

SAE Int. J. Adv. & Curr. Prac. in Mobility

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In this study, the authors investigated the effect of fuel properties on the combustion characteristics by employing methane, methanol, ethanol, and primary reference fuels (PRFs) as the main chamber fuel while using methane for the pre-chamber. Global excess air ratios (λ) from 1.6 to lean limit were tested, while 13% of total fuel energy supplied to the engine was delivered via the pre-chamber. The gaseous methane was injected into the pre-chamber at the gas exchange top-dead-center (TDC). Port fuel injection was tested with both open and closed inlet valves. The pre-chamber assembly was designed to fit into the diesel injector pocket of the base engine, which resulted in a narrow throat diameter of 3.3 mm. The combustion stability limit was set at 5% of the coefficient of variation of gross IMEP, and the knock intensity limit was set at 10 bar. GT-Power software was used to estimate the composition of pre-chamber species and was used in heat release analysis of the two chambers. It was found that the rich limit was controlled by engine knock. Hence a higher reactivity fuel (lower octane) had to be operated leaner. However, with the increasing reactivity, the lean limit was also extended, while the peak efficiency was also obtained with a leaner mixture. With PRF 90, the lean limit was at global-λ = 3.0, while the limit was 2.3 with methane. The alcohol fuels exhibited a different behavior from the methane and the PRFs. Ethanol has the same lean limit as PRF100, but methanol could be operated up to global-λ = 3.2. The pre-chamber combustion did not change much with the different fuels in the main chamber, so the combustion stability trends must be related to the transition from burning jets to ignition of the main chamber charge and its subsequent combustion.

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A comparative study to evaluate the effects of pre-chamber jet ignition for engine characteristics and emission formations at high speed

Cited by 25 publications

References 17 publications

Effect of spark ignition location on the turbulent jet ignition characteristics in a lean burning natural gas engine

Effect of spark ignition location on the turbulent jet ignition characteristics in a lean burning natural gas engine

Lean combustion and emission performance of a gasoline direct injection engine with active pre-chamber

Analysis of Fuel Properties on Combustion Characteristics in a Narrow-Throat Pre-Chamber Engine

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