Experimental study on jet ignition and combustion processes of natural gas

Tian, Jiangping; Cui, Zechuan; Ren, Zhongyong; Tian, Hua; Long, Wuqiang

doi:10.1016/j.fuel.2019.116467

Cited by 64 publications

(15 citation statements)

References 25 publications

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“…26 The PC flame front can be quenched or not at the orifice, depending mainly on its diameter and equivalence ratio. 8,19…”

Section: Research Approach and Validation Toolsmentioning

confidence: 99%

“…Collecting pre-chamber data under real engine conditions may be a challenge due to the lack of physical space, making it difficult to place a pressure sensor or an optical access. For this reason, to allow the access to such information, some studies are performed on experimental facilities, 1,5,8–15 rather than in real engines, with the drawback of reproducing the phenomenon under simplified conditions. The main differences between the conditions in a real engine and an experimental facility can occur in several aspects and levels, such as: on the thermodynamic conditions, mixture composition (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Pre-chamber ignition systems: A methodological proposal to reproduce a reference case in a simplified experimental facility for fundamental studies

Desantes

López

Novella

et al. 2020

International Journal of Engine Research

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To further understand the processes and phenomena taking place in the pre-chamber (PC) ignition concept, many studies under simplified conditions have been carried out in different experimental facilities (e.g. constant volume chambers and rapid compression machines). However limited information is provided about how the volume, orifice diameter and number of orifices were defined, raising the question whether the results are representative of engine-like conditions or not. This novel study arises from the necessity to determine a methodology to reproduce a reference pre-chamber, preserving as much as possible its jet characteristics. A theoretical development based on the first law of thermodynamics has been performed, and a relationship between the effective flow area, pre-chamber volume and engine speed is proposed as the governing parameter of the mass exchange between chambers. Besides, relaying on the know-how of gas jets, a relationship between the orifice diameter, jet tip penetration and engine speed is suggested as the criterion to preserve the relative jet penetration (respect to the distance from the PC hole to the combustion chamber walls). A numerical validation of these assumptions was carried out using a one-dimensional flow calculator to estimate the thermodynamic properties and mass transfer between chambers, and a one-dimensional spray model to estimate the penetration of the PC combustion products jets. Finally, preserving the ratio between the total area of the PC holes and the product of the PC volume and the engine speed for two pre-chamber geometries, an identical pressure rise rate, in an angular basis, is achieved in both pre-chambers. Furthermore, the same relative jet penetration rate, in an angular basis, can be also achieved, even under different engine speeds, when the ratio between the orifice diameter and the product of the square of the jet free length and the engine speed is preserved.

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“…26 The PC flame front can be quenched or not at the orifice, depending mainly on its diameter and equivalence ratio. 8,19…”

Section: Research Approach and Validation Toolsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pre-chamber ignition systems: A methodological proposal to reproduce a reference case in a simplified experimental facility for fundamental studies

Desantes

López

Novella

et al. 2020

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…The second stage is caused by the auto ignition. Tian et al 32 studied the impacts of pre-chamber geometric parameters on ignition and combustion processes in a constant volume chamber, the results show that a larger pre-chamber orifice diameter caused earlier ignition timing and lower ignition position, and the flame would quench when the orifice diameter was smaller than a certain value. Tang et al 33 found that a higher pressure difference between pre-chamber and main chamber produces larger pre-chamber jet penetration speed, over enrichment of the pre-chamber charge reduces the peak pressure difference.…”

Section: Introductionmentioning

confidence: 99%

Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

Duan

Huang

Chen

et al. 2021

Advances in Mechanical Engineering

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Pre-chamber jet ignition is a promising way to improve fuel consumption of gasoline engine. A small volume passive pre-chamber was tested at a 1.5L turbocharged GDI engine. Combustion and emission characteristics of passive pre-chamber at low-speed WOT and part load were studied. Besides, the combustion stability of the passive pre-chamber at idle operation has also been studied. The results show that at 1500 r/min WOT, compared with the traditional spark ignition, the combustion phase of pre-chamber is advanced by 7.1°CA, the effective fuel consumption is reduced by 24 g/kW h, and the maximum pressure rise rate is increased by 0.09 MPa/°CA. The knock tendency can be relieved by pre-chamber ignition. At part load of 2000 r/min, pre-chamber ignition can enhance the combustion process and improve the combustion stability. The fuel consumption of pre-chamber ignition increases slightly at low load, but decreases significantly at high load. Compared with the traditional spark ignition, the NOx emissions of pre-chamber increase significantly, with a maximum increase of about 15%; the HC emissions decrease, and the highest decrease is about 36%. But there is no significant difference in CO emissions between pre-chamber ignition and spark plug ignition. The intake valve opening timing has a significant influence on the pre-chamber combustion stability at idle operation. With the delay of the pre-chamber intake valve opening timing, the CoV is reduced and can be kept within the CoV limit.

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“…However, their test conditions were far from practical engine operation. Tian et al 9 also studied jet ignition process in a CVB, in which the quench effect of small orifices was reported and the enhancement of ignition ability with increasing initial pressure was also observed. The above studies indicate that the orifice geometry plays an important role in determining the performance of jet ignition, however, the deep reasons behind those reported phenomena still need to be further investigated.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of combustion strategy for jet ignition on a natural gas engine

Zhao

Wang

et al. 2020

International Journal of Engine Research

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To explore a suitable combustion strategy for natural gas engines using jet ignition, lean burn with air dilution, stoichiometric burn with EGR dilution and lean burn with EGR dilution were investigated in a single-cylinder natural gas engine, and the performances of two kinds of jet ignition technology, passive jet ignition (PJI) and active jet ignition (AJI), were compared. In the study of lean burn with air dilution strategy, the results showed that AJI could extend the lean limit of excess air ratio (λ) to 2.1, which was significantly higher than PJI’s 1.6. In addition, the highest indicated thermal efficiency (ITE) of AJI was shown 2% (in absolute value) more than that of PJI. Although a decrease of NOx emission was observed with increasing λ in the air dilution strategy, THC and CO emissions increased. Stoichiometric burn with EGR was proved to be less effective, which can only be applied in a limited operation range and had less flexibility. However, in contrast to the strategy of stoichiometric burn with EGR, the strategy of lean burn with EGR showed a much better applicability, and the highest ITE could achieve 45%, which was even higher than that of lean burn with air dilution. Compared with the most efficient points of lean burn with pure air dilution, the lean burn with EGR dilution could reduce 78% THC under IMEP = 1.2 MPa and 12% CO under IMEP = 0.4 MPa. From an overall view of the combustion and emission performances under both low and high loads, the optimum λ would be from 1.4 to 1.6 for the strategy of lean burn with EGR dilution.

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Experimental study on jet ignition and combustion processes of natural gas

Cited by 64 publications

References 25 publications

Pre-chamber ignition systems: A methodological proposal to reproduce a reference case in a simplified experimental facility for fundamental studies

Pre-chamber ignition systems: A methodological proposal to reproduce a reference case in a simplified experimental facility for fundamental studies

Effects of passive pre-chamber jet ignition on combustion and emission at gasoline engine

Experimental study of combustion strategy for jet ignition on a natural gas engine

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