Effect of Relative Mixture Strength on Performance of Divided Chamber ‘Avalanche Activated Combustion’ Ignition Technique in a Heavy Duty Natural Gas Engine

Shah, Ashish; Tunestål, Per; Johansson, Bengt

doi:10.4271/2014-01-1327

Cited by 60 publications

(24 citation statements)

References 15 publications

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“…Shah et al [19] modified Gussak's model to apply to only fuel addition into the pre-chamber, and this methodology is adopted in this study. The details equations used by Shah would not be repeated here.…”

Section: Pre-chamber Excess Air Ratio (λ) Estimationmentioning

confidence: 99%

“…Attard et al [18] determined that the addition of fuel equivalent to 2% of total fuel energy to the pre-chamber led to higher efficiency, approaching 42% net indicated efficiency. Shah et al [19] also conducted experiments with various pre-chamber air-to-fuel ratios and observed that a rich pre-chamber mixture is important in extending the lean limit. Since these experiments were performed in prechamber designs with relatively wide throat diameter, it inspired the authors to investigate the effect of fuel enrichment in a narrow throat pre-chamber.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Pre-Chamber Enrichment on Lean Burn Pre-Chamber Spark Ignition Combustion Concept with a Narrow-Throat Geometry

Hlaing

Marquez

Singh

et al. 2020

SAE Technical Paper Series

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Pre-chamber spark ignition (PCSI) combustion is an emerging leanburn combustion mode capable of extending the lean operation limit of an engine. The favorable characteristic of short combustion duration at the lean condition of PCSI results in high efficiencies compared to conventional spark ignition combustion. Since the engine operation is typically lean, PCSI can significantly reduce engine-out NOx emissions while maintaining short combustion durations. In this study, experiments were conducted on a heavyduty engine at lean conditions at mid to low load. Two major studies were performed. In the first study, the total fuel energy input to the engine was fixed while the intake pressure was varied, resulting in varying the global excess air ratio. In the second study, the intake pressure was fixed while the amount of fuel was changed to alter the global excess air ratio. At each global excess air ratio, the fuel injection to the pre-chamber was varied parametrically to assess the effect of pre-chamber enrichment on engine operating characteristics. Multi-chamber heat release analysis was performed to present the pre-chamber and main chamber heat release characteristics separately. The discharge coefficient of the prechamber nozzles was determined by the model calibration to match the pre-chamber and main chamber pressure traces in the GT Power software. The analyzed data reveals a two-stage combustion mechanism in the main chamber where the latter stage is thought to be contributing to the bulk ignition of the main chamber charge. The pre-chamber heat release is correlated to the mixture strength of the pre-chamber, which affects the phasing of the pre-chamber combustion and the initial heat release in the main chamber. As the global excess air ratio becomes lean, the combustion efficiency deteriorates with high HC and CO emissions, while NOx emission declines significantly. The resulting heat release data is presented alongside the engine-out specific emissions.

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Section: Pre-chamber Excess Air Ratio (λ) Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Pre-Chamber Enrichment on Lean Burn Pre-Chamber Spark Ignition Combustion Concept with a Narrow-Throat Geometry

Hlaing

Marquez

Singh

et al. 2020

SAE Technical Paper Series

Self Cite

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“…The PCC also showed robust ignition quality [6] and high knock tolerance [7]. Ashish et al [8,9] investigated the PCC performance on a heavy-duty engine with a compression ratio of 12 and achieved a maximum gross indicated efficiency of 47.6%. They also studied the effect of PC volume and nozzle diameter on PCC.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Negative PLIF and OH* Chemiluminescence Imaging of the Gas Exchange and Flame Jet from a Narrow Throat Pre-Chamber

Tang¹,

Sampath²,

Marquez³

et al. 2020

SAE Technical Paper Series

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Pre-chamber combustion (PCC) is a promising engine combustion concept capable of extending the lean limit at part load. The engine experiments in the literature showed that the PCC could achieve higher engine thermal efficiency and much lower NOx emission than the spark-ignition engine. Improved understanding of the detailed flow and combustion physics of PCC is important for optimizing the PCC combustion. In this study, we investigated the gas exchange and flame jet from a narrow throat pre-chamber (PC) by only fueling the PC with methane in an optical engine. Simultaneous negative acetone planar laser-induced fluorescence (PLIF) imaging and OH* chemiluminescence imaging were applied to visualize the PC jet and flame jet from the PC, respectively. Results indicate a delay of the PC gas exchange relative to the built-up of the pressure difference (△P) between PC and the main chamber (MC). This should be due to the gas inertia inside the PC and the resistance of the PC nozzle. The PC jet can be either continuous or intermittent depending on the △P and pressure fluctuation amplitude. Distinct PC jet with low speed is witnessed after 15° CA ATDC, which could account for the postcombustion of the PCC engine in the literature. The probability distribution analysis of the PLIF and OH* images presents a much longer penetration length of the PC jet than that of the flame jet. This means that the flame jet resides in an atmosphere of the unburned gas mixture from the PC when it appears in the MC. The flame jet and PC jet show longer penetration length and become more stable with the enriching of the prechamber charge from lean to stoichiometric. However, the overall PC jet characteristics regarding the penetration length and probability distribution become less sensitive to the PC global excess air ratio (λ) when the PC charge is close to stoichiometry.

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“…Due to the rising cost of crude oil and stringent emission regulations, natural gas has become a promising alternative clean fuel for internal combustion engines due to its advantages in fuel costs, fuel economy and pollutant emissions [1][2][3]. At present, most gas engines THERMAL SCIENCE: Year 2018, Vol.…”

Section: Introductionmentioning

confidence: 99%

Impact of the pre-chamber nozzle orifice configurations on combustion and performance of a Natural Gas Engine

Leng¹,

Wang²,

He³

et al. 2018

THERM SCI

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In this study, a pre-chamber was designed to form near stoichiometric mixture and provide multiple turbulent flame jets to ignite the lean mixture and accelerate the combustion in the main combustion chamber for a natural gas engine. A CFD simulation was employed to investigate the impact of the pre-chamber nozzle configurations on flow and combustion processes inside the engine, as well as on the performance of the engine. Various configurations were investigated, including orifice number of 4 to 8 and orifice diameter ranging from 1.6 m to 2.9 mm. A non-dimensional parameter, β, was used to characterize the relative flow area of these configurations. The numerical results indicate that, for a given nozzle flow area, among the design of different orifice numbers, the 6-orifice design can obtain the optimal combustion and engine performance. Otherwise, a design of more orifices leads to slower flame penetrating speed in the main-chamber, and the design of less orifices leads to slower circumferential flames propagations in the main-chamber. Moreover, for a 6-orifice pre-chamber, the optimal orifice diameter was found to be 2.0 mm, corresponding to a β value of 0.3. A design of larger diameters leads to slower penetrating for the flame jets and insufficient radial flame propagations in the main-chamber, while a design of relatively smaller orifice diameters leads to insufficient circumferential flames propagations in the main-chamber. Additionally, for the engine performance, all the pre-chamber designs improve the indicated efficiency and reduce the NO x emission. Especially, the design of 6-orifice with diameter of 2.0 mm achieves a 35.0% increase of indicated thermal efficiency and a 78.0% reduction of NO x emission compared to the prototype engine.

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Effect of Relative Mixture Strength on Performance of Divided Chamber ‘Avalanche Activated Combustion’ Ignition Technique in a Heavy Duty Natural Gas Engine

Cited by 60 publications

References 15 publications

Effect of Pre-Chamber Enrichment on Lean Burn Pre-Chamber Spark Ignition Combustion Concept with a Narrow-Throat Geometry

Effect of Pre-Chamber Enrichment on Lean Burn Pre-Chamber Spark Ignition Combustion Concept with a Narrow-Throat Geometry

Simultaneous Negative PLIF and OH* Chemiluminescence Imaging of the Gas Exchange and Flame Jet from a Narrow Throat Pre-Chamber

Impact of the pre-chamber nozzle orifice configurations on combustion and performance of a Natural Gas Engine

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