Influence of pre-chamber structure and injection parameters on engine performance and combustion characteristics in a turbulent jet ignition (TJI) engine

Hua, Jianxiong; Zhou, Lei; Gao, Qiang; Feng, Zhonghui; Wei, Haiqiao

doi:10.1016/j.fuel.2020.119236

Cited by 71 publications

(37 citation statements)

References 22 publications

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“…The thermodynamics may become the most dominant factor if the volume of prechamber exceeds certain limit. When the volume of prechamber is too large, it will lead to low CR, excessive heat loss in pre-chamber (Hua et al, 2021), and weak hot jet issuing into the main chamber. Under this circumstance, the CR should be fixed during the optimization of pre-chamber geometry to isolate its effects.…”

Section: Regression Analysis Of the Design Parametersmentioning

confidence: 99%

“…The prechamber nozzle umbrella angle and orientation could be further optimized for a given combustion system to achieve reduced combustion heat loss. Hua et al (2021) compared four prechamber designs, passive and active fueling in engine tests. They found that the volume and number of the jet hole are two key parameters for optimizing the structure of the prechamber.…”

Section: Introductionmentioning

confidence: 99%

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CFD Optimization of the Pre-Chamber Geometry for a Gasoline Spark Ignition Engine

Bakir

Yadav

et al. 2021

Front. Mech. Eng.

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In the present paper, an efficient optimization method based on Bayesian updating strategy is developed for the design of a spark-ignition engine equipped with pre-chamber. 3D computational fluid dynamics (CFD) simulation coupled with strategies including design of experiment, genetic algorithm, and machine learning methods is used to optimize the pre-chamber with desired combustion phasing. The optimization process starts from a design of experiment matrix of 11 design parameters, which are used to analytically characterize the pre-chamber geometry and set up the 3D combustion CFD. Taking CA50 as the single objective, the CFD results are then used to train the machine learning models. Different machine learning models are evaluated based on their Root Mean Square Error. Five machine learning models from five different categories are selected for second round evaluation. The trained machine learning model is used in the genetic algorithm optimization, which yields the optimized configuration and is again justified by CFD. The new CFD results based on the optimized design are added into the database to further refine the machine learning model. After 24 iterations for each selected machine learning models, the medium Gaussian support vector machine model is identified as the best method for the present application. Iterations using the medium Gaussian support vector machine model continue until a satisfactory result is achieved. Detailed combustion analysis is conducted to investigate the physical mechanism about how the design of pre-chamber influences the engine's performance. It is found that larger volume of the upper part of the pre-chamber results in stronger jet flow and turbulent intensity which further accelerates the flame propagation inside the pre-chamber, dominating the contrary effects from reduced pressure and temperature. Regression analysis shows that the radius of the pre-chamber is the most influential design parameter. The current work not only sheds light on the optimization of engine design, but also has demonstrated a general strategy applicable to the purpose of arbitrary engine optimization and mechanical system design.

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Section: Regression Analysis Of the Design Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CFD Optimization of the Pre-Chamber Geometry for a Gasoline Spark Ignition Engine

Bakir

Yadav

et al. 2021

Front. Mech. Eng.

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“…The application of lean burning mixtures can increase engine brake thermal efficiency up to 49%, especially when combined with an electric compressor [3], while reducing raw emissions of nitrogen oxides (NO X ) up to 92% [4] compared to conventional IC engines. There are several lean burn combustion concepts that can be adopted in IC engines, such as homogeneous charge compression ignition (HCCI) [5], spark assisted compression ignition (SACI), reactivity-controlled compression ignition (RCCI), jet-controlled compression ignition (JCCI) [6] and pre-chamber spark-ignited (PCSI) engines.…”

Section: Introductionmentioning

confidence: 99%

“…Different air excess ratios in the PC were investigated, and it was found that modification of the air excess ratio from 0.9 to 1.1 reduced flame speed by 40%, indicating the importance of controlling the air-to-fuel ratio in the PC. The influence of injection parameters and different PC geometries on a TJI engine's efficiency and emissions were investigated experimentally in [4]. Several different PC volumes and numbers of nozzles were studied with variations in injection timings.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Pre-Chamber Geometry and Operating Parameters in a Turbulent Jet Ignition Engine

et al. 2022

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A turbulent jet ignition engine enables operation with lean mixtures, decreasing nitrogen oxide (NOX) emissions up to 92%, while the engine efficiency can be increased compared to conventional spark-ignition engines. The geometry of the pre-chamber and engine operating parameters play the most important role in the performance of turbulent jet ignition engines and, therefore, must be optimized. The initial experimental and 3D CFD results of a single-cylinder engine fueled by gasoline were used for the calibration of a 0D/1D simulation model. The 0D/1D simulation model was upgraded to capture the effects of multiple flame propagations, and the evolution of the turbulence level was described by the new K-k-ε turbulence model, which considers the strong turbulent jets occurring in the main chamber. The optimization of the pre-chamber volume, the orifice diameter, the injected fuel mass in the pre-chamber and the spark timing was made over 9 different operating points covering the variation in engine speed and load with the objective of minimizing the fuel consumption while avoiding knock. Two optimization methods using 0D/1D simulations were presented: an individual optimization method for each operating point and a simultaneous optimization method over 9 operating points. It was found that the optimal pre-chamber volume at each operating point was around 5% of the clearance volume, while the favorable orifice diameters depended on engine load, with optimal values around 2.5 mm and 1.2 mm at stoichiometric mixtures and lean mixtures, respectively. Simultaneous optimization of the pre-chamber geometry for all considered operating points resulted in a pre-chamber volume equal to 5.14% of the clearance volume and an orifice diameter of 1.1 mm.

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“…The burning velocity in the main chamber could be sped up to 30 times with the pre-chamber system. Hua et al [26] investigated the injection parameters, combustion characteristics, and optimized pollutant emissions in the pre-chamber. Three types of optimized pre-chambers were tested, and the results showed that with a smaller pre-chamber volume, better engine performance and lower pollutant emissions were achieved.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Pre-Chamber and Nozzle Design in the Gasoline Engine of an Agricultural Tractor

Zheng¹,

Zhou²,

Song³

et al. 2022

Energies

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With the rapid development of agriculture in China today, the demand for agricultural machinery is rapidly increasing. A large amount of exhaust gas emissions poses a severe threat to the environment. To better promote engine fuel and air mixing, enhance engine performance, and achieve low emissions, we conducted a numerical study of the pre-chamber and nozzle design in a gasoline engine for an agricultural tractor by using the G-equation method in Converge CFD software. The relevant optimization of the three model parameters in the G-equation was performed using the improved particle swarm algorithm (PSO). The model parameters after optimization by the PSO algorithm were: a1=0.77, b1=2.0, b3=1.0. It was confirmed that the predicted engine performance was enhanced greatly with the pre-chamber system. More importantly, the results reveal that the volume and area ratios of the pre-chamber played a crucial role in the performance of the pre-chamber. Through a series of parametric studies on the pre-chamber and main chamber characteristics, we can identify the best sets of volume and area ratios based on the combustion reaction progress, the turbulent mixing profiles, and the exhaust gas emission. The turbulent maximum strength and the exhaust gas concentration of nitrogen oxides can differ by 13 and 18 times, respectively. In practical design, we recommend the optimization of the concerned metrics with the findings in the paper.

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Influence of pre-chamber structure and injection parameters on engine performance and combustion characteristics in a turbulent jet ignition (TJI) engine

Cited by 71 publications

References 22 publications

CFD Optimization of the Pre-Chamber Geometry for a Gasoline Spark Ignition Engine

CFD Optimization of the Pre-Chamber Geometry for a Gasoline Spark Ignition Engine

Optimization of Pre-Chamber Geometry and Operating Parameters in a Turbulent Jet Ignition Engine

Numerical Investigation of the Pre-Chamber and Nozzle Design in the Gasoline Engine of an Agricultural Tractor

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