THERMAL SCIENCE

International Scientific Journal

IMPACT OF THE PRE-CHAMBER NOZZLE ORIFICE CONFIGURATIONS ON COMBUSTION AND PERFORMANCE OF A NATURAL GAS ENGINE

ABSTRACT
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 NOx 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 NOx emission compared to the prototype engine.
KEYWORDS
PAPER SUBMITTED: 2017-09-12
PAPER REVISED: 2017-12-29
PAPER ACCEPTED: 2018-01-06
PUBLISHED ONLINE: 2018-02-18
DOI REFERENCE: https://doi.org/10.2298/TSCI170912008L
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2018, VOLUME 22, ISSUE Issue 3, PAGES [1325 - 1337]
REFERENCES
  1. Jamrozik A, Tutak W, Kociszewski A., Sosnowski M Numerical simulation of two-stage combustion in SI engine with prechamber. Applied Mathematical Modelling, 2013, Vol.37, pp. 2961-2982
  2. Shah A., Tunestal P., Johansson B. Effect of Relative Mixture Strength on Performance of Divided Chamber ‘Avalanche Activated Combustion' Ignition Technique in a Heavy Duty Natural Gas Engine. SAE Technical Paper, 2014, 01, 1327
  3. Douailler B., Ravet F., Delpech V., Soleri D. Direct Injection of CNG on High Compression Ratio Spark Ignition Engine: Numerical and Experimental Investigation. SAE Technical Paper, 2011, 01, 0923
  4. Shah A., Tunestal P., Johansson B. CFD Simulations of Pre-chamber Jets' Mixing Characteristics in a Heavy Duty Natural Gas Engine. SAE Technical Paper, 2015, 01, 1890
  5. Toulson E., Schock H., Attard W. A Review of Pre-Chamber Initiated Jet Ignition Combustion Systems. SAE Technical Paper, 2010, 01, 2263
  6. Boeckhoff N., Mögele H. Improvement & new applications of the MAN 51/60 gas engine for marine & power plant
  7. Watanabe K., Goto K., Hashimoto H. Update on Wärtsilä 4-stroke gas product development
  8. Christian T., Andreas B., Nikolaus S. GE's all new J920 gas engine- a smart accretion of two-stage turbocharging, ultra lean combustion concept and intelligent controls
  9. Gao J., Jiang D.M., Huang Z.H.Numerical study on spray and mixture stratified combustion in a direct injection gasoline engine. Transactions of CSICE, 2005, 23,Vol. 4, pp.296-306
  10. Zesty E., Nagy T., Simmie J.M. Reduction of a detailed kinetic model for the ignition of methane/propane mixtures at gas turbine conditions using simulation error minimization methods. Combustion and Flame, 2011, 158, pp.1469-1476
  11. Li S.S., Bai S.Z., Xing X.W. Influence of pre-chamber parameters on combustion process in large natural gas engine. Chinese Internal Combustion Engine Engineering, 2012, 33,Vol. 6, pp.72-76
  12. Allan Kirkpatrick, Giheon Kim, Daniel Olsen. CFD modeling of the performance of a pre-chamber for use in a large bore natural gas engine. ASME ICES 2005, 1049.
  13. Heywood, J.B. Internal Combustion Engine Fundamentals. International edition, McGraw-Hill, New York, 1988
  14. Watson H., Milkins E., Goldsworth L. Optimizing the spark ignition pre-chamber geometry including spark plug configuration for minimum NOx emissions and maximum efficiency. SAE Paper, 1982

© 2024 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence