Comparison of open chamber and pre-chamber ignition of methane/air mixtures in a large bore constant volume chamber: Effect of excess air ratio and pre-mixed pressure. (15th February 2020)

• Record Type: Journal Article
• Authors: Ju, Dehao; Huang, Zhong; Li, Xiang; Zhang, Tingting; Cai, Weiwei
• Is Part Of: Applied energy. Volume 260(2020)
• Publication Date: 2020-02-15
• Subjects: Marine engine -- Methane -- Natural gas -- Open chamber -- Turbulent jet ignition -- Pre-chamber; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2019.114319
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Turbulent jet ignition promotes combustion in large bore constant volume chamber. Turbulent jet propagates slower at high initial pressure or high excess air ratio. Heat losses of flame impinging onto combustion chamber wall is considerable. Spark plug location results in asymmetry of turbulent jets from six orifices. Abstract: Natural gas is an alluring choice to substitute the widely used diesel for environmental and economic reasons as it generates less particulate matter and carbon dioxide emissions. However, natural gas is comparatively difficult to be ignited and its flame penetrates slowly in a large bore combustion chamber especially for the lean condition. In order to analyze how the pre-chamber turbulent jet ignition promotes combustion in a large volume chamber, a comparative study with the traditional open chamber ignition mode was conducted to analyze the effect of excess air ratios and pre-mixed pressures on the combustion characteristics of methane/air mixtures. In rich fuel combustion, the advantage of pre-chamber is not obvious, and the flame propagation rate can only be increased by 2.8 times in maximum. In the case of lean combustion and stoichiometric combustion, the flame propagation speeds can be increased by 5–6 times, especially in lean combustion by pre-chamber. In general, the pre-chamber turbulent jet ignition technique can increase the flame propagation rate of methane/air, and improve combustion and thermal efficiency of natural gas large-bore engines under lean combustion conditions. With comparison to the open chamber ignition mode, the reduction percentage of ignition time by pre-chamber turbulent jet ignition decreases with the rise of initial pressure. However, the asymmetric placement of the spark plug inside the pre-chamber, results in the inhomogeneous spreading of flame jets in the constant volume chamber, which ought to be considered in the design of marine engine.