Large eddy simulation of n-heptane/syngas pilot ignition spray combustion: Ignition process, liftoff evolution and pollutant emissions

Shenghui Zhong, Shijie Xu, Xue-Song Bai, Zhijun Peng and Fan Zhang

Energy, 2021, vol. 233, issue C

Abstract: The utilization of syngas in the internal combustion engine is one way to reach low carbon emission engine. The n-heptane/syngas pilot ignition spray combustion is simulated here by high fidelity model with different syngas compositions. It is found that the ambient syngas suppresses the ignition by diluting the ambient oxidizer (non-chemical effect) and by affecting the chemical reactions (chemical effect). The consumption of OH radicals through H2+OH = H + H2O and CO + OH = CO2+H in low temperature combustion (LTC) stage is shown to be the main reason for the suppression of ignition. Cool flame propagation into the rich mixture in the mixing layer of n-heptane jet is observed during the transition process from LTC to high temperature combustion (HTC). CO is found to assist the transition to HTC through CO + HO2 = CO2+OH. On the contrary, H2 slows down the cool flame propagation and narrows down the cool flame flammability range, which retards the onset of HTC. The effects of syngas compositions on the flame structure and emission formation are discussed in detail. Due to the upstream auto-ignition, a cool/diffusion/hot flame structure is identified at the liftoff position in dual-fuel case, which drastically changes the flame structure. And more soot formation in early stage is found in dual-fuel cases due to the naturally richer mixture.

Keywords: Dual-fuel combustion; Pilot ignition; Syngas; Transported PDF; Engine combustion network (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:233:y:2021:i:c:s0360544221013281

DOI: 10.1016/j.energy.2021.121080

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