Numerical simulation on the effects of n-butanol combined with intake dilution on engine knock

The improvement in thermal efficiency of GDI engine is severely limited by knocking. The effects of n-butanol combined with intake dilution on engine knock and thermal efficiency were studied in this paper. The results show that the combustion activity of n-butanol containing OH functional group can...

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Bibliographic Details
Published in:	Energy (Oxford) 2023-05, Vol.271, p.126918, Article 126918
Main Authors:	Feng, Hongqing, Suo, Xinghan, Xiao, Shuwen, Chen, Xiaofan, Zhang, Zhisong, Gao, Ning, Zheng, Zunqing
Format:	Article
Language:	eng
Subjects:	Compound dilution Intake dilution Knock Lean burn N-butanol/gasoline blends
Online Access:	Get full text
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Summary:	The improvement in thermal efficiency of GDI engine is severely limited by knocking. The effects of n-butanol combined with intake dilution on engine knock and thermal efficiency were studied in this paper. The results show that the combustion activity of n-butanol containing OH functional group can be improved by blending a small amount, and then the detonation intensity and thermal efficiency can be improved. When a high proportion of n-butanol is mixed, the knock strength and thermal efficiency will be reduced due to the effect of low calorific value and latent heat of vaporization. In particular, the maximum value is reached when 15% n-butanol is employed. The spontaneous combustion tendency is reduced by intake dilution, and the influence degree is reduced in the order of EGR dilution, compound dilution and air dilution, which is caused by the different amount of CO2 in the three dilution gases. When RA = 1.2 and RA-E = 1.2, the knock intensity of GDI engine burning Bu15 is reduced by 96.3% and 98.4%, respectively. Therefore, when n-butanol combined with composite dilution is selected, the occurrence of knocking can be suppressed, while ensuring high thermal efficiency. Current study can provide theoretical guidance for knock suppression of GDI engines. •The mechanism about the intake dilution improving the performance of GDI engines.•When the Bu15 is employed, the peaks of both thermal efficiency and knock intensity.•When RA-E = 1.2, engine knock intensity of burning Bu15 is reduced by 98.4%.•Thermal efficiency can be improved by n-butanol combined with compound dilution.
ISSN:	0360-5442