Combustion and emission characteristics of dimethyl ether/gasoline DFSI engine under different excess air coefficients

• Published in: Case studies in thermal engineering 2023-09, Vol.49, p.103342, Article 103342
• Main Authors: Yang, Song, Sun, Ping, Feng, Jincheng, Cui, Kexin, Wang, Chao, Dong, Wei, Yu, Xiumin, Gu, Ye
• Format: Article
• Language: English
• Subjects: Dimethyl ether; Dual fuel; Dual injection; Excess air coefficient; Particulate number
• ISSN: 2214-157X; 2214-157X
• DOI: 10.1016/j.csite.2023.103342

Dimethyl ether (DME) was a carbon neutral alternative fuel for engines.The combustion and emission characteristics of a DME/gasoline Dual Fuel Spark Ignition (DFSI) engine with various excess air coefficients (λs) at different DME ratios (ΦDME) were investigated experimentally in this study.The in-cylinder pressures along with their relevant crank angle were used for the combustion characteristics calculation. The light five component exhaust gas analyzer and particle analyzer were employed for the gaseous and particulate matter emission measurement, respectively. Results showed that the DME/gasoline dual fuel combustion strategy can enhance the Brake Mean Effective Pressure (BMEP) by up to 12.6% because the high diffusivity, superior LTR and fast LFS of DME. Although adding DME was beneficial for the reduction of gaseous emissions (HC, CO and NOx) from DME/gasoline DFSI engines, the gaseous emissions were mainly determined by the variation of λ s. Particularly, up to 93.4% of the CO emissions at stoichiometric condition can be reduced after increasing λ to 1.3. The fast evaporation rate and superior LTR of DME helped to suppress PN emissions, but larger DME ratio (ΦDME > 5%) was needed for λ >1.2. •Performance of DME/gasoline DFSI engine with various λs were evaluated.•ΦDME≥ 15% was required to alleviate the decline of BMEP with increasing λs.•Combustion process and gaseous emissions were mainly affected by λ.•ΦDME around 15% and λ around 1.2 were preferred for medium load and speed.