Effects of Water Ratio in Hydrous Ethanol on the Combustion and Emissions of a Hydrous Ethanol/Gasoline Combined Injection Engine under Different Excess Air Ratios

Decheng Li; Xiumin Yu; Ping Sun; Yaodong Du; Mingjia Xu; Yinan Li; Tianqi Wang; Zhe Zhao

doi:10.1021/acsomega.1c04065

Effects of Water Ratio in Hydrous Ethanol on the Combustion and Emissions of a Hydrous Ethanol/Gasoline Combined Injection Engine under Different Excess Air Ratios

ACS Omega. 2021 Sep 20;6(39):25749-25761. doi: 10.1021/acsomega.1c04065. eCollection 2021 Oct 5.

Authors

Decheng Li¹, Xiumin Yu¹, Ping Sun¹, Yaodong Du¹, Mingjia Xu¹, Yinan Li¹, Tianqi Wang¹, Zhe Zhao¹

Affiliation

¹ State Key Laboratory of Automotive Simulation and Control, Jilin University, Renmin Street 5988, Changchun, Jilin 130022, China.

Abstract

Ethanol is usually combined with gasoline to manufacture ethanol-gasoline with excellent combustion characteristics. However, extracting water from hydrous ethanol to manufacture anhydrous ethanol consumed much energy, which increases the production cost of ethanol-gasoline. Many researchers have studied the combustion and emissions of hydrous ethanol-gasoline to explore the application of hydrous ethanol-gasoline as the fuel for spark-ignition engines. Most previous studies changed the hydrous ethanol ratio with fixed purity in hydrous ethanol-gasoline to study the effects of hydrous ethanol. Different from previous studies, this paper studied the effects of water ratio (Wr) in hydrous ethanol on the combustion and emissions of a hydrous ethanol/gasoline combined injection engine under different excess air ratio (λ) values. The ratios of ethanol and gasoline keep constant, while the purity of hydrous ethanol changes during the research. The experiment adopted the combined injection mode with hydrous ethanol direct injection plus gasoline port injection; the direct injection ratio was 20%. The experiment set three λ (0.9, 1, and 1.2) and five Wrs (0, 5, 10, 15, and 20%). The test engine's speed was 1500 rpm, and the intake manifold absolute pressure was 48 kPa. Results showed that water inhibited combustion, prolonged CA 0-10 and CA 10-90, reduced P _max and T _max, and delayed AP_max; larger λ made the deterioration on combustion more obvious, and the smaller λ had a larger tolerance to water. Water could increase torque and improve emissions, but different parameters corresponded to different optimal Wrs. For torque, the optimal Wr was 5%. For HC emissions, the optimal Wr was 0%; for CO emissions, the optimal value was 5%; and for NO _x emissions, the best value was 20%. The best Wr was 10% for particle number (PN) emissions. Under the optimal Wr condition, when λ values were 0.9, 1, and 1.2, compared with pure gasoline, the torque increased by 7.5, 5.54, and 5.31%; HC emissions decreased by 21.37, 23.43, and 26.58%; NO _x emissions decreased by 4.26, 11.47, and 12.55%; CO emissions decreased by 17.51, 34.56, -50%; and the total PN emissions decreased by 87.64, 89.64, and 76.07%.