A novel approach of water injection optimization applied in gasoline engines: An investigation on heated water injection. (15th May 2023)

• Record Type: Journal Article
• Authors: Wu, Jingtao; Lv, Yuhang; Kang, Zhe; Lv, Yang; Deng, Jun; Li, Liguang; Wu, Zhijun
• Is Part Of: Fuel. Volume 340(2023)
• Publication Date: 2023-05-15
• Subjects: Gasoline engine -- Heated water injection -- Combustion optimization -- Emissions characteristics -- Experimental study; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.127607
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: A method of lowering oil emulsion and metal corrosion risks for water injection is proposed. A heated water injection system above 200℃ is designed. Effects of heated water injection on combustion and emissions are studied experimentally. An optimum strategy of heated water injection for combustion control is established. Abstract: Water injection technique is a promising solution for accurate combustion control, but oil emulsion obstacle its commercial application. The present study proposes a practical approach for optimizing water spray atomization and evaporation, in which water is heated through exhaust gas recovery and directly injected into combustion chamber with a flash boiling. Firstly, a heated water injection (HWI) system was designed and established. Then, experiments were conducted to explore the effects of HWI parameters on engine combustion and emissions characteristics in terms of water injection strategies. The results present that HWI increase water evaporation rate and improves combustion efficiency. The HWI lowers flame propagation speed and improves specific heat ratio of air–fuel mixture. Elevated injection temperature lowers duration of flame kernel formation, which shortens ignition delay prolonged under conventional water injection. CA10 is advanced 4.5°CA under same spark advance while compared to conventional water injection. Moreover, HWI can not only reduce production of NOX and CO emissions but also effectively lower HC emissions by 26.2%, as water injection temperature increased to 205℃. However, excessive water injection mass and inappropriate water injection timing may worsen ignition and flame propagation, increasing unburned loss and misfire probability. The present results provide considerable evidence for the application of HWI within modern gasoline engines.