EFFECTS OF WATER INJECTION ON COMBUSTION EMISSION AND KNOCK CHARACTERISTICS OF TURBOCHARGED DIRECT INJECTION GASOLINE ENGINE
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Junjun Wang 1,2, Fuwu Yan 1, Dong Yan 2, Wenlong Zhang 2, Guoqing Zhang 1,2, Jizhou Zhang 1, Ziyi Chen 1, Yu Wang 1 |
11)School of Automotive Engineering, Wuhan University of Technology 2Powertrain Department, Dong Feng Motor Corporation Technical Center |
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ABSTRACT |
This paper studied the effects of water injection on combustion, emissions and knock. The results showed that
direct water injection (DWI) absorbed more heat than inlet port water injection (PWI), resulting in lower cylinder pressure,
higher oxygen content and longer combustion duration. And the turbulence kinetic energy of DWI model was greater, resulting
in lower soot and CO emissions of DWI. Furthermore, the cooling effect of exhaust port side WI was better than intake port
side, which reduced NOX emission. Besides, the injection pressure of single injector WI was higher than double injector, which
increased the combustion duration and reduced the cylinder pressure. The decrease of temperature under water dilution was the
main reason for the reduction of NOX, while the increase of incomplete combustion increased the soot and CO emission. Finally,
with the same amount of WI, the knock suppression effect of DWI models was better than PWI models. The knock intensity
(KI) of all models decreased gradually with the increase of water, and DWI models decreased more rapidly. For PWI models,
when the amount of water became smaller, the engine pressure fluctuation of certain areas in the cylinder increased slightly,
weakening the influence of WI on engine knock. |
Key Words:
Water injection, Combustion, Emissions, Knock, Direct injection gasoline engine
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