Effect Of Hydrogen-added And Oxygen-enriched Intake On Performance And Combustion Characteristics Of PFI Gasoline Engine

Rigorous energy conservation and emission reduction regulations demand gasoline engine to operate with lower emission and higher fuel efficiency.Then techniques like GDI,turbocharging system have been applied to meet that.While high PM emission and turbo-lag leave challenges for furtherly improving engine performance.With the maturity of vehicle energy recovery technology,it's a fresh research topic to decrease fuel consumption with the recovery energy.Hydrogen-added and oxygen-enriched intake based on water electrolysis device using recovery power to produce hydrogen and oxygen has been proved to be potential on raising engine performance,but the lack of deep understanding of engine combustion characteristics with diverse H₂/O₂-addition strategies at typical operating conditions and how to choose proper strategy would limit the use of this technology.In this thesis,1D and 3D numerical model based on a 1.0L gasoline engine was built under GT-Power and Converge code to systematically investigate the performance and combustion characteristics of engine using hydrogen-added,oxygen-enriched intake air at typical operating condition and study effect of hydrogen-added intake combined with EGR on combustion characteristics.Due to the researches,the following conclusions can be achieved:?1?At part load,indicated thermal efficiency would rise with the addition of H₂,O₂ and 2H₂+O₂,separately and addition of H₂ can achieve the best performance.Under the three addition strategies above,HC and CO emission will reduce obviously,but the NO_x emission will rise sharply with the addition of 2H₂+O₂ and oxygen-enriched intake.Combustion period are shortened and combustion efficiency are raised under the three addition modes.At the same BMEP and 5.06%H₂-addition fraction,heat efficiency can increase 0.6%and comprehensive thermal efficiency?gasoline consumption only?will increase 6.6%than that of original engine.?2?At WOT condition,oxygen-enriched intake can obviously increase the engine power,which can increase 10%at oxygen concentration of25%.While indicated heat efficiency would decrease due to the increase of heat transfer and exhaust energy lose.?3?Adding extra hydrogen in EGR-blended intake can raise the flame propagation speed and enhance the combustion quality which can furtherly cause shorten the flame development period and rapid combustion period.In condition of EGR,hydrogen is useful to increase the indicated thermal efficiency,extend EGR ratio limit and decrease the HC,CO and CO₂ emission,but NO_x emission has a little bit increase.?4?At small load,optimized BSFC of gasoline engine will decrease7.1%,8.7%,21.8%under EGR 0%/H₂ 5.06%,EGR 10%/H₂ 5.06%and EGR 10%/H₂ 10.12%conditions.?5?At part load,engine using hydrogen-added intake can achieve low emission and high fuel economy and furtherly decrease BSFC with introduction of EGR.At WOT condition,engine using oxygen-enriched intake can achieve higher power output level to meet the need of power at vehicle accelerating condition.