Investigation On Dual Fuel Dual Injection System Engine Fuelled With Ethanol And Gasoline For Fuel Economy And Emissions

Energy shortages and environmental pollution are global problems,which have led to more stringent fuel consumption regulations and emission standards around the world.The dual-fuel dual-injection system engine fuelled with ethanol and gasoline combines advantages of the GDI and PFI,which is an effective way to make full use of the advantages of ethanol gasoline,optimize the combustion process,improve fuel economy and reduce particulate emissions.The dual-fuel dual-injection system engine fuelled with ethanol and gasoline is adapted with an intake port injection system on a GDI?gasoline direct injection?engine and the blended ratio can be real-time adjustable.This paper presents an innovative experimental research on the combustion modes of EPI+GDI and EDI+GPI at urban operating conditions,this study is mainly focused on fuel economy,gaseous regulated emissions and particle emissions,the combustion characteristics are also analyzed.The major contributions are listed as follows:When the engine is applied on the EPI+GDI combustion mode:The b_ESFC?equivalent specific fuel consumption?reduces with the increase of R_ethanol?ethanol port injection ratio?.The b_ESFC of 0.2MPa,0.6MPa and 1MPa reaches the lowest with the pure ethanol,and the fuel economy is 8.91%,5.04%and 7.58%higher than that of pure gasoline.What's more,HC emission decreases with the increase of R_ethanol and doesn't depend on the engine loads.CO emission increases first and then decreases with the increase of R_ethanol.Furthermore,particles number and mass of various conditions are reduced with the increase of R_ethanol,the favorable evaporation characteristics as well as the higher oxygen content of ethanol leads to lower soot precursors formation and enhanced particle oxidation.Ethanol forms an azeotropes with gasoline,which enhances the volatility of gasoline and improves the mixture quality,and further reduces particle emission.When the comparative investigation focus on the two combustion modes of EPI+GDI and EDI+GPI:the b_ESFC of the two combustion modes reduces with the increase of R_ethanol,which need less energy input to achieve the same engine power output.The fuel economy of EDI+GPI combustion mode is better than that of EPI+GDI,indicating a more efficient charge cooling effect attributable to the high latent heat of vaporization of ethanol by directly injecting into the cylinder.CO emission decreases first and then increases with the increase of R_ethanol.What's more,NO_X emission of EPI+GDI combustion mode increases with the increase of R_ethanol,while that of the EDI+GPI shows the opposite trend.Particle emission of EDI+GPI combustion mode is obviously higher than that of EPI+GDI.When the engine is applied on different port ethanol injection timing,the initial combustion duration and major combustion duration of L_EPI are less than those of E_EPI.Because of the optimized combustion phase and good mixture quality,HC and CO emission of L_EPI is lower than those of E_EPI,while NO_X emission is higher than that of E_EPI.What's more,the particle emission of pure ethanol at idle speed shows a unimodal distribution,which is obviously lower than the particle emission of pure gasoline at idle speed.When the engine has just started,the particle emission of different R_ethanol is markedly high,the particle emission gradually decrease and then reach a relatively stable level with the increase of coolant temperature.When the engine is warming up,the particle emission of pure ethanol is 1-2 orders of magnitude lower than that of pure gasoline.In a word,dual fuel dual injection system engine fuelled with ethanol and gasoline can improve fuel economy,under the premise of the reduction of gaseous regulated emission or substantially unchanged,particle emission is significantly reduced.