Combustion And Emission Characteristics Of Diesel Engine Fueled With Acetone-Butanol-Ethanol/Diesel

ABE(Acetone-Butanol-Ethanol)produced by bio-fermentation can improve combustion characteristic and reduce emissions.Using it directly as the engine's alternative fuel can simplify the post-processing process,reducing manufacturing cost.ABE related research mainly focus on experimental research,simulation are few.Moreover,the influence of ABE/diesel blending ratio on the soot size distribution is rarely reported.In this thesis,the simplified mechanism of ABE-heptane fuel was constructed,and the mechanism was coupled with FORTE software to simulate the combustion process of ABE-diesel blended fuel.The effect of load and fuel injection timing on the soot size distribution characteristics were experimentally studied in diesel engine fueled with ABE and diesel blending fuel.Firstly,based on the detail PRF(Primary Reference Fuel)chemical reaction mechanism,a reduced mechanism of ABE-heptane fuel including the formation of soot precursors was developed and validated.The results show that the ABE-heptane reduced mechanism can relatively predict the ignition delay of acetone,butanol,ethanol and diesel,the formation tendency of important intermediate products and soot precursors and the cylinder pressure.Secondly,due to the lack of acetone's the physical parameters in the fuel lab of FORTE software,the fuel with its the physical parameters similar to acetone was chosen in the existing fuel database.It is found that the methyl tert-butyl's representing the characteristic of spray is most similar to acetone.A simulation platform is built to simulate the combustion process of ABE-diesel blended fuel.The process of spray and cylinder combustion for ABE-diesel blended fuel's were studied in constant combustion chamber and four cylinder diesel engine.The results show that the spray penetration length,combustion pressure and heat release obtained by simulation are overall consistent with experiment at different ambient temperature and oxygen concentration;Moreover,the cylinder pressure also could be predicted well by simulation.Furthermore,simulation platform can qualitatively predict the tendency of NOx,UHC and soot.Then the effect of ABE ratio and ABE/diesel blending ratio on the combustion and emission characteristics were studied in the condition of at 1800r/min and 50%load through simulation platform.The results show that,compared to net diesel,all fuel with different ABE ratio(A:B:E=3:6:1,6:3:1 and 0:9:1)cause ignition to delay where ABE20(6:3:1)delayed mostly.The fuel with addition to different ABE ratio all make CO,UHC and NO_x emission increasing,but soot emissions reduce,especially for ABE20(6:3:1).As the ABE blend ratio increasing,the heat release timing retards,and the pressure peak firstly reduces then increases;the CO and UHC emission continually increases,however,NO_x emission firstly increases then reduces and soot emission continually reduces.Lastly,the effect of ABE blend ratio at various load and injection timing on The particle size distribution characteristics were experimentally investigated in diesel engine fueled with ABE and diesel.The results show that at low and medium load,it is beneficial for ABE10 and ABE20 to reduce significantly soot PNC(Particle Number Concentration)and PMD(Particle Mass Density).At low load,the soot PNC and PMD for ABE20 are lowest.At medium load,the soot PNC and PMD for ABE10 are lowest.At high load,the soot emissions increase significantly for ABE10 and ABE20.But Compared to diesel,ABE10 soot emissions reduce,ABE20 soot emissions increase.The ABE10 and ABE20 soot PNC increase in nucleation mode,but it reduces in accumulation mode.Moreover,at low and medium load,ABE10 GMD(Geometric Mean Diameter)is biggest,at high load,ABE20 GMD is biggest.Compared to net diesel,the PNC and PMD of ABE10 and ABE20 significantly reduce.Compared ABE10 with ABE20,at late injection,ABE20's PNC and PMD are higher in nucleation and accumulation mode(50nm~150nm),but it is lower in accumulation mode(150nm~1000nm).At early injection,ABE20's PNC and PMD are higher in nucleation mode,the tendency of particles concentration in the accumulation mode against the increase of diameter is consistent with ABE10,but still slightly lowers;Compared to diesel,the soot particles GMD for ABE10 and ABE20 are lower,the change law of particles GMD against injection timing varying is not obvious between ABE10 and ABE20.