The Effect Of Late-post-injection Strategy On The Exhaust Temperature And Emission Of Diesel Engine

As the emission of PM has become a serious threat to human,the research on the characteristics and control technology of PM has been widely concerned.The DPF is commonly thought as the most efficient PM removing technology,however,the application of DPF is limited by the regeneration.The effects of late-post-injection strategy on the engine behaviors including exhaust emission,temperature rise pattern and energy efficiency of DOC,are discussed in this study.The functional groups and oxidation activity of soot were studied using the FT-IR and TGA.The degree of branching and the amount of aliphatic C-H surface functional groups were measured.The characteristic temperature for soot oxidation and oxidation activity were explored.The results offer important theoretical significance to understand the chemical characteristics of soot.The major research content and conclusion are listed as follows:The HC and CO emissions both increase with the increase of post fuel injection rate.With the delay of SOI timing,HC emission stays stable after the initial increase,while CO emission decreases after initial increase.The emissions of NO_x and soot decrease at the beginning and then increase with the delay of SOI timing.The emission of NO_x reduces with the increase of post fuel injection rate.The emissions of soot decreases with the delay of SOI timing before 70deg aTDC,while it shows an opposite trend after 70deg aTDC.The temperature of emission gas increases by 3.9¹28.7?,and the temperature of exhaust gas after DOC increases by-30.1³35.4?.The energy efficiency of DOC increases with the increase of post fuel injection rate,while it stays stabilization after the initial increase with the delay of SOI timing.The energy efficiency of DOC is within the scope of 62.73⁷5.75%when SOI timing is on 80¹40deg aTDC.The value of A₂₉₅₈/A₂₉₂₈ is between 0.157 and 0.439,and it increases with the increase of post fuel injection rate,while it increases at the beginning and then reduces with the delay of SOI timing,and it increases after DOC.The value of A₂₉₂₀/A₁₆₁₀increases with the increase of post fuel injection rate,and it decreases at the beginning and then increase with the delay of SOI timing.The apparent activation energy are in the ranges of 143.6¹85.3 kJ·mol^-1,and it decreases with the increase of post fuel injection rate,and increases at the beginning and then decrease with the delay of SOI timing.The three characteristic temperatures and apparent activation energy of soot both increase after DOC,and they has the same trend under different conditions.