Effects of fuel injection strategies on emissions characteristics of a diesel engine equipped with a particle oxidation catalyst (POC)

In the present study, operating performance of a particle oxidation catalyst (POC) on emission characteristics of hydrocarbon (HC), carbon monoxide (CO), nitrogen oxides (NOx) and particulate matter (PM) under various fuel injection strategies was investigated on a diesel engine at a low load. The results show that, fuel injection strategies present less impacts on CO and HC emissions. By using the POC, CO and HC emissions are significantly reduced by 76.63-97.98% and by 77.42-90.89%, respectively, suggesting nearly zero emissions for CO and HC. The increased fuel injection pressure (FIP) and the advanced start of injection (SOI) could increase the NOx emissions, while by using the POC, nearly 14.52-29.83% NOx were reduced, which is mainly assigned to the transformation of NO to NO2 by the DOC and adsorption of NO2 in the POC. Regarding the PM emissions, the trade-off correlation between the nucleation-mode and the accumulation-mode particles is totally removed by the combination of the POC and the injection strategies, resulting in a reduction efficiency on the PM number concentration varying from 78.96 to 99.15%. Furthermore, fuel injection strategies could promote POC performance on reducing PM emissions. With either increasing FIP or advancing SOI, POC reduction efficiency on PM number concentration increases monotonically. Above all, diesel engine gaseous and particulate emissions could be remarkably reduced by using the present POC and an optimized injection strategy would benefit to a further increase in POC removal efficiency. (C) 2016 Elsevier Ltd. All rights reserved.