A Study of the Effect of a Catalyzed Particulate Filter on the Emissions from a Heavy-Duty Diesel Engine with EGR

The effects of a catalyzed particulate filter (CPF) and Exhaust Gas Recirculation (EGR) on heavy-duty diesel engine emissions were studied in this research. EGR is used to reduce the NOx emissions but at the same time it can increase total particulate matter (TPM) emissions. CPF is technology available for retrofitting existing vehicles in the field to reduce the TPM emissions. A conventional low sulfur fuel (371 ppm S) was used in all the engine runs. Steady-state loading and regeneration experiments were performed with CPF I to determine its performance with respect to pressure drop and particulate mass characteristics at different engine operating conditions. From the dilution tunnel emission characterization results for CPF II, at Mode 11 condition (25% load - 311 Nm, 1800 rpm), the TPM, HC and vapor phase emissions (XOC) were decreased by 70%, 62% and 62% respectively downstream of the CPF II. From the analysis of polynuclear aromatic hydrocarbons (PAHs), fluoranthene emissions associated with the particle associated PAH's and the XOC associated PAH's were reduced by 60% and 38% downstream of CPF II respectively at Mode 11 condition. Pyrene emissions associated with the SOF associated PAHs and XOC associated PAHs were reduced downstream of CPF II by 84% and 63% respectively at Mode 11 condition. 1-nitropyrene emissions were reduced by 30% downstream of CPF II. The mutagenic activity associated with the TPM decreased downstream of CPF II at Mode 11 condition. At Mode 9 condition (75% load - 932 Nm, 1800 rpm), the TPM, HC and XOC emissions were reduced by 30%, 55% and 69% respectively downstream of CPF II. The raw exhaust measurements showed 81% filtering efficiency of solids with CPF II. A 140% increase in nuclei mode particle number concentration was found downstream of CPF II compared to the baseline at Mode 9 condition. The particle associated fluoranthene and pyrene emissions were reduced by 97% and 68% downstream of CPF II respectively at Mode 9 condition. An increase in 1-nitropyrene emissions by 213% was found downstream of CPF II at Mode 9 condition. The SOF associated mutagenic activity could not be compared at Mode 9 condition since samples downstream of CPF II were not tested due to very low masses. The XOC samples for Mode 9 displayed very little mutagenic activity for both the baseline and downstream of CPF II.