The objective of this research was to study the effect of a catalyzed particulate filter (CPF) with a high loading of catalyst (50 gms/ft3) and ultra low sulfur fuel (ULSF -0.57 ppm of sulfur) on the emissions from a heavy duty diesel engine. The particulate emissions were measured using two different analytical methods, i.e., the gravimetric method and the thermal optical method (TOM). The results from the two different methods of analyses were compared. The experiments were performed at four different operating conditions chosen from the old Environmental Protection Agency (EPA) 13-mode test cycle.
A 1995 Cummins M11 heavy-duty engine with manually controlled exhaust gas recirculation (EGR) was used to perform the emission characterization experiments. The emission characterization included total particulate matter (TPM), which is composed of the solids (SOL), soluble organic fractions (SOF) and sulfates (SO4) analyzed using the gravimetric method. The particulate emissions were also analyzed for total carbon (TC), elemental carbon (EC) and organic carbon (OC) using the TOM. Gas phase emissions consisting of the hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOx) and oxygen (O2) were measured along with the particle size distributions. The four operating conditions were at rated speed of 1800 rpm and at loads 25, 50, 75 and 100 %; these conditions are designated as Modes 11, 10, 9 and 8, respectively, from the old EPA 13-mode test cycle. All the emissions (except for the gas phase emissions) were sampled in the dilute exhaust and then converted back into the raw exhaust concentrations. The differences between the two methods of analyses of the particulate matter were studied by comparing the EC and SOL, OC and SOF, TC and TPM-SO4 fractions.