PAH emissions influenced by Mn-based additive and turbocharging from a heavy-duty diesel engine

A manganese-based additive was used in this study to investigate the effects on the polycyclic aromatic hydrocarbons (PAHs) emission from a natural-aspirated heavy-duty diesel-powered engine. A similar turbocharged engine was tested and compared with the natural-aspirated one for the PAH emission. The concentrations of 21 individual PAHs (gas + particle phases) and the metal element (Mn) of the particulate from the engine exhaust and in the diesel fuel, respectively, were determined. Engine exhaust (PAHs and Mn) was collected over the modified JAMA J-13 mode by a PAH sampling system. By adding 400 mg/kg of Mn-based additive in the diesel, the reduction fraction of mean total-PAM (gas plus particle phase) emission was 37.2%, while for the 10 higher molecular weight (HMW) PAHs, the mean reduction fraction was 64.5%. These results indicate that the Mn-based additive in the diesel engine can act as a catalyst enhancing the oxidation process and reducing a considerable amount of PAH emission. In addition, the amount of 10 HMW PAH emission from the turbocharged engine averaged 92.4% of magnitude lower than that of the natural-aspirated engine. This result revealed that the turbocharged engine has higher pressure and temperature and thus makes a more complete combustion of the fuel. (C) 1998 Elsevier Science Ltd.