We evaluated the performance of two passive-type diesel particulate filters (DPFs) for particulate matter (PM) and exhaust gas emissions using six types of diesel-fueled vehicles running on a chassis dynamometer. One filter was a continuously regenerating DPF (CR-DPF) and the other was a catalyzed DPF (C-DPF). Exhaust gases were analyzed for PM and other components. The vehicles were tested on the Japanese Diesel Thirteen Modes Test cycle and the Tokyo transient patterns as well as a city drive cycle. Both DPFs reduced PM emissions by 80 % in the Tokyo transient patterns when used with a ceramic wall-flow filter. The CR-DPF reduced PM emissions by 60 % when used with a wire-mesh filter. Organic carbon and soot were reduced by the same extent as PM. The use of an oxidation catalyst reduced CO and hydrocarbons by 90 % or more. Moreover, there was a large reduction in the hazardous air pollutants (HAPs) , benzene, 1, 3-butadiene, formaldehyde, and acetaldehyde. Both filters were effective in the reduction of HAPs emissions. There were no significant effects on NOx emissions or fuel consumption. Total NOx emissions were unchanged, but the fraction of NO2 increased from 3-5 % to 26-42 %. Although the increased fraction of NO2 has the potential to raise atmospheric NO2 concentrations, the considerable reduction of hydrocarbons is a positive outcome.
An automated instrument which is capable of analyzing elemental nitrogen in particulate matters in real time is developed. Nitrogen compounds in particles (mainly nitrates) are introduced to a flame chimney so as to convert them into nitrogen monoxide with hydrogen-helium mixed gas. Then, nitrogen monoxide is oxidized into nitrogen dioxide by ozone supplied from an ozonizer. The resultant nitrogen dioxide in the excited state emits light and the concentration of elemental nitrogen is determined by using a Nitrogen Chemiluminescence Detector (NCD) . The calibration curve obtained using 0.23 to 2.3 ppm ammonia gas showed clear linearity. The performance and applicability of this method for the aerosol measurement are also evaluated with ammonium nitrate aerosols generated by a spray drying method. The measured concentrations of ammonium nitrate is compared with those measured by ion chromatograph. As a result, this method is applicable to monitor the nitrate particles though the concentration detected by this method is one-third of those detected by the ion chromatograph.