Exhaust emissions from a diesel vehicle were studied using FTIR, SMCA-REMPI, and SMPS. With these techniques, quantitative emission properties of NO, NO2, N2O, NH3, CO, CH4, C 2H4, C3H6, HCHO, toluene, toluene + CH2, toluene + 2CH2, β-methylstyrene, naphthalene, 2-methylnaphthalene, phenanthrene, and o-cresol, as well as particle size distributions, were obtained in constant-speed operation at 0-80 km/h, which corresponds to a brake mean effective pressure (BMEP) of 0-293 kPa. NO emission increased as the in-cylinder temperature increased, corresponding to increased engine load. NO2 and N2O had a strong correlation to equivalence ratio. The emission characteristics of non-aromatic hydrocarbons depended on engine load. At low load, the emissions were high because low in-cylinder temperature and Exhaust Gas Recycling (EGR) prevented complete fuel oxidation. Equivalence ratio had a slight influence on the non-aromatic hydrocarbon emissions. The profiles of aromatic hydrocarbon exhibited two shapes. One was a toluene group and another was a styrene and naphthalene group. The shapes of the toluene group were similar to those of non-aromatic hydrocarbons. On the other hand, the styrene and naphthalene group emissions at idling were low, suggesting that they were not formed at low load. These features concerning the two groups of aromatic hydrocarbons were also observed in a transient driving cycle. Emission of accumulation mode particles was correlated with equivalence ratio. Higher emissions were observed when the equivalence ratio was higher, and the particle diameters also increased. Emission of nucleation mode particles increased as the engine load increased, because the amount of injected fuel per cycle increased.
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