MULTIVARIATE-ANALYSIS OF EXHAUST EMISSIONS FROM HEAVY-DUTY DIESEL FUELS

Particulate and gaseous exhaust emission phases from running 10 diesel fuels on two makes of heavy-duty diesel engines were analyzed with re spect to 63 chemical descriptors. Measurements for one of the fuels we re also made in the presence of an exhaust aftertreatment device. The variables included 28 polycyclic aromatic compounds (PAC), regulated p ollutants (CO, HC, NOx, particles), and 19 other organic and inorganic exhaust emission components. Principal components analysis (PCA) was applied for the statistical exploration of the obtained data. In addit ion, relationships between chemical (12 variables) and physical (12 va riables) parameters of the fuels to the exhaust emissions were derived using partial least squares (PLS) regression. Both PCA and PLS models were derived for the engine makes separately. The PCA showed that the most descriptive exhaust emission factors from these diesel fuels inc luded Fluoranthene as a representative of PAC, the regulated pollutant s, sulfates, methylated pyrenes, and monoaromatics. Exhaust emissions were significantly decreased in the presence of an exhaust aftertreatm ent device. Both engine makes exhibited similar patterns of exhaust em issions. Discrepancies were observed for the exhaust emissions of CO2 and oil-derived soluble organic fractions, owing to differences in eng ine design. The PLS analysis showed a good correlation of exhaust emis sion of the regulated pollutants and PAC with the contents of PAC in t he fuels and the fuel aromaticity. Also, the emission of soluble sulfa te was directly related to the contents of sulfur in the fuels. In con clusion, the PCA clearly indicates that emissions of PAC, particulates , and sulfates are the most descriptive exhaust emission factors. Thes e exhaust emissions can, as shown from the PLS analysis, be much reduc ed by a decrease of aromatics, PAC, and sulfur in the fuels.