Biodiesel has recently reemerged as a common fuel. However, emissions from biodiesel combustion have been studied in much less detail than those from traditional petroleum-based diesel. In this experiment, emissions from the combustion of different fuel blends (B00, B02, B20, B99, where the number after B indicates the percentage, by volume, of biodiesel in the fuel) in a VW TDi engine were analyzed by aerosol time-of-flight mass spectrometers (ATOFMS) for single-particle composition and vacuum aerodynamic size. The ATOFMS results show that the PAH molecular weight distribution is not significantly affected by the fuel composition, and that sulfates are reduced by increased biodiesel content. Octanedioic acid (a carbonyl species) is increased with increased biodiesel concentration. Clustering results from the single-particle spectra show that the particles fall in five main types by chemical composition. The aerodynamic size distribution of these individual clusters was also determined. These results also show that methods used to identify diesel particle emissions for source apportionment are not applicable when significant concentrations of biodiesel are used in fuels.
Bibliographical noteFunding Information:
DDD was funded by the Graduate Research for the Environment Fellowship, Global Change Education Program, Department of Energy . JP was financed through a postdoctoral stipend and the project “Single Particle Chemical Composition and Mixing Characteristics of Fine and Ultrafine Particles in Indoor and Outdoor Settings by the Swedish Research Council FORMAS . DSG was supported by a Bush Fellowship, Faculty Development Grant from Carleton College . JMM was supported by a summer fellowship from the Howard Hughes Medical Institute through Carleton College. Additional support was provided by NSF Grant No. NSF/ATM-00 96555 to the University of Minnesota.