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Effects of Blended Fuel on Diesel Engine Exhaust Particles: From Bulk to Single Particle Compositions
LAURA-HELENA RIVELLINI, Mutian Ma, Nethmi Kasthuriarachchi, Wenbin Yu, Yichen Zong, Wenming Yang, Markus Kraft, Alex Lee, National University of Singapore
Abstract Number: 281
Working Group: Combustion
Abstract
Diesel engine emissions are important sources of fine particulate pollutant, causing negative impacts on climate and human health. Recent studies have shown reduction in emissions of black carbon (BC) and organic aerosol (OA) when blended fuels were used. This work investigates the effects of polyoxymethylene dimethyl ethers (PODE) blended fuels (0%, 10%, 20% and 30% by volume) on the emission characteristics of diesel engine exhausts under various engine loadings using a soot-particle aerosol mass spectrometer (SP-AMS). In addition to the ensemble measurements, a novel single-particle mode of SP-AMS was used to determine the chemical compositions of individual particle, and thus the particle mixing state. This work identified three particle types in the emissions based on a single-particle clustering analysis. While one particle type presented higher BC content (>50 wt% of BC), the rest were dominated by OA that can be further classified by their molecular weight. The distributions of these particle types varied with both engine loadings and fuel compositions. In particular, a global increase of rBC-containing particle mass fractions with engine loadings, except for the blended fuel with 30% PODE whose BC-rich particle fractions remained <10% for all tested conditions. Although increasing the blended volume of PODE to 20% or higher could reduce the BC-rich particle fractions, the blended fuel with 10% PODE enhanced the BC-rich particle fractions compared to that from diesel. Furthermore, increasing the blended volume resulted in decreasing of particle size of each particle type. The chemical characteristics of traffic-related particle observed in urban environment matched well with the particles types identified here, especially for those containing > 50 wt% of BC, hydrocarbon-like OA, and high molecular weight OA. Our observations provide insight into the changes in emission characteristics and environmental implications of diesel engine particles caused by the application of blended fuel.