Nonpolar Organic Compound Emission Rates for Light-Duty Diesel Engine Soybean and Waste Vegetable Oil Biodiesel Fuel Combustion

作者：Kasumba John^*; Holmen Britt A

来源：Energy & Fuels, 2016, 30(11): 9783-9792.

DOI：10.1021/acs.energyfuels.6b01582

Very few studies report the detailed organic chemical composition of biodiesel exhaust PM despite reports that biodiesel exhaust PM leads to more adverse health effects than diesel exhaust PM. Here, we compare light-duty diesel engine exhaust particle-phase emission rates (ng/mu g (PM)) of target nonpolar organic analytes-19 n-alkanes, 16 priority PAHs, and 10 fatty acid methyl esters (FAMEs)-during transient operation for 5 recycled waste vegetable oil (WVO; B00, B10, B20, B50, and B100) and 3 virgin soybean oil (soybean; BOO, B20, and B100) biodiesel blends (where Bxx = volume % biodiesel). Biodiesel fuels were blended volumetrically from ultralow sulfur diesel (ULSD) and B100 from each feedstock. FAMEs emission rates were 3-7 times higher than n-alkanes for the common B20 blend, increasing to 60-100 times for B100. Both total n-alkanes and total FAMES emission rate trends with Bxx were consistent with expected values based on fuel volume percent and similar ratios to ULSD were observed for both feedstocks. Total n-alkane emission rates decreased with increasing biodiesel content (B10 to B100) between 5-86% and 3-79% compared to ULSD, for WVO and soybean, respectively. Total FAMEs emission rates in WVO B100 exhaust PM were about 7, 3, and 2 times higher than WVO B10, B20, and B50 exhaust PM, respectively, with similar ratios for the soybean feedstock. In contrast, PAH emission rates, while statistically similar for both feedstocks, did not decrease as much as expected based on dilution of ULSD with B100 biodiesel, evidence that FAME or lubrication oil combustion account for PAH formation in higher biodiesel blends (greater than B20). Because emission rates of n-alkanes, PAHs, and FAMEs from recycled vegetable oil biodiesel were not statistically different from those for soybean biodiesel, based on nonpolar organic emissions alone, use of recycled waste cooking oil biodiesel is preferable to virgin vegetable oil biodiesel because of its dual use for food preparation prior to use as a renewable, low-carbon transportation fuel. Future studies should quantify how WVO biodiesel emissions are changed by use of emission control devices, such as DPF and SCR.

• 出版日期2016-11