摘要: |
Biofuels, such as biodiesel, offer benefits as a possible alternative to conventional fuels due to their fuel source sustainability and reduced environmental impact. Before they can be used, however, it is essential to understand their physical properties, combustion chemistry, and characterization of the exhaust due to a number of issues associated with fuel propertiesfor example, a lower heating value and higher cloud point than regular diesel. High viscosity of biodiesel may lead to poor atomization of the fuel spray and inaccurate operation of the fuel injectors, so, it may cause fuel injector problems. Biodiesel may produce high NOx emissions. Depending on the feedstocks and blending ratios used to produce the fuel, variations in chemical properties may also be an issue. During this study, physical properties such as flash point, cloud point, and kinematic viscosity of different blends (B0, B10, B20, B50, and B100) were measured on three different feedstocks (soybean methyl ester or SME, tallow oil, or TO, and waste cooking oil, or WCO) while ultra-low sulfur diesel (ULSD) was used as base fuel. The research applied the standard methods of the American Society for Testing and Materials (ASTM). For the study of combustion chemistry and characterization of the exhaust, various tests, such as gravimetric analysis, elemental analysis, elemental carbon/organic carbon (EC/OC) analysis, and gas chromatography (GC) analysis, were conducted for PM emission samples collected from buses, as well as from the laboratory setup. In the field, emission samples were collected for both hot and cold idle conditions. Gravimetric analysis showed a decrease of 17% in PM emissions from the transit buses running on B20 compared to ULSD (B0). A total of eleven elements were detected in the exhaust samples collected from the laboratory experiments, and fifteen elements from the field experiments. Calcium (Ca), sodium (Na), and iron (Fe) were the major elements. The results also indicate |