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Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/27/2011 Publication Date: 12/15/2011 Citation: Dunn, R.O. 2011. Fuel properties of biodiesel/ultra-low sulfur diesel (ULSD) blends. Journal of the American Oil Chemists' Society. 88(12):1977-1987. Interpretive Summary: This research developed a relatively easy and cost-effective technique to determine the volumetric concentration of biodiesel in blends with ultra-low sulfur petrodiesel (ULSD). The recent mandated change to ULSD in on-road transportation applications in the U.S. has created the need to develop a better understanding of the basic fuel properties of biodiesel/ULSD blends. Data from cold flow property, relative density, refractive index, and viscosity (thickness) measurements performed on biodiesel/ULSD blends were correlated to yield equations for calculating volumetric concentrations of biodiesel in the blends. Relative density correlations were shown to be most accurate for purposes of predicting concentrations to within 1.3 volume percent. Results from this study will provide a useful and easy means for fuel distributors and terminal operators to confirm biodiesel concentrations in blends without having to acquire expensive instruments and equipment or waiting for results from contract laboratories. Results will also directly benefit scientists and engineers seeking to increase their understanding of the fuel properties of biodiesel/ULSD blends. Technical Abstract: Biodiesel is an alternative fuel and fuel extender easily derived from vegetable oil or animal fat. In 2006, the U.S. Environmental Protection Agency mandated that maximum sulfur content of diesel fuels be reduced to 15 ppm to protect catalysts employed in exhaust after-treatment devices. Processing to produce this ultra-low sulfur petrodiesel (ULSD) alters fuel lubricity, density, cold flow, viscosity, and other properties. Consequently, there is a need to develop a better understanding of the basic fuel properties of biodiesel/ULSD blends. This work evaluates the effects of biodiesel volumetric blend ratio (VBD) on cloud point (CP), kinematic viscosity (v), specific gravity (SG), and refractive index (RI) of blends with petrodiesel. Properties measured for various blends of soybean oil methyl esters (SME) and used cooking oil (UCOME) in ULSD were compared with those for blends with low sulfur (less than or equal to 500 ppm) petrodiesel fuel (LSD). With respect to increasing VBD, CP and SG increased and RI decreased with each parameter, demonstrating a linear correlation. In contrast, v showed a curvilinear relationship with respect to increasing VBD. Calibration curves were derived from regression analyses to determine VBD in biodiesel/ULSD blends from measurements of each individual property. While the models had generally high coefficients of regression (R² > 0.986), SG models were most accurate for predicting VBD to within 1.3 vol%. |
