Energy & Fuels, Vol.31, No.8, 7800-7808, 2017
Application of the Advanced Distillation Curve Method to the Comparison of Diesel Fuel Oxygenates: 2,5,7,10-Tetraoxaundecane, 2,4,7,9-Tetraoxadecane, and Ethanol/Fatty Acid Methyl Ester Mixtures
Although they are among the most efficient engine types, compression-ignition engines have difficulties achieving acceptable particulate emission and NO formation. Indeed, catalytic after-treatment of diesel exhaust has become common, and current efforts to reformulate diesel fuels have concentrated on the incorporation of oxygenates into the fuel. One of the best ways to characterize changes to a fuel upon the addition of oxygenates is to examine the volatility of the fuel mixture. In this work, we present the volatility, as measured by the advanced distillation curve method, of a prototype diesel fuel with novel diesel fuel oxygenates: 2,5,7,10-tetraoxaundecane (TOU), 2,4,7,9-tetraoxadecane (TOD), and ethanol/fatty acid methyl ester (FAME) mixtures. We present the results for the initial boiling behavior and the distillation curve temperatures and track the oxygenates throughout the distillations. These diesel fuel blends have several interesting thermodynamic properties that have not been seen in our previous oxygenate studies. Ethanol reduces the temperatures observed early in the distillation (near ethanol's boiling temperature). After these early distillation points (once the ethanol has distilled out), B100 has the greatest impact on the remaining distillation curve and shifts the curve to higher temperatures than what is seen for, diesel fuel/ethanol blends. In fact, for the 15% B100 mixture, most of the distillation curve reached temperatures higher than those seen with diesel fuel alone. In addition, blends with TOU and TOD also exhibited uncommon characteristics. These additives are unusual because they distill over most of the distillation curve (up to 70%). The effects of this can be seen both in histograms of oxygenate concentration in the distillate cuts and in the distillation curves. Our purpose for studying these oxygenate blends is consistent with our vision for replacing fit-for-purpose properties with fundamental properties to enable the development of equations of state that can describe the thermodynamic properties of complex mixtures, with specific attention paid to additives.