272490 Surrogate Development for Cloud Point and Distillation Curve Modeling of Bio-Derived Fuel Blends
Alternatives to petroleum based fuels are essential for the future transportation industry. For a fuel to be a viable replacement for a petroleum fuel it must meet a number of specifications. This work considers the compatibility of potential biofuels with diesel and jet fuels with a focus on low temperature properties.
Cloud point measurements are presented for additives in two test diesel blends and a jet fuel. Additive functionalities studied include, diesters, esters, ketones, alcohols, ethers, and alkanes. Diesters, as a class, appear to create liquid-liquid immiscibility and a cloud point higher than that of either the base fuel or the pure diester. Esters decrease the cloud point of diesels fuels. Ethers and alkanes respectively decrease the cloud point even more. These results are consistent with the precipitation of the paraffins from the petroleum fuel, rather than the additive, and the decrease in cloud point is due to a dilution effect. For some ketones, a different effect is observed. Based on the pure component melting temperature of the ketone, the compounds cause either decreases or increases. If the melting point temperature of the ketone is too high, the ketone precipitates rather than the paraffin. Long chain ester components were also tested. These additives have higher cetane numbers than other potential fuel components, and are therefore more desirable as a diesel fuel component. The behavior of potential fuel additives seems to be more related to the oxygen containing functional group rather than extent of branching or size of the alkane groups.
Experimental results will be interpreted with thermodynamic models using surrogates. While multiple surrogates can be found in the literature to model properties such as combustion, spray formation, or boiling point curve, these surrogate compositions result in poor predictions of cold flow properties. New surrogates are proposed based on gas chromatography to characterize the paraffin fraction of the test fuels in combination with high performance liquid chromatography to characterize the aromatic fraction.