Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 29, 1998
Publication Date: N/A
Interpretive Summary: The relatively poor low-temperature flow properties of methyl soyate and other lipid-derived biodiesel fuels preclude their widespread commercialization during cooler weather in moderate temperature climates. This manuscript examines the utility of differential scanning calorimetry (DSC) as an analytical technique for measuirng cold flow properties of biodiesel formulations. Results showed that the standard test parameters for predicting operability of diesel engines and fuel systems in the field may be accurately and quickly measured by DSC. This work establishes DSC as a useful technique for measuring biodiesel fuel quality during cooler weather. This work also provides a foundation for subsequent studies on the formation of solid crystals as well as their growth rate in solution. This fundamental information reported in this work will benefit scientists and engineers in the development of additive compounds to improve the cold flow properties of biodiesel and biodiesel/distillate (petrodiesel) blends.
Technical Abstract: The relatively poor cold flow properties of mono-alkyl esters of vegetable oils and animal fats (biodiesel) present a major obstacle to their development as alternative fuels and extenders for combustion in direct injection compression-ignition (diesel) engines. In this work, differential scanning calorimetry (DSC) heating and cooling curves of methyl tallowate, methyl soyate, admixtures of methyl soyate and methyl tallowate and winterized methyl soyate were analyzed. Completion of melt (COM), crystallization onset (Onset) and other temperatures corresponding to melting and freezing peaks were correlated to predict cloud point (CP), pour point (PP), cold filter plugging point (CFPP) and low-temperature flow test (LTFT) data. Effects of treating methyl esters with cold flow improvers were examined. Results showed that low-temperature flow properties of biodiesel may be accurately inferred from sub-ambient DSC analyses of high melting or freezing (beta-form) peaks. The temperature o maximum heat flow for freezing peaks (P2) gave the best accuracy for predicting CP, PP and CFPP while freezing point (FP) gave the best accuracy for predicting LTFT. Onset also gave good correlations with respect to predicting PP, CFPP and LTFT. In general, cooling curve parameters were more reliable than heating curve parameters.