Low‐temperature properties of triglyceride‐based diesel fuels: Transesterified methyl esters and petroleum middle distillate/ester blends

Abstract

AbstractThis work examines low‐temperature properties of triglyceride‐based alternate fuels for direct‐injection compression‐ignition engines. Methyl esters from transesterified soybean oil were studied as neat fuels and in blends with petroleum middle distillates (No. 1 or No. 2 diesel fuel). Admixed methyl esters composed of 5–30 vol% tallowate methyl esters in soyate methyl esters were also examined. Pour points, cloud points, and kinematic viscosities were measured; viscosities at cooler temperatures were studied to evaluate effects of sustained exposure. Low‐temperature filterability studies were conducted in accordance with two standard methodologies. The North American standard was the low‐temperature flow test (LTFT), and its European equivalent was the cold‐filter plugging point (CFPP). With respect to cold‐flow properties, blending methyl esters with middle distillates is limited to relatively low ester contents before the properties become preclusive. Under most conditions, cold‐flow properties were not greatly affected by admixing the methyl esters with up to 30 vol% tallowate (before blending). Least squares analysis showed that both LTFT and CFPP of formulations containing at least 10 vol% methyl esters are linear functions of cloud point. In addition, statistical analysis of the LTFT data showed a strong 1:1 correlation between LTFT and CP. This result may prove crucial in efforts to improve low‐temperature flow properties of alternate diesel fuels that contain methyl esters derived from triglycerides.