Predicting the surface tension of biodiesel fuels from their fatty acid composition
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The emergence of biodiesel fuels as diesel fuel substitutes has led to several studies on their properties. Surface tension, which plays a role in atomization, has lacked attention compared to other properties. This paper presents a method to predict the surface tension of biodiesel fuels based on the fatty acid composition. Several binary, ternary, and quaternary mixtures of fatty acid ethyl ester gas chromatographic (GC) standards were prepared, and we found that a mass-average equation predicted the surface tension of these mixtures within ±3.5% of their measured values. Six complex mixtures of fatty acid methyl ester GC standards that simulated typical oils used as biodiesel fuels were also prepared. For these complex mixtures the predicted surface tensions of the mixtures, calculated from a mass-average equation, were 2–6% higher than the measured values. A mass-average equation was developed in which we used a weighted surface tension for the individual components, and we found that this method predicted the surface tension of the simulated oils within ±4.5% of their measured values. Five natural vegetable oils were used to produce biodiesel fuels by the transesterification process. The predicted surface tensions of these fuels were all within ±3.5% of their measured values. The surface tensions of 15 biodiesel types were then predicted, based on their fatty acid composition as published in the literature. These results show that the differences in surface tension between biodiesel types are not the main cause of the reported differences in engine tests.
Key wordsBiodiesel fatty acid esters properties surface tension
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- 2.Marshall W.R., Jr., Atomization and Spray Drying, Chemical Engineering Progress Monographs Series No. 2, American Institute of Chemical Engineers, New York, 1954.Google Scholar
- 4.Reid, R.C., J.M. Prausnitz, and B.E. Poling, The Properties of Gases and Liquids, McGraw-Hill, New York, 1987.Google Scholar
- 5.Allen, C.A.W., and K.C. Watts, A Batch Type Transesterification Unit for Biodiesel Fuels, Technical paper 96-404, Canadian Society of Agricultural Engineering, 1996.Google Scholar
- 6.Ackman, R.G., C.A. McLeod, and A.K. Banerjee, An Overview of Analysis by Chromarod-Iatroscan TLC-FID, J. Planar Chromatogr. 3:450–490 (1990).Google Scholar
- 7.Ackman, R.G., Application of Gas-Liquid Chromatography to Lipid Separation and Analysis: Qualitative and Quantitative Analysis, in Analysis of Fats, Oils and Lipoproteins, edited by E.G. Perkins, American Oil Chemists’ Society, Champaign, 1991, pp. 270–300.Google Scholar
- 8.Msipa, C., C. Goering, and T. Karcher, Vegetable Oil Atomization in a DI Diesel Engine, Trans. ASAE 26:1669–1672 (1983).Google Scholar
- 9.Allen, C.A.W., K.C. Watts, and R.G. Ackman, Properties of Methyl Esters of Interesterified Triacylglycerols, in Liquid Fuels and Industrial Products from Renewable Resources. Proceeding of the Third Liquid Fuel Conference, ASAE, St. Joseph, MI, 1996, pp. 73–82.Google Scholar
- 11.Formo, M.W., Physical Properties of Fats and Fatty Acids, in Bailey’s Industrial Oil and Fat Products, edited by D. Swern, John Wiley & Sons, New York, 1979, Vol. 1, pp. 177–186.Google Scholar