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United States Department of Agriculture

Agricultural Research Service


item Dunn, Robert - Bob
item Knothe, Gerhard - Gary

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 9/22/2002
Publication Date: 9/22/2002

Interpretive Summary: Soy biodiesel (methyl soyate) is attractive as an alternative fuel that has shown promise as an extender for aviation fuel applications. During long-term storage, biodiesel readily reacts with oxygen present in ambient air and degrades. This study shows that measurement of the oil stability index (OSI), a standard parameter utilized by the fats and oils industry, is suitable for determining the ability of blends with up to 30 volume percent methyl soyate in jet fuel (JP-8) to resist oxidation degradation. A block temperature of 90 degrees Celsius was recommended for timely determination of OSI under isothermal (constant temperature) conditions. This work is important because it substantially increases knowledge on the fuel characteristics of biodiesel/jet fuel blends. Results on effects of biodiesel on storage stability will directly benefit scientists and engineers seeking to organize aircraft engine performance and emissions testing of biodiesel/jet fuel blends.

Technical Abstract: Biodiesel, an alternative fuel made from transesterification of vegetable oil with methanol, is becoming more readily available for use in blends with conventional diesel fuel for transportation applications. Biodiesel has fuel properties comparable to those of conventional diesel fuel and is known to enhance ignition quality (cetane number) and lubricity characteristics in blends. Biodiesel reduces harmful exhaust emissions including particulate matter, volatile organic compounds, polycyclic aromatic hydrocarbons, carbon monoxide and smoke. Consequently, blending biodiesel with jet fuel for aviation applications may have potential for providing comparable performance while reducing ground level emissions. Given that production of biodiesel in the U. S. grew from 500,000 gal in 1999 to 25 million gal in 2001, storage stability with respect to oxidative degradation will increase in significance as a concern for fuel suppliers and terminal operators. This work investigates effects of soy biodiesel (SME) on the oxidative stability of jet fuel (JP-8). Oil stability index (OSI) data (in h) were measured under isothermal conditions for 10, 20, and 30 vol. percent SME-blends in accordance with the Am. Oil Chem. Soc. standard method Cd 12b-92. For 10 percent blends, OSI = 331.1, 192.0, 100, and 46.3 h with respect to block temperatures = 50, 60, 75, and 90 deg. Celsius. Increasing blend ratio of SME decreased OSI. Finally, a block temperature of 90 deg. Celsius is recommended when measuring OSI as an expeditious means for assessing the relative resistance to oxidation of SME/JP-8 blends.

Last Modified: 06/28/2017
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