Effect of composition on freezing points of model hydrocarbon fuels
A study of the effect of composition on the freezing points of model hydrocarbon jet fuel type mixtures was performed. Solutions of higher n-alkanes (C/sub 12/ to C/sub 17/) in several solvents were emphasized. Freezing points (T/sub m/) of solutions of single alkanes were found to conform with the Van't Hoff ideal solubility equation. From the slopes and intercepts of plots of concentration (Ln X) vs 1/T/sub m/, heats (..delta..H/sub m/) and entropies (..delta..S/sub m/) of fusion, and extrapolated freezing points of pure alkanes (T/sub m,o/) were derived T/sub m,o/ values were in good agreement with the literature values for the pure alkanes. For ..delta..H/sub m/ and ..delta..S/sub m/, only the even carbon numbered alkanes exhibited values similar to literature data for the pure compounds. This alternating behavior for the n-alkanes series has been observed for melting point and other properties of the pure compounds. For alkanes in other solvents, considerable solubility effect was noticed. For C/sub 14/ and C/sub 16/, decalin and Isopar-M were found to be relatively good solvents but aromatic compounds, such as butyl benzenes, were relatively poor. For naphthalene, butyl benzene was a better solvent than isopar-M. For mixtures of C/sub 13/ and C/sub 16/ in Isopar-M, significant changes or reversals of slope were observed for 1/T plotted against Ln X (C/sub 13/ concentration) at various C/sub 16/ concentrations, and this suggested interaction between the two alkane solutes. C/sub 16/ had the predominant effect in C/sub 13/ + C/sub 16/ solutions in Isopar-M. Above about 4% C/sub 16/, changes in C/sub 13/ concentration had no observable effect.
- Research Organization:
- Naval Research Lab., Washington, DC
- OSTI ID:
- 6034336
- Report Number(s):
- CONF-810813-(Absts)
- Journal Information:
- Prepr. Pap. - Am. Chem. Soc., Div. Fuel Chem.; (United States), Vol. 26:3; Conference: National American Chemical Society summer meeting, New York, NY, USA, 23 Aug 1981
- Country of Publication:
- United States
- Language:
- English
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