Structure Design Of The High Thermal Stability Hydrocarbon Fuels

High thermal-stable endothermic fuel is a new concept in the design of hypersonic aircraft fuel systems. It not only has the technical characteristic of the endothermic fuel, but also can inhibit the carbon deposition of the thermal oxidation and thermal cracking in the sharp temperature rise process in the transmission system. High thermal-stable endothermic fuel has been a key technology of designing hypersonic aircraft fuel systems. In this work, several high thermal-stable endothermic fuel were prepared based on the composition- property of jet fuels, and the facility of thermal stability in static condition was developed, which was used to assess the thermal stability .A composition-property database of jet fuel containing 80 samples compositions and their corresponding properties (aniline point, density, freezing point, flashpoint, net heat of combustion) was developed. Jet fuel compositions were determined by GC/MS and grouped into seven hydrocarbon compound classes, including n-paraffins, isoparaffins, cyclopraffins, alkylbenzens, naphthalenes, hydroaromatics. The quantitative composition-property relations incorporating boiling ranges and isoparaffins content of fuels were developed with multiple linear regression (MLR) and back propagation (BP) artificial neural networks. It is interesting to find that it is essential to take the isoparaffins concentrations and boiling ranges into account in the MLR correlations for the improvements of prediction accuracy of some properties. It is indicated that quantitative composition-property relations with BP artificial neural networks is a significant improvement on MLR correlations, and has proven to be effective in the prediction of jet fuel properties with higher reliability.The facility and method of thermal stability, which were used to test the pyrolytic stability in static condition, were developed. The influence of major compound in the pyrolytic stability in the process of the thermal cracking was studied, the change of the composition and the formation of the deposition were also studied. The effect in pyrolytic stability of anti-oxidant 2, 6-di-tert-4-methylphenol, 1, 2, 5-trimethylpyrrole and Dicyclohexyl phenyl phosphine were studied. Using ternary diagram of jet fuel chemical composition- property relation, composition ranges of n-paraffins, isoparaffins, cyclopraffins and aromatics, were established, satisfying the demand of the endothermic hydrocarbon fuels. Static thermal stability test indicated the pyrolytic stability of the defined-range fuels in the ternary diagram were better than that of RP-3, which verifies the reliability of the developed methods. JFTOT was also used to test the oxidative stability of the fuels, their pyrolytic stability was better than that of RP-3. The fuels whose thermal stability was better than that of RP-3 were prepared.