Fundmental Study On Preparation Of High Thermal Stability Endothermal Hydrocarbon Fuel

Heat management of an aircraft is a crucial technique in the development of the hypersonic propellant system. Endothermal hydrocarbon fuels (EHF) is a basic solution on this problem. EHF not only are the necessary propellant for the hypersonic flight, but also can remove heat through physics heat sink and chemical cracking reaction which also yields lower molecular compounds with better ignition performance. High thermal-stable endothermal hydrocarbon fuel has both advantages of EHF and excellent thermal stability depressing the formation of deposition. It is a new conception and a key technique in developing hypersonic propellant aircraft.The relationships of composition-properties of 80 jet fuel samples concerning chemical compositions and several physical properties including density, flash point, freezing point, heat value and boiling range were studied. The chemical compositions of the jet fuel samples were determined by GC/MS, and grouped into five categories of hydrocarbon compounds, including n-paraffins, isoparaffins, cyclo paraffins, hydroaromatic and decalin. Physical properties of fuels were measured by the GB methods. Based on the Cookson's models, 8 new models considering chemical compositions and boiling range were developed to gain the model parameters by multiple linear regressions. Property prediction with the Cookson's and new models, showed that the developed models is significant improvements on the correlations reported in the literaturesBased on ternary diagram of jet fuel chemical composition- property relations and the basic physical property, the composition ranges of n-paraffins, isoparaffins, cyclopraffins and aromatics were established. Five fuels chosen from defined-ranges and RP-3 were evaluated from thermal cracking experiment under supercritical conditions to study the relationships of compositions and thermal stability. The solid deposits, mass fraction of gas products and deposition precursor of JF-1, JF-2 and JF-3 are less than RP-3, showing better thermal stability, while that of JF-4 and JF-5 were more than RP-3, displaying worse thermal stability. Based on the chemical composition of JF-1, JF-2 , JF-3, JF-4 and JF-5,it is concluded the increase of n-paraffins and isoparaffins content is favorable for the thermal stability improvement, but the contrary trend were observed for the cycloparaffins.