Extent and Impacts of Hydrocarbon Fuel Compositional Variability for Aerospace Propulsion Systems

Review on the Relationship Between Liquid Aerospace Fuel Composition and Their Physicochemical Properties

“…Conventional jet fuels with high concentration of aromatics and cyclo-paraffins normally exhibit a low gravimetric NHOC [2] because of the low H/C ratio caused by the cyclic structure and unsaturated bonds [19]. As shown in Table 1, S-8 with 99.0 wt% saturated paraffins exhibits a higher gravimetric NHOC (44.1 MJ/ kg) than other hydrocarbon fuels containing aromatics.…”

“…Differently, strained hydrocarbon fuels (Table 3) can attain high density and gravimetric NHOC due to the extra strain energy stored in their three-or four-membered rings. The gravimetric NHOC of tricyclo[3.2.1.0 2,4 ]octane (0.94 g/cm 3 , 41.19 MJ/kg) with a three-membered ring is lower than that of tetracyclo[3.3.1.0 2,4 .0 6,8 ]nonane (1.00 g/cm 3 , 43.09 MJ/kg) with two three-membered rings [48], indicating that increasing the number of strained rings leads to increased density and gravimetric NHOC. From Table 3, strained fuels with a strained ring molecular structure and low H/C molar ratio exhibit a high gravimetric NHOC, which is contrast to the result for multi-cyclic hydrocarbon fuel.…”

“…From a long-term and strategic perspective, the fundamental properties of hydrocarbon fuels should be further evaluated and improved to meet severe requirements. The difference in the physicochemical properties of aviation fuels should be attributed to their varied chemical composition [2]. Thus, the relationship between the chemical composition and properties of hydrocarbon fuels must be understood to support the development of new alternative fuels and enhance the properties of current aviation fuels.…”

Decomposition Measurements of RP-1, RP-2, JP-7, n-Dodecane, and Tetrahydroquinoline in Shock Tubes

“…The REFPROP database, which includes a surrogate mixture for the thermophysical properties of RP-1 [39], was employed to provide thermodynamic properties for RP-1. The specific heat capacity determined from the resulting NASA polynomial fits (shown in Table 2) was compared to historical data [34,40] and agreed quite well considering the variable nature of the composition of RP-1 [41,42]. The transition from the low-to the high-temperature polynomial was made at 475 K. It was assumed during data analysis that RP-2 and JP-7 have identical thermodynamic properties to RP-1.…”

“…RP-fuels are clearly more reactive than n-dodecane, and this higher reactivity must be related to the influence of components other than n-alkanes that are found in RP-fuels. References [42,48] indicate that RP-1 actually contains a large fraction of iso-alkanes, and these are known to have faster decomposition rates than n-alkanes [49]. This observation suggests that an RP-fuel surrogate may also need to include a more reactive (i.e.…”