## 4 LBV of SAFs
### LBV of Synthetic Fuels  
Synthetic fuels are categorized as natural gas-to-liquid (GTL) or coal-to-liquid (CTL) fuels based on their feedstock. Although both use the Fischer-Tropsch process, variations in preparation equipment and procedures result in significant compositional variations among GTL fuels [53]. Consequently, LBV disparities are observed in GTL fuels obtained from different sources. GTL fuels primarily include Syntroleum S-8 fuel, Shell GTL, and other sources of GTL fuels. [PERSON] et al. determined the LBV of traditional fuels (JP-7 and JP-8) and alternative fuels (synthetic fuel S-8, Shell-GTL, and bio-jet fuel R-8, derived from animal/vegetable oil) using the stagnation flame method, finding no significant difference between measured GTL fuel and bio-jet fuel LBV [54]. In contrast, traditional fuels exhibited smaller LBV values due to higher concentrations of cycloalkanes and aromatics. [PERSON] et al. studied Syntroleum S-8 using the stagnation flame method and compared its LBV at temperatures of 400, 450, and 470 K with Jet A and pure alkanes (n-decane, n-dodecane) [5]. Their results indicated similar combustion characteristics between alternative and traditional fuels. This contrasts with the conclusion of [PERSON] et al., possibly due to the different traditional aviation fuels used in the two studies [54]. [PERSON] et al. measured various fundamental combustion characteristics, including LBV, of three Fischer-Tropsch produced synthetic fuels and three bio-jet fuels [33]. LBV measurements of alternative fuels were conducted using the stagnation flame method at 400 K and 470 K, with no significant differences from Jet A found. Additionally, there is substantial work on LBV testing, mechanistic studies, and simulation calculations concerning synthetic fuels and their surrogate fuels. [PERSON] et al. conducted LBV measurements using the Bunsen burner method for GTL fuel and a blend with 20% hexanol [19]. Within the measured range of 423-473 K, the experimental results are similar to the simulation results of their proposed surrogate fuels (composed of n-decane, iso octane, and 1-hexanol), which involve 3479 reactions and 490 species. Subsequently, [PERSON] et al. extended similar studies to GTL with 20% 1-hexanol or 50% naphthalene [35], validating against models proposed by [PERSON] et al. [55; 56] and demonstrating the practical potential of surrogate fuels. [PERSON] et al. measured the LBV of Syntroleum S-8 using the spherical flame method and a surrogate fuel mixture of 32% iso-octane, 25% n-decane, and 43% n-dodecane, extending the study from 0.5 atm to 4.3 atm pressure and a 490 K-to-620 K temperature range, showing high consistency with simulations using [PERSON]'s chemical kinetics mechanisms in a one-dimensional steady premixed flame code from CANTERA. Z [57]. [PERSON] et al. extended the study to diluted conditions of the same fuel, obtainingsimilar results using the same simulation method [58]. [PERSON] et al. investigated the LBV of liquefied petroleum gas with a composition of 60% butane, 20% isobutane, and 20% propane, finding that adding CH\({}_{4}\), H\({}_{2}\), or O\({}_{2}\) increases LBV, whereas CO\({}_{2}\)/O\({}_{2}\) mixtures decrease it [59]. [PERSON] et al. studied the LBV of S-8 fuel with a surrogate fuel composition of 32% iso-octane, 25% n-decane, and 43% n-dodecane, finding higher agreement with a one-dimensional steady premixed flame code from CANTERA using [PERSON]'s chemical kinetics mechanisms compared to their proposed detailed kinetics model (DKM) [60]. [PERSON] et al. investigated two synthetic jet fuels (Syntroleum S-8 and Shell GTL) and resolved the difficulty in accurately measuring gas-phase fuel equivalence ratios using an in situ laser absorption technique [53]. Both fuels exhibited an LBV\(\_\)max of 60 cm/s under conditions of 403 K and 1 atm pressure.