Thermodynamics study of biokerosene from coconut and palm kernel oils and JP-8 aircraft fuels in the gas phase by the DFT method.

In this work, we performed a theoretical density functional theory (DFT) and semi-empirical (PM3) analysis to calculate thermodynamic properties of biokerosene from coconut and palm kernel oils, Jet Propulsion Fuel 8 (JP-8), and mixtures of these fuels. All simulations were performed in thermal equilibrium and for a temperature range of 0.5-1500 K, considering the canonical ensemble model. We predicted the thermal properties energy, enthalpy, enthalpy change, Gibbs free energy, entropy, and specific heat at constant pressure with respect to temperature. In addition, we compared the performances of the DFT functional hybrid B3LYP and the basis set 6-311++G(d,p) and PM3 methods, in order to determine their accuracy for thermodynamic predictions relating to the fuels. Calculations for combustion enthalpy were carried out using the following methods: B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, G4, and G3/G4. The results showed good agreement with measured values, indicating that DFT may be a good method to calculate and predict thermodynamic properties of the combustion reactions of kerosene and biokerosene.