A review of aviation turbine fuel chemical composition-property relations

The fuel certification process is a necessary step for all aviation fuels before deployment. This approval process is composed of multiple fuel physiochemical properties (e.g., density, viscosity, flash point, freezing point, etc.) testing. Measuring fuel properties is a very time consuming and cost-intensive process. Thus, having a tool capable of predicting fuel properties based on a small amount of fuel, utilizing fuel chemical composition, would be of essential value for an increased incentive towards a long-lasting renewable jet fuel production. The first step in achieving this is discovering the detailed chemical composition. The consecutive step is the development of predictive models that correlate the fuel chemical composition to the fuel physiochemical properties. This review provides an overview of correlation techniques and methods (from 1955 to 2019) organized according to four main categories: NMR spectroscopy (alone and in combination with chromatographic techniques), IR spectroscopy (NIR and FTIR), Raman spectroscopy, and gas chromatography (one-dimensional and two-dimensional). These techniques and their predictive capability were compared according to several criteria, specifically: the coefficient of determination (R2) and the measure of the uncertainty of future predictions, which includes standard deviation of residuals, root-mean-square-error (RMSE), root-mean-square-error of prediction (RMSEP), standard error of prediction (SEP), root-mean-square-error of cross-validation (RMSECV), mean absolute error (MAE), and mean absolute percentage error (MAPE). In conclusion, this work summarizes an in-depth review of all the accomplishments as well as the challenges required to be overcome in the field of accurately correlating chemistry to fuel properties.