Investigation of the criteria for construction of reliable surrogate fuels: A case study of Jet-A aviation kerosene

Abstract

Surrogate fuels are usually constructed by optimizing component selection and component proportions to match the physicochemical indexes of practical fuels. The interaction among the selected components and the influence of the weight factors of the physicochemical indexes on the combustion characteristics of the surrogate fuel have not been well investigated in previous research. In this paper, a systematical method is proposed to construct the Jet-A aviation kerosene surrogate fuel by combining the principle of the selection of the surrogate components and the genetic algorithm, in which the weight factors of the physicochemical indexes are introduced. First, 900 cases including nine groups of surrogate component schemes and 100 groups of weight factor schemes are generated using the Sobol function. Then, optimization is carried out using the genetic algorithm for the 900 surrogate fuels with the candidate component proportions as the input variables and the selected physicochemical properties as the optimization targets. Subsequently, the results of all the surrogate fuels concerning component proportions, physicochemical properties, and combustion characteristics are further analyzed, especially for the prediction performance of the surrogate fuels under different schemes on the combustion characteristics of ignition delay times, laminar flame speeds, and O₂/CO/CO₂ concentrations. It is found that proper weight factors can enhance the prediction performance of the surrogate fuels, especially for the surrogate fuels with fewer surrogate components. However, the optimal limit of the surrogate fuel performance is determined once the surrogate components are confirmed. Through the comprehensive orthogonal analysis and sensitivity analysis on the results of the surrogate fuels, the criteria of surrogate fuel construction for Jet-A are further present: the surrogate fuels do not need to keep the same component proportions as that in the practical fuel. To ensure the reliability of the surrogate fuels, the relative weight factor of the derived cetane number should be enhanced by at least 15 %, while that of the aromatics fraction should be larger than 10 %.