Experimental Study on the Evaporation Characteristics of Multicomponent Fuels under High Pressure

To investigate the evaporation characteristics of Sustainable Aviation Fuel (SAF) and its blends with conventional kerosene, this study presents an experimental investigation of the single droplet evaporation behavior of conventional aviation kerosene RP-3, a SAF, and two blended fuels, BF6 and BF7, with different proportions, under a pressure range of 0.1–0.6 MPa and a temperature range of 353–553 K. It was found that at atmospheric pressure and low temperature (353 K), the evaporation process of the multicomponent fuels deviates from the classical D2-law, exhibiting multi-stage characteristics; under these conditions, the volatility of the light components in the fuel predominantly governs the initial evaporation rate. At atmospheric pressure and high temperature (553 K), the evaporation process becomes more stable, conforming well to the D2-law in the later stages; the evaporation rate is significantly influenced by the least volatile heavy components and aromatic content, with an observed negative correlation between aromatic content and evaporation rate under these conditions. The effect of high pressure on the evaporation rate of multicomponent fuels is complex, demonstrating a dual effect that is dependent on both temperature and fuel composition. Under high-temperature conditions (553 K), the evaporation rates of all tested fuels monotonically increase with an increase in ambient pressure. However, under low-temperature conditions (353 K), the influence of pressure on the evaporation rate exhibits a non-monotonic trend: for fuels A2 and BF6, which have relatively higher aromatic content or lower initial boiling points, the evaporation rate initially decreases and then increases as pressure rises; conversely, for fuels B2 and BF7, characterized by lower aromatic content or higher initial boiling points, the evaporation rate first increases and then decreases. This complex response behavior is attributed to the combined effects of pressure on parameters such as the gas diffusion coefficient, droplet surface temperature, and the surface mass fraction of fuel vapor, as well as inherent differences in the fuel’s unique physicochemical properties, including saturation vapor pressure characteristics, average molecular weight, and distillation range distribution. This research reveals the intricate modulating mechanisms of pressure, temperature, and fuel composition on the droplet evaporation characteristics of multicomponent aviation fuels, providing crucial experimental data and scientific insights for the development, optimization, and application of SAF, and the establishment of high-fidelity evaporation models.