Long-term thermal oxidative deposition of RP-3 jet fuels: Mechanism and modeling

[Display omitted] •The deposition rate change can be divided into the initial, growth and decline stage.•Active metal surface will catalyze and accelerate the formation of deposition.•Deposition rate increase is due to the additional contact area by porous deposits.•High wall temperature accelerates the aging process of deposits.•The decrease of residence time plays an important role in deposition rate decline. The long-term thermal oxidative deposition of jet fuel is of great significance for the design and applications of the fuel-cooled thermal management of advanced aircrafts. In this paper, the long-term (100 h) thermal oxidative deposition of RP-3 jet fuel was carried out in the electric heating tube to understand the complex time-dependent deposition phenomena and behaviors. It was found that there are three typical deposition rates stages in 100 h time-on-stream (TOS) experiment, i.e., the initial stage, the growth stage, and the decline stage. In the initial stage (0–2 h), the average deposition rate continuously decreases by almost 5 times from 8.70 mg/h at 0 h to 1.73 mg/h at 2 h ascribed to the gradual coverage of metal surface by the deposition, and then grows by 4.37 times from 1.73 mg/h at 2 h up to 7.56 mg/h at 70 h attributed to the increased wall surface area from 0.01074 m2 to 0.02483 m2 by the solid deposit in growth stage. However, in the decline stage the average deposition rate slightly decreases to 7.08 mg/h at 100 h as a result of the reduction of local residence time as well as the possible aging of deposition layer. A simplified kinetic model of long-term thermal oxidative deposition process was proposed to describe the complex deposition rate variation and validated that the error between the prediction of total deposition amount and the experimental data is less than 10%.