An improved kinetic model for deposition by thermal oxidation of aviation hydrocarbon fuels

•An improved kinetic model was proposed.•Deposition formation of non-hindered phenols under deoxygenation is studied.•Deposition attributed to sulfides is incorporated in the kinetic model.•Contributions of different deposition pathways are given. The formation of thermal oxidation deposition is a challenging issue for the thermal management technology of advanced aircrafts using onboard aviation hydrocarbon fuel as coolant. In this paper, the effects of dissolved oxygen, polar species (both non-/hindered phenols and organic sulfides) on thermal oxidative deposit of several Chinese aviation hydrocarbon fuels (RP-3) heated from 300 K to 710 K were experimentally studied using electrically heated tube tests under 3 MPa. According to previous studies, the hindered phenols could block thermal oxidation chain reactions and reduced deposition formation, while the non-hindered phenols were important precursors of thermal oxidation deposition. The observed solid deposition in absence of dissolved oxygen revealed that aggregation of polar species like non-hindered phenols was also contributed to the thermal oxidation deposition. Based on the experimental results, an improved kinetic model was proposed by introducing three new pathways forming deposition through hydrocarbon oxidation, sulfur compounds and non-hindered phenols aggregation. Computational fluid dynamics (CFD) simulations of thermal-oxidative deposition formation using the developed kinetic model shows that the simulated results agrees well with experimental data with total deposition. Moreover, the contributions of different deposition formation pathways to deposition amount are studied through CFD simulation results.