Kinetic Modeling of Thermal Oxidation and Coking Deposition in Aviation Fuel

Aviation fuel is also employed as a coolant in advanced aircraft engines, and the associated formation of deposits in heat exchange systems involves a complex combination of physical processes and chemical reactions. On the basis of our previous experimental results, a pseudodetailed chemical kinetic and global deposition mechanism of the aviation kerosene RP-3 under supercritical pressure was developed. This mechanism involves three bulk reactions and three wall deposition reactions and considers temperature gradients, oxygen consumption, and flow regimes. The fluid–thermal–solid interactions in a tube were simulated in conjunction with the above mechanism, and experimental results obtained at various levels of dissolved oxygen were used to validate the simulation. It was found that this model is able to accurately predict the total amounts of deposition and oxygen consumption, as well as the deposit profile along the tube. The effects of air saturation and of low levels of dissolved oxygen on coking deposition were compared, and a decrease in the dissolved oxygen concentration was shown to effectively reduce coke deposition. The contribution of the temperature gradient was assessed on the basis of predictions of local coking deposition, and the rates of wall reactions were determined to be far slower than those of bulk reactions.