Oxidation stability of jet fuel model molecules evaluated by rapid small scale oxidation tests.

Jet fuel, besides its fuel role, can be used as a c oolant for aircraft subsystems and thus it may be exposed to temperatures above 200 °C. Between 140 and 300 °C, an autoxidation phenomenon occurs due to the presence of 70 ppm of dissolved d ioxygen in jet fuel resulting in the formation of oxidized products and solid deposits. The aim of this work is to study the behavior of je t fuel model molecules in order to highlight their oxidation sensitivity and the solid products formed. A rapid small scale oxidation test (RSSOT) is used. Within the RSSOT’s test chamber, 5 mL of fuel is combined with oxygen, at 700 kPa, and heated up to 150 °C. This initiates a fast oxidation process. As the fuel oxidizes, it consumes the dioxygen resulting in a pressure drop that is recorded. Different tests are carried out and stopped at various values of time. Gaseous and liquid samples are recovered and analyzed by gas chromatography. In the case of n-dodecane, its consumption is obser ved up to a pressure drop of 64 %. At the same time, oxidized products are formed among which are alcohols, ketones and carboxylic acids. The gas analysis shows that all the dioxygen has been consumed. Oxydation reactions stop and new reactions appear. They are aldehyde decarbonylations and condensation reactions. Heavy products like esters and lactones are formed.