Thermal cracking and coke deposition characteristics of aviation kerosene RP-3 in an S-bend tube

In this work, an experimental study on the supercritical aviation kerosene RP-3 flowing inside an S-bend tube was conducted to examine the effect of the curved structure and mass flow rate on the thermal cracking and coke deposition behaviours. The results indicated that the conversion and gas yield in the S-bend tube were slightly higher than those in a straight tube. In particular, the maximum conversion in the S-bend tube was 70.1% at 700 degrees C, whereas that in the straight tube was 60.8%. This condition was attributed to the existence of hightemperature fuel in the near-wall region; this fuel was further pushed toward the core flow field under the effect of secondary flow and Dean vortices. In addition, secondary flow strengthened the fuel-mixing effect and increased the local resistance. A considerable peak in the coke deposition rate was observed in the first curved region of the S-bend tube. Moreover, the decreased mass flow rate had a promoting effect on thermal cracking and coke deposition, owing to the high fuel bulk temperature and coke precursor concentration.

Automated summary

This study experimentally demonstrated that the conversion and gas yield in an S-bend tube were slightly higher than those in a straight tube. The maximum conversion in the S-bend tube reached 70.1% at 700 degrees C. This was attributed to the presence of high-temperature fuel near the wall, which was pushed towards the core flow field by secondary flow and Dean vortices. Additionally, a significant peak in the coke deposition rate was observed in the first curved region of the S-bend tube. Furthermore, a decreased mass flow rate promoted thermal cracking and coke deposition due to the high fuel bulk temperature and coke precursor concentration.