Effects of Hydrogen or Ammonia Addition on Soot Formation in Laminar HEFA-SAF Diffusion Flames

This study investigates the impact of co-combusting hydrogen (H₂)and ammonia (NH₃)with hydroproc-essed esters and fatty acids (HEFA-SAF) on soot formation in a laminar coflow diffusion flame. The research em-ploys two methods to verify the soot volume fraction distribution:laser-induced incandescence(LII)and CHEM-KIN kinetics simulation. The study also uses helium(He)and argon(Ar)as control groups to isolate the chemical effects of hydrogen on soot formation while maintaining a similar adiabatic flame temperature. The addition of hy-drogen weakened the soot oxidation process, causing the soot formation region to extend downstream of the flame. The addition of ammonia weakened the growth of polycyclic aromatic hydrocarbons(PAH)and the soot nucleation process, causing the soot formation region to move from the two wings to the center along the flame direction. The experimental and numerical simulation results under the ammonia co-combustion condition were close, while the soot formation mechanism under the hydrogen co-combustion condition requires further investigation in the future.