Combustion characteristics change induced by n-decane catalytic reactions and its effects on the coupled combustion occurrence

Abstract

Flame in homogeneous-heterogeneous coupled combustion can be promoted or restrained, which results from that the upstream catalytic reaction changes the fuel characteristics and gas composition. The fuel gas after n-decane/air catalytic combustion (FGDC) were investigated by experiments and chemical kinetics analysis (τig and SL). Two criteria, t/τig and SL/v, were defined. When coupled combustion occurs, FGDC meets the following limitation: t/τig ≥ αth and SL/v ≥ βth. In view of composition change, catalytic pretreatment slightly increases τig, while greatly reduces SL. τig and SL are mainly affected by the decrease of O2 and C10H22 concentration. H2O significantly shorten τig only at high equivalence ratio. CO2 reduces SL and slightly shortens τig simultaneously. The improvement of ignition performance by adding H2 is mainly reflected in the improvement of SL. The oxidation, dehydrogenation and cracking reactions of large molecules/radicals (C10H22/C10H21) have a greater impact on τig, while SL is mainly affected by the small molecules (C2H3/CH3/HCO). Reaction path and sensitivity analysis found that τig is mainly affected by OH, while H/O/OH have the significant effect on SL. The sensitivity coefficients show that the chain termination reactions generating methane are the main elementary reactions that hinder ignition and combustion. SL presents a linear relationship with (CO + CH + COH)max: SL = 97.1*(CO + CH + COH)max + 0.32.