Comparison of O2-enriched and N2O oxidizers on dual-flame structure and entropy generation

This study utilizes a triple concentric burner to generate a dual-flame structure and investigates the impact of dual flames on entropy generation under varying fuel-oxidizer velocity ratio (R), ultimately identifying the dominant pathways. The study also examined the substitution of nitrous oxide (N 2 O) with a nitrogen-oxygen (N 2 −O 2 ) mixture to understand the influence of N 2 O decomposition on entropy generation. The research evaluated the irreversibility of chemical reactions in the presence of a dual-flame structure. It was observed that the chemical reaction term in the N 2 O case (R = 3) was approximately twice as intense as in the O 2 -enriched case (R = 5) due to the more vigorous reaction of N 2 O, despite similar energy input. Reactions involving N 2 O, such as those related to the cyanato radical (NCO) and isocyanic acid (HNCO), were slightly more pronounced in the N 2 O case compared to the O 2 -enriched case, even though the R ratio was lower in the N 2 O case. In conclusion, increased entropy generation reduces exergy and decreases second-law efficiency (ηII) from 88.5% to 78.8% in O 2 -enriched cases and from 74.3% to 66.3% in N 2 O cases as R increases. This decrease is more pronounced in dual-flame structures, where η II drops below 80%, primarily due to heat conduction and chemical reactions.