Comprehensive analysis of laminar burning velocity in DEK/NH₃-air premixed flames under varied pressure conditions

3-pentanone (DEK) is a biomass oxygenated fuel with high energy density and low emissions. It shows promising potential in increasing the combustion of NH₃. This study examines the laminar burning velocity (LBV) of a fuel mixture composed of DEK/NH₃-air. The LBV of DEK/NH₃-air was determined with a constant-volume combustion bomb under the following conditions: initial temperature (T) of 448 K, pressure (P) of 1 to 3 atm, equivalence ratio (ϕ) between 0.7 and 1.3, and NH₃ mole fraction (X_NH3) varying from 0 % to 90 %. A combustion kinetic model for DEK/NH₃ mixed fuel was developed and verified using experimental results. Overall, the model can capture the trend of LBV well. Subsequently, a comprehensive kinetic analysis was conducted utilizing this mechanism to elucidate the effect of NH₃ mixing on DEK/NH₃-air mixed fuel. The results indicate that LBV of DEK/NH₃-air mixture declines as X_NH3 increases, primarily attributed to the reduction in radical pool concentration. Conversely, the effect of the decrease in flame temperature is relatively minor. Furthermore, as X_NH3 mole fraction decrease, there is a slight alteration in the consumption pathway of NH₃. The elevation in DEK mole fraction leads to an increased production of radicals, thereby amplifying the oxidation process of NH₃. The proportion of the oxidation of NH_i pathway also increases. Finally, the change of NO content in DEK/NH₃-air flame was observed. The rise in X_NH3 leads to a gradual increase in the content of NO until it reaches a peak, after which it starts to decline. This phenomenon is dependent on the presence of O, OH, and NH_i radicals. In addition, it has been discovered that augmenting ϕ can significantly reduce the concentration of NO in DEK/NH₃-air mixture.