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

Abstract

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 (XNH3) 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 XNH3 increases, primarily attributed to the reduction in radical pool concentration. Conversely, the effect of the decrease in flame temperature is relatively minor. Furthermore, as XNH3 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 NHi pathway also increases. Finally, the change of NO content in DEK/NH3-air flame was observed. The rise in XNH3 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 NHi radicals. In addition, it has been discovered that augmenting ϕ can significantly reduce the concentration of NO in DEK/NH3-air mixture.