• Title/Summary/Keyword: 과농-희박

Search Result 12, Processing Time 0.017 seconds

The Characteristics of the Flame Propagation Velocity and Volume Integral of Reaction Rate with the Variation of Nozzle Diameter and Fuel Injection Flow Rate for a Liftoff Flame (부상화염에서 노즐직경과 연료유량에 따른 화염전파속도와 체적연소반응속도의 변화 특성에 관한 연구)

  • Ha, Ji-Soo;Kim, Tae-Kwon
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.34 no.2
    • /
    • pp.250-258
    • /
    • 2010
  • A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.

Studies on the Deactivation-resistant Ru Catalyst (Ru 촉매의 비활성화 억제를 위한 연구)

  • Kim, Young-Kil;Yie, Jae-Eui;Cho, Sung-June;Ryoo, Ryong
    • Applied Chemistry for Engineering
    • /
    • v.5 no.5
    • /
    • pp.808-818
    • /
    • 1994
  • Effects of ceria additive on the activity and thermal aging behavior of supported Ru catalysts were investigated using Ru/${\gamma}$-$Al_2O_3$and Ru/$CeO_2$-${\gamma}$-$Al_2O_3$. The catalysts were characterized by $^{129}Xe$-NMR and $H_2$ chemisorption. The cataltic activity for conversion of CO, HC and $NO_x$ was measured using simulated automobile engine exhausts under lean, rich and stoichiometric conditions. For both fresh and aged catalysts, Ru/$CeO_2$-${\gamma}$-$Al_2O_3$ was more active than Ru/${\gamma}$-$Al_2O_3$ for all three pollutants. Results of $^{129}Xe$-NMR and $H_2$ chemisorption indicated that sintering of Ru particles occurred to the same extent for both catalysts during the thermal aging process. After thermal aging at 673K, however, the catalytic activity of the aged Ru/$CeO_2$-${\gamma}$-$Al_2O_3$ was substantially higher than that of the fresh one, while the activity of Ru/${\gamma}$-$Al_2O_3$ decreased after the thermal aging. This finding may suggest new active sites were created during the thermal aging, probably in the vicinity of the interface between Ru and Ce. For more quantitative investigation of the effect of a cation such as Ce on the thermal aging of Ru metal particles, Ru catalysts supported on cation-exchanged Y-zeolites were used as the model catalysts. The results indicated that when Ba, Ca, La, Y or Ce was used for the cation exchange, the exchanged cation did not affect the thermal aging behavior of Ru in Y-zeolite, as evidenced by $^{129}Xe$-NMR and EXAFS.

  • PDF