采用亚格子湍动能方程,结合大涡模拟方法(Large eddy simulation,LES)模拟提升管气相湍流流动,颗粒矩(Second Order Moments,SOM)模型模拟提升管内颗粒湍流流动,建立大涡模拟颗粒矩(LES-SOM)双流体模型。数值模拟提升管内气固两相流动...采用亚格子湍动能方程,结合大涡模拟方法(Large eddy simulation,LES)模拟提升管气相湍流流动,颗粒矩(Second Order Moments,SOM)模型模拟提升管内颗粒湍流流动,建立大涡模拟颗粒矩(LES-SOM)双流体模型。数值模拟提升管内气固两相流动与燃烧反应过程,得到了提升管内颗粒浓度和速度以及不同气体组分的空间分布规律。分析了Smagorinsky亚格子应力模型对颗粒相浓度和速度的影响,以及对煤颗粒在提升管内燃烧特性的影响。数值模拟颗粒浓度和速度分布与他人实验结果相吻合。展开更多
Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier t...Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier transform infrared spectroscopy （FT-IR） and X-ray powder diffraction （XRD） techniques. And at same time, the catalytic activity of the obtained Cu-ZSM-5 in the trichloroethylene （TCE） combustion with air in the fixed-bed system was also investigated in the present work. The results indicated that the copper content in Cu-ZSM-5 was increased with the increasing Cu2＋ concentration in ion-exchange solution, and however the catalytic activity was not always increased with the copper content in Cu-ZSM-5. It was found that Cu-ZSM-5, prepared with 0.091mol/L of Cu^2＋ solution, exhibited the best catalytic activity in TCE combustion. In combination with the characterization results by DRS-UV-vis and FT-IR techniques, it was deduced that the catalytic active species of Cu-ZSM-5 in TCE combustion with air was the skeletal copper of molecular sieves.展开更多
Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and fractions.Recent experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the ...Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and fractions.Recent experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the gaseous one was considered before.To resolve this drawback,we study the effects of different product phases on the detonation parameters with the hybrid combustion model proposed recently.Numerical results demonstrate that the assumption of gaseous product induces high velocity and pressure,while the assumption of solid product induces low velocity and pressure.To clarify how close-to-experiment results have been obtained with one phase assumption,we revisit previous studies and analyze the models.The inconsistency between the product phase and heat release is found,and then one model with variable heat release dependent on the product phase is proposed.Then simulations with both the gaseous and solid products are carried out,and results reveal the necessity of establishing a relationship between the heat release and reaction products.展开更多
文摘采用亚格子湍动能方程,结合大涡模拟方法(Large eddy simulation,LES)模拟提升管气相湍流流动,颗粒矩(Second Order Moments,SOM)模型模拟提升管内颗粒湍流流动,建立大涡模拟颗粒矩(LES-SOM)双流体模型。数值模拟提升管内气固两相流动与燃烧反应过程,得到了提升管内颗粒浓度和速度以及不同气体组分的空间分布规律。分析了Smagorinsky亚格子应力模型对颗粒相浓度和速度的影响,以及对煤颗粒在提升管内燃烧特性的影响。数值模拟颗粒浓度和速度分布与他人实验结果相吻合。
文摘Cu-ZSM-5 molecular sieves were prepared by the ion-exchange of NH4-ZSM-5 with Cu^2＋ ions in Cu（NO3）2 solution, and was characterized by diffuse reflectance ultraviolet-visible spectroscopy （DRS-UV-vis）, fourier transform infrared spectroscopy （FT-IR） and X-ray powder diffraction （XRD） techniques. And at same time, the catalytic activity of the obtained Cu-ZSM-5 in the trichloroethylene （TCE） combustion with air in the fixed-bed system was also investigated in the present work. The results indicated that the copper content in Cu-ZSM-5 was increased with the increasing Cu2＋ concentration in ion-exchange solution, and however the catalytic activity was not always increased with the copper content in Cu-ZSM-5. It was found that Cu-ZSM-5, prepared with 0.091mol/L of Cu^2＋ solution, exhibited the best catalytic activity in TCE combustion. In combination with the characterization results by DRS-UV-vis and FT-IR techniques, it was deduced that the catalytic active species of Cu-ZSM-5 in TCE combustion with air was the skeletal copper of molecular sieves.
基金supported by the National Natural Science Foundation ofChina(Grant No.90916028)
文摘Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and fractions.Recent experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the gaseous one was considered before.To resolve this drawback,we study the effects of different product phases on the detonation parameters with the hybrid combustion model proposed recently.Numerical results demonstrate that the assumption of gaseous product induces high velocity and pressure,while the assumption of solid product induces low velocity and pressure.To clarify how close-to-experiment results have been obtained with one phase assumption,we revisit previous studies and analyze the models.The inconsistency between the product phase and heat release is found,and then one model with variable heat release dependent on the product phase is proposed.Then simulations with both the gaseous and solid products are carried out,and results reveal the necessity of establishing a relationship between the heat release and reaction products.
