The effect of bed thickness in rectangular fluidized beds is investigated through the CFD-DEM simula- tions of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses...The effect of bed thickness in rectangular fluidized beds is investigated through the CFD-DEM simula- tions of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and par- ticle kinetic energy. Good two-dimensional （2D） flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional （3D） flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20-40 particle diameters. Comparison of velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.展开更多
The biodegradability of three alkylates （2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane） under less agitated aquifer conditions was investigated in this study. All three alkylates biodegraded co...The biodegradability of three alkylates （2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane） under less agitated aquifer conditions was investigated in this study. All three alkylates biodegraded completely under these conditions regardless of the presence or absence of ethanol or benzene, toluene, ethylbenzene, and xylenes （BTEX） in the feed. In the presence of ethanol, alkylates degradation was not inhibited by ethanol. However, alkylates degraded more slowly in the presence of BTEX suggesting competitive inhibition to microbial utilization of alkylates. In the sterile controls, alkylates concentrations remained unchanged throughout the experiments.展开更多
基金support of the National Energy Technology Laboratory’s ongoing research in advanced numerical simulation of multiphase flow under the RES contract DE-FE0004000
文摘The effect of bed thickness in rectangular fluidized beds is investigated through the CFD-DEM simula- tions of small-scale systems. Numerical results are compared for bubbling fluidized beds of various bed thicknesses with respect to particle packing, bed expansion, bubble behavior, solids velocities, and par- ticle kinetic energy. Good two-dimensional （2D） flow behavior is observed in the bed having a thickness of up to 20 particle diameters. However, a strong three-dimensional （3D） flow behavior is observed in beds with a thickness of 40 particle diameters, indicating the transition from 2D flow to 3D flow within the range of 20-40 particle diameters. Comparison of velocity profiles near the walls and at the center of the bed shows significant impact of the front and back walls on the flow hydrodynamics of pseudo-2D fluidized beds. Hence, for quantitative comparison with experiments in pseudo-2D columns, the effect of walls has to be accounted for in numerical simulations.
基金supported by the U.S. Environmental Protection Agency (Contract No.68-C-00-159)
文摘The biodegradability of three alkylates （2,3-dimethylpentane, 2,4-dimethylpentane and 2,2,4-trimethylpentane） under less agitated aquifer conditions was investigated in this study. All three alkylates biodegraded completely under these conditions regardless of the presence or absence of ethanol or benzene, toluene, ethylbenzene, and xylenes （BTEX） in the feed. In the presence of ethanol, alkylates degradation was not inhibited by ethanol. However, alkylates degraded more slowly in the presence of BTEX suggesting competitive inhibition to microbial utilization of alkylates. In the sterile controls, alkylates concentrations remained unchanged throughout the experiments.
