Hydrodynamic simulation of fluidization by using a modified kinetic theory

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	Hydrodynamic simulation of fluidization by using a modified kinetic theory
	Wang, W; Li, YC
刊名	INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
	2001-11-14
卷号	40 期号:23 页码:5066-5073
关键词	discrete particle simulation granular flow bed riser bubble
ISSN号	0888-5885
其他题名	Ind. Eng. Chem. Res.
中文摘要	For a pseudofluid consisting of a particle assembly, particle stress is transmitted through mutual contact between particles. When the particles are densely agglomerated, contacts are usually of long duration and frictional, and this part of the stress is the frictional stress. When the particles are sparsely spaced, on the other hand, contacts are temporary and collisional, and this part of the stress consists of kinetic and collisional stresses. In many cases the particle contact lies between these two extremes in a gas-solid fluidized bed, and all of these three parts of the stress-kinetic, collisional, and frictional stresses-play important roles in particle-phase transport. However, the existing kinetic theory for granular flow (KTGF) only involves the kinetic and collisional parts of transport. In this paper, a frictional particle pressure was introduced for correction of KTGF in the case of highly dense flow, and the solid shear stress was corrected to be consistent with Einstein's effective viscosity equation for dilute suspensions. This modified KTGF model may account for the stress over the entire range between two extremes of a densely packed state and a sparsely spaced state. As verification in the dense gas-solid flow, the time-averaged total pressure drop and the particle pressure predicted by this modified KTGF model were found to be in agreement with the measurements in a cylindrical fluidized bed. The inflection point on the particle pressure curve, implying competition among the three transport mechanisms, was also predicted. Moreover, instantaneous formation of slugs starting from a homogeneous inflow condition was reproduced through simulation and the quantitative comparison of the slug velocity with empirical correlation was approving. For dilute gas-solid flow in a circulating fluidized-bed riser, the model predictions agree with the time-averaged solid viscosity in order of magnitude. Further modeling may require a better understanding of the drag force and turbulence.
英文摘要	For a pseudofluid consisting of a particle assembly, particle stress is transmitted through mutual contact between particles. When the particles are densely agglomerated, contacts are usually of long duration and frictional, and this part of the stress is the frictional stress. When the particles are sparsely spaced, on the other hand, contacts are temporary and collisional, and this part of the stress consists of kinetic and collisional stresses. In many cases the particle contact lies between these two extremes in a gas-solid fluidized bed, and all of these three parts of the stress-kinetic, collisional, and frictional stresses-play important roles in particle-phase transport. However, the existing kinetic theory for granular flow (KTGF) only involves the kinetic and collisional parts of transport. In this paper, a frictional particle pressure was introduced for correction of KTGF in the case of highly dense flow, and the solid shear stress was corrected to be consistent with Einstein's effective viscosity equation for dilute suspensions. This modified KTGF model may account for the stress over the entire range between two extremes of a densely packed state and a sparsely spaced state. As verification in the dense gas-solid flow, the time-averaged total pressure drop and the particle pressure predicted by this modified KTGF model were found to be in agreement with the measurements in a cylindrical fluidized bed. The inflection point on the particle pressure curve, implying competition among the three transport mechanisms, was also predicted. Moreover, instantaneous formation of slugs starting from a homogeneous inflow condition was reproduced through simulation and the quantitative comparison of the slug velocity with empirical correlation was approving. For dilute gas-solid flow in a circulating fluidized-bed riser, the model predictions agree with the time-averaged solid viscosity in order of magnitude. Further modeling may require a better understanding of the drag force and turbulence.
WOS标题词	Science & Technology ; Technology
类目[WOS]	Engineering, Chemical
研究领域[WOS]	Engineering
关键词[WOS]	DISCRETE PARTICLE SIMULATION ; GRANULAR FLOW ; BED ; RISER ; BUBBLE
收录类别	ISTP ; SCI
原文出处	://WOS:000172079200005
语种	英语
WOS记录号	WOS:000172079200005
公开日期	2013-11-14
内容类型	期刊论文
版本	出版稿
源URL	[http://ir.ipe.ac.cn/handle/122111/5749]
专题	过程工程研究所_研究所（批量导入）
作者单位	Chinese Acad Sci, Inst Chem Met, Beijing 100080, Peoples R China
推荐引用方式 GB/T 7714	Wang, W,Li, YC. Hydrodynamic simulation of fluidization by using a modified kinetic theory[J]. INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH,2001,40(23):5066-5073.
APA	Wang, W,&Li, YC.(2001).Hydrodynamic simulation of fluidization by using a modified kinetic theory.INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH,40(23),5066-5073.
MLA	Wang, W,et al."Hydrodynamic simulation of fluidization by using a modified kinetic theory".INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 40.23(2001):5066-5073.