Liu Yongjian - Academia.edu (original) (raw)
Address: Chengdu, Sichuan, China
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Papers by Liu Yongjian
Powder Technology, 2010
Flow behaviors of particles in a two-dimensional spouted bed with a porous draft plates are studi... more Flow behaviors of particles in a two-dimensional spouted bed with a porous draft plates are studied using a fluid dynamic computation with kinetic-frictional stresses models. Gas flow through the porous draft tube is simulated by Brinkman-Darcy-Forchheimer formulation. The distributions of concentration and velocities of particles are predicted. Simulated results predict the solid circulation rate and gas flux rate measured in the spouted bed with a porous draft tube . The solid circulation rate in the spouted bed with a porous draft tube is larger than that with a non-porous draft tube. The predicted bed pressure drop with the porous draft tube is high in comparison to the spouted bed with non-porous draft tube. The effect of the porosity of the porous draft tube on distributions of gas flux rate through the annulus and solid circulation rate are discussed.
Chemical Engineering Science, 2010
ABSTRACT Flow behavior of gas and particles is simulated in the spouted beds using an Eulerian–Eu... more ABSTRACT Flow behavior of gas and particles is simulated in the spouted beds using an Eulerian–Eulerian two-fluid model on the basis of kinetic theory of granular flow. The kinetic–frictional constitutive model for dense assemblies of solids is incorporated. The kinetic interaction of particle collisions is modeled by means of a second-order moment method, while the frictional stress is from the combination of the normal frictional stress model proposed by Johnson and Jackson (1987) and the frictional shear viscosity model proposed by Schaeffer (1987) to account for strain rate fluctuations and slow relaxation of the assembly to the yield surface. The distributions of concentration, velocity, second-order moments and granular temperature of particles are obtained in the spouted bed. Calculated particle velocities, concentrations and spout diameter in a spouted bed are in agreement with experimental data obtained by [13] and [14]. Simulated results indicate that the second-order moment component in the axial direction is higher that the second-order moment component in the lateral direction in both the spout and the fountain. In the annulus, the values of second-order moments are very small. The simulated mean value of the ratio of the normal second-order moment in the axial direction to the normal second-order moment in the lateral direction is in the range of 2.5–3.2 in the spout and the annulus. The bubblelike normal Reynolds stresses per unit bulk density is predicted from the simulated velocity of particles. The predicted bubblelike Reynolds stresses are very low in spouted bed. The values of the normal second-order moments are on the average three magnitudes in order larger than that of the bubblelike Reynolds stresses per unit bulk density in a spouted bed.
International Journal of Heat and Mass Transfer, 2010
Convective heat transfer between gas and cluster in a circulating fluidized bed (CFB) riser is nu... more Convective heat transfer between gas and cluster in a circulating fluidized bed (CFB) riser is numerically studied using a three-dimensional computational fluid dynamic (CFD) model. Distributions of gas velocity and temperature as well as the gas-cluster heat flux and convective heat transfer coefficient are obtained. Variations of heat flux of each particle in the cluster are predicted. The heat flux of the individual particle inside the cluster is smaller than that of an isolated particle. The convective heat transfer coefficients increase with the increase of cluster porosity and Reynolds number. The convective heat transfer coefficients of the downward moving cluster are larger than that of upward moving cluster. Numerical results of an isolated particle are in agreement with data from previously published correlations.
Increased usage of electrical systems in the automotive sector has provided opportunities for the... more Increased usage of electrical systems in the automotive sector has provided opportunities for the application of powder metallurgy (PM) soft magnetic materials mainly due to the ability to form net or near net shape components. In some instances, the design requires both structural and soft magnetic properties from the component. The standard PM soft magnetic materials can't always achieve these strength targets. This study discusses tactics for achieving higher strengths while maintaining optimum soft magnetic properties.
Powder Technology, 2010
Flow behaviors of particles in a two-dimensional spouted bed with a porous draft plates are studi... more Flow behaviors of particles in a two-dimensional spouted bed with a porous draft plates are studied using a fluid dynamic computation with kinetic-frictional stresses models. Gas flow through the porous draft tube is simulated by Brinkman-Darcy-Forchheimer formulation. The distributions of concentration and velocities of particles are predicted. Simulated results predict the solid circulation rate and gas flux rate measured in the spouted bed with a porous draft tube . The solid circulation rate in the spouted bed with a porous draft tube is larger than that with a non-porous draft tube. The predicted bed pressure drop with the porous draft tube is high in comparison to the spouted bed with non-porous draft tube. The effect of the porosity of the porous draft tube on distributions of gas flux rate through the annulus and solid circulation rate are discussed.
Chemical Engineering Science, 2010
ABSTRACT Flow behavior of gas and particles is simulated in the spouted beds using an Eulerian–Eu... more ABSTRACT Flow behavior of gas and particles is simulated in the spouted beds using an Eulerian–Eulerian two-fluid model on the basis of kinetic theory of granular flow. The kinetic–frictional constitutive model for dense assemblies of solids is incorporated. The kinetic interaction of particle collisions is modeled by means of a second-order moment method, while the frictional stress is from the combination of the normal frictional stress model proposed by Johnson and Jackson (1987) and the frictional shear viscosity model proposed by Schaeffer (1987) to account for strain rate fluctuations and slow relaxation of the assembly to the yield surface. The distributions of concentration, velocity, second-order moments and granular temperature of particles are obtained in the spouted bed. Calculated particle velocities, concentrations and spout diameter in a spouted bed are in agreement with experimental data obtained by [13] and [14]. Simulated results indicate that the second-order moment component in the axial direction is higher that the second-order moment component in the lateral direction in both the spout and the fountain. In the annulus, the values of second-order moments are very small. The simulated mean value of the ratio of the normal second-order moment in the axial direction to the normal second-order moment in the lateral direction is in the range of 2.5–3.2 in the spout and the annulus. The bubblelike normal Reynolds stresses per unit bulk density is predicted from the simulated velocity of particles. The predicted bubblelike Reynolds stresses are very low in spouted bed. The values of the normal second-order moments are on the average three magnitudes in order larger than that of the bubblelike Reynolds stresses per unit bulk density in a spouted bed.
International Journal of Heat and Mass Transfer, 2010
Convective heat transfer between gas and cluster in a circulating fluidized bed (CFB) riser is nu... more Convective heat transfer between gas and cluster in a circulating fluidized bed (CFB) riser is numerically studied using a three-dimensional computational fluid dynamic (CFD) model. Distributions of gas velocity and temperature as well as the gas-cluster heat flux and convective heat transfer coefficient are obtained. Variations of heat flux of each particle in the cluster are predicted. The heat flux of the individual particle inside the cluster is smaller than that of an isolated particle. The convective heat transfer coefficients increase with the increase of cluster porosity and Reynolds number. The convective heat transfer coefficients of the downward moving cluster are larger than that of upward moving cluster. Numerical results of an isolated particle are in agreement with data from previously published correlations.
Increased usage of electrical systems in the automotive sector has provided opportunities for the... more Increased usage of electrical systems in the automotive sector has provided opportunities for the application of powder metallurgy (PM) soft magnetic materials mainly due to the ability to form net or near net shape components. In some instances, the design requires both structural and soft magnetic properties from the component. The standard PM soft magnetic materials can't always achieve these strength targets. This study discusses tactics for achieving higher strengths while maintaining optimum soft magnetic properties.