A numerical study of bed expansion in supercritical water fluidized bed with a non-spherical particle drag model

2015 ◽  
Vol 104 ◽  
pp. 164-173 ◽  
Author(s):  
Youjun Lu ◽  
Liping Wei ◽  
Jinjia Wei
Keyword(s):  
Spherical Particle ◽  
Fluidized Bed ◽  
Supercritical Water ◽  
Numerical Study ◽  
Drag Model ◽  
Bed Expansion

Two-fluid Modeling of Geldart A Particles in Gas-solid Bubbling Fluidized Bed: Assessment of Drag Models and Solid Viscosity Correlations

2017 ◽  
Vol 16 (3) ◽  
Author(s):  
Tian Tian ◽  
Zhengrui Jia ◽  
Shujun Geng ◽  
Xiaoxing Liu
Keyword(s):  
Fluidized Bed ◽  
Viscosity Model ◽  
Frictional Stress ◽  
Concentration Profiles ◽  
Solid Concentration ◽  
Drag Model ◽  
Bubbling Fluidized Bed ◽  
Drag Models ◽  
Bed Expansion ◽  
Two Fluid

AbstractIn this work the influences of solid viscosity and the way to scale-down traditional drag models on the predicted hydrodynamics of Geldart A particles in a lab-scale gas-solid bubbling fluidized bed are investigated. To evaluate the effects of drag models, the modified Gibilaro et al. drag model (constant correction factor) and the EMMS drag model (non-constant correction factor) are tested. And the influences of solid viscosity are assessed by considering the empirical model proposed by Gidaspow et al. (1997, Turbulence, Viscosity and Numerical Simulation of FCC Particles in CFB. Fluidization and Fluid-particle Systems, AIChE Annual Meeting, Los Angeles, 58–62) and the models based on kinetic theory of granular flow (KTGF) with or without frictional stress. The resulting hydrodynamics by incorporating the different combinations of the drag model and solid viscosity model into two-fluid model (TFM) simulations are compared with the experimental data of Zhu et al. (2008, Detailed Measurements of Flow Structure inside a Dense Gas-Solids Fluidized Bed.”Powder Technological180:339–349). The simulation results show that the predicted hydrodynamics closely depends on the setting of solid viscosity. When solid viscosity is calculated from the empirical model of Gidaspow et al., both drag models can reasonably predict the radial solid concentration profiles and particle velocity profiles. When the KTGF viscosity model without frictional stress is adopted, the EMMS drag model significantly over-estimates the bed expansion, whereas the modified Gibilaro et al. drag model can still give acceptable radial solid concentration profiles but over-estimate particle upwards and downwards velocity. When KTGF viscosity model with frictional stress is chosen, both drag models predict the occurrence of slugging. At this time, the particle velocity profiles predicted by EMMS drag model are still in well agreement with the experimental data, but the bed expansion is under-estimated.

scholarly journals Three-dimensional numerical study on flow dynamics characteristics in supercritical water fluidized bed with consideration of real particle size distribution by computational particle fluid dynamics method

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401877987 ◽  
Author(s):  
Zhenqun Wu ◽  
Hui Jin ◽  
Guobiao Ou ◽  
Liejin Guo ◽  
Changqing Cao
Keyword(s):  
Fluid Dynamics ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Supercritical Water ◽  
Expansion Process ◽  
Fluidization Velocity ◽  
Bed Expansion ◽  
Dynamics Method

Supercritical water fluidized bed is a promising reactor which can realize the efficient and clean gasification of coal to produce hydrogen. As the high pressure and temperature inside supercritical water fluidized bed, the study of the detail flow behaviors needs the help of numerical method. Considering the limitation of the two-fluid method and discrete element method, the computational particle fluid dynamics method was applied to this work. When particle size distribution was taken into consideration, the simulated results showed that the transformation from fixed bed regime to fluidized bed regime is a gradual process. With the increase in superficial fluid velocity, particles in small diameter migrate to the top of the bed and there exits layering phenomenon in the bed. Besides, though the particles are categorized as Geldart B group, the minimum fluidization velocity is not equal to the minimum bubbling fluidization velocity and there is a complicated bed expansion process after incipient fluidization. The bed expansion process is also influenced by the particle size distribution.

Cluster structure-dependent drag model for liquid–solid circulating fluidized bed

2015 ◽  
Vol 26 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Guodong Liu ◽  
Peng Wang ◽  
Fan Yu ◽  
Yanan Zhang ◽  
Wentao Guo ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Cluster Structure ◽  
Drag Model

Numerical study of heat transfer to supercritical water in an inclined tube

2021 ◽  
pp. 1-21
Author(s):  
Siyang Wang ◽  
Yafei Xin ◽  
Tiantian Niu ◽  
Yinlong Li ◽  
Dong Yang
Keyword(s):  
Heat Transfer ◽  
Supercritical Water ◽  
Numerical Study ◽  
Inclined Tube
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