caa a22 4500 463163192 CHVBK 20180406164754.0 cr unu---uuuuu 170326e20070101xx s 000 0 eng 10.1007/s11242-006-9014-2 doi (NATIONALLICENCE)springer-10.1007/s11242-006-9014-2 Periodic Fluctuations of Flow and Porosity in Spouted Beds [Elektronische Daten] [Roman Szafran, Andrzej Kmiec] The results of experimental investigations of bed flow hydrodynamics in spouted beds are compared with CFD simulations (Eulerian-Eulerian approach) for two different column geometries. The experimental results of bed porosity and fluctuation frequency of mass flow rate of grain in the fountain region are compared with the corresponding results of simulations. The simulation results confirmed the observations of Muir et al. (1990, Chem. Eng. Comm. 88: 153-171) and Yang and Keairns (1978, AlchE Symp. Ser. No. 176 74: 218) that fluctuations of bed flow in DTSB are caused by particle cluster formation in the loading region at the bottom of column. The solids cross into the jet and cover the column inlet and are carried upward periodically through a draft tube. Subsequent figures obtained from simulations, which show stages of particle cluster formation at the entrance of column, exactly match visual observations. The frequency of fluctuations of grain mass flow rate predicted in simulations (~5-6Hz) is in the range of that experimentally determined. The fluctuating inflow of solids results in slug formation and explains the vertical variations of height and porosity of the fountain. Springer Science+Business Media B.V., 2006 Porosity fluctuations nationallicence Spouted beds nationallicence CFD nationallicence Computational fluid dynamics nationallicence Drying nationallicence C D : Drag coefficient nationallicence d s : Particle diameter (m) nationallicence g : Gravity acceleration (m/s2) nationallicence h bed : Initial height of bed (m) nationallicence $$\mathop{I}\limits^{=}$$ : Identity tensor nationallicence K ip, K is, K ps, K sp : Interphase exchange coefficients (kg/m3s) nationallicence $$\dot{m}_{ji}$$ : Phase exchange term (kg/m3s) nationallicence P : Pressure (Pa) nationallicence P s : Solids pressure (Pa) nationallicence Re : Reynolds number nationallicence t : Time (s) nationallicence $$\vec{v}$$ : Velocity (m/s) nationallicence Greek letters nationallicence λ : Bulk viscosity (Pas) nationallicence η : Total fluid viscosity (Pas) nationallicence ρ : Physical density (kg/m3) nationallicence μ : Shear viscosity (Pas) nationallicence $$\mathop{\tau}\limits^{=}$$ : Stress tensor (Pa) nationallicence ω : Volume fraction nationallicence Subscripts nationallicence i,j : Different phases nationallicence p : Fluid phase nationallicence ps : Between fluid and solid phase nationallicence s : Granular phase nationallicence Szafran Roman Department of Chemical Engineering W3/Z7, Wroclaw University of Technology, ul. Norwida 4/6, 50-373, Wroclaw, Poland aut Kmiec Andrzej Department of Chemical Engineering W3/Z7, Wroclaw University of Technology, ul. Norwida 4/6, 50-373, Wroclaw, Poland aut Transport in Porous Media Kluwer Academic Publishers 66/1-2(2007-01-01), 187-200 0169-3913 66:1-2<187 2007 66 11242 https://doi.org/10.1007/s11242-006-9014-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11242-006-9014-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Szafran Roman Department of Chemical Engineering W3/Z7, Wroclaw University of Technology, ul. Norwida 4/6, 50-373, Wroclaw, Poland aut NATIONALLICENCE 700 1- Kmiec Andrzej Department of Chemical Engineering W3/Z7, Wroclaw University of Technology, ul. Norwida 4/6, 50-373, Wroclaw, Poland aut NATIONALLICENCE 773 0- Transport in Porous Media Kluwer Academic Publishers 66/1-2(2007-01-01), 187-200 0169-3913 66:1-2<187 2007 66 11242 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer