Mohsen Fattahi | University of Kurdistan - Iran (original) (raw)
Supervisors: Seyyed Hossein Hosseini, Goodarz Ahmadi
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University of the Basque Country, Euskal Herriko Unibertsitatea
University of the Basque Country, Euskal Herriko Unibertsitatea
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Papers by Mohsen Fattahi
Brazilian Journal of Chemical Engineering, Oct 1, 2017
In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional s... more In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional spouted beds (2DSB) with and without draft plates were investigated using the Eulerian-Eulerian approach. The main objective of the study was to provide an understanding of effects of the presence of draft plates on the hydrodynamics and heat transfer behavior of solid particles in the spouted beds. To validate the model, the predicted mean particle vertical velocity at the bed axis, the lateral profiles of vertical particle velocity at different bed heights for both systems, and the particle velocity vector fields in the beds were compared with the experimental measurements. A close agreement between the CFD results and the experimental data was found for both systems. The simulation results showed that the particle volume fraction in the spout and fountain regions of the spouted bed with draft plates is considerably lower than that in a conventional spouted bed (without draft plates). Simulation results also showed significant differences between the temperature distributions of gas and solid phases in spouted beds with and without draft plates.
A Eulerian–Eulerian two-fluid model in conjunction with the kinetic theory of granular flows (KTG... more A Eulerian–Eulerian two-fluid model in conjunction with the kinetic theory of granular flows (KTGF) was used
for simulation of a pseudo 2D rectangular spouted bed. The thin thickness of the rectangular spouted bed was
included in the analysis. To save the computational time, symmetry framework was used in all simulations.
Comparisons were made for particle velocity distributions along the bed axis and in the radial direction, as well
as, the time-averaged particle velocity vectors for 2D and 3D modeling. Different values of the specularity and particle–
wall restitution coefficients,which are important parameters of the solid wall boundary condition,were used
in these simulations. The simulation results showed that the 3D computational fluid dynamic (CFD)model ismore
sensitive to the specularity coefficient and the particle–wall restitution coefficient compared to the 2D model.
In addition, the 3D model was more significantly affected by the variation of the specularity coefficient when
compared with changes in the particle–wall restitution coefficient. It was also found that the 3D model gives
more accurate results in comparison with the 2D Cartesian frame for spouted bed with low thickness.
The hydrodynamic and transient gas to particle heat transfer for spouted regime was studied using... more The hydrodynamic and transient gas to particle heat transfer for spouted regime was studied using an Eulerian–Eulerian two-fluid model (TFM) including the kinetic theory of granular flows (KTGF). The influence of different expressions for the radial distribution function (RDF) on the CFD results of the spouted beds was evaluated. Detailed analyses of the CFD results showed that the RDF affects the CFD results especially in dense regions on both particle velocity and temperature distributions. Moreover, the best agreement with the experimental data was obtained by the RDF of Lun and Savage for the region near the wall and by RDF of Ma and Ahmadi, as well as, Arastoopour in the fountain region.
CFD study of transient heat transfer in pseudo 2D bed for spouted & fluidized states. Specularity... more CFD study of transient heat transfer in pseudo 2D bed for spouted & fluidized states. Specularity coefficient affects the voidage and particles temperature in the bed. In spouted state incoherent spouting was occurred by proper specularity coefficient. Highest particle temperatures were discerned in spout and fountain regions. Highest particle temperatures were discerned along the jet in fluidized state. a b s t r a c t The transient gas to particle heat transfer for fluidized and spouted regimes was studied using a Eulerian eEulerian two-fluid model (TFM) in conjunction with the kinetic theory of granular flows (KTGF). The inlet gas temperature was transient which increased with time. Effect of modelling parameter of spec-ularity coefficient on the simulation results was studied. It was found that specularity coefficient is a critical parameter which affects on the particles behaviour and the value of 0.025 leads to creation of incoherent spouting similar to the measurements. The temporal variation of particles concentration and temperature distribution in the spouted and fluidized regimes were compared with the corresponding experimental data for three distinct regions of spout, fountain and annulus. It was shown that the CFD model predicted the particles distribution properly for both regimes. In addition, the CFD predictions for particle temperature distribution for the spouted regime were in a better agreement with the measurements , when compared with that for the fluidized regime.
Brazilian Journal of Chemical Engineering, Oct 1, 2017
In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional s... more In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional spouted beds (2DSB) with and without draft plates were investigated using the Eulerian-Eulerian approach. The main objective of the study was to provide an understanding of effects of the presence of draft plates on the hydrodynamics and heat transfer behavior of solid particles in the spouted beds. To validate the model, the predicted mean particle vertical velocity at the bed axis, the lateral profiles of vertical particle velocity at different bed heights for both systems, and the particle velocity vector fields in the beds were compared with the experimental measurements. A close agreement between the CFD results and the experimental data was found for both systems. The simulation results showed that the particle volume fraction in the spout and fountain regions of the spouted bed with draft plates is considerably lower than that in a conventional spouted bed (without draft plates). Simulation results also showed significant differences between the temperature distributions of gas and solid phases in spouted beds with and without draft plates.
A Eulerian–Eulerian two-fluid model in conjunction with the kinetic theory of granular flows (KTG... more A Eulerian–Eulerian two-fluid model in conjunction with the kinetic theory of granular flows (KTGF) was used
for simulation of a pseudo 2D rectangular spouted bed. The thin thickness of the rectangular spouted bed was
included in the analysis. To save the computational time, symmetry framework was used in all simulations.
Comparisons were made for particle velocity distributions along the bed axis and in the radial direction, as well
as, the time-averaged particle velocity vectors for 2D and 3D modeling. Different values of the specularity and particle–
wall restitution coefficients,which are important parameters of the solid wall boundary condition,were used
in these simulations. The simulation results showed that the 3D computational fluid dynamic (CFD)model ismore
sensitive to the specularity coefficient and the particle–wall restitution coefficient compared to the 2D model.
In addition, the 3D model was more significantly affected by the variation of the specularity coefficient when
compared with changes in the particle–wall restitution coefficient. It was also found that the 3D model gives
more accurate results in comparison with the 2D Cartesian frame for spouted bed with low thickness.
The hydrodynamic and transient gas to particle heat transfer for spouted regime was studied using... more The hydrodynamic and transient gas to particle heat transfer for spouted regime was studied using an Eulerian–Eulerian two-fluid model (TFM) including the kinetic theory of granular flows (KTGF). The influence of different expressions for the radial distribution function (RDF) on the CFD results of the spouted beds was evaluated. Detailed analyses of the CFD results showed that the RDF affects the CFD results especially in dense regions on both particle velocity and temperature distributions. Moreover, the best agreement with the experimental data was obtained by the RDF of Lun and Savage for the region near the wall and by RDF of Ma and Ahmadi, as well as, Arastoopour in the fountain region.
CFD study of transient heat transfer in pseudo 2D bed for spouted & fluidized states. Specularity... more CFD study of transient heat transfer in pseudo 2D bed for spouted & fluidized states. Specularity coefficient affects the voidage and particles temperature in the bed. In spouted state incoherent spouting was occurred by proper specularity coefficient. Highest particle temperatures were discerned in spout and fountain regions. Highest particle temperatures were discerned along the jet in fluidized state. a b s t r a c t The transient gas to particle heat transfer for fluidized and spouted regimes was studied using a Eulerian eEulerian two-fluid model (TFM) in conjunction with the kinetic theory of granular flows (KTGF). The inlet gas temperature was transient which increased with time. Effect of modelling parameter of spec-ularity coefficient on the simulation results was studied. It was found that specularity coefficient is a critical parameter which affects on the particles behaviour and the value of 0.025 leads to creation of incoherent spouting similar to the measurements. The temporal variation of particles concentration and temperature distribution in the spouted and fluidized regimes were compared with the corresponding experimental data for three distinct regions of spout, fountain and annulus. It was shown that the CFD model predicted the particles distribution properly for both regimes. In addition, the CFD predictions for particle temperature distribution for the spouted regime were in a better agreement with the measurements , when compared with that for the fluidized regime.