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ABSTRACT
In this paper, an attempt has been made to develop a 3-D simulation model for biomass gasification of pine sawdust in a fluidized bed reactor (FBR), solved using ANSYS Fluent v14. The predictions have been compared to the experimental data available in the literature, which proves that the model is well capable of studying the heat transfer and hydrodynamics of FBRs. Further, the effects of superficial gas velocity ratio (u/umf), bed porosity, static bed height, and particle diameter on pressure drop, and bed expansion ratio (H/HO), solid volume fraction, and gas–solid temperature with respect to bed height have been investigated.
Nomenclature
| di | = | diameter (m) |
| es,s | = | restitution coefficient |
| g0,ss | = | radial distribution coefficient |
| g | = | acceleration due to gravity (m/s2) |
| H | = | expanded bed height (m) |
| HO | = | static bed height (m) |
| I | = | unit tensor |
| I2D | = | second invariant of the deviatoric stress tensor (s−2) |
| Kgs | = | gas–solid momentum exchange coefficient |
| Ksg | = | solid–gas momentum exchange coefficient |
| KΘs | = | diffusion coefficient for granular energy (kg/m.s) |
| p | = | pressure (Pa) |
| Δp | = | pressure drop (Pa) |
| Re | = | Reynolds number |
| t | = | time (s) |
| u | = | superficial gas velocity (m/s) |
| v | = | velocity (m/s) |
| z | = | height from the distributor (m) |
| Subscripts | = | |
| g | = | gas |
| i | = | general index |
| mf | = | minimum fluidization |
| s | = | solids |
| t | = | terminal (e.g., ut is the terminal velocity) |
| T | = | stress tensor |
| ε | = | volume fraction |
| Θ | = | granular temperature (m2/s2) |
| μ | = | shear viscosity (Pa.s) |
| ξ | = | bulk viscosity (Pa.s) |
| ρ | = | density (kg/m3) |
| ϕ | = | angle of internal friction (o) |
| ϕgs | = | fluctuating energy exchange between solid and gas phases |
| γΘs | = | dissipation of fluctuating energy |
| ψ | = | stitching function |
| = | stress tensor (Pa) |
Nomenclature
| di | = | diameter (m) |
| es,s | = | restitution coefficient |
| g0,ss | = | radial distribution coefficient |
| g | = | acceleration due to gravity (m/s2) |
| H | = | expanded bed height (m) |
| HO | = | static bed height (m) |
| I | = | unit tensor |
| I2D | = | second invariant of the deviatoric stress tensor (s−2) |
| Kgs | = | gas–solid momentum exchange coefficient |
| Ksg | = | solid–gas momentum exchange coefficient |
| KΘs | = | diffusion coefficient for granular energy (kg/m.s) |
| p | = | pressure (Pa) |
| Δp | = | pressure drop (Pa) |
| Re | = | Reynolds number |
| t | = | time (s) |
| u | = | superficial gas velocity (m/s) |
| v | = | velocity (m/s) |
| z | = | height from the distributor (m) |
| Subscripts | = | |
| g | = | gas |
| i | = | general index |
| mf | = | minimum fluidization |
| s | = | solids |
| t | = | terminal (e.g., ut is the terminal velocity) |
| T | = | stress tensor |
| ε | = | volume fraction |
| Θ | = | granular temperature (m2/s2) |
| μ | = | shear viscosity (Pa.s) |
| ξ | = | bulk viscosity (Pa.s) |
| ρ | = | density (kg/m3) |
| ϕ | = | angle of internal friction (o) |
| ϕgs | = | fluctuating energy exchange between solid and gas phases |
| γΘs | = | dissipation of fluctuating energy |
| ψ | = | stitching function |
| = | stress tensor (Pa) |