Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Investigation of the Pressure Drop Across Packed Beds of Spherical Beads
T2 - Comparison of Empirical Models With Pore-Level Computational Fluid Dynamics Simulations
AU - Otaru, A.J.
AU - Kennedy, A.R.
PY - 2019/4/8
Y1 - 2019/4/8
N2 - This study uses novel methods, combining discrete element method (DEM) simulations for packing and computational fluid dynamics (CFD) modeling of fluid flow, to simulate the pressure drop across rigid, randomly packed beds of spheres ranging from 1 to 3 mm in diameter, with porosities between 0.34 and 0.45. This modeling approach enables the combined effect of void fraction and particle size to be studied in more depth than that has been previously possible and is used to give insight into the ability of the well-established Ergun equation to predict the pressure drop behavior. The resulting predictions for pressure drop as a function of superficial velocity were processed to yield coefficients α and β in the Ergun equation and were found to be in keeping with equivalent data in the literature. Although the scatter in α with structural variations was very small, the scatter in β was large (±20%), leading to inaccuracies when used to predict pressure drop data at velocities beyond the Darcy regime. Evaluation of the packed particle structures showed that regions of poor packing, in samples with high porosity and large particle sizes, lead to lower β values. The findings bring strong support to the belief that a generalized model, such as that by Ergun, cannot yield a unique value for β, even for identical spheres.
AB - This study uses novel methods, combining discrete element method (DEM) simulations for packing and computational fluid dynamics (CFD) modeling of fluid flow, to simulate the pressure drop across rigid, randomly packed beds of spheres ranging from 1 to 3 mm in diameter, with porosities between 0.34 and 0.45. This modeling approach enables the combined effect of void fraction and particle size to be studied in more depth than that has been previously possible and is used to give insight into the ability of the well-established Ergun equation to predict the pressure drop behavior. The resulting predictions for pressure drop as a function of superficial velocity were processed to yield coefficients α and β in the Ergun equation and were found to be in keeping with equivalent data in the literature. Although the scatter in α with structural variations was very small, the scatter in β was large (±20%), leading to inaccuracies when used to predict pressure drop data at velocities beyond the Darcy regime. Evaluation of the packed particle structures showed that regions of poor packing, in samples with high porosity and large particle sizes, lead to lower β values. The findings bring strong support to the belief that a generalized model, such as that by Ergun, cannot yield a unique value for β, even for identical spheres.
KW - computational fluid dynamics
KW - permeability
KW - porous media
KW - Drops
KW - Finite difference method
KW - Forecasting
KW - Mechanical permeability
KW - Packed beds
KW - Particle size
KW - Porosity
KW - Porous materials
KW - Pressure drop
KW - Spheres
KW - Two phase flow
KW - Void fraction
KW - Computational fluid dynamics modeling
KW - Computational fluid dynamics simulations
KW - Generalized models
KW - Large particle sizes
KW - Particle structure
KW - Randomly packed beds
KW - Structural variations
KW - Superficial velocity
KW - Computational fluid dynamics
U2 - 10.1115/1.4042957
DO - 10.1115/1.4042957
M3 - Journal article
VL - 141
JO - Journal of Fluids Engineering
JF - Journal of Fluids Engineering
SN - 0098-2202
IS - 7
M1 - 071305
ER -