0
Research Papers: Multiphase Flows

Pressure Drop Predictions in Microfibrous Materials Using Computational Fluid Dynamics

[+] Author and Article Information
Ravi K. Duggirala1

Aerospace Engineering Department, Auburn University, 211 Aerospace Engineering Building, Auburn, AL 36849-5338duggirk@vt.edu

Christopher J. Roy

Aerospace Engineering Department, Auburn University, 211 Aerospace Engineering Building, Auburn, AL 36849-5338

S. M. Saeidi, Jay M. Khodadadi

Mechanical Engineering Department, Auburn University, Auburn, AL 36849

Don R. Cahela, Bruce J. Tatarchuk

Chemical Engineering Department, Center for Microfibrous Materials Manufacturing, Auburn University, Auburn, AL 36849

1

Corresponding author.

J. Fluids Eng 130(7), 071302 (Jun 25, 2008) (13 pages) doi:10.1115/1.2948363 History: Received March 16, 2007; Revised April 09, 2008; Published June 25, 2008

Three-dimensional computational fluid dynamics simulations are performed for the flow of air through microfibrous materials for void fractions of 0.41 and 0.47 and face velocities ranging between 0.04ms and 1.29ms. The microfibrous materials consist of activated carbon powder with diameters of 137×106m entrapped in a matrix of cylindrical fibers with diameters of 8×106m. These sintered microfibrous materials are a new class of patented materials with properties that are advantageous compared to traditional packed beds or monoliths. Microfibrous materials have demonstrated enhanced heat and mass transfer compared to packed beds of particles of similar dimensions. In this paper, the simulations are used to predict the pressure drop per unit length through the materials and to analyze the details of the flow that are difficult to interrogate experimentally. Various geometric approximations are employed in order to allow the simulations to be performed in an efficient manner. The Knudsen number, defined as the ratio of the mean free path between molecular collisions to the fiber diameter, is 0.011; thus, velocity-slip boundary conditions are employed and shown to have only a minor effect on the pressure drop predictions. Significant effort is made to estimate numerical errors associated with the discretization process, and these errors are shown to be negligible (less than 3%). The computational predictions for pressure drop are compared to available experimental data as well as to two theory-based correlations: Ergun’s equation and the porous media permeability equation. The agreement between the simulations and the experiments is within 30% and is reasonable considering the significant geometric approximations employed. The errors in the simulations and correlations with respect to experimental data exhibit the same trend with face velocity for both void fractions. This consistent trend suggests the presence of experimental bias errors that correlate with the face velocity. The simulations generally underpredict the experimental pressure drop for the low void fraction case and overpredict the experimental pressure drop for the high void fraction case.

FIGURES IN THIS ARTICLE
<>
Copyright © 2008 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

SEM of sintered composite material of (55–58)×10−6m ACP with 2×10−6m, 4×10−4m, and 8×10−6m Ni fibers

Grahic Jump Location
Figure 2

Pressure drop through 8×10−6m Ni/ACP mesh (experimental data from Ref. 21)

Grahic Jump Location
Figure 3

(a) Isometric view of the simplified geometry; (b) front view of the simplified geometry

Grahic Jump Location
Figure 4

(a) Triangular mesh on the fiber and particle walls; (b) triangular mesh on the top symmetry face with a structured boundary layer mesh around the particles and the fibers

Grahic Jump Location
Figure 5

Illustration of test case geometry for Poiseuille flow

Grahic Jump Location
Figure 6

Comparison of velocity profiles for Poiseuille flow at three Knudsen numbers

Grahic Jump Location
Figure 7

Iterative convergence as determined by residual reduction (left axis) and estimated error in the pressure drop (right axis)

Grahic Jump Location
Figure 8

(a) Velocity magnitude contours; (b) pressure contours Z=4.28×10−5m; ε=0.41; V0=0.04m∕s

Grahic Jump Location
Figure 9

(a) Velocity magnitude contours; (b) pressure contours Z=4.28×10−5m; ε=0.41; V0=0.59m∕s

Grahic Jump Location
Figure 10

(a) Velocity magnitude contours; (b) pressure contours Z=4.445×10−5m; ε=0.47; V0=0.04m∕s

Grahic Jump Location
Figure 11

(a) Velocity magnitude contours; (b) pressure contours Z=4.445×10−5m; ε=0.47; V0=1.29m∕s

Grahic Jump Location
Figure 12

Comparison of the pressure drop from CFD simulations and empirical correlations with experimental data from Ref. 21

Grahic Jump Location
Figure 13

Error in predicting pressure drop with respect to experiments (21); void fraction=0.41

Grahic Jump Location
Figure 14

Error in predicting pressure drop with respect to experiments (21); void fraction=0.47

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In