Analysis of flow through packed beds

WJS van der Merwe, CG du Toit, J-H Kruger

North-West University

Energy Postgraduate Conference 2013

Introduction• What is a packed bed?

• How does a packed bed work?

• Applications.– Packed bed nuclear reactors.– Catalytic reactions.– Filtration.

• Design.– Pressure drop.– Heat transfer mechanisms.– Mass transfer mechanisms.

The wall effect• 2-Dimensionally structured packing at the cylinder walls.

10Dd

Prediction of pressure drop• KTA 3102.3 (Nuclear Safety Standards Commission).

• Eisfeld and Schnitzlein (2001).

0.1

320 6

1 1

KTAp p

Re Re

2

(1 )w wES

p w

KA A

Re B 1.624 250D

d

Dd

mRe

Purpose of investigation• Evaluate the applicability of existing correlations which

predict the pressure drop over beds with small D/d ratios.

• Determine the applicability of the KTA limiting curve.

• Explicit approach.

• Star-CCM+.– DEM.– CFD.

Dd

mRe

Discrete Element Modelling• Generated beds in Star-CCM+ using DEM.• Exported particle centre coordinates to create domains for

CFD simulations.

2.5Dd 20D

d

Computational Fluid Dynamics• Mesh independence study.• Contact treatment.• Turbulence solvers.

3Dd

Validation• C.A. Wentz and G. Thados (1963)• Bed with a square structure.

Results

1.6Dd 6.3D

d

Dd

mRe1.6

6.3

Conclusions• Explicit CFD simulation results compared well with

experimental measurements from literature.

• CFD predictions compared well with the Eisfeld and Schnitzlein correlation predictions.

• The KTA limiting curve is valid, but not exact.

• Further investigation is needed to determine a definition and criteria for the KTA limiting curve.

This work is based upon research supported by the South African Research Chairs Initiative of the Department of Science and

Technology and National Research Foundation.

Thank you.