TY - JOUR
T1 - Measuring hydrodynamic dispersion coefficients in unsaturated packed beds
T2 - comparison of PEPT with conventional tracer tests
AU - Ilankoon, I. M.S.K.
AU - Cole, K. E.
AU - Neethling, S. J.
N1 - Funding Information:
The authors gratefully acknowledge Rio Tinto for their financial support of this project. M. van Heerden and C. Liu are recognised for their support in fabricating PEPT tracers during test work at iThemba Laboratories.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2013/2/5
Y1 - 2013/2/5
N2 - Hydrodynamic dispersion has a major impact on mass transport within packed bed and porous media systems. In this paper, dispersion coefficients of neutrally buoyant tracer particles located with positron emission particle tracking (PEPT) are compared to results obtained using a conventional salt tracer experiment. It is demonstrated that the axial dispersion coefficients obtained from PEPT are very similar to those obtained using the salt tracer. The PEPT method has the advantage that the details of the flow behaviour can be observed, thus allowing analysis of the mechanisms at work to be carried out. In addition, the radial dispersion coefficient was obtained with PEPT, which is hard to obtain using conventional salt tracer tests. The main drawback with the PEPT method is that very low flow rates could not be studied as these result in very low saturations, which causes the tracer particle to become stuck. In this work the tracer particles used are 400μm in diameter, though as the tracer fabrication technology improves, the size of tracer available will continue to decrease, allowing a wider range of conditions and particle beds to be studied.
AB - Hydrodynamic dispersion has a major impact on mass transport within packed bed and porous media systems. In this paper, dispersion coefficients of neutrally buoyant tracer particles located with positron emission particle tracking (PEPT) are compared to results obtained using a conventional salt tracer experiment. It is demonstrated that the axial dispersion coefficients obtained from PEPT are very similar to those obtained using the salt tracer. The PEPT method has the advantage that the details of the flow behaviour can be observed, thus allowing analysis of the mechanisms at work to be carried out. In addition, the radial dispersion coefficient was obtained with PEPT, which is hard to obtain using conventional salt tracer tests. The main drawback with the PEPT method is that very low flow rates could not be studied as these result in very low saturations, which causes the tracer particle to become stuck. In this work the tracer particles used are 400μm in diameter, though as the tracer fabrication technology improves, the size of tracer available will continue to decrease, allowing a wider range of conditions and particle beds to be studied.
KW - Axial dispersion
KW - Hydrodynamics
KW - Packed bed
KW - Positron emission particle tracking (PEPT)
KW - Radial dispersion
KW - Residence time distribution
UR - http://www.scopus.com/inward/record.url?scp=84871761948&partnerID=8YFLogxK
U2 - 10.1016/j.ces.2012.11.013
DO - 10.1016/j.ces.2012.11.013
M3 - Article
AN - SCOPUS:84871761948
VL - 89
SP - 152
EP - 157
JO - Chemical Engineering Science
JF - Chemical Engineering Science
SN - 0009-2509
ER -