Axial dispersion with time variable flow in multiphase systems
Article first published online: 17 JUN 2004
Copyright © 1969 American Institute of Chemical Engineers
Volume 15, Issue 5, pages 745–749, September 1969
How to Cite
Gill, W. N. (1969), Axial dispersion with time variable flow in multiphase systems. AIChE J., 15: 745–749. doi: 10.1002/aic.690150521
- Issue published online: 17 JUN 2004
- Article first published online: 17 JUN 2004
- Manuscript Accepted: 22 MAY 1968
- Manuscript Revised: 20 MAY 1968
- Manuscript Received: 24 JAN 1968
A theory has been developed for heat or mass transfer between phases which may have unsteady time dependent velocity fields. The configuration analyzed involves two concentric tubes, but the analysis can be extended to more than two phases, or streams, and to noncylindrical cross sections. For the configuration considered, the dispersion coefficient is found from first principles.
It is noteworthy that the dispersion model given by Equation (15) or (63) and (64), which is consistent with the basic continuum model of Equations (8) and (9), is based on the superficial velocity rather than the interstitial velocity. This strongly suggests that experimental observations on packed beds, or other multiphase systems, should be interpreted on the basis of um, the superficial velocity, rather than the interstitial velocity which has been used often in the past.