ON AXIAL-DISPERSION IN FIXED-BEDS

The primary purpose of this paper is to show that the criticisms by Tsotsas and Schlunder (1988) of an earlier paper (Gunn, 1969) are based upon elementary mathematical errors on the part of Tsotsas and Schlunder. A summary of experimental data on axial dispersion in liquids and gases shows that the dependence of the axial dispersion coefficient upon the Schmidt group predicted by Tsotsas and Schlunder is not observed despite the large number of empirical factors in their expressions. In particular, the strong dependence of the axial Peclet group upon the Schmidt group for axial dispersion in liquids predicted for Re > 1 is not observed, since the consensus of experimental data is that for this range the dependence of Pe upon Re is slight. The experimental dependence of Pe upon Re for different values of the Schmidt group agrees with the expressions of Gunn (1969).