Methodologies for the TDH determination
Zenz and Weil (1958) performed experimental analysis using materials collected outside the bed; at the beginning, during and after the experiment, in function of the composition remaining in the bed.
Fournol et al., (1973) characterized the bed by the solid samples taken in the diluted phase and by the measure of the column's pressure.
Baron et al., (1988) measured the elutriation flows using a semi-elliptical cone allowing control of the freeboard´s height.
Geldart (1995) show the TDH value relating bulk density (DP/DH) in function of the height above the distributor (Figure 6), obtained it by the intersection of two straight lines between the dense and the diluted phases.