Second, an important confirmation relates to how close isthe effect of such compartment boundaries formed of tubeswhen compared to that of a solid wall. Fig. 7 shows the radialgas holdup inside the tube bundle (diamonds and bottomabscissa) compared to that generated in case of an 18columnwith no tubes inserted (squares and top abscissa).Obviously, at r/R = 0.9 inside the tube bundle (which isequivalent to r/R = ∼0.3 in case of an empty 18column), thegas holdup is 0.216 compared to 0.325 at the same locus shouldthe tube bundle not exist. This represents a decrease of about50% due to the presence of internals at this position. Thisfinding confirms that the impact of the PVC rods in sucharrangement is similar to that of a solid wall diminishing thegas holdup in the vicinity of the wall. This effect on the flowstructure is different than that created in the presence of ahomogeneously distributed tube bundle.In the next section, the comparison between the solid wallcolumn and that formed by the tubes bundle (this work) isdescribed