In a flowing liquid various flow pattern can be developed due to turbulence generated by the use of (a) insert promoters of various geometry (b) vibration or rotations of the fluid of the transfer surface (c) location of transfer element transfer to the flow (d) impinging jets and fluidizing solids etc, large number of studies have been reported in the literature employing the above techniques.

Several studies have been reported on the use of insert promoters (1). Among them are axially displaced promoters such as coiled wires (2), twisted tapes (3, 4), coaxially placed cones on a rod (CPCR) (5) tape mounted on rod (6), a swirl generators are important. Displaced promoters ranged from cylinders of circular and elliptical cross section (7) and other bodies placed across the flow. These include bluff bodies like disks (8), spheres(9) and streamlined bodies other types of devices which promote turbulence are of swirl generating elements at the entrance region such as twisted tapes, static mixers (10) impellers(11) tangential entry of fluid (12). They alter velocity distribution in the conduits resulting in augmentation of transfer rates.

Investigations on disc promoters offered fairly high mass transfer rates. Similarly orifices placed at the entrance region have raised the coefficient to several folds. However studies on the use of disc promoters along with orifice impinging on to the disc have not found place in the literature. In the view of this presentation an effort is made in the present study to harness the beneficial effect of flow through orifice impinging on the disc to enhance mass transfer rates at the confining wall of the tube.

Studies on mass transfer at the outer wall of electro chemical cell with co-axially placed orifice disc as turbulence promoter were conducted. Redox system of potassium ferricyanide-ferrocyanide with sodium hydroxide as indifferent electrolyte were chosen for the study simultaneous pressure drop measurements were made to know the associated energy loss geometric parameters such as disc diameters dd, orifice diameter do, orifice disc spacing ‘h' were studied. Local mass transfer coefficients were calculated from the measured limiting current data and its variation with distance along the length of the cell were presented. Average mass transfer coefficients were computed from local mass transfer coefficient. Effect of geometric parameters on mass and momentum transfer coefficient were explained. Correlations were presented for mass and momentum transfer. The results were compared with those of similar studies from literature. Mass and momentum transfer coefficients increased with an increase in disc diameter and decrease in orifice – disc spacing. Augmentation achieved in mass transfer coefficient is up to 40 fold over smooth tube.