Mass transfer in circular conduit with coaxially placed twisted tape–disc assembly as turbulence promoter

• Tape-disc assembly was used as internal for mass transfer enhancement.
• Correlations developed give the information for electrolytic cell design.
• By optimization one can achieve reduction in size of an electrolytic cell.
• The results could be used to predict heat transfer by analogy.

Studies on the effect of coaxially placed entry region twisted tape-disc assembly as turbulence promoter on mass transfer rates in forced convection flow of electrolyte were conducted. The study comprised of evaluation of mass transfer rates at the outer wall of the electrochemical cell. Mass transfer coefficients were evaluated from the measured limiting currents. The study covered a wide range of geometric parameters such as pitch of the tape (TP), length of the tape (TL), width of the tape (TW), diameter of the disc (Dd) and tape-disc distance (h). The results revealed that the mass transfer coefficient increased with increase in velocity, diameter of the disc (Dd), length of the tape (TL), width of the tape (TW) and decreased with increase in pitch of the tape (TP) and tape-disc distance(h). Within the range of variables covered, the augmentation achieved in mass transfer coefficients were up to 5 fold over the tube flow in absence of promoter. Mass transfer rates were analyzed with roughness mass transfer function and roughness Reynolds number. The following correlation was reported out of the study.g(h+) = 343.95 (Re+)−0.176 (ϕ1)0.244 (ϕ2)−0.001 (ϕ3)−0.033 (ϕ4)0.402 (ϕ5)0.016 Sc−0.345