Mass and heat transfer at an array of horizontal cylinders placed at the bottom of a square agitated vessel

• Mass transfer at an array of cylinders resting on the base of an agitated vessel was studied.
• The (kA) at the cylinders was found to be > flat bottom by a factor of 4.24–9.33.
• The mass transfer data were correlated by dimensionless mass transfer equations.
• Importance of the study in the design of stirred tank with a cooling system was discussed.
• The possibility of using the outer tube surface as a catalyst support was discussed.

Rates of liquid–solid mass transfer at horizontal array of cylinders resting on the base of a square agitated vessel were studied. An electrochemical technique which involves measuring the limiting current of the cathodic reduction of K3Fe(CN)6 in a large excess of NaOH supporting electrolyte was used. The mass transfer data were correlated by dimensionless mass transfer equations. Drag reducing polymers were found to reduce the rate of mass transfer at the tube array by an amount ranging from 2.4 to 21.8% depending on the operating conditions. The volumetric mass transfer coefficient (kA) at the tube array was found to be higher than that of the flat tank bottom cathode by a factor ranging from 4.24 to 9.33. The importance of the present study in the design and operation of stirred square tank reactor with a cooling system at the bottom was noted. Also the importance of the present results in designing semi-continuous tubular dialyzers was highlighted. The possibility of using the outer tube surface as a catalyst support and the inner surface as a cooler for conducting diffusion controlled reactions which need critical temperature control such as immobilized enzyme catalyzed biochemical reactions was discussed.

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