Abstract
In order to enhance the rate of production of catalytic and electrochemical annular reactors used to conduct diffusion controlled reactions the effect of surface roughness on the rate of mass transfer at the inner cylinder of the annulus was studied under swirl flow. The effect of the following parameters on the rate of mass transfer was studied by the electrochemical technique: solution velocity, degree of roughness, physical properties of the solution, height of the inner cylinder and effect of drag reducing polymers. Roughness was made by cutting longitudinal V grooves in the inner cylinder transverse to swirl flow. The mass transfer data at the rough cylinder were correlated by the dimensionless equation: Drag reducing polymers were found to decrease the rate of mass transfer by an amount ranging from 5 to 23%. Importance of the present results for the design and operation of high space-time yield electrochemical reactors and biochemical reactors employing immobilized enzymes was pointed out. Also, the importance of the present results in the design and operation of membrane processes employing annular apparatus with a corrugated membrane was highlighted. By virtue of the analogy between heat and mass transfer the present results can be used to design more efficient double tube heat exchangers.
Highlights
Annular flow reactors are used frequently in industry to conduct liquid-solid diffusion controlled catalytic and electrochemical reactions in view of their advantages which include: (i) Rapid removal of heat generated in case of highly exothermic reactions by passing cold water through the inner side of the inner tube and the cooling jacket surrounding the outer tube
Some work has been done on the mass transfer behavior of smooth annular reactor under swirl flow [78] no studies have been reported on the effect of combined surface roughness and swirl flow on the rate of heat or mass transfer in an annular reactors
The present mass transfer study is important for the rational design and operation of relatively high space-time yield annular reactor suitable for conducting liquid-solid diffusion controlled reactions such as catalytic reactions which include photo catalytic reactions, immobilized enzyme catalyzed biochemical reactions and electrochemical reactions involved in waste water treatment and electro organic synthesis
Summary
Annular flow reactors are used frequently in industry to conduct liquid-solid diffusion controlled catalytic and electrochemical reactions in view of their advantages which include: (i) Rapid removal of heat generated in case of highly exothermic reactions by passing cold water through the inner side of the inner tube and the cooling jacket surrounding the outer tube. (iii) The reactor occupies a low floor space and can be extended vertically saving floor space and capital costs Despite these merits the annular flow reactor suffers from the limited surface area which limits the reactor rate of production. The aim of the present work is to enhance the rate of mass and heat transfer in the annular reactor by the combined swirl flow and surface roughness. The present mass transfer study is important for the rational design and operation of relatively high space-time yield annular reactor suitable for conducting liquid-solid diffusion controlled reactions such as catalytic reactions which include photo catalytic reactions, immobilized enzyme catalyzed biochemical reactions and electrochemical reactions involved in waste water treatment and electro organic synthesis. Drag reducing polymers are used in practice to decrease the pumping power requirement of turbulent flow equipments in view of the ability of polymer molecules to damp the small scale high frequency energy dissipating eddies which prevail in the buffer layer of the hydro dynamic boundary
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