EFFECT OF SURFACE-ROUGHNESS INDUCED BY WOVEN METALLIC SCREENS WRAPPEDON THE INNER SURFACE OF AN ANNULUS ON THE RATE OF TURBULENT-FLOW MASS-TRANSFER

Rates of mass transfer were measured at the inner surface of an annulu s wrapped with a woven metallic screen under developing flow condition s using an electrochemical technique which involved measuring the limi ting current of the cathodic reduction of potassium ferricyanide. Vari ables studied were screen characteristics, solution velocity, and phys ical properties of the solution. Mass-transfer rates based on the proj ected area of the annulus were found to increase by a factor ranging f rom 1.2 to 3 depending mainly on Re. The degree of mass-transfer enhan cement was found to decrease with an increase in Re. Rates of mass tra nsfer based on the true active area of the annulus and the screen were found to be smaller than the values at the smooth surface, the higher the Re the higher being the percentage decrease in the rate of mass t ransfer compared to the values at the smooth annulus. Practical implic ations of the present work in the design and operation of catalytic an d electrochemical reactors used to conduct diffusion-controlled reacti ons have been highlighted.