Natural convection mass transfer correlation of the electropolishing of horizontal cylinders with active ends.

To contribute to quantifying the process of electropolishing, the rates of electropolishing of a horizontal cylinder with active ends were studied under natural convection by measuring the limiting current of the anodic dissolution of copper cylinders in H₃PO₄. Cylinder diameters and H₃PO₄ concentrations were changed to provide a wide range of Sc⋅Gr (Schmidt and Grashof numbers). The data for a horizontal cylinder with active ends for the conditions 8.3 × 10 4 < Sc < 3.6 × 10 5 , 6.5 × 10⁸ < Sc⋅Gr > 1.6 × 10 11 were correlated by the equation S h = 0.049 (S c. G r) 0.3 . For hollow horizontal cylinders (pipes) the outer surface data fit the equation S h = 0.8 (S c. G r) 0.28 . Comparison of the equations obtained for a horizontal cylinder with the equations obtained by previous studies on vertical cylinders with active ends revealed that the orientation of the workpiece plays an important role in determining the rate of electropolishing. [ABSTRACT FROM AUTHOR]