Mass transfer at confining wall of an electrochemical cell with coaxially rotating composite promoter

摘要

Experimental investigations have been carried out on the effect of rotation of a composite promoter -twisted tape mounted on a rod placed coaxially in an electrochemical cell on the liquid-wall mass transfer in homogeneous flow. Limiting current measurements were obtained at point nickel electrodes fixed flush with the inner wall of the electrochemical cell. The promoter rod was housed between two bearings and rotation was carried out using transmission gear mechanism. The swirl was induced by a twisted tape composite promoter element placed concentrically in the cell and the turbulent vortex flow was induced by rotating the promoter element. The present investigation is envisaged to study (ⅰ) the improvements in mass transfer coefficients due to rotation of the composite promoter (ⅱ) the effect of geometrical parameters of rotating composite promoter such as pitch, width of the tape, the diameter of the rod on which the tape was mounted. A dimensionless dynamic parameter, Ψ, defined as the ratio of rotational velocity to the corrected axial velocity, is used as a criterion for segregating the data into appropriate zones. The correlation equations were developed using the j_D-Re format of equation.