ABSTRACT
Mass transfer from a fluid in laminar flow to the surface of a submerged rotating disc was analyzed by von Karman and given by Levich: 10
k1,s = 1.55 D~667(µwfpw)-0167(w/r)oso (17.1) where kLs is the submerged external mass transfer coefficient, r is the radius of the disc, Dw is the diffusivity of the substrate in water, Pw is the fluid density, µw is the fluid viscosity, and w is the rotational speed of the rotating disc. Equation 17.1 indicates that the external mass transfer coefficient will increase with the square root of the rotational speed. In practice, however, both the proportionality constant and the power on the rotational speed may be different due to deviations from the assumptions made in deriving the equation. Nevertheless, it is possible to obtain correlations of the form:
(17.2) where e and f are coefficients with e depending on the physical properties of the fluid and radius of the disc.
