A study of particle-field hydrodynamics and mass transfer in a stirred vessel

A study has been made of transport-controlled mass transfer to particles suspended in a stirred vessel. As the character of the turbulence in a stirred vessel is of fundamental importance to mass transfer processes, special emphasis in this work was placed on the dynamics of both particle and fluid flow. Expressions for the relative velocity between particle and liquid in a turbulent fluid have been presented. This relative or slip velocity, which has important use in equations to describe mass transfer, can only be determined if the intensity and scale of the turbulence is known. Accordingly, mean and fluctuating components of fluid velocity in a 10" diameter stirred tank were measured by streak photography of neutrally-buoyant naphthalene tracer spheres. Lagrangian correlation coefficients and scales of turbulence were also determined by recording the velocity-time history of the tracer particles. The Lagrangian integral length scales varied over the range 0.60-1.46 cm, and were comparable with, but greater than, the corresponding Eulerian scales under similar agitation conditions