Film formation and surface renewal on a rotating spoked disk for polymer devolatilization.

• Film formation was studied using experiments, simulations, and dimensional analyses. • Circulations caused by the competition of gravity and viscous forces were analyzed. • Surface renewal rate of super-high-viscosity liquid decreases with increasing viscosity. • The scraper can limit the film thickness and increase surface renewal rate. The film flow and surface renewal of highly viscous liquid on a rotating spoked disk were investigated experimentally and numerically. In practical applications, the liquid is a polycarbonate melt with very high viscosity and Newtonian behavior at low shear rates. In the experiments, a maltose solution was used. The film thickness on the rotating disk was measured by an electrical conductivity probe. The Volume of Fluid (VOF) model combined with the sliding mesh method was used to simulate the film formation process. The simulated dimensionless film thickness and the film formation process agree well with the experimental results. The film flow and surface renewal under different operation conditions were evaluated. Gravity and viscous forces dominate the process with inertia playing a marginal role. A scraper was designed to intensify transfer processes on the film significantly. [ABSTRACT FROM AUTHOR]