CFD analysis of flow pattern in the agitated thin film evaporator

Agitated thin film evaporator (ATFE) is widely used in chemical, pharmaceuticals and food industries to concentrate the feed solutions. The flow pattern in ATFE has been analyzed using ANSYS-CFX 10.0 software. The flow phenomenon is simulated using free surface multiphase model considering two continuous phases, water and water vapour. The geometry is created in ANSYS-ICEM-10 with 110,300 tetrahedral nodes. The k–ɛ and Reynolds stress homogeneous turbulence models are used with appropriate boundary conditions. The occurrence of bow wave and its variation with respect to flow rate is studied. A thin film of thickness equal to the clearance between blade tip and inner wall is found to adhere to the inner wall. The bow wave is found to travel helically along the inner wall of the evaporator. The shear rate and kinetic energy dissipation is found to be significant at the clearance between blade and inner wall. These values are 10–50 times more than that observed in rest of the volume.

► CFD of two continuous and incompressible phases. ► Studied flow pattern in agitated thin film evaporator. ► Studied bow wave and thin film formation on the inner wall.