Laminar Flow and Heat Transfer in Stirred Vessel Using CFD

Abstract

Agitated vessel have been widely used for blending and mixing operations in process industries such as soap, oil, cosmetic, paint industries, etc. The mixing and blending operations are usually performed at elevated temperature. Hence, the heat transfer is very important phenomenon in agitated vessels. The laminar flow and heat transfer in an agitated vessel were studied numerically using commercial CFD software ANSYS FLUENT. The study has been performed at Reynolds number (Re=20) and for the Prandtl number (Pr) ranges from 0.71-50. The total six (Pr =0.71, 7, 20, 30, 40, 50) intermediate Prandtl number has been chosen in between 0.71-50. An agitated cylindrical vessel equipped with four blade pitched turbine. The vessel has flat top and bottom surface and all the vessel surfaces are kept at uniform constant wall temperature. The impeller was placed concentrically in the vessel. The segregated solver was used to obtain desired simulation results. After validation of our numerical methodology, the results for steady laminar flow and heat transfer have been presented. The results show that the velocity gradient is more near to the impeller region then near to vessel wall. Furthermore, heat transfer is shows that the temperature in the impeller region is almost constant and the steep temperature gradient near to vessel wall. The heat transfer coefficients are presented in terms of average Nusselt number (Nu). Overall the heat transfer increases with increase in Prandtl number at constant value of Reynolds number and a correlation is proposed to get the intermediate values of Prandtl number.