Laminar mixing performances of a stirred tank equipped with telical ribbon agitator subjected to steady and unsteady rotational speed

摘要

Thie paper investigates the way of improving the mixing of highly visocous Newtonian fluids in a tank using suitable operating conditions (unsteady stirring approaches).The agitator used is a non standard helical ribbon impeller fitted with an anchor at the bottom.The degree of homogeneity inthe tank is followed using a conductivity method after a tracer injection.It is shown that the use of time-dependent rotational speed during the mixing process allows energy saving.For the unsteady stirring approaches tested,energy savings can reach up to 60% compared to the energy required to obtain the same mixing time with constant impeller rotatiobnal speed.Finally,a model is provided which allows the prediction of the mixing process of the agitated system with Newtonian fluids for both steady and unsteady stirring approaches.