Numerical investigation of mixing and heat transfer of granular material in a ribbon reactor: effect of impeller speed and filling rate

A better understanding of the relevance between mixing and heat transfer of granular material is necessary for the design of mixers in various industries. In this work, the effect of impeller speed and filling rate on the mixing and heat transfer of granular material in a ribbon reactor was studied based on DEM simulations. Quantitative criteria which are characterized by the critical mixing time and critical heating time were proposed based on the simulation results. It was found that the area near the vessel wall is heated first, and then the top surface area and the region near the impeller shaft are heated sequentially due to the recirculation effect. Increasing the impeller speed and decreasing the filling rate can improve the mixing and heat transfer performance. The effects of impeller speed and filling rate on mixing and heat transfer weaken as they increase. Results obtained in this work indicate that increasing the mixing performance can enhance the heat transfer of granular material in the ribbon reactor.