DEM study of polydispersity and heat transfer in a bladed mixer

Mixing performance and heat transfer was investigated in dry granular flows in cylindrical geometry where heat is transferred from cylindrical walls to granular bed. The discrete element method (DEM) was used to simulate these flows and to investigate the effect of different parameters on mixing and heat transfer that include impeller speed, blade rake angle, number of blades and polydispersity. The effect of impeller rotation on heat transfer was also investigated. Mixing quantification was done by using the latest subdomain mixing index (SMI). Results of DEM simulations for these parameters were concluded for mono and poly-dispersed flows. Velocity and heat transfer profiles were drawn. Better mixing was observed in the case of four blades. Higher impeller speed also showed better mixing and heat transfer. In this study, the effect of polydispersity—an often-overlooked factor—is studied. In all cases it was observed that polydispersity had a negative effect on both mixing and heat transfer due to enhanced segregation and reduced thermal conduction. It is also the first-of-its-kind analysis of coupled impeller-geometry effects on particulate mixing and thermal transport in granular media.

Graphical Abstract