Simulation of an aggregate dryer using coupled CFD and DEM methods

Abstract

This article investigates the use of coupled computational fluid dynamics (CFD) and discrete element methods (DEMs) to simulate heat transfer in an aggregate drum dryer used in the production of hot mix asphalt. To be properly coated by the asphalt binder, the aggregate must be completely dried, a process accomplished in a counter flow drum heated by a direct fire burner. Attached flighting is positioned inside the drum to facilitate heat transfer. Because direct observation is impossible, commercial codes from FLUENT and DEM solutions were used to simulate heat transfer from the burner flame to the aggregate. A fully reacting CFD simulation of a natural gas flame was coupled to a DEM simulation using an Eulerian model with heat transfer and momentum exchanged between the phases. Results indicate that the coupled model correctly captures the dominant mode of heat transfer (convection) as the particles are showered through the hot gases. The methodology established in the study provides a base for further investigation into optimising dryer performance.