CFD-DEM study on heat transfer characteristics and microstructure of the blast furnace raceway with ellipsoidal particles

Coupled computational fluid dynamics and discrete element method (CFD-DEM) simulations are carried out to investigate the heat transfer characteristics and microstructure of the blast furnace (BF) raceway with different particle shapes. Three kinds of particles are considered including prolate and oblate ellipsoidal particles and spheres. The coupled CFD-DEM model is first validated based on experimental data and the capability of the combined sphere method (CSM) to investigate the heat transfer is also demonstrated. Then, the validated model is used to systematically explore formation and evolution of the BF raceway, particle behavior, force structure, heat transfer and temperature distribution with the effect of particle shapes on these issues discussed. Numerical results show that the raceway size formed by prolate ellipsoidal particles is the smallest among the three cases whereas the coordination number of which is the highest. Uniform contact force networks and typical orientation inclined angles of ellipsoidal particles influence the stable packing structure and homogeneous void distribution therein. The large surface area and homogeneous void structure of ellipsoidal particles can enhance the convective heat transfer. All the aforementioned factors collectively promote ellipsoidal particles to possess higher heat transfer efficiency than spheres. These findings could be helpful for the design and optimization of the BF. (C) 2019 Elsevier B.V. All rights reserved.