Superquadric CFD-DEM Simulation of Solid Hydrodynamics and Mixing Effects in a Binary Fluidized Bed

Understanding the velocity characteristics and mixing effects of binary nonspherical mixtures in fluidized bed reactors is essential for enhancing chemical reaction efficiency and energy utilization. In the current work, a superquadric CFD-DEM model was developed to track the motion and fluidization process of binary nonspherical particles in a 2-D fluidized bed. Two binary mixture systems, the cylinder–cylinder (CC) and cylinder–sphere (CS) systems, were established for analysis. The impact of aspect ratio (AR) of cylinders on the fluidization, mixing effect, and particle-scale behaviors was studied. It is found that a higher AR of cylindrical particles significantly increases the interlock effect with the reactor wall. Increasing the AR of cylinders hinders the rotational velocity of them. In addition, a higher AR hinders the mixing of binary mixtures in the CC system. The entropy-based mixing index decreases from 0.994 to 0.887 as the AR of cylindrical particles increases from 2.58 to 3.58. In the CC system, the gas phase exhibits a higher rising velocity in the freeboard region, while the bed pressure drop is lower compared to the CS system. Increasing the AR of cylinders increases the coordinate number between cylinders in the CC system, and between cylinders and spheres and between cylinders in the CS system. The results are beneficial for optimizing chemical processes involving binary mixtures of nonspherical particles.