Effects of cylindrical particle structure modification on the flow and heat transfer characteristics in packed beds

To investigate the effects of different modified cylindrical particle shapes on the wall effect and flow-heat transfer characteristics in packed beds, computational fluid dynamics (CFD) methods were employed to perform numerical simulations on six types of packed beds filled with particles: unmodified cylindrical particles and modified single-hole cylindrical, 3-hole cylindrical, trilobe, 3-hole trilobe, and 9-hole trilobe particles. The radial and axial porosity distributions, flow characteristics, and flow-heat transfer performance were analyzed. The results show that the cylindrical particles can improve the uniformity of fluid flow by either internal openings or external slots. Internal perforation reduces the proportion of flow near the wall, and the number of perforations has no significant effect on the flow near the wall. However, increasing the number of perforations weakens the uniformity of radial flow distribution while enhancing the uniformity of axial flow distribution. External grooving of cylindrical particles into a Trilobe shape improves the heat transfer coefficient but significantly increases the unit pressure drop. In contrast, internal perforation reduces both the heat transfer coefficient and unit pressure drop. Increasing the number of perforations enhances heat transfer performance but also results in a higher pressure drop. Considering both heat transfer performance and flow resistance, the mixed-modified 9-hole trilobe particles exhibit the highest overall heat transfer efficiency and demonstrate the best comprehensive heat transfer performance. © 2025 Materials China. All rights reserved.