CFD analysis of fluid flow and particle-to-fluid heat transfer in packed bed with radial layered configuration

The channeling effect at the container wall results in difficulties for heat transfer in the central part of packed beds with small tube-to-particle diameter ratios. To overcome this shortcoming, a new kind of packed bed is developed with radial layered configuration: a fluid-penetrable wire mesh is used to divide the container into two parts in the radial direction, which allows particles of different sizes for regional loading. Therefore, following the general rule of fluid flow distribution in packed beds, small particles could be filled in the zone at the container wall to restrain the channeling effect and large particles in the center to promote local heat transfer capacity. In the present work, to facilitate the proper functionality of new equipment using the novel method, a CFD simulation combined with the DEM method for random packing generation is conducted to study the characteristics of the new packed bed on the packing structure, fluid flow, and particles-to-fluid convective heat transfer under a high fluid velocity regime (Re similar to 10(4)). It finds that the new packing method could exhibit a much regular structure than the conventional packed beds. And outstanding performance is observed in pressure drop reduction and heat transfer efficiency improvement. Moreover, the well-known equations for pressure drop and convective heat transfer predictions are found not applicable to the new bed and distinctive features of fluid velocity and temperature distribution are identified. These findings are helpful for the design of high efficiency reactors. (C) 2019 Elsevier Ltd. All rights reserved.