抄録
A good qualitative understanding and an accurate quantitative description of fluid flow in randomly water cooled packed bed reactors (WCPBRs) are important. In order to reflect the local phenomena, a spatially resolving three-dimensional (3D) flow simulation is needed. In this work, the packing structure in cylindrical tube was randomly packed with spherical particles and the flow through the packed bed were modeled by discrete element method (DEM) and computational fluid dynamics (CFD) respectively.For modeling an 3D representation of the geometric structure of the packing, DEM were applied to generate the packed bed with random packing of spherical particles. The obtained numerical radial porosity of the generated packed bed is compared with the empirical correlation from the literature. In this work, a method for meshing the particle-particle and particle-wall contact points in the fixed beds was presented. Compared to the shrinkage approach that commonly used in the literature, this method reduces the error of change in porosity, and achieves good quality meshing. CFD simulations were performed for water flow through randomly packed bed, in the laminar, transitional and turbulent flow regime. To validate the proposed geometry and grid, the Ergun correlation and Eisfeld and Schnitzlein correlation for predicting of pressure drop were used. The simulated averaged pressure drops were in a good agreement with the Eisfeld and Schnitzlein correlation. From the simulation, the localized and detailed flow characteristics were captured, and the stagnant regions were identified.
