Numerical investigation on band-broadening characteristics of an ordered packed bed with novel particles

Abstract

Ordered structures are considered as the potential choice to improve the efficiency of separation. Moreover, the pore connectivity and pore size distribution of structured packed beds could be designed to improve the column separation performance. We have investigated the separation performance of different ordered packings in detail with the volume averaging method and numerical simulations, including simple cubic (SC), body center cubic (BCC), and face center cubic (FCC) packing with different particles. The effects of packing forms and particle shapes are discussed. Firstly, it is found that, the effects of packing forms and particle shapes on the plate height are remarkable. In the simple cubic packing, long ellipsoidal models have better separation performance and the channel effect makes molecular longitudinal diffusion insensitive to particle shapes. Secondly, with the same particle shape, the separation performance in the FCC packing is better. Compared with the corresponding configurations with spherical particles, the plate heights of long ellipsoidal particle models are remarkably reduced in the SC and BCC packing. Long ellipsoidal particles can enhance longitudinal diffusion obviously in the BCC and FCC packing. Thirdly, in the composite packing forms, the configurations with the same particles at the eight corners of the unit cell (BCC-S and BCC-S-S, BCC-L2 and BCC-L2-S) have the similar separation performance. Moreover, composite packings do not always improve separation performance. Finally, the unified equation form of separation performance is firstly proposed by the investigation of various ordered packed beds. By data fitting, the reduced longitudinal dispersion can be represented by the same power law pattern. Two velocity dependent factors consist of the same power law and fractional function form. These results provide more detailed flow characteristics and mass transfer process in ordered packed beds.