Simulation of residence time distributions in a packing of equal spheres using a structural model for a fixed bed

Abstract

In this paper a new model for the voidage in a packed bed is presented. In the first part the simulations of the voidage structure are described. The second part contains a deduction of residence time distributions (RTDs) in the fixed bed represented by a structural model. In the first part the real structure of the void space in a random packing of equal spheres is simulated by a network of spherical cells connected by channels. In contrast to other cell models, the present one uses some a priori structural configurations in conjunction with the distributions of coordination numbers and polar angles in a random packing. In the second part RTDs for a passing fluid which does not interact with the packing are deduced as a convolution of RTD functions for separate sequences of channels, spherical holes and remnant spaces. The comparison with other RTDs published in the literature for fixed-bed systems shows a close agreement between the two curve families.