Application of shape factor to determine the permeability of perfusive particles

Abstract

A modified graphical–statistical method for shape factor estimation has been developed and used to estimate the permeability of a perfusive particle as an example. The shape factor was evaluated by calculating the average cross-sectional area for diffusion and the average flow path line length separately. According to this method, a perfusive particle with a sealing surface length ratio, L s, of 0.04, i.e. a contact length of the perfusive particle on the walls of the test cell tube to the perfusive particle diameter of 0.04, would have a shape factor of 1.25 πa. Then, the graphical–statistical method and the geometrical method were used to propose an expression to evaluate the shape factor of any perfusive particle with a sealing surface length ratio of L s and a radius of a. Finally, the shape factor approach was compared with the CFD numerical simulation approach of Pfeiffer et al. [AIChE J. 42 (1996) 932], and excellent agreement between the two approaches has been demonstrated.