Fluidization of variable short fiber/powder mixtures: hydrodynamic investigation

Abstract

The behavior of a particle mixture composed of short fibers and silicon carbide powder in variable proportions has been experimentally investigated. The study shows that the hydrodynamic behavior of a bed initially composed of powder is affected as soon as a few percent of short fibers are added. The minimum fluidization velocity (Umf) is globally lowered and the intrinsic properties of the porous medium (equivalent particle diameter, porosity, flow coefficients…) are altered. Several hydrodynamic equations describing Umf as a function of the pressure are considered and the intrinsic properties of the bed such as the hydraulic diameter or the Darcy and Knudsen coefficients are fitted. The Darcy-Klinkenberg equation on one hand and a semi-empirical correlation based on Ergün’s equation on the other hand, are both adapted to describe the Umf behavior as a function of a limited number of initial parameters. The semi-empirical correlation leads to the best Umf prediction, with an absolute error of less than 10%, using only the temperature, pressure and percentage of fibers in the mixture as input parameters.