PERMEABILITY OF GIGAPOROUS PARTICLES

The volumetric flow rate of liquid and gas though small gigaporous par ticles was measured by a new method that isolates single particles in a rest apparatus. To our knowledge, this is the first direct confirmat ion of flow through gigaporous particles made at pressure drops experi enced during normal operation. High-performance liquid chromatography particles from 30 to 50 mu m in diameter previously reported to exhibi t convection-enhanced intraparticle mass transfer; were studied. Using a CFD model of the rest system the permeability of individual particl es was determined from the pressure-drop -flow-rate relationship. The average measured permeability of the particles studied is 7.89 x 10(-1 5) m(2) with no dependence on particle size. This is 4 to 17 times gre ater than values calculated from models currently used to estimate the permeability of these kinds of particles. No other experimentally mea sured values of permeability have been reported for particles of this size. The results of this study might imply that the intraparticle str ucture does not behave like a bed of uniformly packed mio microspheres , but rather as an inhomogeneous assemblage of microparticles. The mea sured permeability values offer the possibility of developing better m odels of the intraparticle flow field under normal operating condition s. Knowledge of the intraparticle flow field is an important step in d eriving predictive models of convective mass transfer in these types o f particles.