Pressure loss in packed beds of multicomponent mixtures of flat particles with particle overlap, including random chips

Abstract

wPressure loss measurements are presented for packed beds of multi-component mixtures of thin angular parallelepipeds and of random wood chips for a Reynolds number range of 50 to 500. For flat particles like these, the degree to which the particles overlap is an essential factor in pressure loss, and this was measured using two different methods, including a novel technique involving progressive dismantling and photography of the bed. The experimental friction factors were found to be well represented by the Nemec and Levec pressure loss correlation, an Ergun-type equation with an explicit dependence of the parameters on particle sphericity, with the equation expanded to include the effects of particle overlap and of packing anomalies at the wall. The friction losses of the mixtures were found to be somewhat higher than those of the individual component particles, requiring a minor change in the correlation parameters. Estimates of the tortuosity of the bed channels showed that the greater losses of the mixtures correspond to an increase in tortuosity.