Pressure drop in packed beds of angular parallelepipeds, including the effects of particle interference

•Pressure loss in packed beds of parallelepipedal particles is measured.•The reduction of effective surface by particle overlap in the bed is measured.•A theory for calculating the effective surface from pressure loss is presented.

Pressure loss measurements are reported in packed beds of seven different shapes of angular parallelepiped, ranging from nearly cubical particles to thin flat chips, and compared with a number of available correlations, most of which underpredicted the pressure loss. All particle types when packed in the bed were found to overlap each other to some degree, and the extent of this was estimated from photographs, from which the average particle surface area effectiveness η was found to range from 0.69 to 0.85. The pressure loss correlation of Nemec and Levec (2005) was modified to include the effects of particle overlap, and values of η deduced by fitting to the measurements. The resulting values agreed well with those estimated from photographs, indicating that a pressure loss test can be used to assess particle overlap in a bed of known particle geometry. The range of Reynolds numbers covered was about 150-900. This is expected to be useful in assessing effective surface areas for heat and mass transfer and chemical reaction in packed beds.