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The Voidage Function for the Drag Force Ratio in a Liquid‐Fluidized Bed
Author(s) -
Epstein Norman
Publication year - 2005
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450830321
Subject(s) - drag coefficient , reynolds number , drag , physics , settling , thermodynamics , fluidization , terminal velocity , spheres , fluidized bed , astronomy , turbulence
Di Felice (1994) has shown that the ratio of the drag coefficient, C D , on a sphere in a liquid‐fluidized bed of uniform spheres to the drag coefficient, C DS , on the same sphere in isolation and subjected to the same superficial liquid velocity, u , is given by a function ϵ −β , where β was expressed as an empirical function of the particle Reynolds number, Re = du ρ/µ. Here it is shown that C D / C DS is well approximated by ϵ −mm , where the Richardson‐Zaki index n is a function of the terminal free‐settling Reynolds number, Re t = du t ρ /µ, and m is 2 plus the slope of the standard log C DS vs. log Re plot at plot at Re = Re t . The present model, using the best experimentally confirmed equation for n and a new simple equation for and a new simple equation for m , is compared with that of Di Felice in their respective abilities to predict liquid‐fluidized bed expansion.