Page 285 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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To describe the dynamic holdup over the loading point using
experimental data for the same packings, the following equation is proposed
[164]:

1 + 0.0046 n -0Jl

\gd ) [Lp (185)
h

where w = — .
e
The mean error of this equation is 9.5% and the maximal- 36.6%. The
date for determination of the experimental constants are obtained also for the
packings presented in Table 26.
The correct application of the similarity theory for obtaining
experimental equations gives the experimental constants in them really as
constants, and not as functions of the geometrical parameters. But this correct
application is possible only when we have geometrical similarity of the
packings used to determine the experimental constants. Is it is easy to see from
Table 26 that the packings used are not geometrically similar. In such a case the
constants in the obtained equations are practically functions of the geometrical
parameters, being constants only for geometrically similar packings. The type of
the functions could not be predicted theoretically. That is why it is better to try
to find the type experimentally, beginning with the simplest functions, including
constants. Using this method, the following equations for calculation of the
holdup over the loading point are proposed [164]:

o66 o 66
(ah)-°-
= H dn +0.08 " 3 Ga L (ah) 4Ss (186)

and:
, ^(0,61+0.75c) , v
1 + 0.002] (187)

The mean error of (186) is 7.7% and of Eq. (117) - 9.1%. The maximal errors
are 34.3%, respectively 36.3%. It should be taken into account that the