Page 280 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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packing, but also the ratio of the cross-section in the channels to that between
the packing rows, the following form of the equation for the irrigated packing is
proposed [163]:

(i-Af (l-Ajr

The exponent 6.8 is obtained theoretically from the well known
equation for the local pressure drop at an abrupt change of a tube cross-section.
As already mentioned for calculation of the pressure drop over the
loading point, the value of A can be calculated by equation (260), Chapter 1.
The gas velocity in the zones of local pressure drops considerably
exceeds the velocity in the straight channels. Thus, the additional retention in
the channels could be neglected. Introducing AA in Eq.(175), it is obtained:

(178 )

Applying dimensional analysis to the experimental data for the packing
pressure drop below the loading point and excluding the negligible terms, one
can derive the following expression for A®, [163]:

(179)

The precision of the experimental constants at 95 % statistical confidence is
given below:
1.2± 0.24; -0.05 ± 0.022; 0.35 ± 0.017.
The mean error of Eq. (179) is 10.5%.
Similarly, for AA it is obtained:

< _2LJ \0.6 F MJ^\ {J \-0.S (180)
/
,
g.d .e )
h
J MJ \
The precision of these experimental constants at 95 % confidence is: