Page 255 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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Ranun [96] accepted that using in Rei the effective surface area a e
instead of the total packing area a is more grounded theoretically, but according
to him it is difficult to use this area because of absence of any equation for its
calculation in case of liquid-side controlled processes. Later Kolev [34]
discussed the problem and considered that the existing of different effective
surface areas for different processes is impossible at least because in most of the
cases the mass transfer depended on the resistance of the two phases. That is, if
mass is transferred thought a part of the effective surface area in the gas phase,
it has to be transferred in the liquid phase too. I.e. the effective surface area is
the same for each of the phases. The good coincidence of the experimental data
for a e, obtained using the methods of Danckwerts controlled by the rate of the
chemical reaction and of Shulman with gas-side controlled process, also gives a
proof for the mentioned above.
Using equation (105) for determination of the effective surface area and
experimental data for the packings presented in Table 21, Kolev [34] obtained
the equation:

Sh L = 0.030 (153)

where Sh L and G% are determined with the packing size d p.
The comparison between the experimental data for the packings
presented in Table 21 and the line calculated by equation (153) is presented in
Fig. 38.

2 -20 ^.
B
to '**• <
8 m ^=20°/
a f
ft'
7
Iff 4 i 8 10*

Fig. 38. Comparison between the experimental data for the packings presented in Table 21 and
the line calculated by equation (153).