Page 291 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

281

where:

krd.d,.

a.D G

and

The liquid phase has also some influence on the gas-side controlled
mass transfer. This is because the presence of liquid reduces the real free cross-
section of the packing for the gas flow. The second reason is that the real
velocity responsible for the gas-side controlled mass transfer is the relative
velocity between the gas and the liquid phases. These effects are relatively
small. To take them into account, Zhavoronkov et al. [168] proposed the
following equations:

— (196)

where w Gl is the gas velocity in the wetted packing in m/s, measured relative to
the liquid velocity and used instead of wo in calculating Re G;
e H=e-H d;

w L = — surface liquid velocity in m/s,
H
*
Eq. (194) describes the data for 12 different packings in case of
sublimation of naphthalene in air (Packings 1-9 and 11-13, Table 28). Its mean
error is 4.4%.
By analogy with Zhavoronkov [87], Nakov and Kolev [156] developed
the following equation to describe their own experimental data (packings Nr 14-
16, Table 28):

/3
63
=0.28.Re° G ,Sc' G .(h/ d h)~ 016 (195)