Page 252 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

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For using the diffusion model, data for the packing height, which are
not included in equation (142), are necessary. Usually the packing height in
investigation of the mass transfer coefficient is about 1 m or less. To determine
the effect of the packing height on the mass transfer coefficient for the diffusion
model, a numerical experiment is carried out [131]. The results show that the
difference in the obtained values for all investigated packings is not more than
1%, varying the packing height from 0,5 to 1 m. Using the obtained data for
calculating the gas-side controlled mass transfer coefficient for the diffusion
model, the following equation is proposed [131]:

s
= ft J Re°f .Sc" 3 (145)

3.2.1.2.1.6.2. Liquid-side controlled mass transfer coefficient

3.2.1.2.1.6.2.1. Coefficient for the piston flow model
For calculation of the liquid-side controlled mass transfer Kasatkin and
Ziparis [132] proposed the equation:

n
Sh L1=ARe2Sc L , (146)

where:

a.D L

Re = ^

' /3
i s the so called modified film thickness.

After Kasatkin [132] ,4=0.0021, m= 0.75 and «=0.5.
The values of the constants A, m and n in Eq. (146) are presented in
Table 20.