Page 253 - Packed bed columns for absorption, desorption, rectification and direct heat transfer

243

Table 20. Values of the constants A, m and n in Eq. (146) taken from Ranrm [96]
Author Packing A m «
Van Krevelen [133] Rings, coke and others 0.00595 0.67 0.33
Ziparis [132] Rings §-20 mm 0.0021 0.75 O.S
Fujita and Hayakawa Rings 5-35, Saddles 13-40 » 0.67 0.5
[134] mm 0.0251—1
1 s J
Onda, Sada, Murase Rings 6-10 mm 0.0107 0.9 0.5
[135]
Onda, Sada, Otubo [136] Rings 6-10 mm 0.00625 0.5 0.5
Sherwood, Rings 25-50 mm 0.00204 0.78 0.5
HollowEy[137]
Rings 12,5 mm 0.00333 0.65 0.5
Saddles 12.5-38 0.00285 0.72 0.5
Yoshida, Koyanagi [138] Rings 15-25; Saddles 12-25 * 0.5 0.5
mm

Hikita, Ono [139] Fully wetted single element 0.545 O.S

\ J
Ramm, Chagina [140] Raschig Rings 25 and 50 mm 0.00216 0.77 0.5
Pall Rings 50 mm 0.0036 0.77 0.5
Ramm, Chagina [140] Raschig Rings 25 and 50 mm 0.00216 0.77 0.5
Pall Rings 50 mm 0.0036 0.77 0.5

The comparison of the constants given in Table 20 shows that usually
the power n at Set is equal to 0.5. This value is obtained theoretically in the
models of Higbie [1], Danckwerts [2] and Levich [3] and is experimentally
proved in the investigation of Sherwood and Holloway [137]. The value of the
power equal to 0.33 given by Van Krevelen [133] is for SCG in case of gas-side
controlled mass transfer.
Equations with powers at the liquid superficial velocity, quite different
than those presented in Table 20, are proposed by Koch et al. [218] and by
Rixon [219]. They are as follows:

= 0.25(LJ ,0.96 (147)
ia