1 1=3

A0   。qV。  。lV。 X D E U

ShV / ReVScV (51)

M   qL

lL ðReL ÞðFrL ÞðWeLÞðReVÞad

。 Cy

×   A0 m      n

Cx 。

b c 45Þ

for random packings。 There is an additional effect of corrugation

inclination angle on the vapor-side mass-transfer coefficient for

VReV ScVcVDV  þ ReLScLcLDL ð

sheet metal structured packings。 For these, we assume

ShV / Re1 Sc1=3

。  cosðhÞ  。s

(52)

transfer coefficients for the absorption of CO2 into water using Raschig rings and  found

V     V cosðp=4Þ

where ‘‘h’’ is the corrugation inclination angle in radians measured from the vertical。 The metal gauze ‘‘X’’ style structured packings (BX, DX, and EX) tend to have smaller flow channels with friction factors that are more strongly dependent  on  the  vapor  Reynolds  number。  For  them,    we

kLam / L0:96 (59)

Van Krevelen and Hoftijzer35  postulated   that

 kLd

c0 Reb Sc1=3

(60)

assume

1=2

1=3

DL  ¼ L     L

ShV / ReV  ScV (53)

The mass-transfer coefficient correlation

Potnis and Lenz36 studied liquid desiccant systems for gas drying using random as well as structured packings。 They reported that

for liquid film flow

ShL / Reb

1=2

Mathematical solution of the hydrodynamic and mass con- servation  equations  for  the  absorption  of  a  slightly soluble

LScL (61)

with the exponent ‘‘b’’  ranging from 0。9 to 1。2。 Shetty and

37

gas  into  a  laminar,  falling,  liquid  film  on  a  plane   surface

Cerro

studied the flow of liquid films over periodic  surfaces

gives the following result for the liquid-side mass-transfer coefficient30

similar to those found in structured packings。 They    predicted

However, the liquid film’s flow regime in most packed columns is expected to be  turbulent,  partly  due  to the induced shear at the liquid interface due to the turbulent countercurrent  flow of  the  vapor。 There is  much  less general

Given the wide variability in the values of the power-law exponents on the liquid Reynolds number and Schmidt num- ber, we have assumed  that

ficient relation under these circumstances。 Two models often chosen to describe mass transfer  in  a  turbulent  liquid  film are the penetration/surface renewal model and the film model。31,32 The film model predicts that the liquid-side mass-transfer coefficient is directly proportional to the binary diffusivity。 This implies  that