Mass transfer coefficient correlations - Principles of Chemical Separations with Environmental Applications - page 280

Appendix B: Mass transfer coefficient correlations

B.1 Definition(s)

There are several common definitions for a mass transfer coefficient, k . These definitions
are based on the driving force used. The typical units are different which is a “flag” as to
the proper equation to use.

Equation Typical units for k

k C A 1 − C A 2 N A = cm / s

k P A 1 − P A 2

cm 2

N A = mol / · s · atm

k x A 1 −

x A 2 cm 2 N A = mol / · s

There are two generic sources for obtaining mass transfer coefficients. First, you can find
a correlation directly for a mass transfer coefficient. Second, you can find a correlation
for a heat transfer coefficient in the analogous circumstances. For the former, you can
proceed directly to calculate the mass transfer coefficient. In the latter case, you first need
to substitute the appropriate dimensionless numbers to convert the correlation from the
heat transfer to the mass transfer case.

Heat transfer Mass transfer

k = heat transfer coefficient k = mass transfer coefficient

L = characteristic length L = characteristic length

hL
k

kL
D AB

Nu = Sh =

ν
α

D AB

Pr = Sc =