Mass Transfer

Add a Mass Transfer node to include mass transfer from the gas to the liquid.

D O M A I N S E L E C T I O N

From the Selection list, choose the domains to include mass transfer defined in this Mass

Transfer feature node.

M A S S T R A N S F E R

For the mass transfer rate, use a two-film theory model or a user defined expression:

•Select Two-film theory from the Mass transfer model list to use a two-film theory model using the concentration of the dissolved gas.

Henry’s law gives the equilibrium concentration of gas dissolved in liquid c*

(SI unit: mol/m3):

p + pref

c = ------------------

H

where H is Henry’s constant (SI unit: Pa·m3/mol). The molar flux per interfacial area, N (SI unit: mol/(s·m2)), is determined by

N = k c – c

where k (SI unit: m/s) is the mass transfer coefficient and c is the concentration of gas dissolved in liquid (SI unit: mol/m3).

The mass transport from gas to liquid, mgl (SI unit: kg/(m3·s)), is given by

mgl = NMa

where M is the molecular weight (SI unit: kg/mol) and a is the interfacial area per volume (SI unit: m2/m3). See Theory for the Bubbly Flow Interface for details on how a is computed.

-In order to use two-film theory model, you need to select the Solve for interfacial area property in the Bubbly Flow interface settings. You also need to solve for the concentration of the dissolved gas;

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