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-   -   Multiphase Reaction (Mass Arrhenius) (http://www.cfd-online.com/Forums/cfx/79520-multiphase-reaction-mass-arrhenius.html)

 schokoundkeks August 26, 2010 03:49

Multiphase Reaction (Mass Arrhenius)

hey everyone,

i am working actually with an euler/lagrange simulation in ansys cfx 12.1 and i want to establish a reaktion inside a lagrage liquid droplet. The reaktions works with multiphase reaktion (mass arrhenisu). The Problem is that i don't know how to convert the pre exponential faktor from molebase arrhenius to a massbased.

Can anyone help me?

 a.m. August 26, 2010 16:05

I'm not sure, but try this:
1) for 2 reactants the rate is: w = k*c1*c2
where k - Arrhenius reaction rate, c1 [mole/m3], c2 [mole/m3] - reactants concentrations
2) use molar weight of reactants mw1, mw2 [kg/mole] from periodic table.
3) some transformations: w = k [mole^-2 m^6 s^-1] * c1 [mole m^-3]* c2 [mole m^-3] = k1 [mole^-2 m^6 s^-1] * w1 [kg mole^-1] * c1 [mole m^-3]* w2 [kg mole^-1] * c2 [mole m^-3] where k1 = k / (w1*w2) [kg^-2 m^6 s^-1 ]

and if the activation temperature and the temperature exponent is the same, the pre-exponential factor A1 = A / (w1*w2).

Good luck
a.m.

 schokoundkeks August 30, 2010 03:48

thanks so far.

I have a equlibrium reaction. One reaction ist SO2 (liq) -> H Ion + HSO3 Ion

k = 3.265E16 [s^-1]

transformed -> k* = k / M_SO2

The second reaction is H Ion + HSO3 Ion -> SO2 (liq)

k2 = k / Keq [m^3 s^-1 mol^-1]

K eq is the equlibrium constant of the reactions

transformed -> k2* = k2 / (M_H * M_HSO3)

is this the right transformation? Ativation Engery is the same is both reactions and Temperature Exponent ist Zero.

for some reason the expected equilibrium does not work out in the simulation.