how to include reverse chemical reaction

Jiuan · October 26, 2009, 16:38

Hi guys,

I am using Fluent to simulate chemical reactions. In the reaction mechanism, many are reversible reactions. I have the parameters for both forward and backward reactions, such as A, n, E. However in Fluent, it seems that the backward rate constant is calculated from forward rate constant and equilibrium constant. And equilibrium is related to the standard-state entropy and standard-state enthalpy. I cannot get these tow parameters from either Fluent database or other literatures. My question is that: I have known the kinetic parameters for reverse chemical reactions. Is there a way in Fluent to define reverse reactions by inputing these kinetic paramters? Thanks.

t.krishnamohan · October 26, 2009, 18:48

Hi,
You can specify the parameter you have in the Arrhenius expression. If the reaction is reversible, you need to check the backward reaction rate check box in the reaction menu and the solver will calculate the reaction rate using equilibrium constant. Be advised that if the reaction is only forward then the backward reaction rate is zero and Arrhenius expression is used to calculate the forward rate.
Bye

Jiuan · October 26, 2009, 21:30

Thanks for your reply.I totally agree with what you said

The equilibrium xonstant is determined by stant-state entropy and enthalpy of related species. My problem is that I don't have these data. What I have known is the kinetic parameters such as A, n, E for both forward and backward reactions. Do you have any idea how I can use these parameters I have already known to define the rate constant of backward reaction?

October 26, 2009, 16:38	how to include reverse chemical reaction	#1
Jiuan Member Dongzi Wei Join Date: Mar 2009 Posts: 33 Rep Power: 17	Hi guys, I am using Fluent to simulate chemical reactions. In the reaction mechanism, many are reversible reactions. I have the parameters for both forward and backward reactions, such as A, n, E. However in Fluent, it seems that the backward rate constant is calculated from forward rate constant and equilibrium constant. And equilibrium is related to the standard-state entropy and standard-state enthalpy. I cannot get these tow parameters from either Fluent database or other literatures. My question is that: I have known the kinetic parameters for reverse chemical reactions. Is there a way in Fluent to define reverse reactions by inputing these kinetic paramters? Thanks.

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October 26, 2009, 18:48		#2
t.krishnamohan Member Krishna Join Date: Oct 2009 Posts: 34 Rep Power: 16	Hi, You can specify the parameter you have in the Arrhenius expression. If the reaction is reversible, you need to check the backward reaction rate check box in the reaction menu and the solver will calculate the reaction rate using equilibrium constant. Be advised that if the reaction is only forward then the backward reaction rate is zero and Arrhenius expression is used to calculate the forward rate. Bye

October 26, 2009, 21:30		#3
Jiuan Member Dongzi Wei Join Date: Mar 2009 Posts: 33 Rep Power: 17	Thanks for your reply.I totally agree with what you said The equilibrium xonstant is determined by stant-state entropy and enthalpy of related species. My problem is that I don't have these data. What I have known is the kinetic parameters such as A, n, E for both forward and backward reactions. Do you have any idea how I can use these parameters I have already known to define the rate constant of backward reaction?