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essjcx September 11, 2012 07:02

Simulation of adsorption by using CFX
 
Dear All,

I am quite new to CFX and trying to simulate the adsorption process on carbon nanofibre in liquid phase (one organic specie in water and the organic specie can be adsorbed on carbon surface).

I am now stuck with how to set up equilibrium for this adsorption process. Does anybody have relevant information on this case?

I am currently specifying sources terms for the species on the boundary (I used a wall boundary represent the carbon fibre). But this cannot represent the equilibrium process in physical system.

Thank you very much in advance.

Best regards,

Xiaolei

ghorrocks September 11, 2012 07:19

Before you can set anything up like this you need to know the mathematics which describe it. You cannot do much (except random guesses) without knowing the maths.

What is the mathematics of the model you wish to introduce?

essjcx September 11, 2012 07:28

Quote:

Originally Posted by ghorrocks (Post 381211)
Before you can set anything up like this you need to know the mathematics which describe it. You cannot do much (except random guesses) without knowing the maths.

What is the mathematics of the model you wish to introduce?

Thank you for the reply, ghorrocks.

The mechnism is: A + surface <--> Asurface and this is a reversible process (reaction). The Kforward and Kbackward are available. Would you please recommend how to set up a reaction model for setting up the equlibrium of transfering the A in liquid phase to solid phase?

Thank you very much!

ghorrocks September 11, 2012 07:30

You can probably do this with additional variables and source terms, but it might be easier to use the chemistry model to do it. There are some examples of chemistry modelling in the CFX tutorials, and CFX support has more available.

Jovan10 September 17, 2012 03:31

Quote:

Originally Posted by ghorrocks (Post 381215)
You can probably do this with additional variables and source terms, but it might be easier to use the chemistry model to do it. There are some examples of chemistry modelling in the CFX tutorials, and CFX support has more available.

Hi ghorrocks and Xiaolei,

I am also modelling a similar situation (except mine is sugar adsorption onto an activated silica surface). The method I am employing is similar to the one that was mentioned by Xiaolei, in that I have added an additional variable and source terms.

Ghorrocks, when you mention the chemistry modelling tutorial, which one are you referring to? Also, would this actually be a better way to model the problem?

essjcx September 17, 2012 04:40

Quote:

Originally Posted by Jovan10 (Post 382077)
Hi ghorrocks and Xiaolei,

I am also modelling a similar situation (except mine is sugar adsorption onto an activated silica surface). The method I am employing is similar to the one that was mentioned by Xiaolei, in that I have added an additional variable and source terms.

Ghorrocks, when you mention the chemistry modelling tutorial, which one are you referring to? Also, would this actually be a better way to model the problem?


Hi Jovan10,

I think Ghorrocks refers to the acid and base mixing-reacting problem in CFX tutorial. In that tutorial, the reaction rate was specified according to the eddy dissipation model since the problem is turbulence and the reactuon source terms were introduced by simply timing the mass fraction with the rate. I do not think this tutorial is a good example for our adsorption problem because there is no equilibrium described. I can do the adsorption with FLUENT but now I am thinking how to do this wil CFX.

We can chat on this based on the nature of our problem. Let me know.

Cheers,

Xiaolei

Jovan10 September 21, 2012 00:56

Hi Xialoei,

Yes I too have realised that it is easier to model adsorption on Fluent rather than CFX.

The way I have gone about it at this point in time is to just define a basic sink term, but I am unsure on how to model the transfer of the solute to the adsorbent.

I have the same issue as you, and am new to CFX.

Best regards,

Jovan

Micheal May 15, 2014 04:24

Hi xiaolei
I am now facing the similar problem ,I have to simulate the adsorption and desorption process silica-gel water with FLUENT,but now I don't know how to set the model,can you give me some practical advice.Thank you very much.
Micheal


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