Custom reaction rate

[Aimad Er Raiy]

Hello,

I am trying to modify the reaction rate expression in cantera, so that the arrhenius pre-exponential factor becomes soichiometry dependent .i.e k_f=A(phi) exp(-Ta/T)

anyone had already did that? I will be gratefull for any suggestions.

Regards.

[Steven C. Decaluwe]

No, I do not think anything like this currently exists in Cantera, but it would definitely be nice.  My suggestion would be to use the ‘setMultiplier’ function to modify the static (temperature-dependent, actually) Arrhenius parameters in an external routine that you write in your code.

Cheers,

Steven

----------------------------------------------------------

Steven DeCaluwe, Ph.D.

Assistant Professor of Mechanical Engineering

Colorado School of Mines

G. Brown Hall, W410 B

Golden, CO, 80401

deca...@mines.edu

(303) 273-3666

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[Fanne]

Hello all,


We have implemented exactly that for a specific type of kinetic schemes (which only contains 2 reactions), and for a preexponential with a specific format (see "A Two-step Chemical Scheme for Kerosene–Air Premixed Flames", Franzelli et al. 2010), at my lab. However, I believe that if you have a little time on your hand, you could probably find it usefull to peruse our cantera sources and adapt our modifications to fit your needs...
Feel free to visit our cantera website : http://www.cerfacs.fr/cantera/updates.php and to download the sources (based on the cantera 2.1.1 release, though).
Specifically, the modifications are in the routines /oneD/StFlow.h of the folders /src/ and /includes/. You can search for the word "PEA".
Briefly, what we do is we read a file containing the preexponential information (so, with the constants of the fonction A(phi)), then we compute a phi for each point of the domain and then we adapt the routine "getWdot" at each iteration by modyfing the arrhenius coefs with the use of the function "getArrheniusCoeffs(*, C)".

I hope this will help  !
Anne

[Aimad Er Raiy]

Hello all,

Thank you Benedetta for your answer. I will give it a try and then leave a feedback here.

Aimad.

[Srinivasa Rao]

I am trying to the same thing

I am trying to modify rate of reaction , where pre exponential factor is a function of equivalence ratio

Can you please share the cantera code for the same??

Srinivas

[Clayton Fox]

Hi Anne,

This is something I am trying to do now.  Could you provide a bit more information on who you can achieve this?

I wold like to modify the exponential, and activation energy, for a two step reaction as I pass through time inside a constant pressure reactor.   I understand this is a pretty old post you have posted, and if you are able to assist I will provide more information.
Thank you,

[Anne Felden]

Hi,

I am not that familiar with the sources of the recent version of Cantera (2.3) so I might not be of much help. Did you downloa the sources in our website ? Did you search for the PEA world as I suggested in the post ?

Anne

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[Clayton Fox]

Hi,

I am essentially interested in updating the reaction rates as the reaction progresses. 

I have been to the cerfacs cantera site.  I am interested in the two step methane air mechanisms. Found here
(http://www.cerfacs.fr/cantera/mechanisms/meth.php)

I did download all the files associated with the BFER, but I didn't understand the concept of how to use them. (the input thermo and premix DAT files etc.)  

But at the same time, I don't think I will I need to use them all. Can you confirm if these files are for transport properties?  I was originally interested in the Flame speed, but I now realize its transport properties are more complicated then I wish to get into, and instead I will focus on a simple constant pressure reactor problem. 

I am really interested in changing the reaction rates, updating them over time as products and reactants in the gas are produces and consumed. 

I would like to start with a two step mechanism.

Is is possible to start Cantera, (ie run a simple reactor),  stop it after a defined time step, then update the rates from the input file ect. and then continue the reactor?    

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