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Old   May 26, 2003, 22:51
Default Help on premixed combustion heat
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I try to simulate 2-d premixed combustion of methane and air in porous media burner with a laminar flame. Overall reaction model(ch4+2o2--->co2+2h2o) based on Arrhenius reaction laws was employed.

When using the reaction model, one should have the exact velues of some related parameters,eg. the pre-exponential factor,heat of reaction per unit mass reactant and activation energy. After refering to some publications, I was confuseded completely because no any two papers have the same values.

What are the exact velues of the parameters on earth?

What should i do?

Thanks to any response!

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Old   May 27, 2003, 04:38
Default Re: Help on premixed combustion heat
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Hi, The heat of reaction shouldn't be a problem, but I don't think there is such a thing as 'exact' pre-exponential factors and activation energy if you are looking at the overall reaction. As you are describing several hundred elementary reactions in one step, your two parameters can only cover a narrow range of conditions (if they manage that) depending on your application. I would recommend starting with a set of parameters from literature and see if the results make sense. Look for articles by Zhou, Pereira, Bouma, De Goey, Hsu, Ellzey, Viskanta or Echigo. Hope that helps.

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Old   May 27, 2003, 05:28
Default Re: Help on premixed combustion heat
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as Volker said, the 'Activation energy' is always the same,preexponential changes. To check it, bets would be to start with literature values and check the flame velocity S_L under normal condition if you get about the right velocity. Generally most of the codes takes the values for global reactions from Westbrook:

@Article{Westbrook, author = "Westbrook, Ch.K., Dryer,F.L.,", title = "Chemical Kinetic Modeling of Hydrocarbon Combustion", journal = "Prog. Energy Combustion Science", year = 1984, volume = 10, pages = {1--57} }


"On Simplified Reaction Mechanisms for the Oxidation of Hydrocarbon Fuels in Flames by C. K. Westbrook and F. T. Dryer", Combustion Science and Technology, 1985, Vol.43, pp. 333-339.

Are you sure, that single step global methane will do in porus burner? no catalysis?

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