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Blowout characteristic of Hydrocarbon Combustion

  1. May 29, 2015 #1
    Hi everybody!

    The problem which I am dealing with is surprisingly very well depicted in open source lecture notes made in October 29th of 2012, titled: " MAE 5310: COMBUSTION FUNDAMENTALS", available on the web.
    Such lecture notes are concerned with deriving the Blowout Characteristic of hydrocarbon combustion, and are based on a popular example proposed by S.R.Turns in [1].
    The question which I am going to ask you is strictly related with this topic.

    Indeed, I am trying to produce the blowout characteristic of a hydrocarbon combustion process.

    A Steady Well Stirred Reactor model is considered, based on energy and species mass conservations, assuming the same Single Step Global Scheme proposed in such lecture notes.
    I have followed a "fully rigorous" approach:
    - polynomial expression of enthalpies are considered accordingly to report NASA/TP 2002-211556(Gordon, McBride) instead of constant specific heat capacities
    - different molecular weights
    The non linear system of algebric equations is resolved with software MATLAB R2010 (using 'fsolve' function capabilities).
    Rather that applying the species mass conservation proposed in the notes, I have applied a more general method, based on the atomic species conservation, also documented in [2]. What is most important to notice is that the relative reaction rates are NOT dependent upon Equivalence Ratio.

    What I obtain is a blowout envelope which peaks NOT at an equivalence ratio equal to 1.0, but roughly at 0.8, in contrast with what are the theoretical expectations.

    My question for you is wheter this result can be regarded as acceptable or not.
    It would imply that, at light-lean condition, combustion is more stable that at stoichiometric.
    In case it is not, I would really appreciate any comments regarding how the relative reaction rates should be calculated, in particular at lean and rich conditions.

    [1] S.R.Turns, "An Introduction to Combustion", 2nd Edition, pp. 192
    [2] H.S.Fogler, "Elements of Chemical Reaction Engineering", 3rd Edition, pp. 57, formula (2-20)
    Last edited: May 29, 2015
  2. jcsd
  3. Jun 3, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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