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A
Anonymous
December 3, 2021
Question

Odesolve error - Reactor design

  • December 3, 2021
  • 2 replies
  • 2954 views

Hi, 

Im trying to solve an ODE equation system for an adiabatic closed reactor. When I try to solve via ODESOLVE all variables keep as straigth lines.

Thanks in advance!

2 replies

W
Werner_E25-Diamond I
25-Diamond I
December 3, 2021
When I try to solve via ODESOLVE all variables keep as straigth lines.

Not, if you let solve the system with a much larger value for t.end and/or take a closer look..
I would say thats it a much slower reaction than you expected.

Werner_E_1-1638575564683.png

I have not the least expertise concerning the things you are trying to solve, but could it be that your equations expect the time milli- or micro seconds and you assumed seconds? Just a guess in the blue, though.

    N
    NA_101375101-Visitor
    1-Visitor
    December 4, 2021

    Hi Mr. Wegner, thanks for your answer...

    Let me put in context is a reactor for CH4 with complete and stoichometric complete combustion. Reaction takes miliseconds.

    So i'm really newby using this mathcad function, so i cant identify how should I do the realition between step and time.

     

    And now in the new file its not able to increase t.end over 89.. I repeat, really i dont know what means 89... but in the graphic the behavior seems correct (Temp is increasing, CH4 and O2 are consuming until 89).

     

    I would appreciate a lot your help.

    NA_10137510_0-1638604740059.png

     

    W
    Werner_E25-Diamond I
    25-Diamond I
    December 8, 2021

    It looks like the Temperature Tp is shooting up too high when time goes near 89.327 and the algorithm isn't converging anymore. The system might be unstable.
    Sure that all equations you use are correct and that the temperature should be that high?
    Werner_E_0-1638994840378.png

     

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