Ignition Delay in MATLAB

[MAHDI ABOUJAFARI]

Dera sir,

How can I measure the Ignition Delay time when solving the ODEs of the constant volume reactor by MATLAB? Can it be judged by pressure variation or by species concentration?

Thanks for your help in advance,

Mahdi Aboujafari

[Steven DeCaluwe]

Dear Mahdi,

There are multiple methods used in the literature for ignition delay time (IDT), which require processing the data trace from the simulation.

Somebody please correct me if I’m wrong, but I think the most common approach is to use the temperature trace, rather than pressure, and relate the IDT to the location of the maximum rate of temperature increase (dT/dt).  Some choose the time where the maximum dT/dt occurs, while I have seen others use the particular value of the max slope dT/dt and “follow it backwards,” so to speak, to find where that line intercepts the initial temperature.  See the attached graph (which is made up and just for demo purposes) to hopefully illustrate.

For a looser, but still quantitative comparison, you could look for max concentration of some indicator species (such as OH radical).

Best,

Steven

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[MAHDI ABOUJAFARI]

Thanks for your help. So I should study more. 

Of course it would be pleasesd if other people also comment on this issue.

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[Ssue]

Hi Mahdi,

Some information is added based on Steven's reply. The maximum heat release rate has also been practiced for detecting ignition. If heat capacity does not change much, I guess it is almost the same as the maximum of dT/dt. 

I got some treasure from the community. It's pleasent to give something I know, although maybe trivial.

Best,

Ssue