Re: ISSUES CONVERTING .INP TO .CTI

[Ray Speth]

Nik,

(1) I couldn't guess why C(s) has a negative Cp/RT. This is an issue with the mechanism, not with Cantera.

(2) I don't know why Matlab would crash when converting the mechanism. You may have better luck doing the conversion from the command line using the ck2cti program or the ck2cti.py script (new in Cantera 2.0 -- you don't say which version you're using). If you're using the older ck2cti, it will create a "ck2cti.log" file that should indicate the source of the problem. For the mechanism you provided, there are several problems. The Chemkin format has very specific formatting rules that this mechanism does not satisfy.

* LIne 40: Species HCO(s) is not among the declared species

* Line 123: The temperatures for the thermo data are in the wrong columns. They should be one column to the left, like the other thermo entries.

* Line 126: there should be a "4" in the last column, as in all the other thermo entries

(3) More importantly, you should be aware that Cantera's converters for Chemkin-format mechanisms do not currently support any of the features specific to surface mechanisms, e.g. the "SITE", "STICK", and "COV" keywords. You will need to modify the generated .cti file manually to add these parameters. The documentation for the ctml_writer script (http://cantera.github.com/docs/sphinx/html/cti/classes.html) shows the necessary keywords.

Regards,

Ray

On Wednesday, November 7, 2012 6:07:45 AM UTC-5, Nik wrote:

Hello Cantera users,

I'm trying to convert the mechanism of steam reforming (n°6) from detchem.com web site.

 

I have some issues and your help will be really appreciated:

1) starting the ck2cti the conversion works fine until the thermo data where it breaks because Cp/RT of C(s) is negative. I changed the parameter but I do not understand why the Cp/RT was negative.

2) trying to convert the new .inp file (please find the attached file, with thermo data modified) matlab stops working unexpectedly.

Could someone please help me?

Really thanks to everyone

Nik 

[Jorge Navalho]

Hi Nick

I don't know if you have already overcame the first issue about the negative value of Cp/RT for C(s). In any case, if you only want to compute reaction rates you can set all thermodynamic coefficients of all surface species (denoted by (s)) to zero. This is because there are no reversible reactions in the mechanism.

regards.

jn

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