Learning Forum

[z.z.huang]

Hi, I am working on the simulation of the Particle-Size Distribution with Pre-mixed Laminar

Burner-Stabilized Stagnation Flame in CHEMKIN PRO for the BSS ethylene flames (Flame C3), and I already have the chemkin input files for the BBS ethylene flame from the literature support material. However, the input files only include the gas-phase kinetic file, the thermodynamics file, and the transport file, and I need to write my own surface kinetic file. 

 

I am having a lot of problems writing surface kinetic file. One of them is that I am defining the lumped pseudo-species BIN1-BIN20 with the CLASS command and it is not readable by chemkin. I've read the 6.1.3 Particle Class of Ansys Chemkin Pro Input Manual in detail, but the application examples for CLASS are not clear and appear to be mislabeled, as in Figure 6.4. Can you please provide me with an example of the CLASS command? Preferably a definition of BIN1-BIN20 carbon soot particles.

 

In addition, I see the validation of the BBS ethylene flame example in the Model Fuel Library, but the corresponding chemkin input file is garbled, can you provide the specific input file?

 

Below is a surface kinetics file that I wrote myself, please correct me! Thanks!

 

MATERIAL  SOOT

DISPERSED

CLSM SOOT 5

END

 

BULK/CARBON/  CSOLID/1.5/

END

 

THERMO

CSOLID                  C   1               S    300.00   4000.00 1000.00      1

 .145569246E+01 .171706380E-02-.697584100E-06 .135283160E-09-.967649050E-14    2

-.695128087E+03-.852568475E+01-.310872070E+00 .440353690E-02 .190394120E-05    3

-.638546970E-08 .298964250E-11-.108650790E+03 .111382950E+01                   4

END

 

CLASSES

    CLASS 1

        BIN1A BIN1B BIN1C BIN1AJ BIN1BJ BIN1CJ

            COMPOSITION CSOLID:20

        END

BIN2A BIN2B BIN2C BIN2AJ BIN2BJ BIN2CJ

        CLASS 2

            COMPOSITION CSOLID:40

        END

BIN3A BIN3B BIN3C BIN3AJ BIN3BJ BIN3CJ

        CLASS 3

            COMPOSITION CSOLID:80

        END

BIN4A BIN4B BIN4C BIN4AJ BIN4BJ BIN4CJ

        CLASS 4

            COMPOSITION CSOLID:160

        END

BIN5A BIN5B BIN5C BIN5AJ BIN5BJ BIN5CJ

        CLASS 5

            COMPOSITION CSOLID:320

        END

BIN6A BIN6B BIN6C BIN6AJ BIN6BJ BIN6CJ

        CLASS 6

            COMPOSITION CSOLID:640

        END

        ......

END

 

REACTIONS

......

......

END

[jcooper]

Hi:

 

Your mechanism is not in the correct surface reaction format.  Keywords CLASSES, CLASS and CLSM don't belong there.  CLSM is an input parameter to the Chemkin simulation.

 

For an example of soot particle nucleation/aggregation, you can load the tutorial shown in the screenshot below, which also shows the CLSM keyword:

 

[z.z.huang]

Dear jcooper,

Thank you very much for your reply.

Regarding the surface kinetic file for the the lumped pseudo-species BIN1-BIN20, I still haven't learned how to write it, so I hope some tutorials on how to learn it will be provided.

On the other hand, I have studied the surface kinetic file of soot particles in ansys tutorial. 

Now I have a problem, I learned in the tutorial about the oxidation reaction of SOOT particles, i.e., OH+open(se)+C(B)=>CO+H(se)

So how does one go about writing code for SOOT oxidation by O2 using surface site species?

This is the SOOT particle oxidation reaction I have seen in the literature, how do I write this into a surface kinetics file in chemkin pro?

Best regards!

[jcooper]

Hi:

I am not sure what the site specie is in your example, but let's assume it is carbon ( C(S) ) on a soot particle.

For site species you need a declaration of site species in the reaction mechanism, like this:

SITE/SOOT/          SDEN/2.2524E-09/
C(S)

OPEN(S)

END

You can then use the site species in a reaction as below:

C(S) + O2 --> CO2(g) + OPEN(s)

There must be a site balance for the reaction, so we introduce the dummy specie OPEN(S)

 OPEN(S) will have the same thermo entry as the specie that left it ( C(s) ), so that the properites balance, but OPEN(S) has no elements. (Note below in the THERMO entries that there is no H next to the 0 as there is for H(SE))

Site species usually exist on a MATERIAL, which I did not include in my example. The above example in grey is more complete and describes how to setup surface reactions on a dispersed solid 

You can find this described in the ChemkinTheory manual here:

https://ansyshelp.ansys.com/public////Views/Secured/corp/v242/en/chemkin_th/pgfId-1316318.html