Learning Forum

[sudeepns.197me025]

Hello All, 
Greetings! 

I am trying to simulate the Steam methane reforming reaction in Ansys chemkin. 

I have developed 
1. gas phase reaction files
2. surface reaction files
3. Thermodynamic data files
4. transport data file. 

This is a heterogeneous reaction. 

The above files successfully get imported to chemkin, but while running the simulation, I am getting the following error. 

" DASPK--  AT T (=R1) AND STEPSIZE H (=R2) THE                                    

      In above,  R1 =  0.3196622577504D-10   R2 =  0.7023828905648D-15

 DASPK--  ITERATION MATRIX IS SINGULAR.                                          

 

          SITE FRACTIONS AT REACTOR INLET CANNOT BE FOUND

 

          THE MATRIX OF PARTIAL DERIVATIVES MAYBE SINGULAR

 

          SEARCH FOR INLET SITE COVERAGE TERMINATED DUE TO ERROR(S)

 

          Attempting to proceed without solution of initial surface site fractions"

Kindly help me in resolving the issue. 

 

[Ren]

The error messages suggest that the reactor has not been set up fully (missing site fraction data). Please also check the following files for any warning or error messages:

chem.out, surf.out, tran.out

.out in the run directory.

Which reactor do you use?

What is the Chemin release number?

 

[sudeepns.197me025]

Hello Sir, 
Thank you for the reply. 

I am using PFR for steam methane reforming purposes. 
Site fraction data I am giving in the input section of the PFR (Attached image for the reference). 

I use 2024R2 Chemkin

Attached chemkin files for your reference. 

Also, Requesting you to provide the working surface reaction file. 

looking forward for your reply.

 

 

 

 

 

[sudeepns.197me025]

Hello Sir, 
Greetings, 

I could able to get rid of site fraction error, however, DASPK Solver errror remains unrectified from my end. 
I have attached a snap of the same for your reference. 

The below are my solver inputs. 

1. Absolute tolerance = 1e-30

2. Relative tolerance = 1e-22

3. Sensitivity absolute tolerance = 1e-18

4. Sensitivity relative tolerance = 1e-06

5. Solver maximum step distance = 0.01 nm

6. Scaling factor for relaxing surface equations = 1e-08 micro-meter/sec

7. Initial Time step = 0.01 nm

8. Initial integration step = 0.01 nm

9. Maximum relative change in site fractions = 1 e-06

10. Maximum absolute change in site fractions = 0.001

Kindly let me know, what changes are to be made to solve this error. 

Looking forward for your reply.