Beginner Chemistry Help

MFiX
#1

Hi all,

I have been able to run the Silane Pyrolysis case successfully and am working on something of my own.

My goal is to model the pseudo-first order adsorption of a gas into the solid phase. I started by just using a 0th order model but this did not seem to work as I received the following:

image
image872×967 19.5 KB

No computations seemed to have occurred. If anyone can offer any help as to what I may have missed I would really appreciate it. Thanks! Attached are my rates and mfx files.

usr_rates.f (1.5 KB)
Tutorial.mfx (18.1 KB)

#2

Bump. Really hoping someone could help out with this. Maybe it is my solver? MFix has been great thus far and it would be disappointing if I couldn’t continue using it to incorporate chemical reactions.

#3
  1. You should open Energy equation.
  2. You should set your C_p for solid materials. (Setting coefficients a1 to a5)

The attached mfx file is for your reference.Tutorial.mfx (20.4 KB)

#4

The segfault comes from RATES not being declared properly:

Remove “(:)” at the back of RATES when you declare it:

DOUBLE PRECISION, DIMENSION(NO_OF_RXNS), INTENT(OUT) :: RATES

When editing udf, it usually helps if you compile with debug flags so you can get the file and line number where there is an issue

#5

Jeff is correct. It seems that you don’t have to open Energy equation when you simulate Chemical Reactions. However, when you want to use Stiff solver, you still needs to open ENERGY equations, otherwise GUI will report an error.

#6

Thank you both very much! Your suggestions/comments have been of great help.

After making the corrections you both suggested the simulation does run. However looking at the results it seems like no reaction is occurring. The fraction of Solid A does not decrease as time goes on.

I have defined my reaction with CO2 being in the gas phase and Solid A being in the solid phase.

Is this preventing MFix from carrying out this reaction? My workaround would be determine some kind of mass transfer coefficient to bring the CO2 into a pseudo solid phase to react with Solid A. What do you think?