[engrarif]

Hi everyone,
I am working on modelling of PEM fuel cell. I want to change the value of “phase_ch_const” value in the ansys user file (pem_user.c). I am trying to fix since last month, but not getting any clue. Can someone help to get out of this problem. The pic of code is attached.
Cheers,IMG_5124.jpg

[AlexanderZ]

Originally Posted by engrarif

Hi everyone,
I am working on modelling of PEM fuel cell. I want to change the value of “phase_ch_const” value in the ansys user file (pem_user.c). I am trying to fix since last month, but not getting any clue. Can someone help to get out of this problem. The pic of code is attached.
Cheers,Attachment 58914

Hello.

Next time put here code, not picture of code.
Did you try this one?

cxboolean const_rate_from_gui = FALSE;
real phase_ch_const = 999999999999999999999999999;
return phase_ch_const;

Best regards

[engrarif]

Originally Posted by AlexanderZ

Hello.



Next time put here code, not picture of code.

Did you try this one?

cxboolean const_rate_from_gui = FALSE;

real phase_ch_const = 999999999999999999999999999;

return phase_ch_const;

Best regards

Do I need to compel it after making changes?
When I try to compel it after changes I get this error ( pic attached)Image1507687508.794312.jpg

[AlexanderZ]

Go to the C:\Program Files\ANSYS Inc\v170\fluent\fluentXXXX\addons\fuelcells

Inside you have 2 files INSTRUCTIONS-CLIENT and makefile_master-client.nt

In INSTRUCTIONS-CLIENT there is information regarding FC model
For example

======================
Customizing the module
======================

  The PEM module has a user-modifiable component called "pem_user.c", which
  can be edited and recompiled to create a customized version of the PEM
  library.

  On both systems it is recommended that you make a copy of 
  the addons/fuelcells directory to a local directory.  Changes to the 
  user-customizable part of the library should be made in your copy.

  The user customizable file is
  .../addons/fuelcells/src/pem_user.c
 
  This is the only source file you will edit.


  ===================
  Customizing on Unix
  ===================

  * Edit line 11 of fuelcells/src/makefile so that FLUENT_INC points 
    to the official fluent installation directory.  
    This is normally [path]/ansys_inc/vXX.X/fluent
    !!! MAKE SURE THAT THERE ARE NO BLANK SPACES TRAILING THIS DIRECTORY NAME
  * Build the library from the fuelcells directory with the following
    command:
    make -f Makefile-client FLUENT_ARCH=lnx86
    (on other systems, use the appropriate architecture)

  ======================
  Customizing on Windows 
  ======================

  * Define environment variable FLUENT_INC to point to the official
    fluent installation directory.
     - note on Windows this looks like [path]\ANSYS Inc\vXX.X\fluent
  * Build the library from the fuelcells directory with the following
    command:
    nmake /f makefile_master-client.nt

So you need to modify (in Windows) .../addons/fuelcells/src/pem_user.c file as we discussed before.
Then run command nmake /f makefile_master-client.nt from SDK command promt. You should be in this folder C:\Program Files\ANSYS Inc\v170\fluent\fluentXXXX\addons\fuelcells

Best regards

[engrarif]

I have followed the steps but didn’t get any changes in results

[AlexanderZ]

You may try to use UDM variable to plot the contour of phase_ch_const

cxboolean const_rate_from_gui = FALSE;

real phase_ch_const = 999999999999999999999999999;
C_UDMI(c,t,0) = phase_ch_const;
return phase_ch_const;

You may use UDM for both cases (with and without changes) to see the difference

Best regards

[engrarif]

How I can make sure that fluent is now using my customisable file?
Regards,

[AlexanderZ]

That is the way. You will deg user-defined variable that can be monitored directly from Fluent GUI.

The other way, but it is just to check, is to put output message inside the code.
For example

real Phase_Change_const(cell_t c, Thread *t)
{
cxboolean const_rate_from_gui = FALSE;

real phase_ch_const = 999999999999999999999999999;
C_UDMI(c,t,0) = phase_ch_const;
Message("Modification is made, phase_ch_const = %f",phase_ch_const);
return phase_ch_const;
}

Best regards

[engrarif]

I am running my simulations in parallel for 500 iterations to check the changes in results

[AlexanderZ]

For parallel case use

real Phase_Change_const(cell_t c, Thread *t)
{
cxboolean const_rate_from_gui = FALSE;

real phase_ch_const = 999999999999999999999999999;
C_UDMI(c,t,15) = phase_ch_const;
Message0("Modification is made, phase_ch_const = %f",phase_ch_const);
return phase_ch_const;
}

Do not forget to change the number of UDMs in FLuent GUI
Go to User-Defined -> Memory -> change 15 to 16 (15 is default number regarding source file of FC model, it you made other modifications take it into account)

Best regards

[engrarif]

I m using vs12 command prompt instead of sdk, pic attached IMG_5133.jpg

[engrarif]

now i m getting this error after making the above changes
>
No error handler available

Error: Cortex received a fatal signal (SEGMENTATION VIOLATION).
Error Object: ()

[AlexanderZ]

There were errors during compiling process, don't you see?

Looks like your compiler uses x86, but your computer has x64 architecture.
You need to install x64 compiler. I recommend you to read help article:

https://www.cfd-online.com/Wiki/Flue...Fload_a_UDF.3F

Best regards

[engrarif]

Is there any way to check the value of condensation rate constant in GUI?

[AlexanderZ]

I described before the ways, how you can monitor phase content, but it requires modification of source code and compiling

This is a list of built in variables, that you can monitor using default library (without any modifications)

void Set_UDS_Names(char uds[n_uds_required][STRING_SIZE])
{
    strncpy(uds[0], "Electric Potential", STRING_SIZE-1);
    strncpy(uds[1], "Protonic Potential", STRING_SIZE-1);
    strncpy(uds[2], "Water Saturation",   STRING_SIZE-1);
    strncpy(uds[3], "Water Content",      STRING_SIZE-1);
}

void Set_UDM_Names(char udm[n_udm_required][STRING_SIZE])
{
      strncpy(udm[ 0], "X Current Flux Density",         STRING_SIZE-1);
      strncpy(udm[ 1], "Y Current Flux Density",         STRING_SIZE-1);
      strncpy(udm[ 2], "Z Current Flux Density",         STRING_SIZE-1);
      strncpy(udm[ 3], "Current Flux Density Magnitude", STRING_SIZE-1);
      strncpy(udm[ 4], "Ohmic Heat Source",              STRING_SIZE-1);
      strncpy(udm[ 5], "Reaction Heat Source",           STRING_SIZE-1);
      strncpy(udm[ 6], "Overpotential",                  STRING_SIZE-1);
      strncpy(udm[ 7], "Phase Change Source (PEM)",            STRING_SIZE-1);
      strncpy(udm[ 8], "Osmotic Drag Coefficient (PEM)",       STRING_SIZE-1);
      strncpy(udm[ 9], "Liquid Water Activity (PEM)",          STRING_SIZE-1);
      strncpy(udm[10], "Membrane Water Content (PEM)",         STRING_SIZE-1);
      strncpy(udm[11], "Protonic Conductivity",          STRING_SIZE-1);
      strncpy(udm[12], "Back Diffusion Source(PEM)",     STRING_SIZE-1);
      strncpy(udm[13], "Transfer Current",               STRING_SIZE-1);
      strncpy(udm[14], "Osmotic Drag Source (PEM)",            STRING_SIZE-1);
}

Best regards

[engrarif]

Hi Alexander hope u will be fine. I am trying to compare polarization curve of simulation with experimental. My question at which surface should I take the value of current means at membrane/ cathode catalyst interface or external surface ie terminal of cathode side?

[AlexanderZ]

i think you should take a look into ANSYS Fluent Advanced Add-On Modules file
in part V you may find information regarding PEMFC simulation in fluent

best regards

[engrarif]

Thanks for the reply