[ramakant]

Dear All

I have a Multiphase PEM Fuel Cell code that is written for co-flow (parallel flow). That code is working fine for co-flow. However, I need to run a simulation for counterflow also. What is the parameters in the PEM fuel cell code that should be modified for counterflow?

Please give me a suggestion for it. I already changed the boundary condition in the config folder(faceSetCathodefluid.topoSetDict) for cathode flow.

Thank you
Regards
Ramakant

[wyldckat]

Quick answer: I received the PM you sent me, but I don't understand what exactly you are asking about.
If it's just a matter of changing the direction of the flow, you should change it if the boundary conditions files, either in the folder "0" or in the file "system/changeDictionary" if there is one.

[ramakant]

Yes i want to change the direction of flow

[wyldckat]

Originally Posted by ramakant

Yes i want to change the direction of flow

Then it's just a matter of changing the vector direction...

I'm not familiar with the openFuelCell example cases, therefore if you can provide the inlet boundary condition that the example you are using as a reference, then it's easier for me or anyone else to show you how to change the direction... but it should be nearly as simple as changing from "(1.35 0 0)" to "(-1.35 0 0)"...

Although this does beg the question: should this really be the way your cell works? Or should you be changing the outlets into inlets and inlets to outlets?

[ramakant]

this is the error for counter flow

[wyldckat]

Originally Posted by ramakant

this is the error for counter flow

It is somewhat indicating that the flow became non-physical. You will have to look at the results with caution and figure out what is going on wrong with the flow.

You can see what is happening, by reducing the write interval to a smaller value, so that you can see the results with more detail. That is what I or anyone else would have to do, to try and diagnose what is wrong.

[ramakant]

Originally Posted by wyldckat

It is somewhat indicating that the flow became non-physical. You will have to look at the results with caution and figure out what is going on wrong with the flow.

You can see what is happening, by reducing the write interval to a smaller value, so that you can see the results with more detail. That is what I or anyone else would have to do, to try and diagnose what is wrong.

Dear Bruno Santos

I want to change the inlet composition of air (mole fraction).For air 0.2, 0.15 and 0.1 (mole fraction) the pemfcSinglePhase-4.0 is running ,but when i am changing the mole fraction 0.01 (oxygen).Floating point exception (core dumped) error is showing?. Any solution for this kind of error?

Thank you

[hansihans]

Hi Ramakant,

As far as I can see you are using the pemfcMultiPhaseNonIsothermalSolver by Jean-Paul-Kone, aren´t you?

So I am working on this model, too. I also changed the molar fraction of air and fuel (and one or two small changes on the MEA).

For using
YH2fuel = 0.8 , YH2Ofuel = 0.2 and
YH2Oair = 0.1 , YN2air = 0.1, YO2air = 0.8

I managed to get no errors. But I did not change any direction of the flow.

for this I would change the boundary conditions like mentioned before. And change the inlets and outlets, which must be done in the /config folder.

[ramakant]

Originally Posted by hansihans

Hi Ramakant,

As far as I can see you are using the pemfcMultiPhaseNonIsothermalSolver by Jean-Paul-Kone, aren´t you?

So I am working on this model, too. I also changed the molar fraction of air and fuel (and one or two small changes on the MEA).

For using
YH2fuel = 0.8 , YH2Ofuel = 0.2 and
YH2Oair = 0.1 , YN2air = 0.1, YO2air = 0.8

I managed to get no errors. But I did not change any direction of the flow.

for this I would change the boundary conditions like mentioned before. And change the inlets and outlets, which must be done in the /config folder.

Yes I am working on OF with pemfcsmultiphase.I want to check for lowest mass fraction of water vapor.

[bastil]

Originally Posted by ramakant

Yes I am working on OF with pemfcsmultiphase

Just wondering where this solver can be found? Thanks.

[mat16]

Originally Posted by ramakant

this is the error for counter flow

Hi Ramakant,

I'm working on multiphase fuel cell, pemfcMultiPhaseNonIsothermalSolver by Jean-Paul-Kone, and I have the same problem in calculating the overpotentials.

--> FOAM FATAL ERROR:
Root is not bracketed. f(x0) = -0.07406399 f(x1) = -2.00275

From function Foam::scalar Foam::RiddersRoot<Func>::root
(
const scalar x0,
const scalar x1
) const
in file ../src/tools/RiddersRoot/RiddersRoot.C at line 190.

FOAM aborting

min,mean,max (RiMem) = 7.430817e-06 1.864376e-05 3.46878e-05
min,mean,max (ASR)= 1.181346e-05 2.302641e-05 3.907044e-05
min,mean,max (cathodeT) = 359.4382 376.1965 385.5225
min,mean,max (i0Ca) = 0.02150183 0.06645341 0.1128227
min,mean,max (iLCa) = 9.024553e-11 11511.19 39336.9
#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2 ? at ~/OpenFOAM/mattia-4.0/run/Modelli_Esempio/pemfcMultiphaseModel-4.0/pemfcMultiPhaseNonIsothermalSolver/applications/../src/tools/RiddersRoot/RiddersRoot.C:196
#3 ? at ~/OpenFOAM/mattia-4.0/run/Modelli_Esempio/pemfcMultiphaseModel-4.0/pemfcMultiPhaseNonIsothermalSolver/applications/../src/electrochemistry/totalCurrent.H:24 (discriminator 49)
#4 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#5 ? at ??:?

The flow direction is the same for the reagents (coflow) but I changed the geometry by increasing the size (22x22 --> 100x100) and inserting five serpentine channels. The reason for this error is perhaps not the same but can you give me some input on how you solved it? Or can someone else help me?

Thank you

[ramakant]

Originally Posted by mat16

Hi Ramakant,

I'm working on multiphase fuel cell, pemfcMultiPhaseNonIsothermalSolver by Jean-Paul-Kone, and I have the same problem in calculating the overpotentials.

--> FOAM FATAL ERROR:
Root is not bracketed. f(x0) = -0.07406399 f(x1) = -2.00275

From function Foam::scalar Foam::RiddersRoot<Func>::root
(
const scalar x0,
const scalar x1
) const
in file ../src/tools/RiddersRoot/RiddersRoot.C at line 190.

FOAM aborting

min,mean,max (RiMem) = 7.430817e-06 1.864376e-05 3.46878e-05
min,mean,max (ASR)= 1.181346e-05 2.302641e-05 3.907044e-05
min,mean,max (cathodeT) = 359.4382 376.1965 385.5225
min,mean,max (i0Ca) = 0.02150183 0.06645341 0.1128227
min,mean,max (iLCa) = 9.024553e-11 11511.19 39336.9
#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2 ? at ~/OpenFOAM/mattia-4.0/run/Modelli_Esempio/pemfcMultiphaseModel-4.0/pemfcMultiPhaseNonIsothermalSolver/applications/../src/tools/RiddersRoot/RiddersRoot.C:196
#3 ? at ~/OpenFOAM/mattia-4.0/run/Modelli_Esempio/pemfcMultiphaseModel-4.0/pemfcMultiPhaseNonIsothermalSolver/applications/../src/electrochemistry/totalCurrent.H:24 (discriminator 49)
#4 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#5 ? at ??:?

The flow direction is the same for the reagents (coflow) but I changed the geometry by increasing the size (22x22 --> 100x100) and inserting five serpentine channels. The reason for this error is perhaps not the same but can you give me some input on how you solved it? Or can someone else help me?

Thank you

What is the mass flow rate for anode and cathode inlet? How you have calculated?

[mat16]

Originally Posted by ramakant

What is the mass flow rate for anode and cathode inlet? How you have calculated?

Hi Ramakant,

No, I have left the mass flow rates of the base model to see what was happening and it gives me this error. Since the geometry is larger I expected the reagents to wear out immediately, in fact this error gives me it after 0.1 s. I have not calculated the new flow rates but I have increased the input speeds but it stops immediately even in this way even if I increase the speeds a lot.

[ramakant]

Originally Posted by mat16

Hi Ramakant,

No, I have left the mass flow rates of the base model to see what was happening and it gives me this error. Since the geometry is larger I expected the reagents to wear out immediately, in fact this error gives me it after 0.1 s. I have not calculated the new flow rates but I have increased the input speeds but it stops immediately even in this way even if I increase the speeds a lot.

Please assign the correct all inlet boundary condition values properly to run the code.

Thank you

[mat16]

Originally Posted by ramakant

Please assign the correct all inlet boundary condition values properly to run the code.

Thank you

Hi Ramakant,

First of all thanks for your answers.

Maybe I didn't quite understand how to change the initial data so I'll tell you what I did. I want to increase the mass flow rate because it gives me this error with the values ​​of the basic model (m_anode_model = 5.29e-06; m_cathode_model = 4.25e-05; stoichiometric ratio ζ = 8; U_anode_model=1; U_cathode_model=2.1134; Ach=2,20e-05)
I increased it by imposing a higher value (m_anode = 3.00e-04; m_cathode = 2.41e-03 keeping the same ζ = 8) and I calculated the new U_inlet that the model wants to input as:

U_inlet = m / (Ach * rho)

(U_inlet_anode = 2.320 ; U_inlet_cathode= 4.902)

with Ach the area of ​​the face in contact with the GDL

1) Is this procedure correct?

2) Changing the mass flow rate and therefore the speed, the only boundary condition that I have to change in this new case is the U in "0 / folder"?

Thank you

[ramakant]

Originally Posted by mat16

Hi Ramakant,

First of all thanks for your answers.

Maybe I didn't quite understand how to change the initial data so I'll tell you what I did. I want to increase the mass flow rate because it gives me this error with the values ​​of the basic model (m_anode_model = 5.29e-06; m_cathode_model = 4.25e-05; stoichiometric ratio ζ = 8; U_anode_model=1; U_cathode_model=2.1134; Ach=2,20e-05)
I increased it by imposing a higher value (m_anode = 3.00e-04; m_cathode = 2.41e-03 keeping the same ζ = 8) and I calculated the new U_inlet that the model wants to input as:

U_inlet = m / (Ach * rho)

(U_inlet_anode = 2.320 ; U_inlet_cathode= 4.902)

with Ach the area of ​​the face in contact with the GDL

1) Is this procedure correct?

2) Changing the mass flow rate and therefore the speed, the only boundary condition that I have to change in this new case is the U in "0 / folder"?

Thank you

Dear
You need to change the formula for velocity calculation ?

[jose.ceballos]

Hello guys;

I want to run simulations applying different temperatures (equal cell operating and reactant gases temperature). The code is set to work with 353 K, I would like to know how can I run it with different temperatures. I have tried changing different parameters related to T, but I can't pass time 1.


Thanks,

[ramakant]

Originally Posted by jose.ceballos

Hello guys;

I want to run simulations applying different temperatures (equal cell operating and reactant gases temperature). The code is set to work with 353 K, I would like to know how can I run it with different temperatures. I have tried changing different parameters related to T, but I can't pass time 1.


Thanks,

Dear

You need to calculate temperature-based transport properties like density, thermal conductivity, viscosity, etc.
All the best.

[jose.ceballos]

Originally Posted by ramakant

Dear

You need to calculate temperature-based transport properties like density, thermal conductivity, viscosity, etc.
All the best.

I did it, but still can't find convergence. pemfcMultiphaseModel-4.0 is set to 353 K and I want to run it at 313, 323, 333 and 343 K. I calculated all properties and also used values obtained from tables (I have different cases/folders for calculated and table values); but still no convergence, stops at time 1. I suppose, that I have changed all the parameters and properties affected by temperature. Stops at time 1 with bracketing error.

[NKH]

Originally Posted by ramakant

this is the error for counter flow

Hi,
I make the same problems when I try to solve the serpentine geometry. I faced this in the first step. I had checked the boundary condition but I have no idea what I was wrong.