Mass Imbalance in Reaction Stoichiometry in FLUENT

Jenny_W · September 1, 2012, 20:33

Dear All
I'm simulating a simple chemical reaction HCl + NaOH ==> NaCl + H2O.

I create reaction mechanism files in CHEMKIN format and import them into FLUENT. However FLUENT shows "warning: mass imbalance in reaction-1 stoichiometry" and I am confused since the reaction is already balance.

Another problem is that along the centreline of my domain, the concentration of NaOH increases beyond the original concentration at the inlet. This is not realistic. The NaOH concentration should be lower than the concentration at the inlet because some of NaOH has been converted to the products.

I do not know what the problem is. If anyone has any idea or suggestion please kindly advise.
Thank you,
Jenny

sir · September 16, 2012, 23:23

Hi Jenny..

I also got the same warning..I already check the stoichiometry; and it is balance..If you hv any idea, hope u don't mind to share...and i will struggle to find out the solution..

C u

sirly

Jenny_W · September 17, 2012, 06:54

Hi Sirly,
I'm sorry I still cannot find the solution to this. If I can solve the problem, I will let you know

Jenny

epc1 · September 17, 2012, 12:57

Hello, i´ve had this problem sometimes in the past.

I´d recommend to check the Molecular wieghts of the species involved in the reactions, in the materials panel.

Jenny_Wong · September 18, 2012, 12:01

I'll do that. Thank you very much Ernesto.

danielet82 · October 28, 2013, 08:32

Hello, I experienced the same problem and I couldn't initialize the domain and run the simulation. I checked the molecular weights of the species involved in the reaction and it can be initialized and it gives good convergence despite the fact that the same message appears.

September 1, 2012, 20:33	Mass Imbalance in Reaction Stoichiometry in FLUENT	#1
Jenny_W Member Jenny Join Date: Apr 2011 Posts: 34 Rep Power: 15	Dear All I'm simulating a simple chemical reaction HCl + NaOH ==> NaCl + H2O. I create reaction mechanism files in CHEMKIN format and import them into FLUENT. However FLUENT shows "warning: mass imbalance in reaction-1 stoichiometry" and I am confused since the reaction is already balance. Another problem is that along the centreline of my domain, the concentration of NaOH increases beyond the original concentration at the inlet. This is not realistic. The NaOH concentration should be lower than the concentration at the inlet because some of NaOH has been converted to the products. I do not know what the problem is. If anyone has any idea or suggestion please kindly advise. Thank you, Jenny

September 16, 2012, 23:23	Same problem...	#2
sir New Member sirly Join Date: Apr 2011 Posts: 3 Rep Power: 15	Hi Jenny.. I also got the same warning..I already check the stoichiometry; and it is balance..If you hv any idea, hope u don't mind to share...and i will struggle to find out the solution.. C u sirly

September 17, 2012, 12:57		#4
epc1 Member Ernesto Join Date: Dec 2011 Posts: 30 Rep Power: 15	Hello, i´ve had this problem sometimes in the past. I´d recommend to check the Molecular wieghts of the species involved in the reactions, in the materials panel. Jenny_Wong and jumaah like this.

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September 17, 2012, 06:54		#3
Jenny_W Member Jenny Join Date: Apr 2011 Posts: 34 Rep Power: 15	Hi Sirly, I'm sorry I still cannot find the solution to this. If I can solve the problem, I will let you know Jenny

September 18, 2012, 12:01		#5
Jenny_Wong New Member Jenny Join Date: Jan 2012 Posts: 11 Rep Power: 14	I'll do that. Thank you very much Ernesto.

October 28, 2013, 08:32		#6
danielet82 New Member Daniel Sebastià Sáez Join Date: Mar 2012 Posts: 15 Rep Power: 14	Hello, I experienced the same problem and I couldn't initialize the domain and run the simulation. I checked the molecular weights of the species involved in the reaction and it can be initialized and it gives good convergence despite the fact that the same message appears.