Modeling Surface Reaction (CVD)

grapheeene · January 25, 2017, 11:20

Hi guys,

First of all, thank you for your help. I am new in Ansys and Fluent (less than a month), hoping to learn.

I am trying to model a simple and single surface reaction

CH4 (g) -> C(s) + 2H2 (g)

on a "CVD reactor" to grow C(s) (graphene, or graphite). The inlets are gases inyections of Ar and CH4 at the top of the CVD, and two thin parallel Cu surfaces are in the center (the catalyst), where C would be deposited. I am trying to model the growth of C(s) and the amount of H2 on the entire region, with and without thermodifussion (Soret).

The question is that I have some trouble with setting up the mixture and the reaction. I have a confusion with 'site' and 'solid' species in this case, and with reactions and mechanisms (since it's only superficial). I need the system to stop generating H2 when the surface is full of C(s).

Can you guys give me some basic steps to start this?? I don't know how to get the adsorption done. Do I need another reaction??

I guess this problem is not hard to be solved. Thanks so much for your help!!

grapheeene · January 27, 2017, 10:51

My model with and without thermodifussion result in the same profile for H2 mole fraction for steady state.. I think this is wrong, because I should find more H2 moles near heated surfaces with thermodif.

I guess I am giving Fluent a wrong reaction and it never stops. Anyone who knows this type of problems??

January 25, 2017, 11:20	Modeling Surface Reaction (CVD)	#1
grapheeene New Member Felipe Costa Join Date: Jan 2017 Posts: 4 Rep Power: 9	Hi guys, First of all, thank you for your help. I am new in Ansys and Fluent (less than a month), hoping to learn. I am trying to model a simple and single surface reaction CH4 (g) -> C(s) + 2H2 (g) on a "CVD reactor" to grow C(s) (graphene, or graphite). The inlets are gases inyections of Ar and CH4 at the top of the CVD, and two thin parallel Cu surfaces are in the center (the catalyst), where C would be deposited. I am trying to model the growth of C(s) and the amount of H2 on the entire region, with and without thermodifussion (Soret). The question is that I have some trouble with setting up the mixture and the reaction. I have a confusion with 'site' and 'solid' species in this case, and with reactions and mechanisms (since it's only superficial). I need the system to stop generating H2 when the surface is full of C(s). Can you guys give me some basic steps to start this?? I don't know how to get the adsorption done. Do I need another reaction?? I guess this problem is not hard to be solved. Thanks so much for your help!!

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January 27, 2017, 10:51		#2
grapheeene New Member Felipe Costa Join Date: Jan 2017 Posts: 4 Rep Power: 9	My model with and without thermodifussion result in the same profile for H2 mole fraction for steady state.. I think this is wrong, because I should find more H2 moles near heated surfaces with thermodif. I guess I am giving Fluent a wrong reaction and it never stops. Anyone who knows this type of problems??