# Help me for the simulation on hydrogen/air combustion

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 April 13, 2009, 15:59 Help me for the simulation on hydrogen/air combustion #1 New Member   xulixian Join Date: Apr 2009 Posts: 4 Rep Power: 9 I am puzzled by the simulation of H2/air combustion using CFX. I could not get the expected temperature, the maximum flame temperature is always below 980K. I use stoichiometric mixture of hydrogen and air, but after the reaction, their always a lot of O2 left. It looks like a lean combustion. And the in the beginning of the simulation, CFX tell me " Reactants and products do not balance for a reaction. | Products will not be scaled for conservation of mass. | | | | Reaction : Hydrogen Oxygen | | Products scale = 2.7750 " My reaction chamber is a tube with 0.2 mm in diameter and 1.55mm in length, the inlet diameter is 0.1mm. Adiabatic wall condition.The boundary is the following: Inlet: 300K, 6 m/s, Mass fraction H2: 0.02857 O2: 0.22857 N2: constraint, Outlet: static pressure 1 bar Initial temperature: 1000K I use the default stoichiometric coefficient, so the reaction is H2 + 0.5 O2 = H2O, Pre-Exponential Factor : 3.12e7 [m^1.5 s^-1 mol^-0.5] **(the value in Fluent is 9.87e8, I change the value since I have to switch the uint from "kmol" in Fluent to "mol" in CFX.) Temperature Exponent : 0 Activation Energy : 3.1e+04 j/mol. In the begining of the simulation, I use the time step of 1 e-7 s, then I increase the time step to 1 e-5 s. Can you help me to diagnose the simulation? I appreciate for your help. Last edited by xulixian; April 14, 2009 at 03:27.

 April 16, 2009, 15:57 #2 Senior Member   Join Date: Mar 2009 Location: Europe Posts: 168 Rep Power: 9 Are the stoichiometric coefficients balanced?

 Tags combustion, hydrogen, oxygen

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