# N-heptane burning: Kinetic mechanism parameters

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 June 28, 2004, 02:36 N-heptane burning: Kinetic mechanism parameters #1 Julie Polyakh Guest   Posts: n/a Hello! I'm modeling one-step n-heptane combustion. C7H16 + 11O2 -> 7CO2 + 8H2O Does somebody know what are the units and values of pre-exponential factor and activation energy? Rate coefficients also wellcomed Regards, Julie

 June 28, 2004, 05:48 Re: N-heptane burning: Kinetic mechanism parameter #2 4xF Guest   Posts: n/a Remember that STAR-CD uses seconds, meters, kilograms and Joules for the units. Concerning your question, take a look to the methodology guide page 10-4. Remember that the scalars are mass fractions (and no concentrations defined as volumetric fractions -- with the exception of the VOF scalar), so the scalar unit is [kg/kg]. Hope this helps.

 June 28, 2004, 07:02 The answer #3 Julie Polyakh Guest   Posts: n/a This is the answer I got from the support: It is good practice to be consistent with units when inputting data. To this end I would recommend ensuring that the value you use for Activation energy is in j/kg-mol and that the value for the pre-exponential factor (A) is consistent with SI units (i.e. units of reaction rate are kg/m3-s). I am not sure if the values you quote are reasonable but I have attached some values in SI units for the combustion of n-heptane in air that you may wish to compare with your own data: Pre-exponential Factor: 2.868e+9 Activation Energy: 1.256e+8 (j/kg-mol) Rate Exponent (a): 0.25 Rate Exponent (b): 1.5

 June 28, 2004, 09:32 Re: N-heptane burning: Kinetic mechanism parameter #4 Panos Guest   Posts: n/a The activation energy has units of Kcal/kmolK but you might change the Kcal units to joules since STARCD uses the international system of units

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