MIX_FRAC-FUEL_2 in 2-step combustion
 

Hi!

I'm working on n-heptane combustion simulation applying the following two reactions:

C7H16 + 7.5O2 -> 7CO + 8H2O

CO + 0.5O2 -> CO2

As you probably know, there are MIX_FRAC-FUEL_1 and MIX_FRAC-FUEL_2 among other species whose oncentrations are calculated. As the rate model I've choosen COMBINED. The problem is that in the converged solution the temperature is very low for stoichiometric combustion (f=0.066) (about 760 K, when I expect it to be above 1200 K) and MIX_FRAC-FUEL_2 equals to zero in all the cells, while CO2 concentration is not zero. What could be the problem?

Regards,

Julie

Re: MIX_FRAC-FUEL_2 in 2-step combustion
 

Hello! You can try this option: instead 8H2O write 8H2O[r]. For Mix_frac_fuel_2 can be zero, if you have no CO in incoming fuel. I don't know why, but is not calculating it, it seems that program calls this mixture fractions for all reactions, but calculates it only for incoming fuel components. For interest, you can introduce a little CO in the fuel and it should calculate the mixture fraction. Good luck!