Re: Ethane combustion: model for CFD


"Allamarein" <matteo.diplomacy@xxxxxxxxx> wrote in message
news:ad854765-2059-41e0-ace1-e13a84c93445@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I found a very accurate model to ethane combustion.
It runs very well in CHEMKIN.
However too many reactions and species don't allow me to run in a CFD
software as Fluent.

Anyone know an easy mechanism that predict pretty well flame
temperature and CO2, H2O, C2H6 and O2?

The answer is "It Depends". If you just want an overall flame temperature,
then it isn't too hard. If you need the flame temperature at any given
point, then the answer is possibly "no".

Look at your basic reaction equation: fuel + oxygen = heat + CO2 + H2O.
I'll let you balance that out.

Next step. Recognize that oxygen is generally supplied with run of the mill
air, which is about 79% nitrogen. There is also some water in the air, but
we'll forget that fact for now.

Add nitrogen to your equation in the proper quantities:

Fuel + O2 + N2 = heat + H2O + CO2 + N2 all hot)

Next, find the heat of combustion of your fuel. That is the heat of
formation of the fuel, minus the heat of formation of the CO2 and H2O.

Now, all that net heat is going to warm the products plus the nitrogen up to
their final temperature.
Using an equation or perhaps a set of equations for the enthalpy of CO2,
H2O, and N2, find the temperature at which the enthalpy increases (from the
starting temperate) equals the net heat of combustion, and you basically
have your flame temperature.

Note that if you add excess air, you have to heat that up too.

Now, if you want to do that for any point in the flame, then you basically
do the same thing, except recognize that the products of one reaction are
the reactants in the next one, and that the distance from the nozzle at
constant velocity is basically a time dimension. At any given distance
(under a stable flame and continuous conditions) the same reactions are
taking place.

Michael

Michael


.

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