Adiabatic Flame Temperature calculation

Objective:

• Write a program for calculating adiabatic flame temperature (AFT) of methane combustion at a constant volume chamber using python and compare the values with Cantera.
• Calculate the AFT for general hydrocarbon (CxHy) at a constant pressure reactor with heat loss.

Equivalence ratio`(phi)`:

Air–fuel ratio is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process.

Equivalence ratio`(phi)`=`(FAR)/(FAR)_(st oich)`

`phi=1` Stoichiometric

`phi<1` Lean mixture

`phi>1` Rich mixture

Constant volume

From the first law of thermodynamics for a closed reacting system we have,

Where RQP and RWP are the heat and work transferred from the system to surroundings during the process.Up and Ur are the internal energy of the products and reactants respectively, in the constant volume adiabatic flame temperature case, the volume of the system is held constant hence there is no work occurring,

and there is no heat transfer because the process is defined to be adiabatic RQP=0 As a result, the internal energy of the products is equal to the internal energy of the reactants

`U_p=U_r`

Constant pressure

Again there is no heat transfer occurring because the process is defined to be adiabatic RQP=0

`H_P=H_R`

Result:

Adiabatic flame temperature vs equivalence ratio of methane combustion(Constant volume):

`CH4+2(O_2+3.76N_2)rightarrowCO_2+2 H_2O+3.76N_2` Stoichiometric combustion

`CH4+a(O_2+3.76N_2)rightarrowCO_2+a H_2O+3.76N_2+O_2` Lean mixture

`CH4+a(O_2+3.76N_2)rightarrowCO_2+a H_2O+3.76N_2+CO` Rich mixture

The maximum adiabatic flame temperature occurs not at stoichiometric but rather slightly rich equivalence ratio. It is because of the heat of combustion and heat capacity of products declining beyond `phi=1`. For equivalence ratios between `phi=1` and `phi(T_max)` the heat capacity decreases more rapidly with `phi` than `Delta H_c`.

Python code:https://drive.google.com/file/d/12oK_gMfzUFayNbNsfhVNjcGdwl12bC4Q/view?usp=sharing

AFT vs heat loss methane combustion (Constant pressure)

AFT of CH4 with H_loss of 0.35 =2286.222K

Python code:https://drive.google.com/file/d/19ID6A_TU-acMVpm_ytIri6e34NVa0ExN/view?usp=sharing

Comparison of AFT (Ethane, Ethene, Ethyne)

Adiabatic flame temperature is in the order of alkane<alkene

Python code:https://drive.google.com/file/d/12_-o6Z0FkHfCg-7W-5dhoDp3faa_u6jY/view?usp=sharing

AFT vs Number of carbon atoms in alkane

Adiabatic flame temperature increases with the increase in the number of carbon in alkane. The order of adiabatic flame temperature is in Methane>Ethane>Propane.

Python code:https://drive.google.com/file/d/1IzxlrJ5WJvIesPcWnxPcecJiqYmd34QL/view?usp=sharing