Effect of Equivalence Ratio and number of carbon atoms on Adiabatic Flame Temperature

PART 1: Effect of Equivalence ratio on Adiabatic Flame Temperature( Constant Volume) with CH4 as the fuel

1) Without using CanteraAa

A simple Python program was written to find out the effect of equivalence ratio on AFT. The data was taken from GRI MECH (Berkeley\'s website). No dissociation of products is assumed to take place and coefficients of products have been obtained by simple hand calculations. Two cases were considered:

1. Equivalence ratio less than 1: In such a case, the air is present in excess and as a result of this, excess oxygen is present on the product side.

2. Equivalence ratio greater than 1: In this case, fuel is present in abundance compared to the stoichiometric composition. As a result of this, whole of the carbon in the fuel does not get oxidized to CO2 and some amount of CO is present on the product side as a consequence.

As evident from the above plot, the adiabatic flame temperature increases as the equivalence ratio increases from 0.5 to 1 and falls thereafter, suggesting that a stoichiometric combustion provides the maximum AFT.

2) Using Cantera:

As it is evident from the two plots above, the AFT calculated by using Cantera is slightly lower than the AFT calculated without using Cantera. The reason for this is that Cantera assumes that a number of products are formed. And formation of products takes/consumes some of the heat of reaction, thus adiabatic flame temperature is slightly lower. Also, the AFT reaches a maximum when equivalence ratio is aroun 1.1. This suggests that a slightly lean combustion would yield maximum AFT.

PART 2: Effect of number of carbon atoms in alkane on Adiabatic Flame Temperature (Constant Pressure)

A simple Python program was written to find out the effect of equivalence ratio on AFT. The data was taken from GRI MECH (Berkeley\'s website). No dissociation of products is assumed to take place and the combustion is assumed to be stoichiometric. Number of carbon atoms in alkane have been varied from 1 to 3 i.e. Methane, Ethane and Propane have been used. The plot suggests that with increasing the number of carbon atoms/ for higher alaknes, the AFT goes on increasing. This combustion is assumed to be constant pressure combustion without heat loss as stated in the problem.

Link for the Python programs is given below:

https://drive.google.com/open?id=1zUE6P3Baj0Jnn8oJsxjqjFENUXKWzLp9