Stoichiometric Combustion Calculator for Alkane, Alkene and Alkyne fuels.

Stoichiometric Combustion Calculator for Alkane, Alkene and Alkyne fuels.

Stoichiometric or Theoretical Combustion is the ideal combustion process where fuel is burned completely.

A complete combustion is a process burning all the carbon (C) to (CO₂), all the hydrogen (H) to (H₂O) and nitrogen (N₂).

With unburned components in the exhaust gas such as C, H₂, CO, the combustion process is uncompleted and not stoichiometric .

The combustion process can be expressed:

Here

n = Number of moles of C

ar = Stoichiometric co-efficient

a = Number of moles of Carbon-di-oxide

b = Number of moles of water

c = Number of moles of nitrogen

For Alkane, the combustion equation is as;

For Balancing the equation,

a=n (C...Balance)

b=n+1 (H2...Balance)

c=ar (N2...Balance)

ar=a+b/2 = n+(n+1)/2 (O2...Balance)

ar=(3n+1)/2

For Alkene, the combustion equation is as;

CnH2n + ar(O2 + 3.76N2) = aCO2 + bH2O + CN2

For Balancing the equation,

ar=a+b/2 = n+n/2 = 3n/2

ar=(3n)/2

For Alkyne, the combustion equation is as;

CnH2n-2 + ar(O2 + 3.76N2) = aCO2 + bH2O + CN2

For Balancing the equation,

ar=a+b/2 = n+(n-1)/2 = (3n-1)/2

ar=(3n-1)/2

The program was run on Matlab for Carbon atoms ranging form 1 to 10 for all alkanes, alkenes and alkynes and it was noted that the stochiometric ratio varied Linearly with carbon moles. Also, alkanes need more air than alkenes, which need more air than alkynes.

Matlab Code:

clear all
close all
clc

% ar = Stoichiometric Co-efficient
% a = no. of moles of carbon-di-oxide
% b = no. of moles of water
% c = no. of moles of nitrogen
%n = no. of moles
n = 1:10;

%for alkane;
% CnH2n+2 + ar*(O2 + 3.76*N2) = a*CO2 + b*H2O + CN2
% balancing the equation;
% a = n     (C...Balance)
% b = n+1   (H2...Balance)
% c = ar    (N2...Balance)
% ar = a + b/2 = n+(n+1/2) = (3*n+1)/2  (O2...Balance)
ar_alkane = (3*n+1)/2;

%for alkene;
% CnH2n + ar*(O2 + 3.76*N2) = a*CO2 + b*H2O + CN2
%ar = a + b/2 = n+n/2 = 3n/2
ar_alkene = (3*n)/2;

%for alkyne;
% CnH2n-2 + ar*(O2 + 3.76*N2) = a*CO2 + b*H2O + CN2
% ar = a + b/2 = n + (n-1)/2 = (3n-1)/2
ar_alkyne = (3*n-1)/2;

%plotting
plot (n,ar_alkane,'r',n,ar_alkene,'b',n,ar_alkyne,'g')
legend('alkane','alkene','alkyne')

%labelling
xlabel('No. of moles of Carbon')
ylabel('Stoichiometric coefficient')

Output:

The below graphy shows the variation of Stochiometric Coefficient with Number of moles of Carbon.