This page contains engine performance specifications and scripts for determining engine exhaust composition.
Engine Performance Specifications (XLSX)
Main program to call exhaust_compo and plots results: exhaust_compo_main.m
%main driver for exhaust_compo
%Gasoline CHmOn;
m=1.87;n=0;
Lambda=[0.6:0.1:1.4];
[xco2,xh2o,xco,xh2,xo2,xn2]=exhaust_compo(m,n,Lambda);
h=plot(Lambda,[xco2,xh2o,xco,xh2,xo2],'-');
xlabel('\lambda');
ylabel('Exhaust Mole fractions');
legend('CO2','H2O','CO','H2','O2');
Function subroutine to calculate the composition: exhaust_compo.m
function [xco2,xh2o,xco,xh2,xo2,xn2]=exhaust_compo(m,n,Lambda);
%calculate xhaust mole fractions
%For lean to stoichiometric combustion, assume complete burning
%For rich combustion, assume water gas equilibrium constant k=3.7
%Input: m,n are the hydrogen and oxygen to carbon ratios of the fuel
%Input: Lambda is the column vector of air equilvalence ratio
%Ouput are the mole fractions of the exhaust composition
k=3.7;
nL=length(Lambda);
xco2=zeros(nL,1);
xco=zeros(nL,1);
xh2o=zeros(nL,1);
xh2=zeros(nL,1);
xo2=zeros(nL,1);
xn2=zeros(nL,1);
for i=1:nL;
L=Lambda(i);
if (L<=0);error('Lambda must be positive');end;
if(L>=1);%=============== Lambda >=1 ==================
z=1+0.25*m-0.5*n;
Lm1=L-1;
co=0;h2=0;co2=1;h2o=0.5*m;
n2=z*3.773*L;
o2=Lm1*z;
else; %=============== Lambda < 1 ==================
z=n*(1-L)+2*L*(1+0.25*m);
B=2+(0.5*m-1)*k-(1-k)*z;
A=0.5*m*(1-k);
C=k*(1-z);
b=(-B+sqrt(B.*B-4*A*C))/(2*A);
a=b./(k+(1-k)*b);
co2=a;
co=1-a;
h2o=0.5*m*b;
h2=0.5*m*(1-b);
n2=(1+0.25*m-0.5*n)*3.773*L;
o2=0;
end %=============================================
total=co+h2+co2+h2o+n2+o2;
xco(i)=co./total;
xh2(i)=h2./total;
xco2(i)=co2./total;
xh2o(i)=h2o./total;
xo2(i)=o2./total;
xn2(i)=n2./total;
end