% Following is a function which performs Dew T calculation for
% Water-Ethanol system using Raoults LAw
% Similar Method can be followed for Modified Raoults Law and Dew P, Bubble
% P, Bubble T calculations
function F=system(x,a)
% Specie 1 is water and specie 2 is ethanol
%x(1) is x1
%x(2) is x2
%x(3) is y1
%x(4) is y2
%x(5) is T
%x(6) is P
%x(7) is P1sat
%x(8) is P2sat
F(1)= exp(x(7))==(16.3872-((3885.70)/(x(5)+230.170)));% Water Antoine Equation
F(2)= exp(x(8))==(16.8958-((3795.17)/(x(5)+230.918))); % Ethanol Antoine Equation
F(3)= x(1)*x(7)- x(3)*x(6); % Raoiults Law for water
F(4)= x(2)*x(8)- x(4)*x(6); % Raoiults Law for Ethanol
F(5)= x(1)+x(2)-1; % fractions reation to each other
F(6)=x(3)+ x(4)-1; % fractions reation to each other
F(7)=x(6)-(200); % input of Pressure
F(8)=x(3)-a; % input of y1
% number of variables are now equal to number of equations
a=0:0.1:1;
for ct = 1:numel(a)
x0 = [0.5,0.5,0.5,0.5,273,100,200,200];
options = optimoptions('fsolve','Display','iter');
x(ct,:)= fsolve(@(x)system(x,a(ct)),x0)
end
for i=1:1:10
xvalue(1,i)=x(i,4);
yvalue(1,i)=x(i,2);
end
plot(xvalue,yvalue)
Error:
Index exceeds matrix dimensions. Error in Sample13 (line 16) F(1)= exp(x(7))==(16.3872-((3885.70)/(x(5)+230.170)));% Water Antoine Equation
