% Authors: Nasri Zakia and Housam Binous
% VLE diagram of Ethane-Benzene binary mixture at 175�C
function f=PT2(x)
global z
phi=0;
Pc=[709.8 714.2];
Tc=[550.0 1012.7];
w=[0.1064 0.2116];
T=347+459.67;
Tre=T./Tc;
Pre=x(5)./Pc;
m=0.480+1.574.*w-0.176.*w.^2;
a=(1+m.*(1-Tre.^0.5)).^2;
Ap=0.42747.*a.*Pre./Tre.^2;
Bp=0.08664.*Pre./Tre;
for i=1:2
for j=1:2
Ab(i,j)=(Ap(i)*Ap(j))^0.5;
end
end
Av=0;
for i=1:2
for j=1:2
Av=Av+x(i+2)*x(j+2)*Ab(i,j);
end
end
Bv=0;
for i=1:2
Bv=Bv+x(i+2)*Bp(i);
end
Bl=0;
for i=1:2
Bl=Bl+x(i)*Bp(i);
end
Al=0;
for i=1:2
for j=1:2
Al=Al+x(i)*x(j)*Ab(i,j);
end
end
Zv=max(roots([1 -1 Av-Bv-Bv^2 -Av*Bv]));
Zl=min(roots([1 -1 Al-Bl-Bl^2 -Al*Bl]));
phiv=exp((Zv-1).*Bp/Bv-log(Zv-Bv)...
-Av/Bv*log((Zv+Bv)/Zv).*(2.*Ap.^0.5./Av^0.5-Bp./Bv));
phil=exp((Zl-1).*Bp/Bl-log(Zl-Bl)...
-Al/Bl*log((Zl+Bl)/Zl).*(2.*Ap.^0.5./Al^0.5-Bp./Bl));
K=phil./phiv;
for i=1:2
f(i)=x(i+2)-K(i)*x(i);
end
for i=1:2
f(i+2)=x(i)-z(i)/(1+phi*(K(i)-1));
end
f(5)=0;
for i=1:2
f(5)=f(5)+z(i)*(K(i)-1)/(1+phi*(K(i)-1));
end
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