Hello
In the following code, the "roots" command should give us 3*6 matrix with 18 values, because A and B have 6 values and the equation is 3rd order. But a 3*1 matrix with 3 values have been obtained. It seems that only one step has passed. What is the problem?
clc
clear
close all
k1 = 0.841;
k2 = 0.537;
k3 = 0.942;
k4 = 0.019;
k5 = 0.720;
T = 333.15:10:383.15;
P = 2e7:0.2e7:3e7;
Tc = 304.12;
Pc = 73.74e5;
Vc = 9.407e-5;
Zc = 0.274;
w = 0.225;
R = 8.314;
Mw = 44.01;
Tr = T/Tc;
Pr = P/Pc;
m1 = 0.2513+(0.4178*w)-(0.0207*w^2);
m2 = -0.1382-(0.5923*w)-(1.0493*w^2);
m3 = 0.1931+(1.3955*w)+(0.1961*w^2);
alpha = 1+(m1*(1-Tr))+(m2*(1-Tr).^2)+(m3*(1-Tr).^3);
n = 0.2155-(0.9069*w)-(0.206*w^2);
beta = 1+(n*(1-Tr));
a = 0.47448*(((R*Tc)^2)/Pc)*alpha;
b = 0.06824*((R*Tc)/Pc)*beta;
zarib = (k1+k2*log(Tr)+k3*log(Pr))./(1+k4*log(Tr).^2+k5*log(Pr).^2);
A = zarib.*(a.*P)./((R.*T).^2);
B = (b.*P)./(R.*T);
for u = 1:6
Root = roots([1 ...
(-1)...
(A(u)-B(u).^2-2*B(u))...
(-A(u).*B(u)-B(u).^2)]);
zmax = 0;
zmin = 1;
for r = 1:3
if imag(Root(r)) == 0
if Root(r) > 0 && Root(r) > zmax && Root(r) < 1
zmax(u) = Root(r);
end
if Root(r) > 0 && Root(r) < zmin
zmin(u) = Root(r);
end
end
end
end
vm = (zmax.*R.*T)./(P);
ro = (0.001)^2*(Mw./vm);
