Stability Testing - Githubissues

Dear Ali,

I am very grateful to study PVTtool. Here I have a question. When I run code of the 'testcase2':

% test case
% liquid-two-phase phase transition
clc; clear;
% Define the components and load pure physsical properties
[component, comp_flag] = addComponents({'CH4', 'C2H6', 'C4H10', ...
'C6H14', 'C10H22', 'C15H32'});
% Define the thermodynamic models
T0 = 300; % [K]
p0 = 100e5; % [Pa]
thermo1 = addThermo();
thermo1.EOS = @PREOS;
mixture1 = addMixture(component, T0, p0);
% Define flash options
options.accuracy = 1e-7;
options.iteration = 100;
% Negative flash
[vapor_y, liquid_x, vapor_frac] = ...
        vleflashnegative(mixture1, thermo1, options)
%mixture1.temperature=T_range(i);
[liquid_z, vapor_z, fugacity, HR] = PREOS(mixture1, thermo1)    

[s1, sl, sv] = stabilityTest(mixture1, thermo1)

I found that the result is:

vapor_y =

    0.8653    0.1097    0.0198    0.0048    0.0004    0.0000

liquid_x =

    0.4053    0.1472    0.1165    0.1114    0.1099    0.1097

vapor_frac =

   -0.5188

liquid_z =

    0.5924

vapor_z =

    0.5924

fugacity =

    1.9419    0.3795    0.0352    0.0037    0.0001    0.0000

HR =

  -3.0503e+04

s1 =

     1     1

sl =

    0.9910

sv =

    1.0000

The problem is

s1 =

     1     1

that means it converged to trivial solution. If so, the system is single-phase but the simulation gives me two phase data. I think this code did not implement stability analysis to flash calculation directly. If it is problem, I would be happy to help modify this model.

Thank you so much.

simulkade / PVTtool

Stability Testing #2