Stability Testing #2
Description
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.