fenvelopes: Phase diagrams with Equations of State.

This is an ongoing project that intends te be a fully fledged generator of phase equilibria diagrams from multicomponent systems, using Equations of State.

Capabilities

Right now fenvelopes calculates three kinds of phase-envelopes.

• Two-phase PT envelopes
• Three-phase PT envelopes
  • PT envelopes based on double saturation points.
  • Isolated PT envelopes
• DSP lines:
  • DSP lines from a PT DSP
• Two-phase Px envelopes
• Three-phase Px envelopes
  • Px envelopes based on double saturation points.
  • Isolated Px envelopes:
    • Isolated Px from PT
    • Isolated Px from search
• Python wrappers to ease up scripting and plotting.

Usage

This program is intended to be used as a CLI software. The command used to calculate phase diagrams is:

fenvelopes --infile input_file.nml

This will generate an fenvelopes_output directory. Which contains all the generated output files with the relevant data.

Input files

The input files

! input.nml
!
! Namelist based input file
! =========================
!
! Units:
!  - Pressure: bar
!  - Temperature: K
!  - Volume: L
! =========================


&nml_setup
    ! General settings
    nc=5,                ! Number of components
    model="PR78",        ! SRK PR76 PR78
    mixrule="ClassicVdW" ! only ClassicVdW for now
/

&nml_composition
    names="PC1" "PC2" "PC3" "PC4" "H2O"
    spec="critical", ! critical or parameters specification
    z=0.15 0.10 0.10 0.15 0.50
/

&nml_classicvdw ! Classic VdW mixing rule parameters
    ! kij matrix
    kij(1, :)=0      0      0      0      0.7192
    kij(2, :)=0      0      0      0      0.4598
    kij(3, :)=0      0      0      0      0.2673
    kij(4, :)=0      0      0      0      0.2417
    kij(5, :)=0.7192 0.4598 0.2673 0.2417 0
    
    ! lij matrix
    lij(:, :) = 0
/

&nml_critical
    ! Critical constants
    
    ! Critical Temperature
    tc=305.586 638.889 788.889 838.889 647.3
    
    ! Critical Pressure
    pc=48.82 19.65 10.2 7.72 220.89

    ! Acentric Factor
    w=0.098 0.535 0.891 1.085 0.344
/

&nml_px ! Px envelopes relevant info
    ! Temperature
    T=350.0
    
    ! Initial composition, ussualy the same as the main fluid.
    z_0=0.15 0.10 0.10 0.15 0.50 
    
    ! Injection fluid composition
    z_injection=1 0 0 0 0

    ! Which kind of injection to realize
    injection_case="displace" ! [dilute|displace]
/

Output

All the output is directed to a generated folder fenvelopes_output. With the files

env-<nphases>ph-<env_kind>_<envnumber>.dat

Were all the envelope's calculated points are written in a csv-like format, delimited by spaces.

Installation

This program uses fpm as a builder. fpm handles all the needed dependencies and compiling procedures. It is distributed in many ways, but we recommend the pip distribution.

# using pipx
pipx install fpm

To install this program is as simple as:

git clone https://www.github.com/fedebenelli/envelopes
cd envelopes
fpm install --profile release

This will make fenvelopes accessible from any directory of your computer

If you don't want to install the program and just run it you can also run it with fpm

fpm run --profile release -- --infile <infile.nml PATH>