Methods in the cubic class
ThermoPack - 2.1.0
The cubic class, found in addon/pycThermopack/thermopack/cubic.py, is the interface to the
Cubic Equation of State. This class implements utility methods to access mixing parameters etc.
The sections Initialiser keys, Pure fluid α, α mixing rules and β mixing rules summarise the various valid input keys that can be used to modify mixing rules, the &alpha -parameter and the underlying EoS.
Documentation for the methods in the cubic class is found in the remaining sections, summarised in the table of contents below.
Table of contents
Initialiser keys
| Model | Input key |
|---|---|
| Van der Waal | VdW |
| Soave Redlich Kwong | SRK |
| Peng Robinson | PR |
| Schmidt-Wensel | SW |
| Patel Teja | PT |
| Translated consistent PR | tcPR |
Pure fluid α
| Model | Input key |
|---|---|
| Model default (*) | Classic |
| Twu-Coon-Bluck-Cunninghan | TWU |
| Mathias-Copeman | MC |
| Graboski and Daubert | GD |
| Redlich-Kwong | RK |
| Soave | Soave |
| Peng Robinson 76 | PR |
| UMR α formulation | UMR |
| Peng Robinson 78 | PR78 |
| Van der Waal | VdW |
| Schmidt-Wensel | SW |
| Patel Teja | PT |
(*) Will use original α for specified EOS. E.g. SRK will use Soave α, Peng-Robinson will use PR α etc.
α mixing rules
- van der Waals
- Huron-Vidal/NRTL
- UNIFAC.pdf
- WongSandler.pdf
| Model | Input key |
|---|---|
| Van der Waal | Classic or vdW |
| Huron-Vidal | HV or HV2 |
| Wong-Sandler | WS |
| NRTL | NRTL |
| UNIFAC | UNIFAC |
β mixing rules
- ….
Constructor
Methods to initialise Cubic model.
Table of contents
__init__(self, comps=None, eos=None, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Initialize cubic model in thermopack Unless both ‘comps’ and ‘eos’ parameters are specified, model must be initialized for specific components later by direct call to ‘init’. Model can at any time be re-initialized for new components or parameters by direct calls to ‘init’
Args:
comps (str, optional):
Comma separated list of component names
eos (str, optional):
Equation of state (SRK, PR, …)
mixing (str, optional):
Mixture model. Defaults to “vdW”.
alpha (str, optional):
Alpha model. Defaults to “Classic”.
parameter_reference (str, optional):
Which parameters to use?. Defaults to “Default”.
init(self, comps, eos, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Initialize cubic model in thermopack
Args:
comps (str):
Comma separated list of component names
eos (str):
Equation of state (SRK, PR, …)
mixing (str, optional):
Mixture model. Defaults to “vdW”.
alpha (str, optional):
Alpha model. Defaults to “Classic”.
parameter_reference (str, optional):
Which parameters to use?. Defaults to “Default”.
Utility methods
Set- and get methods for interaction parameters, mixing parameters …
Table of contents
get_ci(self, cidx)
Get volume correction parameters
Args:
cidx (int):
Component index
Returns:
ciA (float):
Volume shift param of component cidx (m3/mol)
ciB (float):
Volume shift param of component cidx (m3/mol/K)
ciC (float):
Volume shift param of component cidx (m3/mol/K^2)
ci_type (int):
Volume shift type (CONSTANT=1, LINEAR=2, QUADRATIC=3)
get_covolumes(self)
Get component covolumes (L/mol)
Returns:
np.ndarray:
Component covolumes (L/mol)
get_energy_constants(self)
Get component energy constants in front of alpha. (Pa*L^2/mol^2)
Returns:
np.ndarray:
Component energy constants in front of alpha. (Pa*L^2/mol^2)
get_hv_param(self, c1, c2)
Get Huron-Vidal parameters
Args:
c1 (int):
Component one
c2 (int):
Component two
Returns:
alpha_ij (float):
alpha param i-j
alpha_ji (float):
alpha param j-i
a_ij (float):
a param i-j
a_ji (float):
a param j-i
b_ij (float):
b param i-j
b_ji (float):
b param j-i
c_ij (float):
c param i-j
c_ji (float):
c param j-i
get_kij(self, c1, c2)
Get attractive energy interaction parameter kij, where aij = sqrt(aiaj)(1-kij)
Args:
c1 (int):
Component one
c2 (int):
Component two
Returns:
kij (float):
i-j interaction parameter
get_lij(self, c1, c2)
Get co-volume interaction parameter lij, where bij = 0.5(bi+bj)(1-lij)
Args:
c1 (int):
Component one
c2 (int):
Component two
Returns:
lij (float):
i-j interaction parameter
get_ws_param(self, c1, c2)
Get Wong-Sandler parameters
Args:
c1 (int):
Component one
c2 (int):
Component two
Returns:
alpha_ij (float):
alpha param i-j
alpha_ji (float):
alpha param j-i
k_ij (float):
k param i-j
k_ji (float):
k param j-i
tau_ij (float):
tau param i-j
tau_ji (float):
tau param j-i
set_ci(self, cidx, ciA, ciB=0.0, ciC=0.0, ci_type=1)
Set volume correction parameters
Args:
cidx (int):
Component index
ciA (float):
Volume shift param of component cidx (m3/mol)
ciB (float):
Volume shift param of component cidx (m3/mol/K)
ciC (float):
Volume shift param of component cidx (m3/mol/K^2)
ci_type (int):
Volume shift type (CONSTANT=1, LINEAR=2, QUADRATIC=3)
set_hv_param(self, c1, c2, alpha_ij, alpha_ji, a_ij, a_ji, b_ij, b_ji, c_ij, c_ji)
Set Huron-Vidal parameters
Args:
c1 (int):
Component one
c2 (int):
Component two
alpha_ij (float):
alpha param i-j
alpha_ji (float):
alpha param j-i
a_ij (float):
a param i-j
a_ji (float):
a param j-i
b_ij (float):
b param i-j
b_ji (float):
b param j-i
c_ij (float):
c param i-j
c_ji (float):
c param j-i
set_kij(self, c1, c2, kij)
Set attractive energy interaction parameter kij, where aij = sqrt(aiaj)(1-kij)
Args:
c1 (int):
Component one
c2 (int):
Component two
kij (float):
i-j interaction parameter
set_lij(self, c1, c2, lij)
Set co-volume interaction parameter lij, where bij = 0.5(bi+bj)(1-lij)
Args:
c1 (int):
Component one
c2 (int):
Component two
lij ([type]):
[description]
set_ws_param(self, c1, c2, alpha_ij, alpha_ji, k_ij, k_ji, tau_ij, tau_ji)
Set Wong-Sandler parameters
Args:
c1 (int):
Component one
c2 (int):
Component two
alpha_ij (float):
alpha param i-j
alpha_ji (float):
alpha param j-i
k_ij (float):
k param i-j
k_ji (float):
k param j-i
tau_ij (float):
tau param i-j
tau_ji (float):
tau param j-i