Methods in the cubic class
ThermoPack - 2.2
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.
In addition to the cubic class, there are several convenience classes to give easy access to specific cubic equations of state. 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 α -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.
Input keys
Specific cubics
Table of contents
Parent class “cubic”
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
- ….
SoaveRedlichKwong
Interface to the SoaveRedlichKwong EoS
__init__(self, comps, mixing='vdW', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='SRK'.
RedlichKwong
Interface to the RedlichKwong EoS
__init__(self, comps, mixing='vdW', alpha='RK', parameter_reference='Default', volume_shift=False)
Convenience class for Redlich-Kwong, calls the cubic constructor. Set alpha=Soave in order to get SRK model.
VanDerWaals
Interface to the VanDerWaals EoS
__init__(self, comps, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='VdW'.
PengRobinson
Interface to the PengRobinson EoS
__init__(self, comps, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='PR'. Default alpha is the original 1976 correlation.
PengRobinson78
Interface to the PengRobinson78 EoS
__init__(self, comps, mixing='vdW', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='PR'. Using the 1978 alpha correlation.
PatelTeja
Interface to the PatelTeja EoS
__init__(self, comps, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='PT'.
SchmidtWensel
Interface to the SchmidtWensel EoS
__init__(self, comps, mixing='vdW', alpha='Classic', parameter_reference='Default', volume_shift=False)
Basic convenience class, calls the cubic constructor with eos='SW'.
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”.
init_pseudo(self, comps, Tclist, Pclist, acflist, Mwlist=None, mixing='vdW', alpha='Classic')
Initialize pseudocomponents of cubic model in thermopack. The cubic init routine must have been called first.
Args:
comps (str):
Comma separated list of names for all components
Tclist (array_like):
Critical temperatures (K)
Pclist (array_like):
Critical pressures (Pa)
acflist (array_like):
acentric factors (-)
Mwlist (array_like):
Molar masses (kg/mol)
mixing (str):
Mixing rule
alpha (str):
alpha correlation
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_alpha_corr(self, ic, corrname, coeffs)
Set alpha correlation
Args:
ic (in):
Component number
corrname (string):
Name of correlation
coeffs (ndarray):
Coefficients in correlation
set_beta_corr(self, ic, corrname, coeffs)
Set beta correlation
Args:
ic (in):
Component number
corrname (string):
Name of correlation
coeffs (ndarray):
Coefficients in correlation
set_ci(self, cidx, ciA, ciB=0.0, ciC=0.0, ciD=0.0, ciE=0.0, ciF=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, QUINTIC=6)
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