pytherm.activity.unifac¶

This module contains classes and methods to calculate activity coefficients with the UNIFAC model.

How to use¶

To use UNIFAC it’s nessesary to define substances with SubstancesUNIFAC, load parameters with ParametersUNIFAC and set-up the model:

>>> import pytherm.activity.unifac as uf
>>> subs = {
...    "n-hexane": "2*CH3 4*CH2",
...    "butanone-2": "1*CH3 1*CH2 1*CH3CO",
... }
>>> system = {
...    'n-hexane': 0.5,
...    'butanone-2': 0.5,
... }
>>> substances = uf.datasets.SubstancesUNIFAC()
>>> substances.get_from_dict(subs)
>>> am = uf.UNIFAC(dataset=uf.datasets.DOR, substances=substances)
>>> am.get_y(conc=system, T=298)
{'n-hexane': 1.514766775270851, 'butanone-2': 1.4331647782163541}

UNIFAC class¶

class pytherm.activity.unifac.UNIFAC¶

Implementation of the UNIFAC model to work with molar fractions

UNIFAC type (classic or modified) depends on ParametersUNIFAC

Parameters:

dataset (ParametersUNIFAC) – ParametersUNIFAC object with interaction parameters
substances (SubstancesUNIFAC) – Substances UNIFAC object with substance’s group representation

Methods

`get_a`(self, conc, T)	Calculate activities for conc array
`get_y`(self, conc, T)	Calculate activity coefficients for conc array

__init__(self: pytherm.cpp.UNIFAC, arg0: pytherm.cpp.ParametersUNIFAC, arg1: pytherm.cpp.SubstancesUNIFAC) → None¶

get_a(self: pytherm.cpp.UNIFAC, conc: list[float], T: float) → list[float]¶

Calculate activities for conc array

Concentrations must be in molar fractions

Parameters:

conc (list[float]) – Input concentration array, [molar fraction]
T (float) – Temperature, [K]

Returns:

Activities

Return type:

list[float]

Examples

>>> UNIFAC.get_a([0.5, 0.5], T=298)

get_y(self: pytherm.cpp.UNIFAC, conc: list[float], T: float) → list[float]¶

Calculate activity coefficients for conc array

Concentrations must be in molar fractions

\[\gamma_i = \exp\left(\ln \gamma_i^c + \ln \gamma_i^r \right)\]

Parameters:

conc (list[float]) – Input concentration array, [molar fraction]
T (float) – Temperature, [K]

Returns:

Activity coefficients

Return type:

list[float]

Examples

>>> UNIFAC.get_y([0.5, 0.5], T=298)

UNIFAC_W class¶

class pytherm.activity.unifac.UNIFAC_W¶

Bases: UNIFAC

Implementation of the UNIFAC model to work with weight fractions

UNIFAC type (classic or modified) depends on ParametersUNIFAC

Parameters:

dataset (ParametersUNIFAC) – ParametersUNIFAC object with interaction parameters
substances (SubstancesUNIFAC) – Substances UNIFAC object with substance’s group representation

Methods

`get_a`(self, conc, T)	Calculate activities for conc array
`get_y`(self, conc, T)	Calculate activity coefficients for conc array

__init__(self: pytherm.cpp.UNIFAC_W, arg0: pytherm.cpp.ParametersUNIFAC, arg1: pytherm.cpp.SubstancesUNIFAC, arg2: list[float]) → None¶

get_a(self: pytherm.cpp.UNIFAC_W, conc: list[float], T: float) → list[float]¶

Calculate activities for conc array

Concentrations must be in weight fractions

Parameters:

conc (list[float]) – Input concentration array, [weight fractions]
T (float) – Temperature, [K]

Returns:

Activities

Return type:

list[float]

Examples

>>> UNIFAC.get_a([0.5, 0.5], T=298)

get_y(self: pytherm.cpp.UNIFAC_W, conc: list[float], T: float) → list[float]¶

Calculate activity coefficients for conc array

Concentrations must be in weight fractions

\[\gamma_i = \exp\left(\ln \gamma_i^c + \ln \gamma_i^r \right)\]

Parameters:

conc (list[float]) – Input concentration array, [molar fraction]
T (float) – Temperature, [K]

Returns:

Activity coefficients

Return type:

list[float]

SubstancesUNIFAC class¶

Substances must be a special SubstancesUNIFAC object

class pytherm.activity.unifac.SubstancesUNIFAC¶

A special class that holds UNIFAC substances

Methods

get_from_dict(self, subs_dict)

Create SubstancesUNIFAC from dict

get_from_dict(self: pytherm.cpp.SubstancesUNIFAC, subs_dict: dict) → None¶

Create SubstancesUNIFAC from dict

Parameters:: subs_dict (dict) – Substances dict

Examples

>>> subs = {
...    "n-hexane": "2*CH3 4*CH2",
...    "butanone-2": "1*CH3 1*CH2 1*CH3CO",
... }
>>> substances = SubstancesUNIFAC()
>>> substances.get_from_dict(subs)