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Commit 7f9b0815 authored by Ian Bell's avatar Ian Bell
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k_ij for PCSAFT too

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%% Cell type:markdown id:f406bbb5 tags:
# PC-SAFT
The PC-SAFT implementation in teqp is based on the implementation of Gross and Sadowski (https://doi.org/10.1021/ie0003887), with the typo from their paper fixed. It does NOT include the association contribution, only the dispersive contributions.
The model in teqp requires the user to specify the values of ``sigma``, ``epsilon/kB``, and ``m`` for each substance. A very few substances are hardcoded in teqp, for testing purposes.
%% Cell type:code id:7bbd7129 tags:
``` python
import teqp
TeXkey = 'Gross-IECR-2001'
ms = [1.0, 1.6069, 2.0020]
eoverk = [150.03, 191.42, 208.11]
sigmas = [3.7039, 3.5206, 3.6184]
coeffs = []
for i in range(len(ms)):
c = teqp.SAFTCoeffs()
c.m = ms[i]
c.epsilon_over_k = eoverk[i]
c.sigma_Angstrom = sigmas[i]
coeffs.append(c)
model = teqp.PCSAFTEOS(coeffs)
```
%% Cell type:markdown id:578630c8 tags:
The model parameters can be queried:
%% Cell type:code id:d4e47e54 tags:
``` python
model.get_m(), model.get_epsilon_over_k_K(), model.get_sigma_Angstrom()
```
%% Output
(array([1. , 1.6069, 2.002 ]),
array([150.03, 191.42, 208.11]),
array([3.7039, 3.5206, 3.6184]))
%% Cell type:markdown id:5cbb382d tags:
## Adjusting k_ij
Fine-tuned values of $k_{ij}$ can be provided when instantiating the model, for Peng-Robinson and SRK. A complete matrix of all the $k_{ij}$ values must be provided. This allows for asymmetric mixing models in which $k_{ij}\neq k_{ji}$.
%% Cell type:code id:a32c41b5 tags:
``` python
k_01 = 0.01; k_10 = k_01
kmat = [[0,k_01,0],[k_01,0,0],[0,0,0]]
teqp.PCSAFTEOS(coeffs, kmat)
```
%% Output
<teqp.teqp.PCSAFTEOS at 0x19478910bf0>
%% Cell type:markdown id:ca52e844 tags:
## Superancillary
The superancillary equation for PC-SAFT has been developed, and is much more involved than that of the cubic EOS. As a consequence, the superancillary equation has been provided as a separate package rather than integrating it into to teqp to minimize the computational overhead. It can be installed from PYPI with: ``pip install PCSAFTsuperanc``
......
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