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{"@context":"https://schema.org","@type":"QAPage","mainEntity":{"@type":"Question","name":"How can the binary parameters _epsilon_k_ab_ and _kappa_ab_ be explicitly submitted for a mixture?","text":"
Dear all,
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we are developing a Python program for calculating LLE using FeOs for PC-SAFT calculations of chemical potential. In our case: One component has both a negative and positive association site. The other component only has a negative association site.
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Short Python example:
\nhmf = PureRecord(identifier=Identifier(name=\"HMF\"), molarweight=126.11, model_record=PcSaftRecord(m=2.72266, sigma=3.83791, epsilon_k=433.125, kappa_ab=0.0052651, epsilon_k_ab=2524.61, na=1, nb=1))
\nmthf = PureRecord(identifier=Identifier(name=\"MTHF\"), molarweight=86.132, model_record=PcSaftRecord(m=2.7191, sigma=3.6567, epsilon_k=265.09, kappa_ab=0, epsilon_k_ab=0, na=0, nb=1))
\npures = [hmf, mthf]
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In order to take the induced association in the mixture into account, we would like to explicitly specify epsilon_k_ab and kappa_ab as parameters for the mixture between the two components. However, when creating the equation of state we were not able to find a way for submitting epsilon_k_ab and kappa_ab to the PcSaftParameters object.
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Short Python example (unfortunately, this formulation didnt work and only adopts k_ij and not the other two parameters):
\nbinary = BinaryRecord(id1=Identifier(name=\"HMF\"),\tid2=Identifier(name=\"MTHF\"),model_record=PcSaftBinaryRecord(k_ij=0.015, kappa_ab=0.50, epsilon_k_ab=1800.0))
\nparams = PcSaftParameters.from_records(pures, [binary])
\neos = EquationOfState.pcsaft(params)
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How can we access the modelRecord constructor to submit the binary parameters epsilon_k_ab and kappa_ab for a mixture to the PC-SAFT EoS?
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Thanks for your help!
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Best regards,
\nMoritz
","upvoteCount":1,"answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"
Hello Moritz,
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the parameter handling was revised a bit from going from feos 0.8 to 0.9. One aspect we added was to increase the flexibility of the association scheme so that any (well most I guess) kinds of hydrogen bonding arrangements can be modeled.
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With the current feos version the code would look like this:
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import feos\n\nhmf = feos.PureRecord(identifier=feos.Identifier(name=\"HMF\"), molarweight=126.11, m=2.72266, sigma=3.83791, epsilon_k=433.125, association_sites=[{\"kappa_ab\": 0.0052651, \"epsilon_k_ab\": 2524.61, \"na\": 1, \"nb\": 1}])\nmthf = feos.PureRecord(identifier=feos.Identifier(name=\"MTHF\"), molarweight=86.132, m=2.7191, sigma=3.6567, epsilon_k=265.09, association_sites=[{\"nb\": 1}])\npures = [hmf, mthf]\n\nbinary = feos.BinaryRecord(id1=feos.Identifier(name=\"HMF\"),\tid2=feos.Identifier(name=\"MTHF\"), k_ij=0.015, association_sites=[{\"kappa_ab\": 0.50, \"epsilon_k_ab\": 1800.0}])\nparams = feos.Parameters.from_records(pures, [binary])\neos = feos.EquationOfState.pcsaft(params)\ndisplay(params)\neos.parameters
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eos.parameters contains the fully assembled matrix of association parameters, so that you can check whether everything was read in correctly. I move this to a discussion, because it could be interesting for other users as well.
","upvoteCount":2,"url":"https://github.com/feos-org/feos/discussions/326#discussioncomment-15150844"}}}