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75 lines
2.6 KiB
ReStructuredText
75 lines
2.6 KiB
ReStructuredText
.. _pcsaft_backend:
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**************************
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PC-SAFT Equations of State
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**************************
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.. contents:: :depth: 2
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Introduction
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============
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CoolProp (as of version 6.4) includes the PC-SAFT equation of state. The PC-SAFT equation of state was originally proposed in 2001 by `Gross and Sadowski <>`. In addition to the hard chain and dispersion terms, the PC-SAFT backend in CoolProp also includes terms for associating, polar, and electrolyte compounds. For the polar term the formulation given by `Gross and Vrabec (2006) <>` was used, and this is sometimes called PCP-SAFT. For electrolyte compounds the equations presented by `Held et al. (2014) <>` were used, and this version of the equation of state is sometimes called electrolyte PC-SAFT (ePC-SAFT).
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Caveats
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-------
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.. warning:: NOT ALL PROPERTIES ARE AVAILABLE AS INPUTS/OUTPUTS
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Only a limited subset of properties are available currently. You can do:
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* Flash calculations with TP, PQ, DT, QT inputs
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* Calculation of some mixture flashes
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.. warning:: The flash algorithm for the PC-SAFT backend is not yet as robust as for other backends. For some conditions it may fail to find the correct solution.
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Pure Fluids
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===========
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Usage
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-----
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Similar to other backends in CoolProp, in the :ref:`high-level interface <high_level_api>`, all that you have to do to evaluate properties using the PC-SAFT equation of state is to change the backend name.
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.. ipython::
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In [0]: import CoolProp.CoolProp as CP
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# The multi-parameter Helmholtz backend
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In [0]: CP.PropsSI("T","P",101325,"Q",0,"HEOS::Propane")
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# PC-SAFT
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In [0]: CP.PropsSI("T","P",101325,"Q",0,"PCSAFT::PROPANE")
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The same holds for the :ref:`low-level interface <low_level_api>`:
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.. ipython::
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In [0]: import CoolProp.CoolProp as CP
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In [0]: AS = CP.AbstractState("PCSAFT", "PROPANE"); AS.update(CP.QT_INPUTS, 0, 300); print(AS.p())
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The PC-SAFT equation of state is available for more than 100 fluids for which parameter were available in the literature.
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Mixtures
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========
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Interaction Parameters
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----------------------
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For mixtures, PC-SAFT generally uses a binary interaction parameter between pairs of fluids. CoolProp does have some of these parameters for the PC-SAFT EOS, and it is possible to add more yourself.
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.. ipython::
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In [0]: import CoolProp.CoolProp as CP
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In [0]: CAS_water = CP.get_fluid_param_string("WATER","CAS")
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In [0]: CAS_aacid = "64-19-7"
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In [0]: CP.set_mixture_binary_pair_pcsaft(CAS_water, CAS_aacid, "kij", -0.127)
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In [0]: T = CP.PropsSI("T", "P", 72915.92217342, "Q", 0, "PCSAFT::WATER[0.2691800943]&ACETIC ACID[0.7308199057]")
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In [0]: print(T)
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