#!/usr/bin/python3
# -*- coding: utf-8 -*-
r"""Pychemqt, Chemical Engineering Process simulator
Copyright (C) 2009-2025, Juan José Gómez Romera <jjgomera@gmail.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>."""
from scipy.constants import R
from lib.EoS.cubic import Cubic
[docs]
class RK(Cubic):
r"""Equation of state of Redlich-Kwong (1949), [1]_.
.. math::
\begin{array}[t]{l}
P = \frac{RT}{V-b}-\frac{a}{V\left(V+b\right)\sqrt{T}}\\
a = 0.42747\frac{R^2T_c^{2.5}}{P_c}\\
b = 0.08664\frac{RT_c}{P_c}\\
\end{array}
Examples
--------
Example 4.3 from [2]_, Propane saturated at 300K
>>> from lib.mezcla import Mezcla
>>> mix = Mezcla(5, ids=[4], caudalMolar=1, fraccionMolar=[1])
>>> eq = RK(300, 9.9742e5, mix)
>>> '%0.1f' % (eq.Vl.ccmol)
'101.4'
>>> eq = RK(300, 42.477e5, mix)
>>> '%0.1f' % (eq.Vg.ccmol)
'97.3'
"""
__title__ = "Redlich-Kwong (1949)"
__status__ = "RK"
__doi__ = (
{
"autor": "Redlich, O., Kwong, J.N.S.",
"title": "On the Thermodynamnics of Solutions V. An Equation of State."
" Fugacities of Gaseous Solutions",
"ref": "Chem. Rev. 44 (1949) 233-244",
"doi": "10.1021/cr60137a013"},
{
"autor": "Poling, B.E, Prausnitz, J.M, O'Connell, J.P",
"title": "The Properties of Gases and Liquids 5th Edition",
"ref": "McGraw-Hill, New York, 2001",
"doi": ""})
[docs]
def _cubicDefinition(self, T):
"""Definition of individual components coefficients"""
# Schmidt-Wenzel factorization of terms
self.u = 1
self.w = 0
ai = []
bi = []
for cmp in self.componente:
a, b = self._lib(cmp, T)
ai.append(a)
bi.append(b)
self.ai = ai
self.bi = bi
[docs]
def _lib(self, cmp, T):
a0 = 0.42747*R**2*cmp.Tc**2/cmp.Pc
alfa = (T/cmp.Tc)**-0.5
b = 0.08664*R*cmp.Tc/cmp.Pc
return a0*alfa, b
[docs]
def _GEOS(self, xi):
am, bm = self._mixture("RK", xi, [self.ai, self.bi])
delta = bm
epsilon = 0
return am, bm, delta, epsilon
if __name__ == "__main__":
from lib.mezcla import Mezcla
from lib import unidades
# mix = Mezcla(2, ids=[10, 38, 22, 61],
# caudalUnitarioMolar=[0.3, 0.5, 0.05, 0.15])
# eq = RK(340, 101325, mix)
mezcla = Mezcla(2, ids=[1, 2, 40, 41],
caudalUnitarioMolar=[0.31767, 0.58942, 0.07147, 0.02144])
P = unidades.Pressure(485, "psi")
T = unidades.Temperature(100, "F")
eq = RK(T, P, mezcla, flory=1)
