Delete preos.py

preos.py

@@ -1,225 +0,0 @@
-import numpy as np
-import matplotlib.pyplot as plt
-from scipy.optimize import newton
-
-R = 8.314e-5  # universal gas constant, m3-bar/K-mol
-class Molecule:
-    """
-    Store molecule info here
-    """
-    def __init__(self, name, Tc, Pc, omega):
-        """
-        Pass parameters desribing molecules
-        """
-        #! name
-        self.name = name
-        #! Critical temperature (K)
-        self.Tc = Tc
-        #! Critical pressure (bar)
-        self.Pc = Pc
-        #! Accentric factor
-        self.omega = omega
-
-    def print_params(self):
-        """
-        Print molecule parameters.
-        """
-        print("""Molecule: %s.
-        \tCritical Temperature = %.1f K
-        \tCritical Pressure = %.1f bar.
-        \tAccentric factor = %f""" % (self.name, self.Tc, self.Pc, self.omega))
-
-def preos(molecule, T, P, plotcubic=True, printresults=True):
-    """
-    Peng-Robinson equation of state (PREOS)
-    http://en.wikipedia.org/wiki/Equation_of_state#Peng.E2.80.93Robinson_equation_of_state
-    :param molecule: Molecule molecule of interest
-    :param T: float temperature in Kelvin
-    :param P: float pressure in bar
-    :param plotcubic: bool plot cubic polynomial in compressibility factor
-    :param printresults: bool print off properties
-
-    Returns a Dict() of molecule properties at this T and P.
-    """
-    # build params in PREOS
-    Pr = P/molecule.Pc
-    Tr = T / molecule.Tc  # reduced temperature
-    a = 0.457235 * R**2 * molecule.Tc**2 / molecule.Pc
-    b = 0.0777961 * R * molecule.Tc / molecule.Pc
-    kappa = 0.37464 + 1.54226 * molecule.omega - 0.26992 * molecule.omega**2
-    #kappa = 0.378893 + 1.4897153*molecule.omega - 0.17131848*molecule.omega**2 + 0.0196554*molecule.omega**3
-    alpha = (1 + kappa * (1 - np.sqrt(Tr)))**2
-
-    A = a * alpha * P / R**2 / T**2
-    B = b * P / R / T
-
-    # build cubic polynomial
-    def g(z):
-        """
-        Cubic polynomial in z from EOS. This should be zero.
-        :param z: float compressibility factor
-        """
-        return z**3 - (1 - B) * z**2 + (A - 2*B - 3*B**2) * z - (
-                A * B - B**2 - B**3)
-
-    # Solve cubic polynomial for the compressibility factor
-    z = newton(g, 1.0)  # compressibility factor
-    rho = P / (R * T * z)  # density
-    fugacity_coeff_PengRobin = np.exp(z - 1 - np.log(z - B) - A / np.sqrt(8) / B * np.log((z + (1 + np.sqrt(2)) * B) / (z + (1 - np.sqrt(2)) * B)))
-    #R = 8.314
-    def reduce_func(Vr):
-        #return Vr**3 - (1/3 + 8/3 * Tr/Pr)*(Vr**2) + 3*Vr/Pr - 1/Pr
-        return (Pr + 3/(Vr**2))*(3*Vr - 1) - 8*Tr
-    Vr = newton(reduce_func, 10)
-    #z = (Vr / (Vr - 1/3)) - 9 / (8*Vr*Tr)
-    Vm = z*R*T / P
-    a = (27*(R*molecule.Tc)**2) / (64*molecule.Pc)
-    b = (R*molecule.Tc) / (8*molecule.Pc)
-
-    # fugacity coefficient comes from an integration
-    fugacity_coeff_vander = np.exp(b / (Vm - b) - 2*a / (Vm*R*T) - np.log(1 - a*(Vm - b) / (R*T*(Vm**2))))
-    
-
-    if printresults:
-        print("""PREOS calculation at
-        \t T = %.2f K
-        \t P = %.2f bar""" % (T, P))
-        print("\tCompressibility factor : ", z)
-        print("\tFugacity coefficient: ", fugacity_coeff)
-        print("\tFugacity at pressure %.3f bar = %.3f bar" % (
-                P, fugacity_coeff * P))
-        print("\tDensity: %f mol/m3" % rho)
-        print("\tMolar volume: %f L/mol" % (1.0 / rho * 1000))
-        print("\tDensity: %f v STP/v" % (rho * 22.4 / 1000))
-        print("\tDensity of ideal gas at same conditions: %f v STP/v" % (
-                rho * 22.4/ 1000 * z))
-
-    if plotcubic:
-        # Plot the cubic equation to visualize the roots
-        zz = np.linspace(0, 1.5)  # array for plotting
-
-        plt.figure()
-        plt.plot(zz, g(zz), color='k')
-        plt.xlabel('Compressibility, $z$')
-        plt.ylabel('Cubic $g(z)$')
-        plt.axvline(x=z)
-        plt.axhline(y=0)
-        plt.title('Root found @ z = %.2f' % z)
-        plt.show()
-    return {"density(mol/m3)": rho, "fugacity_coefficient_peng": fugacity_coeff_PengRobin,
-            "fugacity_coefficient_van": fugacity_coeff_vander,
-            "compressibility_factor": z, "fugacity(bar)": fugacity_coeff_PengRobin * P,
-            "molar_volume(L/mol)": 1.0 / rho * 1000.0}
-
-def preos_reverse(molecule, T, f, plotcubic=False, printresults=True):
-    """
-    Reverse Peng-Robinson equation of state (PREOS) to obtain pressure for a particular fugacity
-    :param molecule: Molecule molecule of interest
-    :param T: float temperature in Kelvin
-    :param f: float fugacity in bar
-    :param plotcubic: bool plot cubic polynomial in compressibility factor
-    :param printresults: bool print off properties
-
-    Returns a Dict() of molecule properties at this T and f.
-    """
-    # build function to minimize: difference between desired fugacity and that obtained from preos
-    def g(P):
-        """
-        :param P: pressure
-        """
-        return (f - preos(molecule, T, P, plotcubic=False, printresults=False)["fugacity(bar)"])
-
-    # Solve preos for the pressure
-    P = newton(g, f)  # pressure
-
-    # Obtain remaining parameters
-    pars = preos(molecule, T, P, plotcubic=plotcubic, printresults=printresults)
-    rho = pars["density(mol/m3)"]
-    fugacity_coeff = pars["fugacity_coefficient"]
-    z = pars["compressibility_factor"]
-
-    return {"density(mol/m3)": rho, "fugacity_coefficient": fugacity_coeff,
-            "compressibility_factor": z, "pressure(bar)": P,
-            "molar_volume(L/mol)": 1.0 / rho * 1000.0}
-
-# TODO: Implement mixture in object-oriented way as well
-def preos_mixture(molecule_a, molecule_b, delta, T, P_total, x, plotcubic=True, printresults=True):
-    """
-    Peng-Robinson equation of state (PREOS) for a binary mixture
-    http://en.wikipedia.org/wiki/Equation_of_state#Peng.E2.80.93Robinson_equation_of_state
-    :param molecule_a: Molecule molecule 1 of interest
-    :param molecule_b: Molecule molecule 2 of interest
-    :param delta: binary interaction parameter between molecules a and b
-    :param T: float temperature in Kelvin
-    :param P_total: float total pressure in bar
-    :param x: array mole fractions
-    :param plotcubic: bool plot cubic polynomial in compressibility factor
-    :param printresults: bool print off properties
-    """
-    # build arrays of properties
-    Tc = np.array([molecule_a.Tc, molecule_b.Tc])
-    Pc = np.array([molecule_a.Pc, molecule_b.Pc])
-    omega = np.array([molecule_a.omega, molecule_b.omega])
-
-    # build params in PREOS
-    Tr = T / Tc  # reduced temperature
-    a0 = 0.457235 * R**2 * Tc**2 / Pc
-    b = 0.0777961 * R * Tc / Pc
-    kappa = 0.37464 + 1.54226 * omega - 0.26992 * omega**2
-    a = a0 * (1 + kappa * (1 - np.sqrt(Tr)))**2
-    
-    # apply mixing rules
-    aij = (1.0 - delta) * np.sqrt(a[0] * a[1])
-    a_mix = a[0] * x[0]**2 + a[1] * x[1]**2 + 2.0 * x[0] * x[1] * aij
-    b_mix = x[0] * b[0] + x[1] * b[1]
-    A = a_mix * P_total / R**2 / T**2
-    B = b_mix * P_total / R / T
-
-    # build cubic polynomial
-    def g(z):
-        """
-        Cubic polynomial in z from EOS. This should be zero.
-        :param z: float compressibility factor
-        """
-        return z**3 - (1 - B) * z**2 + (A - 2*B - 3*B**2) * z - (
-                A * B - B**2 - B**3)
-
-    # Solve cubic polynomial for the compressibility factor
-    z = newton(g, 1.0)  # compressibility factor
-    rho = P_total / (R * T * z)  # density
-    
-    Lnfug_0 = -np.log(z - B) + (z - 1.0) * b[0] / b_mix - A / np.sqrt(8) / B * (2.0 / a_mix * (x[0] * a[0] + x[1] * aij) - b[0] / b_mix) *\
-        np.log((z + (1.0 + np.sqrt(2)) * B) / (z + (1.0 - np.sqrt(2)) * B))
-    Lnfug_1 = -np.log(z - B) + (z - 1.0) * b[1] / b_mix - A / np.sqrt(8) / B * (2.0 / a_mix * (x[1] * a[1] + x[0] * aij) - b[1] / b_mix) *\
-        np.log((z + (1.0 + np.sqrt(2)) * B) / (z + (1.0 - np.sqrt(2)) * B))
-
-    # fugacity coefficient comes from an integration
-    fugacity_coefs = np.exp(np.array([Lnfug_0, Lnfug_1]))
-
-    if printresults:
-        print("""PREOS calculation at
-        \t T = %.2f K
-        \t P, total = %.2f bar""" % (T, P_total))
-        print("\tDensity: %f mol/m3" % rho)
-        print("\tCompressibility factor : %f" % z)
-        print("Component 0, %s:" % molecule_a.name)
-        print("\tFugacity coefficient: %f" % fugacity_coefs[0])
-        print("\tFugacity: %f bar" % (fugacity_coefs[0] * x[0] * P_total))
-        print("Component 1, %s:" % molecule_b.name)
-        print("\tFugacity coefficient: %f" % fugacity_coefs[1])
-        print("\tFugacity: %f bar" % (fugacity_coefs[1] * x[1] * P_total))
-
-    if plotcubic:
-        # Plot the cubic equation to visualize the roots
-        zz = np.linspace(0, 1.5)  # array for plotting
-
-        plt.figure()
-        plt.plot(zz, g(zz), color='k')
-        plt.xlabel('Compressibility, $z$')
-        plt.ylabel('Cubic $g(z)$')
-        plt.axvline(x=z)
-        plt.axhline(y=0)
-        plt.title('Root found @ z = %.2f' % z)
-        plt.show()
-    return {"density(mol/m3)": rho, "fugacity_coefficients": fugacity_coefs,
-            "compressibility_factor": z}