Added IAPWS Permittivity formulation; and CoolProp dependency in setu…

…p.py.

setup.py

@@ -51,18 +51,18 @@
   name = 'thermo',
   packages = ['thermo'],
   license='MIT',
-  version = '0.1.11',
+  version = '0.1.12',
   description = 'Chemical properties component of Chemical Engineering Design Library (ChEDL)',
   author = 'Caleb Bell',
-  install_requires=['fluids', 'scipy', 'pandas', 'matplotlib'],
+  install_requires=['fluids', 'scipy', 'pandas', 'matplotlib', 'coolprop'],
   extras_require = {
       'Coverage documentation':  ['wsgiref>=0.1.2', 'coverage>=4.0.3']
   },
   long_description=open('README.rst').read(),
   platforms=["Windows", "Linux", "Mac OS", "Unix"],
   author_email = 'Caleb.Andrew.Bell@gmail.com',
   url = 'https://github.com/CalebBell/thermo',
-  download_url = 'https://github.com/CalebBell/thermo/tarball/0.1.11',
+  download_url = 'https://github.com/CalebBell/thermo/tarball/0.1.12',
   keywords = ['chemical engineering', 'chemistry', 'mechanical engineering', 
   'thermodynamics', 'databases', 'cheminformatics'],
   classifiers = classifiers,

tests/test_permittivity.py

@@ -73,3 +73,11 @@ def test_Permittivity_class():
     assert_allclose(w.T_dependent_property(200.), 115.79462395999997)
     w.tabular_extrapolation_permitted = False
     assert None == w.T_dependent_property(200.)
+
+
+def test_permittivity_IAPWS():
+    Ts = [238., 256., 273., 273., 323., 323., 373., 373., 510., 523., 614., 647., 673., 673., 773., 773., 873.]
+    rhos = [975.06, 995.25, 999.83, 1180., 988.10,  1258., 958.46, 1110., 15.832, 900., 94.29, 358., 100., 900., 100., 900., 450.]
+    permittivity_calc = [permittivity_IAPWS(T, rho) for T, rho in zip(Ts, rhos)]
+    permittivity_exp = [106.31159697963018, 95.19633650530638, 87.96431108641572, 107.06291112337524, 69.96455480833566, 97.7606839686273, 55.56584297721836, 67.73206302035597, 1.1224589212024803, 32.23229227177932, 1.7702660877662086, 6.194373838662447, 1.7541419715602131, 23.59653593827129, 1.6554135047590008, 20.160449425540186, 6.283091796558804]
+    assert_allclose(permittivity_calc, permittivity_exp)

thermo/dippr.py

@@ -43,7 +43,7 @@ def EQ100(T, A=0, B=0, C=0, D=0, E=0, F=0, G=0):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -81,7 +81,7 @@ def EQ101(T, A, B, C, D, E):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -117,7 +117,7 @@ def EQ102(T, A, B, C, D):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -152,7 +152,7 @@ def EQ104(T, A, B, C, D, E):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -187,7 +187,7 @@ def EQ105(T, A, B, C, D):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -227,7 +227,7 @@ def EQ106(T, Tc, A, B, C=0, D=0, E=0):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -264,7 +264,7 @@ def EQ107(T, A=0, B=0, C=0, D=0, E=0):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -309,7 +309,7 @@ def EQ114(T, Tc, A, B, C, D):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -345,7 +345,7 @@ def EQ115(T, A, B, C=0, D=0, E=0):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -381,7 +381,7 @@ def EQ116(T, Tc, A, B, C, D, E):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples
@@ -421,7 +421,7 @@ def EQ127(T, A, B, C, D, E, F, G):
 
     Returns
     -------
-    Y: float
+    Y : float
         Property [constant-specific]
 
     Examples

thermo/heat_capacity.py

@@ -318,7 +318,8 @@ class HeatCapacityGas(TDependentProperty):
     property_min = 0
     '''Heat capacities have a minimum value of 0 at 0 K.'''
     property_max = 1E4
-    '''Maximum valid of Heat capacity; arbitrarily set.'''
+    '''Maximum valid of Heat capacity; arbitrarily set. For fluids very near
+    the critical point, this value can be obscenely high.'''
 
 
     ranked_methods = [TRCIG, POLING, COOLPROP, LASTOVKA_SHAW, CRCSTD, POLING_CONST, VDI_TABULAR]
@@ -967,8 +968,9 @@ class HeatCapacityLiquid(TDependentProperty):
     property_min = 1
     '''Allow very low heat capacities; arbitrarily set; liquid heat capacity
     should always be somewhat substantial.'''
-    property_max = 1E4
-    '''Maximum valid of Heat capacity; arbitrarily set.'''
+    property_max = 1E4 # Originally 1E4
+    '''Maximum valid of Heat capacity; arbitrarily set. For fluids very near
+    the critical point, this value can be obscenely high.'''
 
 
     ranked_methods = [ZABRANSKY_SPLINE, ZABRANSKY_QUASIPOLYNOMIAL,

thermo/permittivity.py

@@ -23,6 +23,7 @@
 from __future__ import division
 import os
 import numpy as np
+from scipy.constants import N_A, epsilon_0, k
 import pandas as pd
 from thermo.utils import TDependentProperty
 
@@ -34,6 +35,91 @@
 _CRC_Permittivity_data_values = CRC_Permittivity_data.values
 
 
+def permittivity_IAPWS(T, rho):
+    r'''Calculate the relative permittivity of pure water as a function of.
+    temperature and density. Assumes the 1997 IAPWS [1]_ formulation.
+
+    .. math::
+        \epsilon(\rho, T) =\frac{1 + A + 5B + (9 + 2A + 18B + A^2 + 10AB + 
+        9B^2)^{0.5}}{4(1-B)}
+        
+        A(\rho, T) = \frac{N_A\mu^2\rho g}{M\epsilon_0 kT}
+        
+        B(\rho) = \frac{N_A\alpha\rho}{3M\epsilon_0}
+        
+        g(\delta,\tau) = 1 + \sum_{i=1}^{11}n_i\delta^{I_i}\tau^{J_i} 
+        + n_{12}\delta\left(\frac{647.096}{228}\tau^{-1} - 1\right)^{-1.2}
+
+        \delta = \rho/(322 \text{ kg/m}^3)
+        
+        \tau = T/647.096\text{K}
+
+    Parameters
+    ----------
+    T : float
+        Temperature of water [K]
+    rho : float
+        Mass density of water at T and P [kg/m^3]
+
+    Returns
+    -------
+    epsilon : float
+        Relative permittivity of water at T and rho, [-]
+
+    Notes
+    -----
+    Validity:
+    
+    273.15 < T < 323.15 K for 0 < P < iceVI melting pressure at T or 1000 MPa,
+    whichever is smaller.
+    
+    323.15 < T < 873.15 K 0 < p < 600 MPa.
+    
+    Coefficients:
+    
+    ih = [1, 1, 1, 2, 3, 3, 4, 5, 6, 7, 10];
+    jh = [0.25, 1, 2.5, 1.5, 1.5, 2.5, 2, 2, 5, 0.5, 10];
+    Nh = [0.978224486826, -0.957771379375, 0.237511794148, 0.714692244396,
+          -0.298217036956, -0.108863472196, 0.949327488264E-1, 
+          -.980469816509E-2, 0.165167634970E-4, 0.937359795772E-4, 
+          -0.12317921872E-9];
+    polarizability = 1.636E-40
+    dipole = 6.138E-30
+    
+    Examples
+    --------
+    >>> permittivity_IAPWS(373., 958.46)
+    55.56584297721836
+
+    References
+    ----------
+    .. [1] IAPWS. 1997. Release on the Static Dielectric Constant of Ordinary 
+       Water Substance for Temperatures from 238 K to 873 K and Pressures up 
+       to 1000 MPa.
+    '''
+    dipole = 6.138E-30 # actual molecular dipole moment of water, in C*m
+    polarizability = 1.636E-40 # actual mean molecular polarizability of water, C^2/J*m^2
+    MW = 0.018015268 # molecular weight of water, kg/mol
+    ih = [1, 1, 1, 2, 3, 3, 4, 5, 6, 7, 10]
+    jh = [0.25, 1, 2.5, 1.5, 1.5, 2.5, 2, 2, 5, 0.5, 10]
+    Nh = [0.978224486826, -0.957771379375, 0.237511794148, 0.714692244396,
+          -0.298217036956, -0.108863472196, 0.949327488264E-1, 
+          -.980469816509E-2, 0.165167634970E-4, 0.937359795772E-4, 
+          -0.12317921872E-9]
+
+    delta = rho/322.
+    tau = 647.096/T
+
+    g = (1 + sum([Nh[h]*delta**ih[h]*tau**jh[h] for h in range(11)])
+        + 0.196096504426E-2*delta*(T/228. - 1)**-1.2)
+
+    A = N_A*dipole**2*(rho/MW)*g/epsilon_0/k/T
+    B = N_A*polarizability*(rho/MW)/3./epsilon_0
+    epsilon = (1. + A + 5.*B + (9. + 2.*A + 18.*B + A**2 + 10.*A*B + 9.*B**2
+        )**0.5)/(4. - 4.*B)
+    return epsilon
+
+
 CRC = 'CRC Handbook polynomials'
 CRC_CONSTANT = 'CRC Handbook constant'
 permittivity_methods = [CRC, CRC_CONSTANT]