'''Chemical Engineering Design Library (ChEDL). Utilities for process modeling.
Copyright (C) 2016, 2017, 2018, 2019, 2020 Caleb Bell <Caleb.Andrew.Bell@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
This module contains implementations of :obj:`TDependentProperty <thermo.utils.TDependentProperty>`
representing liquid permittivity. A variety of estimation
and data methods are available as included in the `chemicals` library.
For reporting bugs, adding feature requests, or submitting pull requests,
please use the `GitHub issue tracker <https://github.com/CalebBell/thermo/>`_.
.. contents:: :local:
Pure Liquid Permittivity
========================
.. autoclass:: PermittivityLiquid
:members: calculate, test_method_validity,
name, property_max, property_min,
units, Tmin, Tmax, ranked_methods
:undoc-members:
:show-inheritance:
:exclude-members:
.. autodata:: permittivity_methods
'''
__all__ = ['PermittivityLiquid']
from chemicals import permittivity
from chemicals.iapws import iapws95_Pc, iapws95_rho, iapws95_rhol_sat, iapws95_Tc
from chemicals.permittivity import permittivity_IAPWS
from fluids.numerics import isnan
from thermo.utils import IAPWS, TDependentProperty
CRC = 'CRC'
CRC_CONSTANT = 'CRC_CONSTANT'
permittivity_methods = [CRC, CRC_CONSTANT, IAPWS]
"""Holds all methods available for the :obj:`PermittivityLiquid` class, for use in
iterating over them."""
[docs]class PermittivityLiquid(TDependentProperty):
r'''Class for dealing with liquid permittivity as a function of temperature.
Consists of one temperature-dependent simple expression, one constant
value source, and IAPWS.
Parameters
----------
CASRN : str, optional
The CAS number of the chemical
load_data : bool, optional
If False, do not load property coefficients from data sources in files
[-]
extrapolation : str or None
None to not extrapolate; see
:obj:`TDependentProperty <thermo.utils.TDependentProperty>`
for a full list of all options, [-]
method : str or None, optional
If specified, use this method by default and do not use the ranked
sorting; an exception is raised if this is not a valid method for the
provided inputs, [-]
Notes
-----
To iterate over all methods, use the list stored in
:obj:`permittivity_methods`.
**CRC**:
Simple polynomials for calculating permittivity over a specified
temperature range only. The full expression is:
.. math::
\epsilon_r = A + BT + CT^2 + DT^3
Not all chemicals use all terms; in fact, few do. Data is available
for 759 liquids, from [1]_.
**CRC_CONSTANT**:
Constant permittivity values at specified temperatures only.
Data is from [1]_, and is available for 1303 liquids.
**IAPWS**:
The IAPWS model for water permittivity as a liquid.
References
----------
.. [1] Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of
Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.
'''
name = 'liquid relative permittivity'
units = '-'
interpolation_T = None
"""No interpolation transformation by default."""
interpolation_property = None
"""No interpolation transformation by default."""
interpolation_property_inv = None
"""No interpolation transformation by default."""
tabular_extrapolation_permitted = True
"""Allow tabular extrapolation by default."""
property_min = 1.0
"""Relative permittivity must always be larger than 1; nothing is better
than a vacuum."""
property_max = 1000.0
"""Maximum valid of permittivity; highest in the data available is ~240."""
ranked_methods = [IAPWS, CRC, CRC_CONSTANT]
"""Default rankings of the available methods."""
_fit_force_n = {}
"""Dictionary containing method: fit_n, for use in methods which should
only ever be fit to a specific `n` value"""
_fit_force_n[CRC_CONSTANT] = 1
_fit_max_n = {CRC: 4}
@staticmethod
def _method_indexes():
'''Returns a dictionary of method: index for all methods
that use data files to retrieve constants. The use of this function
ensures the data files are not loaded until they are needed.
'''
A = permittivity.permittivity_data_CRC['A'].values
return {CRC_CONSTANT: permittivity.permittivity_data_CRC.index,
CRC: [CAS for i, CAS in enumerate(permittivity.permittivity_data_CRC.index)
if not isnan(A[i])],
}
custom_args = ()
def __init__(self, CASRN='', extrapolation='linear', **kwargs):
self.CASRN = CASRN
super().__init__(extrapolation, **kwargs)
def load_all_methods(self, load_data):
r'''Method which picks out coefficients for the specified chemical
from the various dictionaries and DataFrames storing it. All data is
stored as attributes. This method also sets :obj:`Tmin`, :obj:`Tmax`,
and :obj:`all_methods` as a set of methods for which the data exists for.
Called on initialization only. See the source code for the variables at
which the coefficients are stored. The coefficients can safely be
altered once the class is initialized. This method can be called again
to reset the parameters.
'''
methods = []
self.T_limits = T_limits = {}
CASRN = self.CASRN
if load_data and CASRN:
if CASRN in permittivity.permittivity_data_CRC.index:
methods.append(CRC_CONSTANT)
self.CRC_CONSTANT_T, self.CRC_permittivity, A, B, C, D, Tmin, Tmax = permittivity.permittivity_values_CRC[permittivity.permittivity_data_CRC.index.get_loc(CASRN)].tolist()
if isnan(Tmin) and isnan(Tmax):
Tmin, Tmax = self.CRC_CONSTANT_T, self.CRC_CONSTANT_T
T_limits[CRC_CONSTANT] = (self.CRC_CONSTANT_T, self.CRC_CONSTANT_T)
self.CRC_coeffs = [0 if isnan(x) else x for x in [A, B, C, D] ]
self.CRC_Tmin = Tmin
self.CRC_Tmax = Tmax
if self.CRC_coeffs[0] and not isnan(Tmin):
methods.append(CRC)
T_limits[CRC] = (Tmin, Tmax)
if CASRN == '7732-18-5':
methods.append(IAPWS)
T_limits[IAPWS] = (273.15, 873.15)
self.all_methods = set(methods)
[docs] def calculate(self, T, method):
r'''Method to calculate permittivity of a liquid at temperature `T`
with a given method.
This method has no exception handling; see :obj:`T_dependent_property <thermo.utils.TDependentProperty.T_dependent_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate relative permittivity, [K]
method : str
Name of the method to use
Returns
-------
epsilon : float
Relative permittivity of the liquid at T, [-]
'''
if method == CRC:
A, B, C, D = self.CRC_coeffs
epsilon = A + T*(B + T*(C + D*T))
elif method == CRC_CONSTANT:
epsilon = self.CRC_permittivity
elif method == IAPWS:
if T <= iapws95_Tc:
rho = iapws95_rhol_sat(T)
else:
# reduce discontinuities
rho = iapws95_rho(T, iapws95_Pc)
epsilon = permittivity_IAPWS(T, rho)
else:
epsilon = self._base_calculate(T, self._method)
return epsilon
[docs] def test_method_validity(self, T, method):
r'''Method to check the validity of a method. Follows the given
ranges for all coefficient-based methods. For tabular data,
extrapolation outside of the range is used if
:obj:`tabular_extrapolation_permitted` is set; if it is, the
extrapolation is considered valid for all temperatures.
It is not guaranteed that a method will work or give an accurate
prediction simply because this method considers the method valid.
Parameters
----------
T : float
Temperature at which to test the method, [K]
method : str
Name of the method to test
Returns
-------
validity : bool
Whether or not a method is valid
'''
return super().test_method_validity(T, method)