Permittivity/Dielectric Constant (thermo.permittivity)¶
This module contains implementations of 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.
Pure Liquid Permittivity¶
- class thermo.permittivity.PermittivityLiquid(CASRN='', extrapolation='linear', **kwargs)[source]¶
Bases:
thermo.utils.t_dependent_property.TDependentProperty
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
- CASRNstr, optional
The CAS number of the chemical
- load_databool, optional
If False, do not load property coefficients from data sources in files [-]
- extrapolationstr or None
None to not extrapolate; see
TDependentProperty
for a full list of all options, [-]- methodstr 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
permittivity_methods
.- CRC:
Simple polynomials for calculating permittivity over a specified temperature range only. The full expression is:
\[\epsilon_r = A + BT + CT^2 + DT^3 \]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(1,2)
Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics. [Boca Raton, FL]: CRC press, 2014.
- Attributes
Methods
calculate
(T, method)Method to calculate permittivity of a liquid at temperature T with a given method.
test_method_validity
(T, method)Method to check the validity of a method.
- property Tmax¶
Maximum temperature (K) at which the current method can calculate the property.
- property Tmin¶
Minimum temperature (K) at which the current method can calculate the property.
- calculate(T, method)[source]¶
Method to calculate permittivity of a liquid at temperature T with a given method.
This method has no exception handling; see
T_dependent_property
for that.- Parameters
- Tfloat
Temperature at which to calculate relative permittivity, [K]
- methodstr
Name of the method to use
- Returns
- epsilonfloat
Relative permittivity of the liquid at T, [-]
- name = 'liquid relative permittivity'¶
- property_max = 1000.0¶
Maximum valid of permittivity; highest in the data available is ~240.
- property_min = 1.0¶
Relative permittivity must always be larger than 1; nothing is better than a vacuum.
- ranked_methods = ['IAPWS', 'CRC', 'CRC_CONSTANT']¶
Default rankings of the available methods.
- test_method_validity(T, method)[source]¶
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
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
- Tfloat
Temperature at which to test the method, [K]
- methodstr
Name of the method to test
- Returns
- validitybool
Whether or not a method is valid
- units = '-'¶
- thermo.permittivity.permittivity_methods = ['CRC', 'CRC_CONSTANT', 'IAPWS']¶
Holds all methods available for the
PermittivityLiquid
class, for use in iterating over them.