acentric¶
All data and methods for estimating a chemical’s accentric factor.
References
- 1
Pitzer, K. S., D. Z. Lippmann, R. F. Curl, C. M. Huggins, and D. E. Petersen: The Volumetric and Thermodynamic Properties of Fluids. II. Compressibility Factor, Vapor Pressure and Entropy of Vaporization. J. Am. Chem. Soc., 77: 3433 (1955).
- 2
Horstmann, Sven, Anna Jabłoniec, Jörg Krafczyk, Kai Fischer, and Jürgen Gmehling. “PSRK Group Contribution Equation of State: Comprehensive Revision and Extension IV, Including Critical Constants and Α-Function Parameters for 1000 Components.” Fluid Phase Equilibria 227, no. 2 (January 25, 2005): 157-64. doi:10.1016/j.fluid.2004.11.002.
- 3
Passut, Charles A., and Ronald P. Danner. “Acentric Factor. A Valuable Correlating Parameter for the Properties of Hydrocarbons.” Industrial & Engineering Chemistry Process Design and Development 12, no. 3 (July 1, 1973): 365-68. doi:10.1021/i260047a026.
- 4
Yaws, Carl L. Thermophysical Properties of Chemicals and Hydrocarbons, Second Edition. Amsterdam Boston: Gulf Professional Publishing, 2014.
- 5(1,2)
Lee, Byung Ik, and Michael G. Kesler. “A Generalized Thermodynamic Correlation Based on Three-Parameter Corresponding States.” AIChE Journal 21, no. 3 (1975): 510-527. doi:10.1002/aic.690210313.
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thermosteam.properties.acentric.
acentric_factor_LK
(CASRN, Tb=None, Tc=None, Pc=None)[source]¶ Estimate the acentric factor of a fluid using a correlation in 5. Return None if acentric factor cannot be estimated.
- Parameters
CASRN (str) – CASRN for retrieving Tb, Tc, and Pc.
Tb (float, optional) – Boiling temperature of the fluid [K]
Tc (float, optional) – Critical temperature of the fluid [K]
Pc (float, optional) – Critical pressure of the fluid [Pa]
Notes
Internal units are atmosphere and Kelvin. The correlation is as follows:
\[\omega = \frac{\ln P_{br}^{sat} - 5.92714 + 6.09648/T_{br} + 1.28862 \ln T_{br} -0.169347T_{br}^6} {15.2518 - 15.6875/T_{br} - 13.4721 \ln T_{br} + 0.43577 T_{br}^6}\]Examples
Example value for Isopropylbenzene from Reid (1987):
>>> acentric_factor_LK(425.6, 631.1, 32.1E5) 0.32544249926397856
Using ASPEN V8.4, LK method gives 0.325595.
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thermosteam.properties.acentric.
acentric_factor
(CASRN, Tb=None, Tc=None, Pc=None, Psat=None, method='Any')[source]¶ Retrieve the acentric factor of a chemical, omega, or calculate it from correlations or directly through the definition of acentric factor, if possible. Requires a known boiling point, critical temperature and pressure for use of the correlations. Requires accurate vapor pressure data for direct calculation.
Will automatically select a method to use if no method is provided; returns None if the data is not available and cannot be calculated.
Examples
>>> acentric_factor(CASRN='64-17-5') 0.635
- Parameters
CASRN (str) –
- Returns
omega – Acentric factor of the fluid [-].
- Return type
float or dict(str-float)
- Other Parameters
method (string, optional) – The method name to use. Accepted methods are ‘PSRK’, ‘PD’, ‘Yaws’, ‘LK’, and ‘DEFINITION’. If method is “Any”, the first available value from these methods will returned. If method is “All”, a dictionary of method results will be returned.
Tb (float, optional) – Boiling temperature of the fluid [K]
Tc (float, optional) – Critical temperature of the fluid [K]
Pc (float, optional) – Critical pressure of the fluid [Pa]
Psat (function(T), optional) – Model to calculate vapor pressure [Pa].
Notes
A total of five sources are available for this function. They are:
‘PSRK’, a compillation of experimental and estimated data published in the Appendix of [2]_, the fourth revision of the PSRK model.
‘PD’, an older compillation of data published in (Passut & Danner, 1973) 3.
‘Yaws’, a large compillation of data from a variety of sources; no data points are sourced in the work of 4.
‘LK’, a estimation method for hydrocarbons 5.
‘DEFINITION’, based on the definition of omega as presented in [1]_, using vapor pressure data.
See also
acentric_factor_LK()
,acentric_factor_DEFINITION()
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thermosteam.properties.acentric.
Stiel_Polar
(CASRN, Tc=None, Pc=None, omega=None, Psat=None)[source]¶ Return the Stiel Polar factor of a chemical through the definition of Stiel-polar factor if possible.
- Parameters
CASRN (string) –
Tc (float, optional) – Critical temperature of fluid [K].
Pc (float, optional) – Critical pressure of fluid [Pa].
omega (float, optional) – Acentric factor of the fluid [-]
Psat (function(T)) – Vapor pressure model [Pa].
- Returns
factor – Stiel polar factor of compound
- Return type
float
Notes
The Stiel Polar factor as presented in [1]_ is given by:
\[x = \log P_r|_{T_r=0.6} + 1.70 \omega + 1.552\]A few points have also been published in [2]_, which may be used for comparison. Currently this is only used for a surface tension correlation.
Examples
>>> Stiel_Polar(647.3, 22048321.0, 0.344, CASRN='7732-18-5') 0.024581140348734376
References
- 1
Halm, Roland L., and Leonard I. Stiel. “A Fourth Parameter for the Vapor Pressure and Entropy of Vaporization of Polar Fluids.” AIChE Journal 13, no. 2 (1967): 351-355. doi:10.1002/aic.690130228.
- 2
D, Kukoljac Miloš, and Grozdanić Dušan K. “New Values of the Polarity Factor.” Journal of the Serbian Chemical Society 65, no. 12 (January 1, 2000). http://www.shd.org.rs/JSCS/Vol65/No12-Pdf/JSCS12-07.pdf