Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent twophase calculations
Abstract
The fidelity of Gradient Theory simulations depends on the accuracy of saturation properties and influence parameters, and require equations of state (EoS) which exhibit a fundamentally consistent behavior in the twophase regime. Widely applied multiparameter EoS, however, are generally invalid inside this region. Hence, they may not be fully suitable for application in concert with Gradient Theory despite their ability to accurately predict saturation properties. The commonly assumed temperaturedependence of pure component influence parameters usually restricts their validity to subcritical temperature regimes. This may distort predictions for general multicomponent interfaces where temperatures often exceed the critical temperature of vapor phase components. Then, the calculation of influence parameters is not well defined. In this paper, one of the first studies is presented in which Gradient Theory is combined with a nextgeneration Helmholtz energy EoS which facilitates fundamentally consistent calculations over the entire twophase regime. Illustrated on pentafluoroethane as an example, reference simulations using this method are performed. They demonstrate the significance of such highaccuracy and fundamentally consistent calculations for the computation of interfacial properties. These reference simulations are compared to corresponding results from cubic PR EoS, widelyapplied in combination with Gradient Theory, and mBWR EoS. The analysis reveals that neither ofmore »
 Authors:
 Sandia National Lab. (SNLCA), Livermore, CA (United States)
 Publication Date:
 Research Org.:
 Sandia National Lab. (SNLCA), Livermore, CA (United States)
 Sponsoring Org.:
 USDOE Office of Secretary of Energy (S); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC22)
 OSTI Identifier:
 1235923
 Alternate Identifier(s):
 OSTI ID: 1244591
 Report Number(s):
 SAND201520792J
Journal ID: ISSN 00219797; PII: S0021979714010388
 Grant/Contract Number:
 AC0494AL85000
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Journal of Colloid and Interface Science
 Additional Journal Information:
 Journal Volume: 445; Journal Issue: C; Journal ID: ISSN 00219797
 Country of Publication:
 United States
 Language:
 English
 Subject:
 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Gradient Theory; interfacial tension; influence parameter; equation of state; pure fluid; metastability
Citation Formats
Dahms, Rainer N. Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent twophase calculations. United States: N. p., 2014.
Web. doi:10.1016/j.jcis.2014.12.069.
Dahms, Rainer N. Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent twophase calculations. United States. doi:10.1016/j.jcis.2014.12.069.
Dahms, Rainer N. 2014.
"Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent twophase calculations". United States.
doi:10.1016/j.jcis.2014.12.069. https://www.osti.gov/servlets/purl/1235923.
@article{osti_1235923,
title = {Gradient Theory simulations of pure fluid interfaces using a generalized expression for influence parameters and a Helmholtz energy equation of state for fundamentally consistent twophase calculations},
author = {Dahms, Rainer N.},
abstractNote = {The fidelity of Gradient Theory simulations depends on the accuracy of saturation properties and influence parameters, and require equations of state (EoS) which exhibit a fundamentally consistent behavior in the twophase regime. Widely applied multiparameter EoS, however, are generally invalid inside this region. Hence, they may not be fully suitable for application in concert with Gradient Theory despite their ability to accurately predict saturation properties. The commonly assumed temperaturedependence of pure component influence parameters usually restricts their validity to subcritical temperature regimes. This may distort predictions for general multicomponent interfaces where temperatures often exceed the critical temperature of vapor phase components. Then, the calculation of influence parameters is not well defined. In this paper, one of the first studies is presented in which Gradient Theory is combined with a nextgeneration Helmholtz energy EoS which facilitates fundamentally consistent calculations over the entire twophase regime. Illustrated on pentafluoroethane as an example, reference simulations using this method are performed. They demonstrate the significance of such highaccuracy and fundamentally consistent calculations for the computation of interfacial properties. These reference simulations are compared to corresponding results from cubic PR EoS, widelyapplied in combination with Gradient Theory, and mBWR EoS. The analysis reveals that neither of those two methods succeeds to consistently capture the qualitative distribution of obtained key thermodynamic properties in Gradient Theory. Furthermore, a generalized expression of the pure component influence parameter is presented. This development is informed by its fundamental definition based on the direct correlation function of the homogeneous fluid and by presented highfidelity simulations of interfacial density profiles. As a result, the new model preserves the accuracy of previous temperaturedependent expressions, remains welldefined at supercritical temperatures, and is fully suitable for calculations of general multicomponent twophase interfaces.},
doi = {10.1016/j.jcis.2014.12.069},
journal = {Journal of Colloid and Interface Science},
number = C,
volume = 445,
place = {United States},
year = 2014,
month =
}
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