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Displaying 26 - 50 of 91

Entropy Scaling of Viscosity for Molecular Models of Molten Salts

January 9, 2023
Author(s)
Jeffrey Young, Ian Bell, Allan H. Harvey
Entropy scaling relates dynamic and thermodynamic properties by reducing the viscosity to be a function of only the residual entropy. Molecular simulations are used to investigate the entropy scaling of the viscosity of three models of sodium chloride and

Linking viscosity to equation of state using residual entropy scaling theory

October 13, 2022
Author(s)
Xiaoxian Yang, Xiong Xiao, Monika Thol, Markus Richter, Ian Bell
In our previous work, a residual entropy scaling (RES) approach was developed to link viscosity to residual entropy (a thermodynamic property calculated with an equation of state, EoS) using a simple polynomial equation for refrigerants. This work extends

Connecting entropy scaling and density scaling

August 17, 2022
Author(s)
Ian Bell, Robin Fingerhut, Jadran Vrabec, Lorenzo Costigliola
It is shown that the residual entropy (entropy minus that of the ideal gas at the same temperature and density) is mostly synonymous with the independent variable of density scaling, identifying a direct link between these two approaches. The residual

Thermal Conductivity of Binary Mixtures of 1,1,1,2-Tetrafluoroethane(R-134a), 2,3,3,3-Tetrafluoropropene (R-1234yf), and trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E)) Refrigerants

July 28, 2022
Author(s)
Aaron Rowane, Ian Bell, Marcia L. Huber, Richard A. Perkins
A total of 2160 thermal conductivity data points, measured using a transient hot-wire instrument, are reported for binary mixtures of R-134a, R-1234yf, and R-1234ze(E) refrigerants from 200 to 340 K to pressures of 12 MPa for mixtures containing R-1234yf

New Thermodynamic Mixture Models for HFO-containing Blends

July 11, 2022
Author(s)
Ian Bell
With the modern use of fluorinated olefins as refrigerants, there is a pressing need for reference thermodynamic models to design components and cycles. Recent activities at NIST are summarized, including a survey of existing literature data and results

Implementing an Equation of State without Derivatives: teqp

April 26, 2022
Author(s)
Ian Bell, Ulrich K. Deiters, Allan Leal
This work uses advanced numerical techniques (complex differentiation and automatic differentiation) to efficiently and accurately compute all the required thermodynamic properties of an equation of state without any analytical derivatives─particularly

A Reference Correlation for the Viscosity of Krypton From Entropy Scaling

October 27, 2021
Author(s)
Sofia Polychroniadou, Konstantinos Antoniadis, Marc Assael, Ian Bell
We present a new wide-ranging correlation for the viscosity of krypton based on critically evaluated experimental data. For the first time, such a correlation has as its basis the entropy scaling approach. We base the residual contribution on the Lennard

Low-GWP Alternative Refrigerant Blends for HFC-134a: Interim Report

October 13, 2021
Author(s)
Piotr A. Domanski, Mark O. McLinden, Valeri I. Babushok, Ian Bell, Tara Fortin, Michael Hegetschweiler, Mark A. Kedzierski, Dennis Kim, Lingnan Lin, Gregory T. Linteris, Stephanie L. Outcalt, Richard A. Perkins, Aaron Rowane, Harrison M. Skye
This project addresses the objectives of the Statement of Need number WPSON-17-20 "No/Low Global Warming Potential Alternatives to Ozone Depleting Refrigerants." Its goal is to identify and demonstrate performance of low global-warming-potential (GWP), non

Dynamic Crossover in Fluids: From Hard Spheres to Molecules

July 7, 2021
Author(s)
Ian Bell, Stephanie Delage-Santacreu, Hai Hoang, Guillaume Galliero
We propose a simple and generic definition of a demarcation reconciling structural and dynamic frameworks when combined with the entropy scaling framework. This crossover line between gas- and liquid-like behaviors is defined as the curve for which an

Super-Ancillary Equations for Cubic Equations of State

June 29, 2021
Author(s)
Ian Bell, Ulrich K. Deiters
Calculation of thermodynamic phase equilibrium is error-prone and can fail both near the critical point and at very low temperatures because of the limited precision available in double precision arithmetic. Most importantly, these calculations frequently

Survey of Data and Models for Refrigerant Mixtures Containing Halogenated Olefins

June 1, 2021
Author(s)
Ian Bell, Demian Riccardi, Ala Bazyleva, Mark O. McLinden
We survey existing data for refrigerant blends containing halogenated olefins (hydrofluoroolefins (HFO), hydrochlorofluoroolefins (HCFO), and hydrochloroolefins (HCO)) in the open literature. The data are primarily taken from the NIST SOURCE database and

Unphysical critical curves of binary mixtures predicted with GERG models

October 19, 2020
Author(s)
Ian H. Bell, Ulrich K. Deiters
When applied to asymmetric binary mixtures (e.g., methane + pentane or heavier alkanes, hydrogen-containing mixtures), the GERG equation of state (GERG-2004 or GERG-2008) predicts critical curves with physically unreasonable temperature maxima above the

Entropy Scaling of Viscosity - II: Predictive Scheme for Normal Alkanes

October 16, 2020
Author(s)
Ian H. Bell
In this work, entropy scaling as applied to normal alkanes is used to probe the physics of entropy scaling for fluids with internal degrees of freedom. This approach results in the identification of a universal transition in the behavior of the normal

Differential equations for critical curves of fluid mixtures

September 22, 2020
Author(s)
Ian Bell, Ulrich K. Deiters
A novel, particularly robust method for the calculation of critical curves of fluid mixtures is proposed that makes use of differential equations representing the critical conditions (isochoric thermodynamics formalism). These differential equations are
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