Theory and Modeling of Fluids
Group
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Group Leader:
Daniel G. Friend
NIST, Physical and Chemical Properties Division
Mail Stop 838.08
325 Broadway
Boulder, CO 80303
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Phone: (303) 497-5964
Fax: (303) 497-5224
Email: daniel.friend@nist.gov
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The Theory and Modeling of Fluids Group performs
theoretical research, modeling activities, and computer tasks related to
the determination and application of thermodynamic and transport properties
of fluids over wide ranges of temperature, pressure, and composition. The
fluids of interest include pure or mixed common inorganic and industrial
chemicals, natural gas and petroleum fluids, cryogens, refrigerants,
aqueous systems, suspensions, and gels. The group develops computer
programs to calculate or predict fluid properties with uncertainties
commensurate with the available experimental data and the complexity of the
system. The studies include research into properties near phase
transitions and critical points, properties of dilute systems, the
relationship between microscopic structure and macroscopic properties,
computational fluid dynamic calculations of processes in which fluid flow
and properties play a primary role, and computer simulation studies.
Selected Research Projects - Index
Databases Available from the
Fluid Properties Data Center
Thermodynamic Properties of Air and Nitrogen
Properties of Advanced Working Fluids
Kinetic Theory and Transport Properties
Computer Simulation of Aggregating Systems Under
Shear
Thermophysical Properties of
Refrigerants and Refrigerant Mixtures
Modeling of the Thermophysical
Properties of Cryogens, Hydrocarbons, and their Mixtures
Phase Behavior of Mixtures in the Critical
Region
Molecular Theory of Solid-Liquid
Equilibrium
Properties of Heavy-Hydrocarbon
Systems
Properties of Water
Modeling and Interpretation of Diffraction
Data from Disordered Systems
Thermodynamics of Dilute Systems
Computer Simulations: Hard Sphere Mixtures
and Dendritic Polymers
These Technical Highlights were selected to represent the
contributions of the Theory and Modeling of Fluids Group to the efforts of
the Physical and Chemical Properties Division. The complete list of
hightlights for the Division can be found at
http://www.boulder.nist.gov/div838/tar/index.html
Some Recent Papers - Click for Abstracts
- Abdulagatov, I.M., J.W. Magee, S.B. Kiselev, and D.G. Friend,
- Isochoric Heat Capacity of
Light and Heavy Water at Subcritical and Supercritical Conditions
- Anisimov, M.A., A.A. Povodyrev, J.P. Roseli, J.V. Sengers, S.B. Kiselev,
and D.G. Friend,
- Critical Amplitudes of H2O
and D2O in the Near-Vicinity of the Critical Point
- Bellows, J.C., Friend, D.G., Harvey, A.H., Levelt Sengers, J.M.H.,
Parry, W.T., Sengers, J.V., Sewell, J.B., and White, Jr., H.J.,
- New Steam Properties are
Coming
- Butler, B.D., D.R. Haeffner, P.L. Lee, and T.R. Welberry,
- High-Energy X-ray Diffuse
Scattering Using Weissenberg Flat-Cone Geometry
- Drabarek, E., J.R. Bartlett, H.J.M. Hanley, J.L. Woolfrey, C.D. Muzny,
and B.D. Butler,
- Shear-Induced
Restructuring of Colloidal Silica Gels
- Gay, S. C., J.C. Rainwater, and P.D. Beale,
- Two-Dimensional hard
Dumbbells: I. Fluctuating Cell Model
- Gay, S.C., J.C. Rainwater, and P.D. Beale,
- Two-Dimensional Hard
Dumbells: II. Pressure in terms of Free Volumes and Surfaces
- Gay, S.C., Beale, P.D., and Rainwater, J.C.,
- Solid-Liquid Equilibrium of
Dipolar Heteronuclear Hard Dumbbells in a Generalized van der Waals Theory:
Application to Methyl Chloride
- Harvey, A.H.,
- Application of
First-Principles Calculations to the Correlation of Water's Second Virial
Coefficient
- Harvey, A.H., and Parry, W.T.,
- Keep Your `Steam Tables'
up to Date
- Harvey, A.H.,
- Applications
of Near-Critical Dilute-Solution Thermodynamics
- Harvey, A.H., Gallagher, J.S., and Levelt Sengers, J.M.H.,
- Revised Formulation for the
Refractive Index of Water and Steam as a Function of Wavelength,
Temperature and Density
- Huber, M.L., E.W. Lemmon, and R.T Jacobsen,
- Modeling the Thermodynamic Properties of Natural Gas
- Kiselev, S.B., Lue, L. and Belyakov, M.Y.,
- Universal Crossover Function
and Non-Universal Order-Parameter Profiles for Critical Adsorption
- Kiselev, S.B., Abdulagatov, I.M., and Harvey, A.H.,
- Equation of State and
Thermodynamic Properties of Pure D20 and D20 + H20 Mixtures In and Beyond
the Critical Region
- Kiselev, S.B., Perkins, R.A., and Huber, M.L.,
- Transport Properties of
Refrigerants R32, R125, R134a, and R125 + R32 Mixtures in and Beyond the
Critical Region
- Lemmon, E.W., and R.T. Jacobsen,
- An international Standard
Formulation for the thermodynamic properties of 1,1,1-
trifluoroethane (R143a) for Temperatures from 161 to 450K and Pressures to
50 MPa
- Lue, L.,
- The Volumetric Behavior of
Athermal Dendritic Polymers: Monte Carlo Simulation
- Lue, L.,
- Equation of State for Polymer
Chains in Good Solvents
- Lue, L., D.G. Friend, and J.R. Elliott,
- Critical Compressibility
Factors for Chain Molecules
- Lue, L., and S.B. Kiselev,
- Penetration Function for Star
Polymers in Good Solvents
- Najafi, B.; Araghi, R.; Rainwater, J.C.; Alavi, S.; and Snider, R.,
- Prediction of the Thermal
Conductivity of Gases based on the Rainwater-Friend Theory and a New
Corresponding States Function
- Parry, W.T., J.C. Bellows, J.S. Gallagher, and A.H. Harvey,
- ASME International Steam Tables for Industrial Use
- Rainwater, J.C. and R. Tillner-Roth,
- Critical Region
Vapor-Liquid Equilibrium Model of Ammonia-Water
- Rainwater, J.C.,
- A Nonclassical Model of
a Type 2 Mixture with Vapor-Liquid, Liquid-Liquid, and Three-Phase
Equilibria
- Span, R., E.W. Lemmon, R.T. Jacobsen, W. Wagner, and A. Yokozeki,
- A Reference Equation of
State for the Thermodynamic Properties of Nitrogen for Temperatures from
63.151 to 1000 K and Pressures to 2200 MPa
- Watts, L.A.,
- Book Review of
Electrolytes. Properties of Solutions. Methods for Calculation of
Multicomponent System and Experimental Data on Thermal Conductivity and
Surface Tension
- Watts, L.A., and B. Louie,
- Apparatus for Measuring
Vapor-Liquid Equilibrium and Phase Density of Aqueous-Organic-Salt
Solutions
Address and telephone information for the Contact for each research project
described below is available by clicking on the individual's name.
Selected Research Projects
Fluid Properties Data Center
This Data Center engages in the systematic development, review, and
evaluation of models to describe the thermophysical properties of
industrially important fluid systems. Computer databases which
implement these models are a major result of these efforts; these
software packages are available through the Standard Reference Data
office of NIST; the complete catalog of SRD products can be found
on-line in the Standard Reference Data Products
Catalog. Currently the Data Center has
available the following computer products:
Databases Available from the Fluid
Properties Data Center
Thermodynamic Properties of Air and
Nitrogen
Because of the importance of these systems to aerospace and
industrial applications, equations of state have been developed to
calculate the thermodynamic properties of nitrogen and air over all
liquid and vapor phases up to high temperatures and pressures. In
addition, mixture models have been developed to calculate the
thermophysical properties, including vapor-liquid equilibrium and
transport properties, of nitrogen-oxygen-argon mixtures. The equations
of state and mixture equation are generally accurate to within 0.1% in
density, 0.2% in speed of sound, and 1% in heat capacities. Information
about these fluids is included in SRD Database #23.
Properties of Advanced Working Fluids
In addition to the working fluids included in other topics, we have been
studying the properties of ammonia-water mixtures which are used in
refrigeration cycles and which have been proposed for extensive use in
advanced power cycles. The goal of this project is to produce reference
quality thermophysical property surfaces for the mixture which can be
reliably used in engineering design, optimization, and system
evaluation.
Kinetic Theory and Transport Properties
We have developed what is now known as the Rainwater-Friend theory
for density corrections to gaseous viscosity and thermal conductivity.
These are analogous to the second virial coefficient for pressure. Our
theory complements the Chapman-Enskog theory for transport properties in
the dilute gas limit. Currently we are employing state-of-the-art
interatomic potentials for noble gases and are investigating
corresponding states approaches for extending transport property
correlations to higher density. Correlations and predictive models for
viscosity and thermal conductivity are included in many of the databases
available from the Fluid Properties Data Center.
Thermophysical Properties of Refrigerants
and Refrigerant Mixtures We have been very active in the
modeling of the thermophysical properties of refrigerant working fluids, in
part because of environmental concerns which have received great
attention. Recently, equations of state have been developed for the pure
fluid refrigerants R-32, R-123, R-125, R-134a and R-143a and a mixture
model, explicit in Helmholtz energy, has been developed that is capable of
predicting thermodynamic properties of refrigerant mixtures containing
R-32, R-125, R-134a, and R-152a. Much of the modeling work has been
incorporated into Version 6 of the NIST Refprop database. In
addition, we are developing models for the phase equilibrium and
equilibrium properties of mixtures containing a refrigerant and a
lubricant.
Modeling of the Thermophysical
Properties of Cryogens, Hydrocarbons, and their Mixtures
We have been very active in the development of reference correlations
for pure components and mixtures in the area of cryogenic fluids and
hydrocarbons. In addition, we have been working on predictive models for
systems for which only limited data are available. Some of this work has
been incorporated in NIST Databases #4, #12, and #14. Recently, a mixture
model explicit in Helmholtz energy has been developed which is capable of
predicting thermodynamic properties of mixtures containing nitrogen, argon,
oxygen, carbon dioxide, methane, ethane, propane, n-butane, and i-butane
within the estimated accuracy of available experimental data.
Phase Behavior of Mixtures in the Critical
Region
We have used a modification of the Leung-Griffiths model to
obtain accurate correlations of vapor-liquid equilibrium in the critical
region for a wide variety of binary mixtures, as well as a few ternary
and multicomponent ones. In collaboration with Professor Kiselev, we
have added a crossover function to the model and have developed an
alternative, corresponding-states approach valid for the supercritical
one-phase region and caloric properties. Most recently, we have
developed an extended model that includes both vapor-liquid and
liquid-liquid equilibrium.
Molecular Theory of Solid-Liquid Equilibrium
We are developing a theory of solid-liquid equilibrium with emphasis
on the roles played by molecular shape and electric multipole moments.
In our current models, the free energy of the liquid is obtained from
simulation or from an equation of state. The free energy of the solid
comes from either simulation or the Lennard-Jones Devonshire cell model,
and we are developing methods to make the cell model calculations more
efficient. As a specific application, we have shown that the
experimental crystal structure of methyl chloride is favored only in the
presence of a molecular dipole moment, and have derived reasonable
estimates for triple point temperature and volume change on freezing.
Properties of Heavy-Hydrocarbon
Systems
In this project we model the transport properties of heavy petroluem
fractions that typically are characterized by a mean average boiling point
and an API specific gravity. Work is in progress to develop models for the
equilibrium properties of these fluids, as well as their mixtures with
defined hydrocarbons.
Properties of Water This activity
largely involves participation in the work of the International Association
for the Properties of Water and Steam (IAPWS), which sets international standards
for the thermophysical properties of water. Efforts at NIST include
participation in the development of improved formulations, dissemination of
these property standards (for example, "Steam Tables" in software form),
and research on the properties of aqueous systems of interest to
industry. The NIST Database
#10 includes results from this work.
Thermodynamics of Dilute Systems
This research focuses on the properties of solutes when their
concentration in a solvent approaches zero; this limit often permits
increased opportunity to make use of theoretical insights. Areas of
particular interest include dilute aqueous systems, the solubility of
solids in supercritical fluids, and dilute mixtures near the solvent's
critical point.
Computer Simulations: Hard Sphere Mixtures
and Dendritic Polymers
Hard-sphere fluids have played an important role in the modeling of
molecular fluids and colloidal systems, because in many of these systems
the repulsive interactions dominate the structure and thermodynamics.
Recently, there has been a renewed interest in binary, additive
hard-sphere mixtures, motivated by theoretical predictions that the
fluid phase becomes unstable at packing fractions lower than that
expected for typical fluid-solid transition for hard-sphere diameter
ratios of around 0.2 and lower; however, the nature of this transition
is still controversial. We are currently performing molecular dynamics
and Monte Carlo simulations in various ensembles, for binary hard-sphere
mixtures to examine these questions. In addition, we are studying Monte
Carlo simulations for dilute to concentrated solutions of homogeneous,
athermal dendritic polymers to determine the structure and
thermodynamics of these systems. These simulations investigate the
effect of hyperbranching on the structure and thermodynamics of polymer
solutions, and, in addition, test the accuracy of current theories for
polymeric fluids.
Generation 5 dendritic polymer. The white atom is the "core" of the
dendrimer, and the red atoms are the surface atoms on the dendrimer. The
first figure is for a dendrimer at infinite dilution, while the second one
is for a concentrated dendrimer solution.
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Please send comments and suggestions to Gary Hardin
<gary.hardin@nist.gov>
Last modified: 13 March 2000