Arno R. Laesecke

New International Formulation for the Viscosity of H2O

The International Association for the Properties of Water and Steam (IAPWS) encouraged an extensive research effort to update the IAPS Formulation 1985 for the Viscosity of Ordinary Water Substance, leading to the adoption of a Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance. This manuscript describes the development and evaluation of the 2008 formulation, which provides a correlating equation for the viscosity of water for fluid states up to 1173K and 1000MPa with uncertainties from less than 1% to 7% depending on the state point.

Reference Correlation of the Viscosity of Propane

A new representation of the viscosity of propane includes a zero-density correlation and an initial-density dependence correlation based on the kinetic theory of dilute gases and on the Rainwater–Friend theory. The higher density contributions of the residual viscosity in the representation are formed by a combination of double polynomials in density and reciprocal temperature, and a free-volume term with a temperature-dependent close-packed density. The full surface correlation is based on a set of primary experimental data selected as a result of a critical assessment of the available information from 37 original viscosity studies. The review refers to 96 citations altogether. The validity of the representation extends from the triple point to 600 K and 100 MPa in accordance with the modified Benedict–Webb–Rubin equation of state. The uncertainty of the representation varies from ±0.4% for the viscosity of the dilute gas phase between room temperature and 600 K, to about ±2.5% for the range 100–475 K up...

Transport coefficients of the Lennard-Jones model fluid. III. Bulk viscosity

In an extensive computer simulation study, the transport coefficients of the Lennard-Jones model fluid were determined with high accuracy from equilibrium molecular-dynamics simulations. In the frame of time-correlation function theory, the generalized Einstein relations were employed to evaluate the transport coefficients. This first of a series of four papers presents the results for the viscosity, and discusses and interprets the behavior of this transport coefficient in the fluid region of the phase diagram. Moreover, the kinetic-kinetic, kinetic-potential, and potential-potential viscosity contributions are resolved over the whole range of fluid states, and their characteristic dependence on temperature and density is described. Finally, an additional analysis of the shear-stress correlation functions reveals aspects of the momentum-transport mechanisms on the molecular scale.

Viscosity and Thermal Conductivity of Nitrogen for a Wide Range of Fluid States

The viscosity and the thermal conductivity of fluid nitrogen were critically evaluated and correlated on the basis of a comprehensive literature survey. Recommended values were generated in a temperature range from 70 to 1100 K and pressures up to 100 MPa using the residual concept. To retain consistency with the IUPAC Thermodynamic Tables, the same thermodynamic key data were used. Additionally, a so‐called transport equation of state was established that makes it possible to achieve a unified representation of the viscosity and thermal conductivity in terms of pressure and temperature.

The effect of dissolved water on the viscosities of hydrophobic room-temperature ionic liquids

Data for viscosity vs. water content for three hydrophobic room-temperature ionic liquids show that their viscosities are strongly dependent on the amount of dissolved water.

Transport coefficients of the Lennard-Jones model fluid. II Self-diffusion

In an extensive computer simulation study, the transport coefficients of the Lennard-Jones model fluid were determined with high accuracy from equilibrium molecular-dynamics simulations. In the frame of time-correlation function theory, the generalized Einstein relations were employed to evaluate the transport coefficients. This second of a series of four papers presents the results for the self-diffusion coefficient, and discusses and interprets the behavior of this transport coefficient in the fluid region of the phase diagram. The uncertainty of the self-diffusion data is estimated to be 1% in the gas region and 0.5% at high-density liquid states. With the very accurate data, even fine details in the shape of the self-diffusion isotherms are resolved, and the previously little-investigated behavior of the self-diffusion coefficient at low-density gaseous states is analyzed in detail. Finally, aspects of the mass transport mechanisms on the molecular scale are explored by an analysis of the velocity autocorrelation functions.

An improved extended corresponding states method for estimation of viscosity of pure refrigerants and mixtures

Abstract The extended corresponding states method for calculating the viscosity of pure refrigerants and mixtures is investigated. The accuracy of pure fluid viscosity values is significantly improved by introducing a third shape factor evaluated using available pure fluid viscosity data. A modification to the method of Huber and Ely (Fluid Phase Equilibria, 1992, 80 , 45–46) is proposed for estimation of the viscosity of mixtures; this modification eliminates the possibility of discontinuities at the critical point, ensures that the pure component viscosity is provided in the limit of a component mole fraction approaching 1, and improves the overall accuracy of the method. The method has been applied to 12 pure refrigerants including three hydrocarbons and mixtures. The average absolute deviations between the calculated and experimental viscosity values are within 4% for all of the pure fluids and most of the mixtures investigated.

Transport Properties of Fluid Oxygen

Supplementing the recently completed IUPAC tables for the thermodynamic properties of oxygen, this paper presents a data evaluation of the transport properties, viscosity, and thermal conductivity. From a comprehensive literature survey the available data have been complied, and their quality was assessed. Selected measurements were correlated to generate skeleton tables of the most reliable data along the vapor‐liquid coexistence curve and for the fluid region at pressures from 0.1 to 100 MPa and at temperatures from 70 to 1400 K. The set of correlations which was developed includes residual concept formulations as well as transport equations of state. These allow the direct calculation of viscosities and thermal conductivities from pressure and temperature as input variables. The simplified crossover model was employed to represent the enhancement of the thermal conductivity in the critical region.

A New Reference Correlation for the Viscosity of Methanol

A new reference-quality correlation for the viscosity of methanol is presented that is valid over the entire fluid region, including vapor, liquid, and metastable phases. To describe the zero-density viscosity with kinetic theory for polar gases, a new expression for the collision integral of the Stockmayer potential is introduced. The initial density dependence is based on the Rainwater‐Friend theory. A new correlation for the third viscosity virial coefficient is developed from experimental data and applied to methanol. The high-density contribution to the viscosity is based on the Chapman‐Enskog theory and includes a new expression for the hard-sphere diameter that is a function of both temperature and density. The resulting correlation is applicable for temperatures from the triple point to 630 K at pressures up to 8 GPa. The estimated uncertainty of the resulting correlation with a coverage factor of 2 varies from 0.6% in the dilute-gas phase between room temperature and 630 K, to less than 2% for the liquid phase at pressures up to 30 MPa at temperatures between 273 and 343 K, 3% for pressures from 30 to 100 MPa, 5% for the liquid from 100 to 500 MPa, and 10% between 500 MPa and 4 GPa. At very high pressures, from 4 to 8 GPa, the correlation has an estimated uncertainty of 30% and can be used to indicate qualitative behavior.

Viscosity correlations for minor constituent fluids in natural gas: n-octane, n-nonane and n-decane

Natural gas, although predominantly comprised of methane, often contains small amounts of heavier hydrocarbons that contribute to its thermodynamic and transport properties. In this manuscript, we review the current literature and present new correlations for the viscosity of the pure fluids n-octane, n-nonane, and n-decane that are valid over a wide range of fluid states, from the dilute gas to the dense liquid. The new correlations represent the viscosity to within the uncertainty of the best experimental data and will be useful for engineers working on viscosity models for natural gas and other hydrocarbon mixtures.