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Showing papers in "Journal of Physical and Chemical Reference Data in 2019"


Journal ArticleDOI
TL;DR: Experimental data on viscosity of typical ionic liquids in the liquid state were compiled and critically evaluated in this paper, where the influence of contamination water and residual halide ions on the reported viscosities of these typical Ionic liquids was evaluated or quantitatively corrected.
Abstract: Experimental data on viscosity of typical ionic liquids in the liquid state were compiled and critically evaluated. The compilation contains data for 268 ionic liquids from 215 literature references and covers the period from 1998 through the end of December 2018. Equations for corrections of influences of contamination water and residual Cl− on viscosities of a series of typical ionic liquids are established. The influences of experimental methodology and the impurities (i.e., contamination water and residual halide ions) of the samples used on the reported viscosities of these typical ionic liquids are critically evaluated or quantitatively corrected, and the viscosities for these “pure” ionic liquids are recommended. The parameters of the Vogel–Fulcher–Tammann equation for temperature dependence of the recommended viscosities of these ionic liquids were reported. The effects of ionic structures on the viscosity of ionic liquids are presented.

42 citations


Journal ArticleDOI
TL;DR: In this paper, a new mixture model (EOS-LNG) is presented for the accurate representation of thermodynamic property data of multicomponent natural gas mixtures in the liquid state.
Abstract: A new mixture model (EOS-LNG) for the accurate representation of thermodynamic property data of multicomponent natural gas mixtures in the liquid state is presented. The mathematical approach of the GERG-2008 equation of state of Kunz and Wagner is adopted and new binary-specific functions for methane + n-butane, methane + isobutane, methane + n-pentane, and methane + isopentane are developed. The representation of all experimental data available in the literature for the corresponding binary systems is carefully analyzed so that these functions can also be applied at fluid states beyond the liquefied natural gas (LNG) region. The EOS-LNG represents all available binary and multicomponent data in the LNG region within their specified experimental uncertainty, which is significantly more accurate than the GERG-2008 model. The main focus was given to the representation of new density data measured between 100 K and 180 K with a maximum pressure of 10 MPa. Deviations from the EOS-LNG presented here do not exceed 0.02% for binary data and 0.05% for multicomponent systems. Deviations of calculated values of these data from experimental data in other fluid regions are similar to or better than those calculated with the GERG-2008 model.A new mixture model (EOS-LNG) for the accurate representation of thermodynamic property data of multicomponent natural gas mixtures in the liquid state is presented. The mathematical approach of the GERG-2008 equation of state of Kunz and Wagner is adopted and new binary-specific functions for methane + n-butane, methane + isobutane, methane + n-pentane, and methane + isopentane are developed. The representation of all experimental data available in the literature for the corresponding binary systems is carefully analyzed so that these functions can also be applied at fluid states beyond the liquefied natural gas (LNG) region. The EOS-LNG represents all available binary and multicomponent data in the LNG region within their specified experimental uncertainty, which is significantly more accurate than the GERG-2008 model. The main focus was given to the representation of new density data measured b...

37 citations


Journal ArticleDOI
TL;DR: In this article, a survey of the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered.
Abstract: Cross section data are compiled from the literature for electron collisions with oxides of nitrogen (NxOy) molecules: the species nitric oxide (NO), nitrous oxide (N2O), and nitrogen dioxide (NO2) are explicitly considered. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, and dissociative attachment. For each of these processes, the recommended values of the cross sections are presented. The literature has been surveyed up to the end of 2017. These results are supplemented by a reanalysis of the swarm measurements for NO and newly calculated cross sections for rotational excitation of N2O and for rotational excitation and electronic excitation of NO2.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a critical analysis of available experimental and theoretical cross section data for positron scattering from atomic systems is presented, and recommended cross sections for total scattering, positronium formation, inelastic scattering, and direct ionization processes.
Abstract: We present a critical analysis of available experimental and theoretical cross section data for positron scattering from atomic systems. From this analysis, we present (where data are available) recommended cross sections for total scattering, positronium formation, inelastic scattering, and direct ionization processes. A complete bibliography of available measurement and theory is also presented.

23 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm to determine the energy levels of the 16O2 molecule.
Abstract: Accurate, empirical rovibronic energy levels, with associated uncertainties, are determined for the lowest seven electronic states of the 16O2 molecule using the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm. After careful analysis and validation of 30 671 rovibronic transitions (including 24 376 measured and 6295 artificial transitions), collected from 91 publications, 4279 empirical rovibronic energy levels are determined. The highly accurate empirical (MARVEL) energy database is then augmented with rovibronic energies obtained from accurate effective Hamiltonians for the lowest six electronic states, establishing a hybrid database containing 15 946 rovibronic energy levels. Based on this hybrid database, complete up to the first dissociation limit, 41 260 cm−1, an accurate temperature-dependent ideal-gas partition function, Qint(T), and some related thermochemical functions [isobaric heat capacity, Cpo(T), entropy, So(T), and (absolute) enthalpy, Ho(T)] are derived for 16O2 employing the direct-summation technique. All thermochemical functions are reported, in 1 K increments up to 5000 K, in the supplementary material to this paper.

14 citations


Journal ArticleDOI
TL;DR: In this article, the energy levels of the 1sns and 1snp states of ions along the helium isoelectronic sequence from carbon to uranium are calculated, with n = 3-7.
Abstract: Energy levels of the 1sns and 1snp states of ions along the helium isoelectronic sequence from carbon to uranium are calculated, with n = 3–7. The computation is performed within the relativistic configuration-interaction method, including the relativistic nuclear recoil effect, the leading quantum electrodynamics effects, and the frequency dependence of the Breit interaction. All theoretical energies are supplied with uncertainty estimates.Energy levels of the 1sns and 1snp states of ions along the helium isoelectronic sequence from carbon to uranium are calculated, with n = 3–7. The computation is performed within the relativistic configuration-interaction method, including the relativistic nuclear recoil effect, the leading quantum electrodynamics effects, and the frequency dependence of the Breit interaction. All theoretical energies are supplied with uncertainty estimates.

12 citations


Journal ArticleDOI
TL;DR: In this paper, reference correlations for the viscosity of 13 inorganic inorganic molten salts have been proposed, with estimated uncertainties at the 95% confidence level given in parentheses.
Abstract: In 1988, reference correlations for the viscosity of a selection of molten inorganic salts were proposed by Janz and have been used extensively. During the last 31 years, many additional measurements have been published. In a very recent paper, new reference correlations for the thermal conductivity of 13 inorganic molten salts were proposed. In this paper, reference correlations for the viscosity of those same salts are proposed. All available experimental data for the viscosity of 13 inorganic molten salts have been critically examined with the intention of establishing improved or new reference viscosity correlations. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. Standard reference correlations are proposed for the following molten salts (with estimated uncertainties at the 95% confidence level given in parentheses): LiNO3 (6.7%), NaNO3 (3.0%), KNO3 (3.0%), NaBr (1.6%), KBr (2.0%), RbBr (2.2%), LiCl (3.7%), NaCl (2.4%), KCl (1.6%), RbCl (3.6%), CsCl (1.1%), NaI (1.5%), and RbI (1.5%).

9 citations


Journal ArticleDOI
TL;DR: In this paper, reference correlations for the viscosity of molten LiF-NaF-KF, LiF -BeF2, and Li2CO3-Na2Co3-K2CO 3 were proposed.
Abstract: In 1974, reference correlations for the viscosity of molten LiF-NaF-KF, LiF-BeF2, and Li2CO3-Na2CO3-K2CO3 were proposed by Janz and have been extensively used since then. However, in the last 45 years, many additional measurements have been published. This is why in this paper, new reference correlations for the viscosity of these salts are proposed. All available experimental data for the viscosity of these three molten salts have been critically examined with the intention of establishing improved or new reference viscosity correlations. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The reference correlation proposed for LiF-NaF-KF, with an uncertainty of 2.9% at the 95% confidence level, expands the temperature range of the previous correlation from (770–970) K to (732–1163) K and retains its uncertainty. The correlation proposed for LiF-BeF2, with an uncertainty of 4.9% at the 95% confidence level, expands the high temperature range of the previous correlation from (740–870) K to (793–1573) K, with a slight loss in its uncertainty. It is, however, a much better correlation as it is based upon measurements not available at the time of the previous one. Finally, the reference correlation for Li2CO3-Na2CO3-K2CO3, with an uncertainty of 3%, also expands the temperature range of the previous correlation from (920–1170) K to (738–1170) K and retains its uncertainty.

8 citations


Journal ArticleDOI
TL;DR: In this article, the authors apply optical potential and relativistic optical potential models to positron scattering from gas-phase beryllium (Be) and magnesium (Mg) gases.
Abstract: Results from the application of our optical potential and relativistic optical potential models to positron scattering from gas-phase beryllium (Be) and magnesium (Mg) are presented. Specifically, total cross sections and integral cross sections for the elastic, positronium formation, summed discrete electronic-state excitation, and ionization scattering processes are reported for both species and over an extended incident positron energy range. Where possible, these results are compared against the existing theoretical and experimental data, although it must be noted here that no current measurements are yet available for Be and those that are available for Mg are largely restricted to the total cross section. Nonetheless, on the basis of that comparison, recommended cross section datasets, for all the aforementioned cross sections, are formed. Those recommended cross section data are subsequently employed in a Boltzmann equation analysis to simulate the transport of positrons, under the influence of an applied (external) electric field, through the background Be and Mg gases. Note that relativistic optical potential results for the elastic momentum transfer cross section are also reported, to allow us to account for anisotropy effects in our transport simulations. Finally, our positron simulation results for quantities such as the ionization rate coefficients and flux and bulk drift velocities are compared with the corresponding electron transport results with significant differences being observed.

6 citations


Journal ArticleDOI
TL;DR: In this paper, the GCV of CH4 was determined with unprecedented precision and accuracy using the renewed Groupe Europeen de Recherches Gazieres (GERG)-Physikalisch-Technische Bundesanstalt collaboration.
Abstract: Due to the commercial transfer of billions of cubic meters of natural gases, the knowledge of the gross calorific value (GCV) of the main natural gas components and, in particular, of methane, is of outstanding interest. On the basis of previous work carried out by a Groupe Europeen de Recherches Gazieres (GERG)–Physikalisch-Technische Bundesanstalt collaboration, the so-called GERG calorimeter was further developed on the hardware as well as on the software side. With the renewed GERG calorimeter, the GCV of CH4 could be determined with unprecedented precision and accuracy. Important elements for improving the measuring methodology of flame calorimetry included the in situ calibration of the mass of the burned gas, the determination of the actual exhaust gas temperatures, and the detection of the water input by countercurrent water absorption from ambient air. For the first time, it was possible to determine the GCV not only via direct online weighing of the mass of burned gas but also via the stoichiometric water balance with a consistency of about 3.5 ppm. Based on 27 weighings of the mass of burned gas, the real-gas GCV of methane is determined as Hs(CH4) = 890 202.1 J mol−1 with a confidence interval of ±52.6 J mol−1 (t95% = 2.056). This value is by ΔHs/Hs = (−0.0436 ± 0.0059)% below the real-gas GCV of Hs(CH4) = (890 590 ± 380) J mol−1 (k = 2) converted according to ISO 6976:2016. The difference can be explained by systematic influences as well as by failures in the stoichiometric water balance in all other measurements.

5 citations


Journal ArticleDOI
TL;DR: In this paper, a new wide-ranging correlation for the viscosity of cyclopentane based on critically evaluated experimental data is presented, which is designed to be used with a recently developed equation of state, and it is valid from the triple point to 360 K in liquid range up to 380 MPa and 460 K in low-pressure vapor range.
Abstract: This paper presents a new wide-ranging correlation for the viscosity of cyclopentane based on critically evaluated experimental data. The correlation is designed to be used with a recently developed equation of state, and it is valid from the triple point to 360 K in the liquid range up to 380 MPa and 460 K in the low-pressure vapor range. The average absolute percent deviation of the fit for all primary data is 0.8% with a bias of −0.3%. The estimated expanded uncertainty of the whole fit is 2.7% (at the 95% confidence level), while the uncertainty near atmospheric pressure from 298 K to 460 K increases to 4%. The correlation behaves in a physically reasonable manner when extrapolated to 500 MPa; however, care should be taken when using the correlations outside of the validated range.

Journal ArticleDOI
TL;DR: The Journal of Physical and Chemical Reference Data (JPCRD) as mentioned in this paper is a reference database for physical and chemical properties data, with a focus on critical evaluations of existing data in a field.
Abstract: The Journal of Physical and Chemical Reference Data (JPCRD) has historically limited its scope to critical evaluations of existing data in a field, producing recommendations for the best available physical and chemical property data, preferably withuncertainty analysis. In early 2018, the scopewas expanded to include Review Articles, which might describe and document a reference database, review the data situation in a particular field, provide an overview of a series of JPCRD articles, review reference-quality measurement techniques, or review data evaluation methods. JPCRD has excluded from its scope original experimental or theoretical work, such as that found in the primary research literature; the only exception is when the experimental or theoretical results are needed to fill a “gap” in the input data for a paper whose fundamental purpose is producing critically evaluated correlations or recommended data. We are now expanding this scope slightly. While most experimental measurements and theory will still be out of scope, we will publish experimental or theoretical work if—in the judgment of the Editors—it provides definitive “reference data.” By this, we mean data that are clearly the most accurate possible (with small and well-documented uncertainties) and that provide a state-of-the-art standard that is expected to last for many years. Especially welcome are data that can serve as a reference for purposes outside their immediate context, such as calibration of instruments. Examples of past work that could fit in this category include the experiments that established the 0.01 K difference between the ice point and the triple point of water (thus setting 273.15 K as the zero of theCelsius scale), the careful determination of the absolute viscosity of liquid water that has served as a calibration standard for decades, the accurate absolute determination of the dipole moment of the OCS molecule that is a reference for spectroscopic determination of dipolemoments,measurements or calculations that establish the energies of key molecules or ions with subchemical accuracy for use in a thermochemical network to provide self-consistent energies for related compounds, and the ab initio computation of low-density thermophysical properties of helium for use in calibrations and metrology. As always, authorswith questions about the suitability of an article for JPCRD are encouraged to contact either of the Editors.