Wide-Ranging Reference Correlations for Dilute Gas Transport Properties Based on Ab Initio Calculations and Viscosity Ratio Measurements

Xiong Xiao,Darren Rowland,Eric F May,Saif Z S Al Ghafri

doi:10.1063/1.5125100

Abstract

The combined use of experimental viscosity ratios together with ab initio calculations for helium has driven significant improvements in the description of dilute gas transport properties. Here, we first use improvements made to ab initio helium calculations to update viscosity ratios measured for H2, Ar, CH4, and Xe by May et al. [Int. J. Thermophys. 28, 1085 (2007)] over the temperature range of 200–400 K, reducing the uncertainties of the data to 0.055%, 0.038%, 0.067%, and 0.084%, respectively. Separately, we extend the technique of combining viscosity ratios with ab initio calculations to develop new reference correlations for the dilute gas viscosity of 10 gases: helium, neon, argon, krypton, xenon, hydrogen, nitrogen, methane, ethane, and propane. This is achieved by combining the ratios of viscosities calculated ab initio at the target temperature and at 298.15 K with experimentally based reference viscosity values for each gas at 298.15 K. The new reference dilute gas viscosity correlations span temperature ranges from at least 150 K to 1200 K with relative uncertainties between 30% (krypton) and 85% (methane) lower than the original ab initio results. For the noble gases, ab initio calculations for the Prandtl number are used to develop reference correlations for thermal conductivity ranging from at least 100 K to 5000 K, with relative uncertainties ranging from 0.04% (argon) to 0.20% (xenon). The new reference correlations are compared with available experimental data at dilute gas conditions. In general, the data agree with the new correlations within the claimed experimental uncertainty.

Highlights

IntroductionDilute gas transport properties serve as a basis for predicting transport properties at high pressures and are important for calibrating scientific apparatus and other measurement devices.[1, 2] For example, accurate viscosities are crucial for the calibration of certain low-flow meters for mass spectrometers,[3, 4] and precise thermal conductivities at low densities are required for acoustic thermometry, determination of the universal gas constant,[5, 6] and were important to recent (and final) measurements of the Boltzmann constant prior to its redefinition.[7]Several experimental methods are available for measuring viscosities accurately under low density conditions, including rotating-body viscometers,[8,9,10] oscillating-disk viscometers[11,12,13,14] and capillary viscometers.[3, 4, 15] With these apparatus, relative uncertainties in the order of 0.1% of the fluid viscosity are possible for temperatures from (200 to 700) K (all the uncertainties mentioned in this work are standard uncertainties corresponding to a coverage factor of k=1)
We considered the variation in rηgas(T)AI produced when the constituent ηgTa,AsI were derived from different potentials.,[33,34,35, 39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55] and/or experimental data at dilute gas conditions[14, 56,57,58,59] when a sufficient number of suitably accurate potentials were not available
Updated values of the dilute gas viscosities for H2, Ar, CH4, and Xe measured in 2007 by May et al.[4] were calculated using the highly accurate reference viscosity for helium calculated ab initio in 2012 by Cencek et al.;[32] this reduced the uncertainties of the measured data by between (23 and 55) %

Summary

Introduction

Dilute gas transport properties serve as a basis for predicting transport properties at high pressures and are important for calibrating scientific apparatus and other measurement devices.[1, 2] For example, accurate viscosities are crucial for the calibration of certain low-flow meters for mass spectrometers,[3, 4] and precise thermal conductivities at low densities are required for acoustic thermometry, determination of the universal gas constant,[5, 6] and were important to recent (and final) measurements of the Boltzmann constant prior to its redefinition.[7]Several experimental methods are available for measuring viscosities accurately under low density conditions, including rotating-body viscometers,[8,9,10] oscillating-disk viscometers[11,12,13,14] and capillary viscometers.[3, 4, 15] With these apparatus, relative uncertainties in the order of 0.1% of the fluid viscosity are possible for temperatures from (200 to 700) K (all the uncertainties mentioned in this work are standard uncertainties corresponding to a coverage factor of k=1).

Objectives

Results

Conclusion