Xiaopo Wang

Calculations of the thermophysical properties of binary mixtures of noble gases at low density from ab initio potentials

Interaction potentials determined ab initio from quantum mechanics were used to calculate the thermophysical properties of six binary mixtures of noble gases: helium–neon, helium–argon, helium–krypton, neon–argon, neon–krypton and argon–krypton. From the ab initio potentials, the second pressure virial coefficient, the binary diffusion coefficient and the thermal diffusion factor were computed for the considered binary mixtures at low density in the temperature range 100–5000 K employing well-established formulas in statistical thermodynamics and the kinetic theory of dilute gases. In all cases, while not as good as that for pure noble gases, close agreement between experimental data and the theoretically calculated values shows that ab initio potentials are reliable for the calculation of accurate thermophysical properties of binary mixtures of noble gases over a wide temperature range.

Recommended gas transport properties of argon at low density using ab initio potential

The most important transport properties of argon have been calculated using classical kinetic theory expressions in conjunction with high-quality ab initio potential energy values computed by Patkowski and Szalewicz. Dilute gas transport properties have been calculated for the viscosity, thermal conductivity, self-diffusion coefficient and thermal diffusion factor from 83 to 10,000 K. Comparisons between experimental transport property data and values presently calculated indicate that the present theoretical predictions may be employed as recommended values for this set of transport properties over a wide temperature range.

Gaseous transport properties of hydrogen, deuterium and their binary mixtures from ab initio potential

A spherically symmetric representation of the ab initio potential, developed by K. Patkowski, W. Cencek, P. Jankowski, K. Szalewicz, J.B. Mehl, G. Garberoglio and A.H. Harvey, J. Chem. Phys. 129, 094304 (2008) [16], has been used to calculate transport properties of hydrogen, deuterium and their binary mixtures by means of the classical kinetic theory. Results are reported for viscosity, thermal conductivity, diffusion coefficient and thermal diffusion factor in the dilute-gas limit for temperatures ranging from 298 to 2000 K. Available experimental data have been investigated and compared with the theoretically calculated values to check the quality of this work. Reasonable agreements show that the high-quality potential is effective in accurately predicting transport properties of hydrogen, deuterium and their binary mixtures, which can provide useful support to experimental measurements over a wide temperature range.

Densities of FAMEs or FAEEs with ethanol at temperatures from 283.15 to 318.15 K

ABSTRACT Ethanol is usually considered as an additive to blend with biodiesels to improve its cold flow characteristics. The thermophysical properties of ethanol with biodiesels are therefore of interest in its applications. In the present work, the densities of ethanol with six components of biodiesel (including methyl caprate, methyl laurate, methyl myristate, ethyl caprylate, ethyl caprate and ethyl laurate) mixtures were measured from 283.15 to 318.15 K and at atmospheric pressure in the overall composition range. Redlich–Kister equation was used to correlate the excess molar volumes of the mixtures, which were calculated from the experimental densities. In addition, Apelblat’s equation was extended to correlate and predict the densities of the studied mixtures as a function of concentration and temperature.

Determination of the potential energy surfaces of refrigerant mixtures and their gas transport coefficients

In this work, the inversion scheme was used to determine the potential energy surfaces of five polar refrigerant mixtures. The systems studied here are R123-R134a, R123-R142b, R123-R152a, R142b-R134a, and R142b-R152a. The low-density transport coefficients of the refrigerant mixtures were calculated from the new invert potentials by the classical kinetic theory. The viscosity coefficient, binary diffusion coefficient, and thermal diffusion factor were computed for the temperature range from 313.15-973.15 K. The agreement with the NIST viscosity data demonstrates that the present calculated values are accurate enough to supplement experimental data over an extended temperature range. Correlations of the transport properties were also provided for the refrigerant mixtures at equimolar ratios.