High-precision virial coefficients of argon and carbon dioxide from integration of speed of sound data in the pressure-temperature domain

作者：Estrada Alexanders Andres F^*; Guzman Orlando; Perez Vidal Brenda

来源：Molecular Physics, 2012, 110(11-12): 1349-1358.

DOI：10.1080/00268976.2012.655340

• virial coefficient
• acoustic virial coefficient
• argon
• carbon dioxide
• experimental pVT data

We put forward a method for determining second and third pVT virial coefficients using accurate speed-of-sound measurements. Compared with previous determinations, our results' root-mean-square uncertainty is smaller by a factor of three for argon, and six for carbon dioxide. Our acoustic method avoids previous approaches' need for assumed forms of the interaction potentials and iterative procedures to achieve thermodynamic consistency between acoustic and pVT virial coefficients. Second and third acoustic virial coefficients beta(a)'(T) and gamma(a)'(T) are found from the low-pressure behaviour of speed of sound in the pressure-temperature representation. They are related to the virial coefficients B'(T) and C'(T) for the pressure expansion by ordinary differential equations. Density-expansion virial coefficients B and C are found algebraically from the numerical solution of those equations. Uncertainties of B and C (arising from uncertainties from that of acoustic virial coefficients, initial values of the volumetric virial coefficients and their derivatives) are estimated by Monte Carlo sampling. This method can provide high-precision determinations of virial coefficients of pure gases over wide temperature ranges and therefore a fundamental equation of state for the gaseous phase.

• 出版日期2012