Gaseous density calculation by means of relative permittivity measurement

Abstract

This study presents a gaseous density calculation method on the basis of relative permittivity measurement. The relative permittivity of a gas sample is measured by using a cylindrical microwave cavity resonator in wide temperature and pressure ranges. The obtained relative permittivity data along each isotherm are fitted to the dielectric-virial equation with a polynomial function of pressure. The density-virial coefficients are theoretically evaluated from the intermolecular potential or the corresponding state principle so that the dielectric-virial coefficients are separately determined from the polynomial regression analysis. The gaseous density is finally calculated by using the measured relative permittivity data in combination with the determined dielectric-virial coefficients. Following the above procedure, gaseous densities of Ar and He were calculated and compared with the reference values.

Keywords

• Density
• Relative permittivity
• Microwave resonator
• Virial-equation