VIRIAL-COEFFICIENTS AND COMPRESSION FACTORS OF 9 TERNARY GASEOUS-MIXTURES OBTAINED BY THE DIELECTRIC-CONSTANT METHOD

Pressure and dielectric virial coefficients and compression factors of three mixtures of the CH4-C2H6-N-2 system, three mixtures of the CH4- CO2-N-2 system and three mixtures of the CH4-C2H6-CO2 system have been investigated experimentally using the dielectric constant method. Pre cise (+/-5 ppm) measurements of the dielectric constant epsilon as a f unction of the pressure P along one isotherm T are combined with the f irst three dielectric virial coefficients A(epsilon), B-epsilon and C- epsilon of each mixture to obtain accurate values of the molar density p. The compression factor Z = P/(rho RT) was obtained from the measur ed values of epsilon, P and T. We report the values of Z at 298.15 K u p to 12 MPa for the nine mixtures. The first three dielectric virial c oefficients, and the second and third pressure virial coefficients for most of the mixtures agree with the calculated or literature values w ithin the limits of uncertainty. Experimental values of Z are compared with the calculated values from the GERG equation. The mean deviation in Z is of the order of 0.11% for all the mixtures. This is quite sim ilar to the expectation accuracy of 0.1% for the GERG equation. (C) 19 97 Elsevier Science B.V.