PVT data from burnett and refractive index measurements for the nitrogen—hydrogen system from 270 to 353 K and pressures to 30 MPa

Abstract

The P, ϱ and T behaviour of four nitrogen—hydrogen mixtures (0.8505 N 2, 0.7501 N 2, 0.4998 N 2 and 0.2503 N 2) was measured in the temperature range 270–353 K and pressures up to 30 MPa. Measurements were carried out with a Burnett apparatus and an optical device, also termed a grating interferometer. The experimental results were used to obtain tables of compressibility factors for each mixture. The compressibility factors obtained by the two methods, the Burnett and optical experiments, are accurate to ±0.1%. For pressures below 10 MPa the accuracy of the Burnett data is estimated to be ±0.07%. The P, ϱ and T data were used to determine the second and third virial coefficients, B and C, for each mixture. Unlike interaction virial coefficients, B 12, C 112 and C, 122 were determined from the mixture virial coefficients by using the like interaction virial coefficients, B 11, B 22, C 111 and C 222, of the pure components from Jaeschke and Hinze. The deduced values of B 12 are accurate to ±0.4 cm 3 mol −1. These values agree excellently with the B 12 results determined from the P, ϱ and T data of Michels and Wassenaar.