Optische Bestimmung von Virialkoeffizienten der Gase C2H4, C2H6 und SF6 (Optical Determination of the Virial Coefficients of the Gases C2H4, C2H6 and SF6)

摘要

The third thermodynamic virial coefficients of C2H4, C2H6, and SF6 were determined as a function of temperature using an optical interferometric method based on the refraction index. The effects of the measuring apparatus, the pressure measurement, and the mathematical evaluation methods on the virial coefficients were determined. The pressure measurement has to be improved with respect to resolution and hysteresis. The measurement of the refraction index can be improved using a longer cuvette. The use of a faster interface-computer system for the data acquisition could significantly reduce the measuring time. The most important results are the qualitatively similar curves of the investigated gases; a maximum of the virial coefficients is found in the neighborhood of the critical temperature.