Global thermodynamic behavior of fluid mixtures in the critical region

Abstract

In a previous publication [Z. Y. Chen, A. Abbaci, S. Tang, and J.V. Sengers, Phys. Rev. A 42, 4470 (1990)] a renormalized Landau expansion was constructed for the thermodynamic free energy of one-component fluids that incorporates the crossover from singular thermodynamic behavior at the critical point to regular behavior far away from the critical point. In the present paper the approach is extended to obtain a crossover free energy for binary fluid mixtures in the region around the vapor-liquid critical line. The thermodynamic equations thus obtained are compared with experimental equation-of-state and specific-heat data for mixtures of carbon dioxide and ethane.