Vapour-liquid equilibrium for the difluoromethane (R32) + n-butane (R600) system

Vapor-liquid equilibria (VLE) for the difluoromethane (R32) + n-butane (R600) system that shows liquid-phase immiscibility below 246 K were measured at (263.15, 278.15, and 293.15) K by means of a static analytical method. The (T-P-x-y) VLE data were correlated using various equations of state and various mixing rules to compare the ability of these models to correlate data for this strongly nonideal system. The correlation of the VLE data and published VLLE data shows that the system is azeotropic at temperatures higher than the upper critical end point, UCEP, (246 K), heterohomoazeotropic between (246 and 230) K, and heteroazeotropic below 230 K. A comparison with the available VLE data in the literature was performed.