Measurements of the vapor-liquid coexistence curve and the critical locus for several refrigerant mixtures

Measurements of the vapor-liquid coexistence curve in the critical region for the systems of binary refrigerant mixture, i.e., Refrigerant 22 + Refrigerant 114 and Refrigerant 13B1 + Refrigerant 114, have been made by visual observation of the meniscus at the vapor-liquid interface within an optical cell. The experimental uncertainty of the temperature, density, and mass fraction is estimated within 15 mK, 0.5%, and 0.05%, respectively. The critical locus for these mixtures has been determined taking into consideration the disappearing meniscus level and the intensity of the critical opalescence. In accordance with the previous results of the Refrigerant 12 + Refrigerant 22 system, the coexistence curve for binary refrigerant mixtures is discussed. The composition dependence of the critical parameters for refrigerant mixtures is also discussed and compared with that of several predictive methods.