Measurement of Critical Parameters for the Binary Mixture of R744 (Carbon Dioxide) + R1243zf (3,3,3-Trifluoropropene)

A new variable-volume apparatus equipped with a metal-bellows volumeter was improved by replacing the temperature bath and sensors with higher accuracy. The measurement process was also optimized. The critical parameters for the binary mixture of R744 (carbon dioxide) + R1243zf (3,3,3-trifluoropropene) were measured. The critical point was determined by visually observing the critical opalescence and disappearance of the meniscus. The expanded uncertainties of the critical temperature, critical pressure, critical density, and composition measurements were assessed to be less than 50 mK, 21 kPa, 0.006, and 0.010 (k = 2, 0.95 level of confidence), respectively. The experimental critical properties for the mixture correlated by Redlich-Kister equations were 0.18% for critical temperature, 0.74% for critical pressure, 0.82% for critical density, and 0.81% for critical molar volume.