Measurements of the Vapor-liquid Coexistence Curve and Determination of the Critical Parameters for Refrigerant 13B1

Abstract

Measurements of the vapor-liquid coexistence curve in the critical region for Refrigerant 114 (C4Cl2F4) were made by visual observation of the disappearance of a meniscus at the vapor-liquid interface within an optical cell. Twenty-three saturated densities between 410 K and the critical temperature were obtained in the density range 290 to 894 kg/m3. The experimental uncertainties of temperature and density were estimated within ±15 mK and ±0.5%, respectively. On the basis of these results, the critical temperature TC and the critical density pC for R 114 were determined to be 418.78 K and 576 kg/m3, respectively, in consideration of the disappearing meniscus level as well as the intensity of the critical opalescence. The critical pressure PC for R 114 was calculated to be 3.252 MPa by the available vapor-pressure correlation with the present value of TC. In addition, the critical exponent β and the law of the rectilinear diameter near the critical point were discussed.