Measurements of the vapor-liquid coexistence curve and determination of the critical parameters for R114.

Abstract

the measurements of the vapor-liquid coexistence curve in the critical region for R 114 (C2CL2F4) were made by visual observation of the disappearance of the meniscus at the vapor-liquid interface within an optical cell. Twenty-three saturated densities between 410 K and critical temperature were obtained in the range of densities 290 to 894 kg/m3. The experimental errors of temperature and density were estimated within ±0.5%, respectively. On the basis of there results, the critical temperature Tc and the critical density ρc for R114 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 R114 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 low of rectilinear diameter near the critical point were also discussed.