Critical parameters for 1,1,1-trifluoroethane (R-143a)

Measurements of the vapor-liquid coexistence curve near the critical point were carried out for 1,1,1-trifluoroethane (R-143a) in the reduced temperature range of 0.97 < TTc < 1 and in the reduced density range of 0.45 < ϱϱc < 1.53. Taking into consideration of the disappearing level of the meniscus as well as the intensity of the critical opalescence, the critical temperature Tc and critical density ϱc were determined. With respect to the critical pressure Pc, we calculated the value from the new vapor-pressure equation made by ourselves in order to represent the behavior of vapor-pressures near the critical point. The critical parameters determined in this paper are Tc = 345.88 + δT K, δT = 0.00 ± 0.01 K, ϱc = 431 ± 3 kg m−3, and Pc = 3764 + 78.73δT ± 5 kPa. In addition, the critical exponent β along the coexistence curve was also discussed.