Three high-pressure optical cells for phase equilibrium investigations

Abstract

The construction of three high-pressure optical cells of simple construction and large volume (30, 110 and 550 cm³) is described, the total cell content being observable in the 30 and 110 cm³ cells. In conjunction with a simple metering, stirring and heating system, the cells permit rapid and precise measurement of phase equilibria up to 200 MPa (30 cm³ cells) and 100 MPa (110 and 550 cm³ cells) and up to 350 degrees C, according to the synthetic method, without additional analytical effort. Using the 550 cm³ cell, the dew points of very sparingly volatile substances can be determined up to concentrations of 0.01 kg m^-3 with a relative error of about 0.05. The validity of the experimental technique has been tested on known systems, and excellent agreement with literature values has been obtained. The solubility of methane in cyclohexane has been measured at 37.8 and 71.1 degrees C and up to about 18 MPa.