The present work classifies the experimental methods for vapor-liquid equilibria at high pressure. Specially, it focuses on the systems which contain very low concentration compounds. The apparatuses for the measurement of the solid-vapor, vapor-liquid, and liquid-liquid equilibria, developed in our laboratory, are described and the experimental data are reported.
Apparatuses and methods for measuring the dielectric constant εr and density ρ for liquids independently under high pressure are reviewed. Some experimental results and correlation equations for εr and ρ with pressure p are also given briefly. Furthermore an apparatus is described for simultaneous measurements of εr and ρ for fluids under high pressure.
Solubilities and diffusion coefficients of high-pressure gases in polymers are important in the production of polymers. This article reviews techniques to measure these properties at high pressures. The pressure decay method measures the change in the amount of a solute gas in its vapor phase with the dissolution of the gas in a polymer. This technique requires a precise measurement of pressure. The electric balance method measures the weight of a polymer sample with an electric balance installed in a high-pressure chamber. Temperatures and pressures are limited in this method. The magnetic suspension balance method is a newly developed one. An electric balance outside the high-pressure chamber and a polymer sample are connected magnetically. This method can measure the gas solubility most accurately and can be used with a wide range of temperatures and pressures. Diffusion coefficients of gases in polymers are evaluated by applying an appropriate diffusion equation to measured uptake.
The accumulation of accurate experimental data on transport properties over wide temperature and pressure ranges is in critical demand in current chemical industrial fields. Various methods for the measurement of fluid thermal conductivity and viscosity are briefly reviewed in this article. Since the principle of measurement tends to be partially broken in dilute conditions, the measurements of these properties in the gas phase become more difficult. This article summarizes the special attention which should be paid in applying a transient hot-wire method and vibrating-wire method to gaseous thermal conductivity and viscosity measurements, respectively.
In this article, we review our experimental method for the viscosity measurement of supercritical fluid mixtures. We show some key points to consider in the construction of an oscillating disk viscometer. We discuss the role of density in the course of deriving the viscosity values from the Newell theory. Other important factors observed in the viscosity measurement for saturated liquid refrigerants near the critical point and aqueous solutions dissolving CO2 were also pointed out.
We measured solubilities of several inorganic and organic compounds at high pressures up to 400 MPa, and temperatures between 273 and 323 K. For this purpose, care should be exercised for instrumentation. The results are shown for aqueous solutions of NaCl, NaCl·2H2O, CsCl, NH4Cl, toluene, anthracene, phenanthrene, and amino acids (Gly, Ala, Val, Leu, and Ile). In addition, we determined the solubility of C60 in n-hexane. The data for an individual system served to elucidate the mechanism of dissolution. For example, the data for toluene, anthracene, and phenanthrene in water provided insight into hydrophobic hydration.
The solubility characteristics of aromatic compound isomers in supercritical carbon dioxide and the microscopic structures of supercritical carbon dioxide around the aromatic compound isomers were studied using the Monte Carlo simulation with a group contribution site model. Calculated solubilities were in good agreement with experimental data and the solubilities of isomers can also be quantitatively distinguished by the model. The microscopic structures of supercritical carbon dioxide around the aromatic compound isomers were found to be different because of the screen effect of substituents. The adsorption separation of aromatic compound isomers dissolved in supercritical carbon dioxide using zeolites, a process called “supercritical phase adsorption separation”, was newly proposed and the method was found to be effective for the separation of the isomers.
Physical properties of lubricants under high pressure (e.g., density, elastic constant and viscosity) are the fundamental properties for the tribological evaluation (i.e. friction and wear) of rolling bearings, gears and traction drives. This paper introduces the importance of such physical properties of lubricants under high pressure in tribology and the application of a diamond-anvil pressure cell (DAC) for tribological measurements. A falling sphere viscometry in the DAC facilitated the viscosity measurements up to 2 GPa. A photon-correlation technique with laser light scattering in the DAC enabled the viscosity estimation of solidified glassy state lubricants (viscosity is about 109 Pa·s) from structural relaxation. Dynamic elastic moduli were obtained from Brillouin light scattering measurements in the DAC up to 4 GPa, which enabled the evaluation of the frequency dispersion of elastic moduli with quasi-static data.